what's up guys,
i was wondering if any of you have ever heard of or done this before.
my heads have been shaved and my block has been decked. i have really high compression and i cant afford 100 octaine. so i'm forced to run 93 octaine and i have a severe timing knock. in a hotrod magazine from 1985, the guys built an engine very similar to mine and they ended up with a timing knock. they shimmed their distributor and it solved their problem. i'm going to a local speed shop later today and i'm picking up some of these shims. i was hoping one of you could help shed some light on this subject, any advice will be greatly appreciated.

 

No no, that's not what they are for.

You can shim the distributor to eliminate end play, which basically just corrects for slop in the mechanism.
Or if you block and heads have both been decked, and your distributor doesn't sit flush on the intake, you can use some kind of shims there (like stacking gaskets). That just makes sure it has a surface to sit on.

Neither one will have anything to do with spark knock. What's your compression ratio? Give us the rest of the details of your combo, there might be other things you can do. However if you built a "100 octane engine" and are running it on 93, then I think you may have painted yourself into a corner eh?

 

i had the engine built five years ago back when 100 octaine was 350 a gallon. the engine has a little over 10.5 to 1 compression. the engine runs good except when i'm on the gas really hard, that is when all of the racket begins. i believe my only choice is a different set of heads but i can have my car painted for what a set of heads cost.

any ways here is my set up. 350 block,010 casting, bored 40, decked 10. heads have the casting that match 1967 327, or 283 head. they have been shaved 7 thous. completely reworked.

i dont have a lot of money to spend on the car and i would like to get all that i can out of what i have, but the future of these heads are looking dim. just wondering if there is any other options besides a head swap. thanks for the input!

 

What are the exact specs?
Which pistons? Deck height? Head gasket? Chamber size on the heads?

You could swap in pistons, that's a cheaper way to lower your CR, but it's a bit more work.

What induction is on this car? Carb?

There are other ways to help it run better. What is your timing curve look like (if carbed)? What spark plugs are you using? Cool plugs? Hows the air intake? Warm open element, or CAI? When you're at the ragged edge like you are, small little things might be able to put you on the safe side.

Regardless, those heads have a poor chamber design, so you need all the help you can get.