[Silveradolasvegas]

Hey fellas, hows it going.
I just put in a new crate bottom end in my 91 Silverado. Redone a pair of 86 Corvette center bolt aluminum heads but are pre 86 intake manifold bolt. I hope that makes sense. Also with a mother thumper cam. I had the spring seats worked to allow for possible spring bind, screw in studs n guides n so forth. Now when i get good timing when you can really hear the cams beat i get pinging w o t. When i retard the timing enough to not get any ping.... it sounds retarded. Some guys say my carb is not big enough, some say i didnt dial in my cam at install. It feels like its advancing to fast and has a hard time reaching top end. But at the same time my bottom end to midrange is awsome. Doesnt fall off the line and picks up well untill around 4-4500 rpm.
Any ideas?

[techinspector1]

Originally Posted by Silveradolasvegas

Hey fellas, hows it going.
Now when i get good timing when you can really hear the cams beat i get pinging w o t. When i retard the timing enough to not get any ping.... it sounds retarded.

The motor is detonating because of excessive cylinder pressure for the fuel being used. Possibly no squish built into the motor or mismatch of camshaft timing with the static compression ratio.

[Greg T]

How about some numbrs? Static timing, amount of advance and total timing at what RPM?

[Silveradolasvegas]

So i should dial in the camshaft? Run higher octane fuel?

[Greg T]

Originally Posted by Silveradolasvegas

So i should dial in the camshaft? Run higher octane fuel?

Maybe. But you need to spill your guts about the info. Static compression ratio, initial timing, total timing all in by what RPM, etc.

[hcompton]

I larger cam will stop the detonation but need to know more about the problem.

this covers the basic. More initial and a lot less vacum and mechanical advance may solve the issue.
HEI Tuning Secrets

Basicly if you have a stock hei without a re curve kit that is your problem fix it and go from there. Adjustable vacum can and mechanical advance recurve kit with new modual. should help alot. my even solve the problem all together. You can block off vacum advance for testing until you get everything working right.

If not then you may need to work toward a larger cam. You can google for DCR to help understand what I mean by the cam fixing knocking.

Hope this helps.