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blown69stang 03-03-2003 07:25 AM

I'm going to make a bonfire out of my car
I have had it!! I have spent $1500 trying to figure out why my car runs like ****!! I recently rebuilt my engine (5000 miles and by a professional race shop) and it won't run good. For about 2000 miles, it ran like a beast-400 horsepower- but now it barely runs when it is cold-sounds and feels like it only has 2 cylinders- and won't go faster than about 20 mph for a mile unless the car has been heating up for 10 minutes. I started with a 600cfm Holley and stock dist after the rebuild; I now have a new MSD ProBillet RTR distributor and 650cfm Speed Demon carb. The fuel pump is a Holley 70+ gph mechanical and the gauge has been showing 7 psi when cold and it drops to below 2 psi when hot. This is the second gauge on the distribution block for the fuel supply and both have been broken. I ordered another one to see if it is the fuel pump but it is fairly new. I can't figue it out and I'm come to two conclusions: 1) I'm going to drive the car off a cliff, or 2) I'm going to light it on fire and have a barbeque! Please help anyone. I know my name makes it look like it is blown but it is not yet. I have plans for it once I can get it running correctly. :mad: :mad: :mad: :mad: :mad:

DoubleVision 03-03-2003 09:17 AM

take it easy man, and take you a breather for a few days, or months like i did on my car. First off, I`d make sure it`s not vapor locking when hot, make sure the fuel line is not close to nothing hot. Second off, check the fuel pressure very carefully, if it is excessive, it`ll be dumping fuel or just dripping out of the boosters at idle and unless you look closely, you won`t even notice, that`s what my car was doing. third off, i`d throw the holley pump away and get something else, Holley products have a sorry rep for there quality control, i`m not knocking them, but after I sent 2 fuel pressure regulators back before I got one that worked and countless other items, I won`t use anymore of there products. If your carb has no choke, it`s gonna run like crap when it`s cold, my Demon has no choke, and my car has to warm up real good before it`ll run right. also, with you being in Okie, and it`s winter, the moisture in the air can freeze on the butterflies and cause flooding due to blockage of the passages, and if you have the heat riser passages blocked off there`s no heat to combat the problem, so use some fuel antifreeze that you can get at any parts store. hope some of this helps you. good luck and don`t give up.

tm454 03-03-2003 11:34 AM

I agree with DoubleVision, I'd look into the choke if you have one hooked up. The Holley carb is great on the track but I run Edelbrock on the street. I have no experience with the Speed demon, I hope that is not your problem as I was planning on running one when my funds were right. When I get P.O.'d at a project or one of my rides I park it and come back later when my heads clear and I'm not flustered with it. My truck once sat for 3 months before I could work on it again and fix it.

Todd :cool:

Rat Rods Rule!

blown69stang 03-03-2003 03:07 PM

Thanks guys. I was really pissed off today when I got out and I couldn't accelerate past 20mph. When I got done with my 9:30, I came here. I have spent 10 months and $1500 trying to figure out what is going on and I'm about to break. I would put my car off for a little while except I sold my daily driver so I have had to drive the classic for a while. The problems have been happening even before the weather got cold but it got worse with the temp. drop. The speed demon has a choke on it that works well. We have watched it open up while running while it was sitting in the shop. After I posted this morning, I got on Summit and ordered a new fuel gauge and am going to try that. If I have to replace/fix the pump, I am thinking of switching it to an electric. Any brand suggestions? I was thinking about the Holley electrics but also thinking about Aeromotive. I have 8AN line running from pump to carb and would probably run 10An from tank to dist block if I go with the electric. My budget is starting to run dry with all these problems and I had planned on having some interior restoration but can't afford it now, so you can appreciate my anger hopefully. I also am a little upset that three different garages have done work on it and none can figure out what is happening. I have come to the conclusion that Oklahoma mechanics aren't even smart enough to tighten a nut on a bolt. I wish I had the money to have the complete car done by some of the custom shops in Florida or California but I don't and have to do it piece by piece and that hasn't turned out to well. Thanks for the help.

MopaRV 03-03-2003 03:50 PM

Let me know when the barbeque is, so I can add my 440 to the fire. Never mind, my Dodge probably couldn't even do THAT right. Don't feel too bad about those Okie mechanics. Las Vegas mechanics wouldn't even know what a bolt IS.

fireschenie 03-03-2003 07:30 PM

Don't forget marshmellows to make some smores. Those things are really good. Just take it easy. Everything will be fine.

mustang66maniac 03-03-2003 08:17 PM

i would try a new fuel pump..if its readin 2 psi, i dont see how an engine could run good like that. Plus, a buddy of mine had problems with his high volume holley pump too. If you get an electric pump, youll have to mount if close to the tank, they are much better at pushing than pulling. You'll also need a fuel pressure regulator to keep a cap on things cuz they dont regulate themselves like mechanical pumps. Have you tried a leakdown test or compression test? Or checked the vacuum?

