Corvette Forum : DigitalCorvettes.com Corvette Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1
I am in the process of restoring a barn find. 1968 vert. It is not the original color. But it has not been molested. All the little pieces are there except for the steering wheel and two AG rims. I can find these parts. It is a 327/350HP 4 speed car and numbers matching. I was going to do like most and redo the car to my liking. But after researching the cars numbers and ownership (I bought from the second owner) and the fact that after learning of having a lot of one off parts (which I have) I will restor back to original. It probably wont be NCRS but close. My real question is the 327 motor came with 11:1 CR. Most I talk with say to lower the CR to 10:1. This is going against the grain for me. I understand the point of lowering the CR but I was wondering of you out there that keep your cars original how did you or do you deal with the gas octane today. :bang
 

·
Registered
Joined
·
1,845 Posts
In my experience, 93 octane easily supports 10.5:1.

Don't know what to say on the originality question, but I know I would want to drive it and therefore, I'd have to do something. Engine operating temperature, ignition advance and camshaft all affect how an engine runs with respect to pre-ignition. Retarding the cam also would help.
 

·
Premium Member
Joined
·
10,260 Posts
I've had no trouble running my 11:1 L46 on 91 octane fuel, but my motor is hardly in pristine condition. I'd say stick to original and see if you have any trouble. If you do, you can either buy race gas, try some octane booster, or if you plan to do a lot of driving you can pursue some other adjustments as Fred has mentioned :thumbsup:
 

·
Registered
Joined
·
230 Posts
It's not the static compression that you need to be concerned about. It's the dynamic compression. The size of the cam has a big effect on it.
Mike
 

·
Registered
Joined
·
265 Posts
I would suggest some careful trial & error. Starting with some custom ignition timing curve work. Some fuel additives can help compensate. This could be a measure between the cost of these products and higher octane race fuel.
If you hear the engine rattling at all, back off and resume adjustments.
For me with approx. 10:1 comp, every new tank of fuel can vary. Just goes to show that fuel manufacturers can have inconsistent results. 90% of the time 93 octane works fine for me. I still carry around a bottle of additive.
I personally applaud your decision on your goal for the car.
Have Fun! :cheers:
 
1 - 7 of 7 Posts
Top