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Old 02-08-2009, 08:28 AM
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terrible driveability, tuning problem

Vehicle: 88' s-10 4x4 pick-up, 31 inch tires, 3.73 gears, 700r4 overdrive tranny.

Motor; Brand new HT383 GM Performance crate motor with Weiand "stealth air strike" intake, 1 inch spacer, GM distributer "vacuum disconnected" Holley 670 Street avenger with vacuum secondary's.

GM recommends a initial timing of 10 degrees at idle. I started with that and the motor seemed pretty strong. Acted like it could use a little more advance actually.

Huge problem: Shifting into overdrive with low RPMS or trying to cruise at 60 mph, 1700 rpms. It pings really bad.

In order to eliminate the pinging I had to back the timing all the way down to 4 degrees.

Now it has zero power, absolutely shudders and shakes and bucks when I accelerate, trys to stall when shifts happen.

On the highway temp is 180-185 and in town it will climb to 195. It's 30 degrees out here.

Engine vacuum is 18 inchs maybe a little higher depending on timing and carb adjustment.

Can a carb with to small of jets cause pinging? Just a guess.

GM recommends 87 octane, which is what I got in it. And yes it is fresh.

I really need help with this. I can't drive this money pit until it's fixed.

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Old 02-08-2009, 09:10 AM
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Do you have the TV cable on the tranny set up correctly. You may need a special throttle bracket to keep the correct geometry on the cable. If not set up right you can burn up your tranny in no time.
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Old 02-08-2009, 10:01 AM
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Yes, I have the adapter on the carb. And it shifts just like a dealership vehicle. Varys according to engine speed, load, and vehicle speed. I have no complaints there. The 700r4 guy at AAMCO transmission sold me a new auto adjusting cable and showed me how to do it and we clicked it one click tighter in order to increase the pump pressure so the clutches and band would grab a little stronger to hold the extra power I'm throwing at it.
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Old 02-14-2009, 07:51 AM
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Well, I've been doing alot of tuning and tweaking and I believe I got it almost perfect now.

GM claims this motor is built to run on 87 octane. This could be true, but GM can't control the quality of 87 octane throughout this country.

I put 89 octane in it and that cured alot of my issues instantly.

My out of the box 670 street avenger was jetted perfectly for my last motor set-up. Not the case for this motor and set-up.

Stock primarys were 65's and secondary's were 68's and the power valve is a 6.5 which is rather low.

I am now running 67 primary's and 70 secondary's and the same power valve. The motor is timed at 8 degrees and runs really nice now. In town driving is fun now and at 70mph on the interstate the motor is so smooth and efficient the flowmaster 44's are quietly humming instead of drowning out a polite conversation. It shifts solid and strong with no ignition ping and will lug all the way down 50mph in overdrive "approx 1400 rpm's" and take it with no problems.

My main focus right now has been to get this truck driveable so I can break this motor in properly and thats what been happening. Something about breaking in new motors makes my eyes roll back in my head so I 've been having my fiance do it for me. She's made two 150 mile round trips on the interstate varying her speed from 60mph to 80mph in 5mph increments every 5 minutes and throwing in a little two lane black tops at slower speeds with farming towns every ten miles for variety.

Understand that I have already put 200 miles on this new motor just trying to get it to run right and within the first 100 miles of her driving to seat those rings in properly, it now idles in gear 75 rpms higher than I had it set and in park it idles 150 rpms higher than before.

With her driving in this unusual manner, she has managed 15.2 MPG both times! Facter in that this truck has a suspension lift, bodylift, 31 inch tires, bug guard, lund moonvisor, 4 wheel drive, 383 stroker motor, 300 Ibs of sand bags in the back, and its freaking cold out, I'm very impressed. She would have gotten better mileage on the second run but the temps had dropped down to 26 degrees. Just imagine what 70mph wind chill is doing to my 80w-90 gear lube in my front and rear diff's and the fluid in my transfercase.

It does not matter how you tune it, jet it, anything, this motor DOES NOT RUN GOOD with the vacuum hooked up, ported or manifold pressure.

There's alot more hidden power in this motor. With 70 primary jets, it would make a NASTY Saturday night special. The power and acceleration is insane but it loads up bad at stoplights and at speed on the highway.

