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  #16 (permalink)  
Old 10-26-2008, 02:46 PM
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I think your asking to much from the engine you have, which is just basically a stock mildly warmed over Chevy 350. If you wanted high performance, then you should have been prepared to spend the money needed to get high performance.

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  #17 (permalink)  
Old 10-26-2008, 03:38 PM
How fast is fast enough?
 
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Quote:
Originally Posted by yknot
I think your asking to much from the engine you have, which is just basically a stock mildly warmed over Chevy 350. If you wanted high performance, then you should have been prepared to spend the money needed to get high performance.
I agree it will take some more moeny- mostly in the short block. I have no idea why people spend all of their money on a used up low compression short block- its the FIRST part of the engine I go for.
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  #18 (permalink)  
Old 10-26-2008, 07:36 PM
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A little from the heart

I don't mean to cry about it, but even BEFORE I started doing anything, I was out in cybernet asking questions, and the first things I heard from the masses, were to change Heads, cam, exhaust & to get the smog stuff out of the way! (Which I diligently did) ... then it was on to intake & carb, they got a little kick into it, but still not what I expected (in comparison to what I had stock). Then the rear end got moded from 3.08 to 3.73. I liked the idea of the 2004r in comparison with the 350 tranny as I would take her on the road and it had better suited 1st for what I wanted to do.

I agree about the low end, but it was a learning experience as well as an ego builder ...... so since it was okay at the time, now I am not sure .....

Everytime I turn around (and I realize everyone has their own GOOD opinions about things, I sure could use some solid advice that doesn't just involve spending more cash (that I truly do not have), but have lived through this all by will and desire that the learning experience is worth my efforts.

Some people that I have met along the way, have been short of INCREDABLE and UNBELIEVABLY helpful in their time spent with a stranger, so I have come to start listening to some that I can tell have only the best intentions and want to share their experience (that someday, I can, with someone that is coming "around")

So instead of berating or saying that I should have done something different or stop reaching for a goal, I really do appreciate those that truly care about their fellow man and their quests - and I hope to be known as one of those .... so if I have any such brotheren close by in GA .... I would surely come by and help you turn a wrench!!!!!!

Enough of that - NOW WHAT ??????? Live with what I got or ?????
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  #19 (permalink)  
Old 10-26-2008, 09:12 PM
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350

You don't have enough timing for low compression,if it is 38 try 44 total. Is the timing pointer and balancer correct.Set the dist setup for total timing at about 2500 rpms. I set up a 400 for a blower for my friends 32 and and we broke the motor in without the blower had to have the timing set up to 50 total for it to run good on pump gas.Get a dial back timing light and adjust the timing .Try 44 all in by 2500 rpms ,make sure vacuum advance hose is unhooked when setting total,then hook it up to manifold vacuum after.
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  #20 (permalink)  
Old 10-27-2008, 06:02 AM
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Timing

NOW THAT IS INTERESTING!!!!!

When I was setting timing, I started down in mid-30*s .... worked up to 38* (vac can disconnected and hose plugged to carb). Was going to try 40*, but started getting concerned about going too high .....

But what you are saying, makes sense to me .... I will give that a shot and see what it does .... I have a dialback timing light, get all-in about 2500.

Can you tell me what I am technically doing in laymans terms, so that I am following???

What is your opinion on changing head gasket to get my quench down to minimum (but surely over .040") and getting compression UP to whatever my max is without changing to 5cc flat-tops?? A friend and I were planning on doing this, over the weekend and I already have all the needed gaskets etc ... I am going to dyno run car, before and after, to see exactly what it did!!!

And just to reiterate, this car was a stock 8.2:1 dog when I started, I am coming up on 8.9:1 now and figure over 9:1 with head gasket change ... but that is a guess until I know if I have been bored out and how far down the hole I actually am.

Last edited by Tomard; 10-27-2008 at 06:13 AM.
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  #21 (permalink)  
Old 10-27-2008, 06:26 AM
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I will grant comp. is a little low but for a comparison my neighbors 79 camaro with stock dished pistons, 461 heads and 292 comp cam ran 13.12 .Now this was with 3000 stall convertor and 4.56 gears but your cam is smaller, car is lighter. I would double check timing , play with the carb before tearing into the engine.
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  #22 (permalink)  
Old 10-27-2008, 06:37 AM
How fast is fast enough?
 
