[1981zapper]

I’m having trouble timing my 355, I messed with the timing all day, the engine was rebuilt before I purchased the car and has radial cam, and I estimate the compression to be around 10:1, I started off with 18* initial and 38* Total, and took her for a run and at wide open throttle I heard pining, I then lower the timing to 15* initial and 36* Total I got all kinds of power and getting 13 PSI of vacuum pressure, but when I took her out for a run I still heard some pinging but not as much as I did when I had it 38*, I tried lowering the timing again but didn’t help still heard some pinging and you can feel the loss of power, I’m running 91 Octane but the fuel is from June 2012, do you think the fuel is gone bad?

 

[Greg T]

Need to know everything you can tell about the motor. You could have compounded issues going on.

 

[bygddy]

I’m having trouble timing my 355, I messed with the timing all day, the engine was rebuilt before I purchased the car and has radial cam, and I estimate the compression to be around 10:1, I started off with 18* initial and 38* Total, and took her for a run and at wide open throttle I heard pining, I then lower the timing to 15* initial and 36* Total I got all kinds of power and getting 13 PSI of vacuum pressure, but when I took her out for a run I still heard some pinging but not as much as I did when I had it 38*, I tried lowering the timing again but didn’t help still heard some pinging and you can feel the loss of power, I’m running 91 Octane but the fuel is from June 2012, do you think the fuel is gone bad?

Cam #'s, heads, intake, Carb.....etc etc.....more info needed.....but no, i doubt 5 month old fuel is "gone bad" .......sounds like you get the initial nailed down but to much total, a recurve would likely help, what plugs, gapped at what etc.....just more info.....a flyweight car may get away with more total, a 4x4 truck....not so much....just need to know more before everyone chimes in...

 

[1981zapper]

Cam #'s, heads, intake, Carb.....etc etc.....more info needed.....but no, i doubt 5 month old fuel is "gone bad" .......sounds like you get the initial nailed down but to much total, a recurve would likely help, what plugs, gapped at what etc.....just more info.....a flyweight car may get away with more total, a 4x4 truck....not so much....just need to know more before everyone chimes in...

The engine is in a 1981 Camaro Z28, with a Turbo 350 automatic and 3000 Stall Converter,
like i said i have no engine specs, the pervious owner said he rebuilt the motor in the 90's and does not have any mileage on it, he said the compression is around 10:1, the heads casting #: 462624, its got the factory cast-iron intake manifold, Qjet carb, i'm running Delco R45TS plugs gapped at .45, i just changed the wires to Taylor 8MM Street wire, its a pretty radical cam in there,

 

[1981zapper]

i bought the car in 09 and never had a problem with it pinging, but i had to pull the distributor, there was no timing tape so i didn't know what the pervious owner set the timing at, here is a pic of the engine when i bought her

Here is a pic of the springs in the distributor, the rotor and cap looked all good

 

[Custom10]

20 deg mech adv is on the high side, may want to try about 14-15 and bump the base up to 20 ish again. But if it is rattling at WOT then the changes to the mech limit may not matter. I see the vacuum adv is not hooked up so that is not the issue. Ensure he dist is really clean and the mech adv is free to move and wont hang up. Its got the heavy springs so the curve is not agressive

I am un wise to the ways of the qjet but it may be a lean AF ratio causing the ping issue. Check the fuel psi, filter and jetting + carb functions etc. If the motor is carboned up that can make it rattle as well.

vacuum leaks?, the basics

 

[vinniekq2]

run a few tanks of fuel,gas goes stale quickly with out stabiliser.cam sounds mild enough

 

[1981zapper]

20 deg mech adv is on the high side, may want to try about 14-15 and bump the base up to 20 ish again. But if it is rattling at WOT then the changes to the mech limit may not matter. I see the vacuum adv is not hooked up so that is not the issue. Ensure he dist is really clean and the mech adv is free to move and wont hang up. Its got the heavy springs so the curve is not agressive