[ March 03, 2003: Message edited by: mustang66maniac ]</p>

blown69stang 03-03-2003 08:32 PM

The last garage said that vacuum was good but how do I really know? I am sick and tired of paying guys $200-400 for them to tell me it is good and two weeks later it does the same thing. I'm going to try the fuel pump but after that I may just give up. Short of pulling this one and sticking another in, I don't know what else to do. I have thought of one other thing besides Air/Fuel (carb) and ignition- cam. If the cam is not "timed" to the crank, I have a feeling it might cause some of this. I have had the ignition everywhere from 8 to 16 degrees with only slight difference. They have changed the jets in the carb both ways and helped only moderately. The vacuum secondaries springs should have been played with at one of the garages. Every Adjustment has been tried on the carb. The distributor has been recurved. I wish I still had my 302 in it. Even with 80,000 miles it still ran better than this new engine. I am just plain tired. I've been beaten down by this problem for 10 months and have about given up.
After 8+ times in the shop, I've decided there may not be any hope for this engine. I went out and bought a nice rack of ribs and will probably go get some brisket to do on the hood. I'm thinking beans would be good and while I'm letting all that smoke, I'll fix some cole slaw and potato salad. I figure if this car is going out, I might as well do it right.

cuda66 03-03-2003 08:40 PM

well I would leave the beans out!!! You could slip one out and the whole place could blow!!! I have been in the same boat. I had a friend of mine tell me that the fun begind when the engine is in and the tuning starts!!!! I always had a fairy tale dram that iw works like it does on the tv at the two guys garage!!! litle to my dismay I was wrong!!! The best wat is to check all you readings with a vacum gage. but what kind of cam are you running does it have a large overlap? Is your dist new used? Is your timing set new or used? are you running adjustable rockers? If so have you checked your valve lash? these can all play factors in what you are describing? Joel

blown69stang 03-03-2003 09:05 PM

The engine was built pretty basic. New Distributor (now, before was old stock part), new parts throughout the engine. The rockers are solid aluminum style. The heads are ported stock heads. Timing set is new, cam is warmer than stock but not radical at all. It was built for about 350-360 horses but surprisingly we got very close to 400. The pistons are 10:1 hypereutic(? spelling) new pushrods, new tappets, new everything. It has a Victor Jr. intake, MSD RTR Pro Billet Distributor at 13 degrees initial with about 35 degrees total mechanical and 45 total with vacuum advance. There is not even a hint of detonation with pump gas. This engine was a beast for 2000 miles; it accelerated from idle without any lag and it had power up to 6000 rpm. I have only put accelerator to the floor about 4 times and not even abruptly, kind of worked up to WOT. I have practically babied this car with the exception of proving imports suck 4 times. I was hoping to add a supercharger or nitrous so I could race this summer but that won't happen unless I can even get it to run naturally!

KULTULZ 03-04-2003 02:55 AM

I would check the fuel pressure with a quality mechanical gauge, the best being a low pressure GM TBI gauge (0-15lbs) plumbed in at the fuel block and taped to the windshield during road test. If the pressure does drop, you need to find the cause, whether a bad pump, vapor lock as mentioned or the system drawing air before the pump (dried out rubber fuel line section).

It may be something as simple as sediment in the tank blocking the pickup filter after running awhile. Where is your inline filter?

[ March 04, 2003: Message edited by: KULTULZ ]</p>

dhaza 03-04-2003 07:12 AM

I have never work on a demon carb but on the Corvette Forums they were having all kinds of problems with Demon carbs. Not because there was anything wrong with the carb they are just different requirements during setup. I copy and pasted the instructions below....

This tech paper will discuss basic set-up of the Barry Grant Speed Demon carbs to establish an initial starting point for a good-running carb.

The BG carbs are similar to the Holley carbs in their layout and design. The BG carbs have some refinements that make them easily tunable for most street applications, providing this tuning is done correctly and in the right sequence. BG carbs come factory-set so that they will run well right out of the box, but I have found that the setup can be refined and tweaked a little to optimize the carb a little better. It is also important that the tuner/owner understand these tuning processes when re-adjusting idle speeds and idle mixtures so as not to get the carb settings really messed up.

This paper will only discuss basic initial setup. For tuning and tweaking, check out my paper on How to Tune a Holley – the tuning processes for the BG are very similar once the initial setup described here has been completed.

Tech Tip #1
BG carbs use mostly the same gaskets as a Holley. However, the throttle plate gasket (the gasket between the bottom throttle plate and the upper body of the carb) on a BG has 4 idle fuel transfer holes that are not in the same location as the Holley. If you use a Holley gasket, you will not get any fuel flow through the idle metering circuit on the BG, and the idle mixture screws will not work. You can use the Holley gasket, but you need to slot the idle fuel transfer holes in the gasket to match the holes in the BG carb.

