"help!'' gotta 79 camaro 388 stroker. stumbling? hesistating? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 06-15-2011, 02:26 AM
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"help!'' gotta 79 camaro 388 stroker. stumbling? hesistating?

i just got it and i want to get it running perfect. its got tons of money invested but its got a bug somewhere..

1979 chevy camaro
388 stroker

this is what i was told when i bought it.. some parts were verified just from looking.

350 block .060 over
400 crank
eagle rods 6''
dish top pistons. ? didnt give me a name brand.

dart iron eagle heads.
1.5 roller rockers they are a stainless steel color..
heavy duty valve springs.

all he said was the cam had a .640 lift.
didnt say what brand or anything..

hooker long tube headers.
3'' exhaust run out to flowmasters..

victor jr. high rise
holley 750dp 1450 series.

dont know much about it .. this is the most i can tell you.. but i need help please.

at first i thought it was loading up on fuel but it dont smell rich and the plugs look fine. if anything they look a little hot..

when u first hit the gas it falls on its face. then goes .. if you hold it at 30% throttle is just bucks and hesitates.. wot it hauls *** but hesitates a little..

i was going to check timing but the timing pointer is missing due to new chrome timing cover..

anyways i was just wondering what u guys think ..

it seems like it is detonating but i dont hear spark knock. its a loud car so i probly wouldnt hear it anyways..
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Old 06-15-2011, 12:20 PM
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You need to get all the information you can, because based on what your combination looks like, it's pretty roudy and biased more towards a race combination, and it's out of tune.

Begin with the fuelling. Check the fuel system from tank to carburetor. You need 6 psi seat pressure, and if you don't have a psi gauge, get one. Next pull the plugs and see what they look like. If you are running a stock, out of the box carburetor, the combination might be all wrong for what you have.
Do you have any vacuum leaks? If you do, then any work you do to the carburetor is going to be off.

Next work the ignition side. Are the cap, rotor, wires in good condition, are the wires routed properly to prevent crossfire, is the coil good. If you have an amplifier box, is it wired and running properly? Are the plugs gapped properly? Is the distributor functioning properly? Where's the timing at?

Valvesprings. You are running a .640" lift cam, and even though you didn't disclose the timing specs, more than likely pretty raunchy. Did the springs go soft? Are you getting coil bind anywhere?

Piston to valve clearance. If it has not been checked with that cam, you could be kissing the pistons and that will cause a miss.

What kind of fuel are you running? Is the octane too low?

Get the timing light out and a vacuum gauge. Install an O2 bung into your headers and see exactly what the air/fuel ratio is like. If you are not comfortable dialing in the carb, send it out to a reputable carb shop with all the details to your car so that they can get the jetting, power valve, accelerator pump combination specific for your vehicle.

Last edited by cleanspeed1; 06-15-2011 at 12:26 PM.
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Old 06-17-2011, 01:15 AM
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thanks for all the info. sounds like you know you stuff. found the problem it was a plug wire melting out the #7 header. it was sparking on the header. I just ordered new moroso wires. do I need the hei wires? I hope not cause I ordered non hei. its got msd dizzy. I eas reading and I think only stock oldet dizzys have hei.. idk
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Old 06-17-2011, 04:07 AM
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Use a quality 8mm wire set specific for the HEI distributor.
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Old 06-17-2011, 07:01 AM
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Sounds like low initial timing to me or maybe not enough accelerator pump.

First thing to do is get a pointer for the timing. Then you need to check for true TDC with a piston stop.

Big cams need lots of initial timing. But I kind of doubt 0.640" lift, so you need to check that also.

What distributor do you have? I hope it is an aftermarket hei that is adjustable because your engine will need a custom ignition curve.

25 degrees initial and 35 degrees total would be a good starting point.
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Old 06-17-2011, 08:22 AM
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how do I knowif its an hei dizzy
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Old 06-17-2011, 09:21 AM
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My mistake, read your post wrong; if it has a small cap non HEI, big cap with coil in the middle, HEI. If you have a coil wire that goes in the middle, like most regular distributors, it's a non HEI.
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Old 06-17-2011, 09:49 AM
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25 degrees initial sounds a little high. I thought. about 14 degrees initial made around 34 total at 3k rpms
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Old 06-17-2011, 12:21 PM
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Quote:
Originally Posted by ekcoupe69
25 degrees initial sounds a little high. I thought. about 14 degrees initial made around 34 total at 3k rpms
Sort the timing out, then go on to the carburetor.

Until you get a grip on what it is you have and how/what to tune it like, just be damn sure the total timing is not over 34 or the damage caused will be expensive! Once the initial timing and the rate that the timing is added in by the mechanical advance weights and springs is dialed in, you can change the total to a bit more than 34 to see if the 1/4 mile trap speed increases any. Once the trap speed quits climbing, go back 2 and use that as the maximum total timing.

25 initial is not at all too high for a cam w/specs that would support 0.640" lift. Even a solid roller w/that much lift will have a lot of duration/overlap- and thus the need for a lot of initial ignition advance. A flat tappet cam even more so. In fact, if the cam is as radical as it could be if the lift is really what you think it is, the timing curve may be superfluous and would be better off locked at the maximum w/o a curve, period!

That said, regarding the ignition timing/curve, start lower and work your way upwards rather than the other way around. As you add initial remember that you need to reduce the mechanical to compensate otherwise the total will be too high- and you have to avoid excessive total timing at all costs. I cannot stress this strongly enough! The rate of added advance will want to be as fast as you can add timing, w/o getting into detonation. This is largely a trial and re trial type of process. Take your time, take NOTES as you make changes (trust me- you think you will remember, but you won't) and soon enough it will be dialed in better than before.

Pay attention to the plugs and performance as you increase the timing. An adjustable vacuum advance might be a good addition if you find the carb is getting too far into the transition slots at idle, but that remains to be seen, you might not have a vacuum advance as an option, and the engine might have such erratic vacuum at idle as to make using a vacuum advance difficult if not impossible, anyway.

Last edited by cobalt327; 06-17-2011 at 12:29 PM.
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Old 06-17-2011, 08:16 PM
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run a colder plug

what plug is in it had a 388 doing the same bottom line the plugs were to hot.
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