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Quote:
Originally Posted by barnym17
I will grant comp. is a little low but for a comparison my neighbors 79 camaro with stock dished pistons, 461 heads and 292 comp cam ran 13.12 .Now this was with 3000 stall convertor and 4.56 gears but your cam is smaller, car is lighter. I would double check timing , play with the carb before tearing into the engine.

With a 3000 stall and 4.56 gears I could almost get a loaded dump truck into the 13's. That stall helps compensate for a lazy low end- if he had compression he'd also have a little more snap.

As far as timing goes- 40 advance is a HELL of a LOT- I'm not saying it won't make the most power there, but the more you have to advance the timing the less efficent your engine is.

By the time you swap the gears and stall (as a crutch) you are basically at the cost of a good street short block. Fix the problem rather than treating the symptom! We all agree it needs compression and quench. Yea its going to cost him between $1,000-$2,000 to build a good reliable short block, and at this point the budget is shot but you can't wish the problem away.
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  #23 (permalink)  
Old 10-27-2008, 06:52 AM
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"What is your opinion on changing head gasket to get my quench down to minimum (but surely over .040") and getting compression UP to whatever my max is without changing to 5cc flat-tops?? A friend and I were planning on doing this, over the weekend and I already have all the needed gaskets etc ... I am going to dyno run car, before and after, to see exactly what it did!!!"


I would do as others have recommended and get your tune dialed in for what you have now before spending any more money on parts. You really don't know what your engine is doing until you do this. A head gasket won't fix a lean carb and adding compression without taking care of that might make it worse!

Then, If you're already set to change the head gasket I'd do that. I don't think it's going to solve all of your problems but you could use the tiny bump in compression. Those thin head gaskets can have a problem sealing if there are any issues with the block or heads though. I know you have new AFRs on it but that's no guarantee, especially since they've been bolted to your block and heated and cooled a few times. Just wanted to warn you..

While you're in there MEASURE how far down in the hole those pistons are. Knowing this for sure will be worth the effort even if you put thicker gaskets back on. Also take a pic or two of the tops of those pistons. I know you said they were "fly cut dished" but depending on the shape you may never get any appreciable quench in your engine if the dish is under the flat part of the head. All you'll get is a compression boost. That's O.K. though, having a good quench has benefits but there are plenty of engines out there making power with less than ideal quench. Short of pulling the engine and having the block decked and replacing the pistons you have what you have..
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  #24 (permalink)  
Old 10-27-2008, 09:17 AM
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Update

SD & GTA - you guys ROCK!!!!

I went out to garage and said the hell with it, I am going to see how she runs with higher timing ..... set it to 44* (no vac adv) and she sounded strong ..... she now runs about 60* with vac adv all in .....

I took her out expecting to hear the dreaded PING (that I still think is a myth as I have never heard it!!!!) And no ping, and she DOES RUN STRONGER for sure!!!!

What is the process to OPTIMALLY time her? Is it going to max timing 2* at a time without getting a ping? or some other method ????

The Dyno & carb A/F mixture adjustments are coming up with head gasket change next weekend!
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  #25 (permalink)  
Old 10-27-2008, 09:19 AM
How fast is fast enough?
 
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THAT IS A LOT OF FRIGGAN TIMING!!

You must be running REALLY crappy compression.
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  #26 (permalink)  
Old 10-27-2008, 09:23 AM
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I know, but it seems like what the motor wants!!!! And if I am not pinging, am I hurting anything?????

Also, remember that when I started out, it was a 8.2:1 motor .... so the smaller 65cc chambers bumped it some, but the thick headgasket put me in opposite direction of where I wanted to go!
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  #27 (permalink)  
Old 10-27-2008, 09:39 AM
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It was 8.2 at best... A lot of times compression numbers are rounded up. And as long as you're not detonating you're not hurting anything, but your engine is REALLY inefficent. On the plus side you could probably get the thing to run off of fuel oil or kerosene.

Are you sure you really have 45 of mech+initial advance? I mena its entirely possible, but wow...
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  #28 (permalink)  
Old 10-27-2008, 09:57 AM
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I guess the tdc pointer could be off ...... guess I better verify that next?????