Tools and Equipment Required
As a minimum, you will need the following tools:

1. Vacuum Gauge
2. Small cup to drain fuel into
3. Screwdrivers
4. Box end wrenches
5. Spark plug removal tools
6. Rags

Here is my recommended sequence and procedure for doing a basic BG set-up:

1. Bench-Set the Idle Speed & Idle Mixture.
The BG Speed Demon carbs have 4-corner idle metering. This means that they meter idle fuel and idle air through all 4 of the throttles – primary and secondary. For this system to work properly, it is absolutely critical that all 4 of the throttle blades ALWAYS be set at the same setting (NEVER set idle speed by only adjusting the primary idle speed screw), and all 4 of the idle mixture screws should be set to the same metering setting. This will assure that the carb is balanced and working right from the beginning. Once you get the engine up and running well, a slight difference in mixture screws between the primary and secondary side may be required, but start by balancing everything out as follows:

Before installing the carb to the engine (if you have installed it, yank it off), turn the carb upside-down on your workbench. If you look at the throttle bores just below the edge of the throttle plates (“butterflies”), you will see a vertical slot. Open the throttles a little to see the whole slot. This slot is called the “transfer slot,” and it provides a fuel discharge transition circuit between the idle circuit (which discharges fuel out of the round idle discharge holes below the throttle plates) and the main metering circuit (which discharges fuel out of the main discharge nozzles once airflow through the venturies is high enough to pull the fuel through the nozzles). The transition slot receives its fuel from the idle metering supply circuit.

With the throttles fully closed against their idle stop screws (not on the fast idle cam), noting that the secondaries and primaries both have separate idle stop screws, there should be exactly .020” of the transition slot exposed below the throttle plates. Use a .020” feeler gauge to measure this: Place the feeler gauge on the throttle plate up against the transition slot and adjust the idle speed screw so that the slot JUST BARELY disappears behind the feeler gauge. At .020” slot exposure, the slot will appear to be a perfectly square hole. Adjust the primary and the secondary idle speed screws so that both of the throttle shafts are at this same position.

Once the primary and secondary throttles have been set to this initial idle speed setting (which should make your car idle very close to the correct idle rpm range), it is your job as a tuner to assure that any further idle speed changes occur by adjusting both of the screws equally from this point on. Never adjust the idle speed by only adjusting the primary screw: if you adjust the primary idle speed by ¼ turn, you MUST adjust the secondary idle speed screw ¼ turn as well. Keep the two throttles adjusted the same.

Now, turn all 4 of the idle mixture screws all the way IN until they LIGHTLY seat, and then back them all out ¾ turn.

2. On-Engine Settings.
You can now bolt the carb onto the engine and hook up your fuel and choke (if you’re running a choke). If you have a choke, make sure you hook up the wire to a switched 12-volt source. Note that the “hot” wire going to the “+” side of the coil is not 12 volts due to the resistor wire in the ignition circuit, so don’t use the coil wire for your choke. BG chokes tend to be set very rich from the factory, so you might want to loosen the 3 choke cover screws and rotate the black choke housing cover so that the choke plate begins to open – in its factory setting, it is tightly closed. Note that the BG carbs do not have in-carb fuel filters like a Q-Jet, so you MUST run an in-line filter between your fuel pump and the carb (don’t install filters on the suction side of the fuel pump).

Start the engine and allow it to warm up. If you have a choke, you can adjust the fast idle screw to your preference at this time. If you do not have a choke, you can turn BOTH idle speed screws in the same amount (usually about ½ turn-or-so) to keep the engine running during this warm-up period. NOTE how much you turn them both in. While the engine is warming up, you can check and verify your float levels: There are 3 lines on the bowl sight glasses: for a street car, set the primary and the secondary float levels to the lower line. The float levels are set by loosening and adjusting the float adjusters on the tops of the float bowls. If your float levels need to be lowered, do this slowly, as the fuel in the bowl will only drop as fast as the engine is using the fuel at idle speed.

As the engine warms up, make sure the choke is opening, and get the engine off fast idle. Once the engine is up to normal operating temperature, start playing with your idle speed screws: Adjust both of the screws equally to obtain the slowest practical idle. This should be very close to your bench setting. If the 2 screws need to be turned IN more than a full turn from the bench setting, you need to consider installing idle bleed restrictors as outlined in the BG documentation that came with your carb, since cranking the idle speed screws IN too far will make you engine idle on the transition circuit instead of on the idle circuit. Once a low idle speed has been obtained, you are running on the idle circuit. You can now adjust idle mixtures.