But for now, no more tuning until the motor is fully broke in and it's warmer out.
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Old 02-14-2009, 01:25 PM
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Quote:
Originally Posted by klr650
Vehicle: 88' s-10 4x4 pick-up, 31 inch tires, 3.73 gears, 700r4 overdrive tranny.

Motor; Brand new HT383 GM Performance crate motor with Weiand "stealth air strike" intake, 1 inch spacer, GM distributer "vacuum disconnected" Holley 670 Street avenger with vacuum secondary's.

GM recommends a initial timing of 10 degrees at idle. I started with that and the motor seemed pretty strong. Acted like it could use a little more advance actually.

Huge problem: Shifting into overdrive with low RPMS or trying to cruise at 60 mph, 1700 rpms. It pings really bad.

In order to eliminate the pinging I had to back the timing all the way down to 4 degrees.

Now it has zero power, absolutely shudders and shakes and bucks when I accelerate, trys to stall when shifts happen.

On the highway temp is 180-185 and in town it will climb to 195. It's 30 degrees out here.

Engine vacuum is 18 inchs maybe a little higher depending on timing and carb adjustment.

Can a carb with to small of jets cause pinging? Just a guess.

GM recommends 87 octane, which is what I got in it. And yes it is fresh.

I really need help with this. I can't drive this money pit until it's fixed.
This is a common problem with Vortec headed engines in vehicles using a carb and an overdrive transmission. The engine revs get pretty low and the mixture flow in the intake is insufficient to keep even cylinder to cylinder ratios. With the OEM L-31 port injection, this isn't a problem since there is no dependency on air flow in the manifold to keep the cylinder to cylinder mixture distribution consistent. But with a carb or Throttle Body Injection, this gets to be a big issue.

The least expensive solution is to up the octane. This will let you lean out the carb, push up the advance and still cruise in OD all of which will significantly improve fuel mileage without the engine trying to blow the heads off. You'll probably want to restore the vacuum advance as well.

Actually, the Swirl Port heads are a lot better in a set up like yours where the cruise revs are pretty low and induction is either a carb or TBI. Hot rodders tend to overlook them because they run out of breath over 4000 RPM. But if you're looking for good street manners and good mileage in the 2000-3000 RPM range in an OD gear, they make a lot of sense as they deliver better mixture ratios and higher swirl at low revs than the Vortecs do, which translates into more mid range torque which is right where you need it in this situation.

Bogie
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Old 02-14-2009, 06:45 PM
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I'm starting to think that I've fallen for more marketing schemes and outright lies. This motor has been raved about by several performance magazines as being the motor that is extremely easy to set up for 87 octane and used for any type of daily driver purpose. It's claimed to be perfect for any and all types of towing purposes in overdrive with having enough extra torque to rip up that next hill pulling a trailer without needing to downshift.

I won't dwell on that though. I do like this motor quite a bit now that it's starting to run really good.

Your comment about blowing the heads off has me concerned. This is absolutley the last thing I would want to happen.

Could you explain with more detail what I should be looking for, listening for, concentrating on, etc......

I'm still having bad memories of the last motor that was in this truck. It ran completely perfect and never had any tuning issues "after I started running 92 octane" or cooling problems and it ended up blowing oil out the tops of the valve covers the whole short time it lived and blew a head gasket at 6000 miles.

Blowing the heads off sounds far to familiar to me.
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Old 02-14-2009, 07:22 PM
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Quote:
Originally Posted by klr650
I'm starting to think that I've fallen for more marketing schemes and outright lies. This motor has been raved about by several performance magazines as being the motor that is extremely easy to set up for 87 octane and used for any type of daily driver purpose. It's claimed to be perfect for any and all types of towing purposes in overdrive with having enough extra torque to rip up that next hill pulling a trailer without needing to downshift.

I won't dwell on that though. I do like this motor quite a bit now that it's starting to run really good.

Your comment about blowing the heads off has me concerned. This is absolutley the last thing I would want to happen.

Could you explain with more detail what I should be looking for, listening for, concentrating on, etc......

I'm still having bad memories of the last motor that was in this truck. It ran completely perfect and never had any tuning issues "after I started running 92 octane" or cooling problems and it ended up blowing oil out the tops of the valve covers the whole short time it lived and blew a head gasket at 6000 miles.

Blowing the heads off sounds far to familiar to me.
I was referring somewhat tongue and cheek to detonation which in reality is more likely to take a piston.