Check my thinking here:

1) will go slightly past 0* on dampner/pointer, verify #1 firing by looking at distrib
2) Use a wrap around dampner handle tool that I can turn it back until it stops on my piston stop bolt if I go too far past - make a mark on pointer tab
3) Continue Turn it all the way around using either crank bolt or my little handle tool until it stops on coming up again against bolt, make mark
4) exactly center between marks, s/b TDC???

IF it isn't correct, I will put my little adjustable pointer on tab so that it is and recheck my timing .... and yes, it does run stronger now!!!!
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  #29 (permalink)  
Old 10-27-2008, 11:39 AM
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TDC timing tab

The tab was a few degrees off, and I adjusted it ..... and still put timing to 44* all in w/o vac adv can .... and she is running real good.

Going to leave it until I get it up to put it on dyno and make any a/f adjustments I need to, and will get all that is planned done, then test it again.
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  #30 (permalink)  
Old 10-27-2008, 11:57 AM
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Quote:
Originally Posted by Tomard
I had a stock remanufactured 350 and have done LOTS of mods ..... although the car runs well, it doesn't produce what i thought it would ....

It is going on the Dyno, and I am going to get a wee better compression out of it after changing head gasket next weekend, but I still thought it would have been smokin' tires left and right without much if any effort ......

Here is a list:

AFR 180cc 65cc chamber eliminator heads
XE 274H cam
Ebrock 1406 (Will have to + A/F at wot, but will wait until dyno'd)
Ebrock EPS 2701 Intake
Summit G9001 headers
True dual 2.5" exaust Flowmaster mufflers
No smog
MSD 8501 Distrib

Good compression - all cylinders are around 150psi
Timing set 38* all in / 52* total

3.73 rear end
27.1" street tires
2004r OD GN tranny/2500 stall

8.2 stock compression, I am about 8.9 now, and over 9:1 with new .015 head gasket. I am not for sure yet, but think I am PROBABLY around .050 down in the hole, 4.030 bore AND a .041 Head Gasket .... Will know for sure this coming weekend

Stock crank, fly-cut 12cc dished pistons

Anyone see anything blatent that would hinder this motor from TAKING OFF and snapping my head back, without mentioning pistons, rods or crank????
Biggest violations are squish/quench, compression and total timing.

A dished piston .050 down the hole will have extremely poor combustion from the lack of squish/quench. Squish/quench are two features of the combustion chamber directly related to combustion efficiency thus power produced and to detonation resistance. These events are promoted by the shape, size, and closure distance of the piston crown to the cylinder head step opposite the spark plug. Inclusive of the gasket this should be .040 to .050 inch from the piston crown surface to the cylinder head's deck for an engine using steel connecting rods, add .010 inch more if you're using aluminum rods.

Your problem is two fold; the piston is too far from the head's squish/quench deck and this is exacerbated by the presence of a dished piston which puts much of the crown surface even further away.

Many replacement pistons raise the pin location which lowers the piston in the bore as an anticipation that a rebuild will include a milled block deck. If the block wasn't milled, this puts the piston a long ways down the bore at TDC wiping out the squish/quench function and reducing compression to boot.

What is needed, as the piston approaches TDC firing, is a violent expulsion of mixture toward the spark plug, this is called squish. It breaks up the fuel droplets and throughly mixes them with the air for a fast and complete burn to get all the energy possible from the mixture. At the other end of the burn cycle is "quench" . From the moment of ignition the temperature and pressures climb rapidly. If uncontrolled, the temperature and pressure can become so extreme that the unburnt mixture ahead of the flame front explodes, this is detonation. To control the temperature rise ahead of the flame front, the close closing of the piston and head deck opposite the spark plug and valve pocket offers an area of small volume to a large surface area where excess heat is transfered to the cooling system thus preventing spontaneous combustion from occurring ahead of the flame front. So with your piston deep in the hole and the combination of a dished piston, you're not getting the effect that's needed for best power. The solution here is proper piston choice, you need either flat tops, or D dish pistons to correct both the squish/quench and compression which with your cam needs to be close to 10 to one.

You have way too much timing, 52 degrees is excessive by about 20 degrees. This much advance is an indicator of poor combustion and inadequate compression for the cam.

Bogie
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