If desired, you can now hook up a vacuum gauge to use as a tuning aid. Using a small screwdriver, turn one of the primary mixture screws IN ¼ turn and observe the reaction of the engine. Turn the screw back out to its original setting, and then turn it OUT ¼ turn. Observe the engine response. This test will tell you if you need to go IN or OUT from the original setting. Once this has been determined, go back to the original setting, and turn ALL of the screws 1/8 turn at a time in the direction needed until best idle is obtained. While doing this, the idle speed may need to be lowered/adjusted to keep the car at a slow idle. Be sure to adjust both idle speed screws the same. Once the optimum idle mixture has been obtained in this fashion, go back and set up your idle speed to the final rpm desired using both screws equally.

With the engine now good and hot, re-check your float levels (making sure the car is on a level surface). Float levels will change slightly as the engine/carb/fuel heats up. If the levels seem a little high, you can slowly discharge some fuel out of the bowls by actuating the accelerator pump lever(s). If the level remains the same, you need to lower the float slightly.

This completes the initial setup of your BG carb. You should now have a very good idle, and off-idle throttle response should be crisp and instant.

3. Accelerator Pump Arm.
To assure proper operation of the accelerator pump, make sure that the pump arm is properly set up against the pump arm screw (spring loaded screw on the lever). With the engine OFF, verify that there is no gap at all between the end of the screw and the pump lever – it should have a little bit of “pre-load.” Verify that the SLIGHTEST movement of the throttle produces an instant discharge of fuel out of the discharge nozzles. Now, open the throttle fully and verify that there is still a little bit of travel left in the pump arm (make sure it’s not bottomed out and jammed solid).

4. Throttle Cable Check.
Before you go for a drive, make sure you have full throttle travel, and make sure you have a positive throttle stop. One of the most common performance problems I see are carbs that do not go to Wide Open Throttle (WOT) due to improperly adjusted linkage. Also make sure that your throttle linkage does not restrict the carb from a full return to idle speed. Make sure you have a throttle return spring attached (don’t rely on the carb throttle shaft spring to do the work for you). Now, with a helper in the car, observe the throttle shaft lever as the helper slowly presses the gas pedal to the floor. Verify that the throttle opens fully. Verify also that the gas pedal hits the floor or a fabricated pedal stop just as the throttle hits its wide open point. If you rely on the carb to stop your gas pedal, you will bend and destroy your carb – your leg has more power in it than the sheet metal lever on your carb. You may need to swap throttle cable attach points on the carb throttle level, and you may need to play with your throttle linkage geometry to make this al work right, but it’s imperative to check and correct as required.

5. Secondary Opening Rate (Vacuum Secondaries).
If you’re running a vacuum secondary BG, you can gain some performance by playing a little with the secondary diaphragm spring. BG sets up the secondary opening rate very conservatively to avoid a secondary tip-in bog. But this results in secondaries that open very slowly, and often they fail to ever open fully. You can buy a secondary spring assortment kit from BG, Summit, Holley, Jeg’s, or your local NAPA store and play with this a little. I have had best success using the lightest spring in the kit or the second-lightest spring. Use the lightest spring you can that prevents a bog when you go into the secondaries.

Shortblock 03-04-2003 07:23 AM

Just a crazy thought, but have you checked for a plugged exhaust?

I had a muffler with a collapsed baffle drive me nuts until I found it.

blown69stang 03-04-2003 08:04 AM

The filter is near the carb on the distribution block. I took it out of the series to see if it was blocking flow, it was not the problem. I have replaced the gauge three times and they work for about 2 months and then stop working. After removing this last one, it had some kind of hollow screw inside the distribution block. I took the pieces out and cleared the block and plugged the hole with a cap and no change in performance. This morning on my way to my 8:30, The car ran on about 4-6 cylinders for approx. 6 miles. Then it started running smoother but at high idle. When I stopped and turned the key off, it dieseled and when I checked the carb out, it had 2 psi fuel pressure, the choke was stuck half closed, the throttle was stuck right above idle. There appearantly is not rebuild kit for the pump so I am debating getting a new one. Right now, the gauge is installed and showing 2psi with slow leak out over about 3 days. The fuel level remains constant in the bowls when at idle and immediately after acceleration. I don't know why the choke was stuck, there was nothing in the way. Once I got the choke unjammed, idle slowed but was rough. This problem was happening before with the Holley and I went to the Demon to get more flow and to try something different. No change after that swap. The stock distributor was replaced with a MSd with no change. The exhaust is a new 3" flowmaster setup with Hedman Long Tube headers. I don't have the specs on the cam but it shouldn't be a problem since everything was running fine for 2000 miles. Only after it began this problem did I start to replace parts. I wish Popular Hot Rodding would use my car a project for a an article. I can see the headline: "Fix it or barbeque it"

bullheimer 03-04-2003 10:46 AM

what do you think about the possibility that your cam went flat?

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