I am un wise to the ways of the qjet but it may be a lean AF ratio causing the ping issue. Check the fuel psi, filter and jetting + carb functions etc. If the motor is carboned up that can make it rattle as well.

vacuum leaks?, the basics

Well when I had it at 38* Total you can really hear it rattle at wide open but I find that the motor likes 15* initial and 36* Total it still rattles but not nothing like at 38*, I do not have the vacuum advan hooked up, the distributor moves free, I never had a problem before with the Qjet, I can tell you that the plugs are all black, when I pulled the plugs out I put my Camera inspector into the combustion chamber and you can see the carbon on the pistons, this engine does more idling more than anything, this year I only took her out once

 

[DoubleVision]

Wrong post. disregard

 

[bygddy]

I agree with Vinnie, doesn't sound like a real lumpy cam or anything, typical 268 sound to me. But if you pulled the dist, and this started after you reintalled it your going to have to go back to basics, find true tdc, get a timing tape on it and a dial back light and start from scratch....typical hei has 20 degrees built into it. But without knowing your initial is what you think it is your kinda guessing here....

 

[bygddy]

If its full of carbon, and sits around that much, get the timing sorted out, your likely going to want to limit total to 34 or 35, get the highest octane pump you can get, and go drive the damn thing and clean it out lol.......good gas, and a little abuse (assuming its not rattling anymore with conservitive timing) will do wonders, once its de- carboned (is that a word) then you can sneak back up on the timing to see what it wants for maximum performance....

 

[Custom10]

find true tdc, get a timing tape on it and a dial back light and start from scratch....typical hei has 20 degrees built into it. But without knowing your initial is what you think it is your kinda guessing here....

agree, could be getting 45 btdc actual,,, and reading 36, check TDC and balancer tab accuracy should always be #1 thing before the light goes on it

 

[Custom10]

First problem your chip moduale says gm on it. You need an after market one. Stock one drops off at 5500 or so. If you dont already, buy a kit with recurve, moduale, coil, cap and rotor the works. Then google for hei setup usally you need to make several small adjustments for bigger cams. And usally all work toward restricting advace from mechanical and vacum and using more inital advance.

I wont go over all the steps here i have seen great stuff on the web for hei setups. With lots of good close up pix.

http://www.crankshaftcoalition.com/wiki/Hot_rodding_the_HEI_distributor

 

[1981zapper]

agree, could be getting 45 btdc actual,,, and reading 36, check TDC and balancer tab accuracy should always be #1 thing before the light goes on it

when i say 36* total that's without the vaccum advance hooked up, i have it plugged

 

[Custom10]

I know, what we mean is that checking for correct tdc and balancer tab accuracy ensures that your timing light readings are accurate, balancers can slip etc

 

[bygddy]

First problem your chip moduale says gm on it. You need an after market one. Stock one drops off at 5500 or so. If you dont already, buy a kit with recurve, moduale, coil, cap and rotor the works. Then google for hei setup usally you need to make several small adjustments for bigger cams. And usally all work toward restricting advace from mechanical and vacum and using more inital advance.

I wont go over all the steps here i have seen great stuff on the web for hei setups. With lots of good close up pix.

Not really the first step no......stock intake, 624 heads, and even if the cam is large by huge, its all done by 5500 with his set up....stock module is just fine.....the car ran fine, the the dist was removed and reinstalled, then he had issues....
Step 1 = find tdc and make sure balancer and timing tab make sense...then move on.

 

[1981zapper]

I know, what we mean is that checking for correct tdc and balancer tab accuracy ensures that your timing light readings are accurate, balancers can slip etc

i have already done that, i made sure my 0 on the balancer lines up with the 0 on timing tab

 

[bygddy]

i have already done that, i made sure my 0 on the balancer lines up with the 0 on timing tab

Just because they line up, doesn't make it accurate ....

 

[Custom10]

You need to get the #1 piston at TDC first right? using piston stop

http://www.crankshaftcoalition.com/wiki/Determining_top_dead_center

 

[1981zapper]

Just because they line up, doesn't make it accurate ....

lol yes i made sure that the piston is accurate with the timing marks