When towing the transmission shouldn't be in OD nor the torque converter locked up. It puts too much load on the engine (an example of lugging) for the RPMs it's turning. In this situation, the burn time is too slow for the revolutions which results in a tendency to detonate and the moment on the crank journal becomes too high which blows the oil wedge out of the bearing.

Bogie
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Old 02-14-2009, 08:14 PM
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Quote:
Originally Posted by oldbogie
I was referring somewhat tongue and cheek to detonation which in reality is more likely to take a piston.

When towing the transmission shouldn't be in OD nor the torque converter locked up. It puts too much load on the engine (an example of lugging) for the RPMs it's turning. In this situation, the burn time is too slow for the revolutions which results in a tendency to detonate and the moment on the crank journal becomes too high which blows the oil wedge out of the bearing.

Bogie
Okay??!! Does 87, 89, or 91 octane have different or the same burn rates? Assuming the motor's state of tune is the constant. Lugging the motor with 87 octane creates pinging, "which is a form of detonation". Lugging with 91 octane could be detonating but I just can't hear it. Surely the crank journal would be subjected to similar high pressures.

Lugging creates higher cylinder temps than norm, I think or am I wrong. Diesel motors rely on high cylinder temps to ignite the fuel, which is a form of deliberate detonation and I have had the opportunity to run some very nice diesel powered trackhoes that at speed ran silky smooth and quiet. These motors truly hummed with no noise whatsoever.

Another thought thats bouncing in my head is that I can increase my jet size to eliminate pinging but if burn time is always the same then the extra fuel must be cooling the cylinders charge but detonation "ping" is still lurking. Possibly still having excessively high of cylinder pressures without the telltale "ping" talking to me.

NOT trying to argue. I find this a very interesting topic and just trying to understand it all. Technically setting my timing at 8 degrees before top dead center is a form of detonation. Yes I do understand that the flame front is relative and that is why timing must change to meet the rpm requirements.
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Old 02-14-2009, 09:38 PM
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what total timing/

whats your total and also what ignition system are you running?plugs wires and gap.that motor should have gobbs of torque.
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Old 02-15-2009, 10:24 AM
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Thank you F-BIRD'88. I've been waiting several days now for your input. Glad to hear from you. Obviously you remember me and my earlier situation.

I would like to clear this current situation up so we could make some headway.

When we talked last you firmly told me the L-31 heads would much better meet my needs than iron eagles and that If I couldn't find a reputable builder than I should consider a crate motor.

I took your advice to heart and did exactly that. I bought a GM Performance crate motor. It's the HT383. In case your not familiar with this motor, It is a L-31 headed stroker with 9.1 compression that you recommended. Smaller roller cam with almost the exact lift and duration that you suggested. In fact the whole motor set up seemed to have been tailer made with you in mind.

1. this is a GM built CARBURATOR crate motor that they built to run on 87 octane to be used for towing purposes and all daily driver uses.

2. I am using the GM required distributor for this motor that doesn't give full advance until 4000 rpms

3. GM's stated timing for this motor is 10 degrees at 650 rpms with full advance of 32 degrees at 4000 rpms. Repeated several times in the manual and instruction sheet that came with this motor, "DO NOT ATTACH OR USE THE VACUUM ADVANCE AT ANY TIME, THIS MOTOR IS TUNED AND TESTED TO USE THE ABOVE STATED DISTRIBUTOR WITH TIMING CURVE TAILERED FOR THIS MOTOR".

4. I have it at 7 and 29 respectively. I'm not trying to blow it up

5. I use two timing lights. different manufactures.One adjustable,one fixed,both are accurate with each other.

6. I am not allowing it to ping or driving it while pinging. My timing lights and wrench are on the seat next to me when I leave the driveway. Doesn't a person Have to test drive to find out if a tuning change has worked or not?

7. I'm not towing with it, just pointing out GM's huge claims of the torque monster this motor is. It should be able to haul my 4000Ib truck around with out struggling. On one dyno claim this motor is cranking 300ftIb at 1500rpm. If any small block chevy can knock out 300ftIb at 1500rpms, its not struggling.

8. As you well know, Holley factory jets their carbs with the secondary's being 5 to 8 sizes bigger than the primary's and popular opinion 7-8 sizes is perfect. Did you know that ALL the 670 and 770 series are ALL jetted and calibrated with a 3 size difference. WHY? WHY? WHY?

9. I can try 68's. It could run on them. I know it won't take 69's. 70's were drowning it bad.

10. My carb and spacer gaskets are not leaking and the intake is not leaking on the outside but, I Don't know how to check for a internal leak.

11. I am 100% positive that I don't have a vacuum device or line leak.

12. I am running the recommended AC plugs with recommended gap.

13. MSD 8.5 super conductor wires.

14. The recommended PCV by GM. It's chattering away like a machine gun.

15. currently tuned with idle 850rpms vacuum is 20 when the dual electric fans kick in, "THEY SUCK A TON OF JUICE" the vacuum drops to 19.

16. When I talk mileage "are we on the same page?"? Sure getting decent mileage is a concern and it is a goal to have a efficient vehicle. I plan on switching the whole drivetrain to synthetc. BUT, most importantly, when I talk mileage I am attempting to use mileage as another tool to use to tune the motor. If the motor is struggling, mileage will suffer. If the motor is strong and happy the mileage will be as good as it's gonna get. Follow me?

17. Maybe your right about my intake. I do know that several independant intake dyno comparo's have been done and that the results are the same. the Airstrike when tested on a L-31 headed motor has slightly better air distribution and stronger torque earlier in the rpm's in comparison to the RPM airgap. The RPM airgap out edges the Airstrike on any other motor configuration but for some reason the Airstrike likes L-31 heads. With or without spacer, results are the same. As you said before L-31's run out of breath quickly, and the Airstrike is supposed to be more tailered to the L-31's rpm range.

Your absolutely right. 100%. It is up to me to tune this motor properly and If I am driving around with my head up my *** allowing it to ping and rattle, then I deserve a busted motor. If I was ignoring all the recommendations on what fuel to use and what timing to use by the very people who developed this motor, than I deserve a busted motor. This motor was thrashed on by Hot Rod, Super Chevy and many others using a rpm intake and my distributor on 87 octane with excellent reviews. So what the heck is going on.

I don't care one bit about the price of fuel. What I do care about is that this motor is supposed to run excellent on 87 and it won't. When I first fired the motor up, I still had 91 in the tank for the last motor and it ran awesome until it got a taste of 87. 89 octane and a jet change helped some, not enough.

What would be your thoughts if you bought a 91 octane motor that wouldn't run unless you had 104 race gas in it?

YOU are the "pro with a clue"!! My advisers say screw GM's recommendations and hook up the advance, crank the timing to 36 degrees at 3000rpms and keep throwing bigger jets at it until it runs right. Can you imagine what my timing would be at idle? I"m guessing 16-18. yeah that'll work reeaall good.
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Old 02-15-2009, 01:31 PM
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Not to butt in here but I always thought higher octane burned slower and thats how it stopped or lessened detonation. But thinking about it now, it must just take a higher temperature to ignite? Is that right?
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Old 02-15-2009, 02:42 PM
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i know it's frustrating when an engine isn't running right, add to that a few very knowledgeable people that don't totally agree on everything, and all of a sudden, we let our emotions take control of what we really are seeking, good advice. i think we can all agree we are here to help, not hurt. my opinion, is that most of your problems, if not all, lie in your distributor timing. i would consider contacting performance distributors 901-396-5782, trying a different distributor. f-bird seems to know alot.
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Old 02-15-2009, 04:34 PM
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Quote:
Originally Posted by klr650
Okay??!! Does 87, 89, or 91 octane have different or the same burn rates? Assuming the motor's state of tune is the constant. Lugging the motor with 87 octane creates pinging, "which is a form of detonation". Lugging with 91 octane could be detonating but I just can't hear it. Surely the crank journal would be subjected to similar high pressures.

Lugging creates higher cylinder temps than norm, I think or am I wrong. Diesel motors rely on high cylinder temps to ignite the fuel, which is a form of deliberate detonation and I have had the opportunity to run some very nice diesel powered trackhoes that at speed ran silky smooth and quiet. These motors truly hummed with no noise whatsoever.

Another thought thats bouncing in my head is that I can increase my jet size to eliminate pinging but if burn time is always the same then the extra fuel must be cooling the cylinders charge but detonation "ping" is still lurking. Possibly still having excessively high of cylinder pressures without the telltale "ping" talking to me.

NOT trying to argue. I find this a very interesting topic and just trying to understand it all. Technically setting my timing at 8 degrees before top dead center is a form of detonation. Yes I do understand that the flame front is relative and that is why timing must change to meet the rpm requirements.
Octane rating in gasoline and cetane rating in diesel is used to demonstrate the fuel's resistance to spontaneous combustion. In both cases you want the burn to be controlled. For a gas fueled engine you want the fuel's ignition point to be controlled by the spark plug not just starting to catch fire because the compression heat is enough to set it off, this is a form of preignition. A diesel has the same issue except there's a certain optimum point in the compression cycle that causes the fuel to catch fire. Like a gas engine, it's undesirable to have that happen too early. Preignition is mostly associated with extreme temperature rises, it tends to melt pistons and spark plugs. There is a significant pressure rise but it's nothing to the extreme of detonation.

Detonation occurs in the post ignition time frame where the fuel, gas or diesel, has insufficient resistance to spontaneous combustion from the burn's normal temperature and pressure rise. In this case an explosion of the unburnt mixture occurs ahead of the normal flame front. It features extremely high pressure gains which blows holes in the piston, blows spark plugs apart, and in diesels damages the injector. The loads transfered into the connecting rod are so high that they are associated with bearing and journal failures of the rod and crank because the oil wedge is blown out of the clearance allowing metal to metal contact.

Detonation is often associated with preignition, one tends to feed off the other, but when viewing the damage the predominance of events will be shown by the high temperature damage of preignition where the edge of the piston crown is melted down the side thru the ring pack. The spark plug will be coated with aluminum from the piston if its electrodes and insulator haven't been melted away. The upper combustion chamber may also be splattered with aluminum from the piston and the valves may be burnt as well. Detonation will usually be a chunk out of the piston crown, usually toward the center rather than down the side, the edges will be abrupt not melted. The spark plugs innards may be blasted apart. Damage at the crank if that happens will be hard to tell from any other failure of the oil film, but is sometimes evidenced in low mileage engines as a flat spot pounded into the journal close to the TDC position. It's possible to see some degree of both failures when preignition and detonation are both present.

High octane fuels do test with a bit more density than lower octane fuels whether leaded or unleaded. The burn rates for higher octane fuels are probably somewhat slower but this isn't the major effect in reducing detonation tendency. That's mostly a greater resistance by the higher octane fuels to flash-over from pressure nad temperature increases.

It is possible to build some mechanical octane into the combustion chamber shape. High turbulence chambers are less prone to uncontrolled burn. To that end was my recommendation of a slow turning carbed engine with Swirl Port rather than Vortec heads where low to mid RPM performance takes priority over high RPM performance. Another significant trick is maximizing squish and quench. This is a place where the factory lets us down. The Vortec head has an excellent squish/quench deck (that area opposite the spark plug and valve pocket) but the piston they use has a circular relief for compression control. This reduces the flat area of the piston that can close to the head's squish/quench deck significantly reducing the effect of both functions. The squish function happens first as the piston closes upon TDC such that the mixture on the far side is ejected toward the plug. This is one last stir of the fuel and air molecules and pushes a high density of mixture into the spark plug reducing miss fires and increasing burn speed (i.e. Fastburn heads of which the Vortec is one). Once the burn is started pressure and temperature increase, the quench function comes next, where the piston crown and head squish/quench deck are in close proximity to each other, it provides a place where there is a lot of surface area to volume. As the hot flame front reaches this area it's cooled below a point where the mixture will spontaneously ignite. To the end of optimizing the squish/quench feature closing the piston crown to the deck around .040 to .050 inch is ideal. With the piston .025 in the hole and with .025 thick head gasket, you're already on the upper limit of effectiveness. Then take away 1/2 or more of the area with a round dish in the piston that then adds another .030 inch or more distance to the dish's floor, the needed effects are mostly lost with this configuration. A flat top piston or a D dish piston greatly extends the area that comes into close proximity. A D shaped dish is used to establish overall compression ratio because as good as squish/quench is, in the end the fuel is only capable of so much compression. So idealize the configuration around maximizing squish/quench and holding a livable overall compression ratio. The D dish is the best choice with a tight chamber head, where a larger 76cc head may let you get away with a flat top or at least a shallow D dish. The down side of large chamber heads is they tend to move the spark plug away from the middle of the chamber, this makes a longer burn path which takes more time and starts running down the road that leads to a detonation prone chamber. If you look at engines running the pro NASCAR circuit you will find very tight chambers, often less than 50 ccs. The valves are in a tight pocket (so much for the theory of shrouding) the squish/quench is pushed right to the edge of the valve and the spark plug is shoved as much into the center of the chamber as can be done given the need to clear the valves.

Running a rich mixture does two things, the excess fuel does provide a cooling function and it does slow the burn rate which is help full in resisting detonation. Water/alcohol injection can be used to provide a similar benefit for the different reason that it absorbs a lot of heat for a state change and slows the burn as the flame front has to pass thru stuff that either doesn't burn in the case of water or burns at a lower temperature as in alcohols.

Backing the advance down lowers the peak temperatures thus the pressures as the piston is near TDC reducing the detonation tendancy, but the late burn throws energy out the exhaust which reduces power on the crank and runs the exhaust valves excessively hot.

Lugging is term used to define a situation where the load on the engine is too high for the engine speed. Its a corner of the envelop where for the RPMs there is too much throttle opening which reduces manifold vacuum and advance. Advance gets to be a double whammy in that as the manifold vacuum falls the vacuum advance reduces or eliminates advance from the distributor, while at the same time the engine RPMs are too low for the centrifugal advance to be coming in. The engine ends up being heavily loaded while operating with insufficient ignition lead and probably a leaned out mixture ratio. These days with high ratio rear ends and overdrive transmissions, one can easily get into a situation where the engine is turning to slowly for the load on it. Modern EFI systems can deal with this because they are not dependent on carburetor signal for fuel metering, they are not dependent upon mixture velocity in the ports and manifold to evenly distribute the mixture to each cylinder, they don't need manifold heat to force liquid fuel into its gaseous state. So when you start mixing components such as EFI cylinder heads on a carbed engine, with slow turning gearing, and analog spark timing, it gets easy for problems to develop.

Bogie
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Old 02-17-2009, 03:09 PM
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oldbogie

I sincerely thank you for your time to write in detail what I needed to know. I have read it several times now and really like it. Things are making sense now.

Thank you again.
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Old 02-17-2009, 06:47 PM
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Well, the truck's been parked for two days and I pulled the plugs. What I found is NOT what I expected. #1 plug dry with a little bit of tan on one side of the porceline. #2 dry and looked like I just put it in. All of the rest dark golden ground strap, white porceline, and gas/oil damp. Not soaked and gassy but definately has a residue with #7 and #8 being the worst. Mixture screws are 1 and half out. Maybe to far.

This with #67 jets and the #70's had drowned it like niagra falls within 4 miles and 7 degrees timing. I cleaned the carb and put a complete kit in it when I put the #67's in. After the bad flooding problem.

I put the plugs back in, upped the jets to #68, rechecked float level, idle mixture screws 1 and 3/8 turns out "1/8th turn past affecting motor", advanced the timing to 10 degrees at 650rpms, syphoned the 89 octane out and put 91 octane in. Best I can get in this area.

As it was getting late last night I only drove it for about 20 minutes. In the short time I did drive it, it didn't try to load up at a light and wasn't loading up at speed. Outstanding throttle response and the power level of the motor has skyrocketed. Since I am focusing on primary tuning I am staying out of the secondarys when driving.

Haven't started it today. Tommorow I'll pull a couple plugs. Is 20 minutes enough time to put some color on those plugs. After feeling the huge increase in the motor I think I'd like to see what #69's will do.

I do have some confusion going on. My 406 was bigger than this 383, it had more cam, and the eagle heads are less efficant than the L-31's and used alot less jet. Shouldn't the 383 use less jet than the 406? I don't have "some confusion" I have "alot" of confusion. I just can't believe there is this much of a difference in jetting between the two motors.

A new problem is developing now. I use a non-adjustable vacuum switch to control torque converter lock-up and un-lock. Purely by accident that switch worked perfectly with the 406. Now that the 383 is starting to run right, it has to much vacuum. A gentle prod used to unlock it at 50mph, now I have to stomp on it. A gentle prod won't even unlock it at 40mph. I'll need to fix this right away. Locked up at 40mph, lugging is a understatement, it's almost idling. On the positive side, it still waits till 60mph with part throttle to lock up.

To be perfectly honest I have never given the EGR a single thought. I never realized it could lower temps too. Again your right. I have the manifold that came with the motor and it has EGR provisions. This added with oldbogies input explains somemore of my tuning issues.

I really like airgap design and shudder at the thought of going back. I'll see what happens tommorow.
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