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I’m restoring a 69 Z28 old school style to near stock. 4:11’s, 4 speed. I’d like the solid lifter sound and run on pump gas.

I’ve read hours of 11:1 CR on 93 octane pump gas threads. I came to the conclusion an 11:1 engine with a 30-30 cam may or may not be happy with 93 octane. I’m hoping to have an engine that doesn’t need reduced timing or need timing creativity. I don’t really want to run a bigger duration cam than a 30-30.

I’m going to put the original 302 on a shelf. I have an old school LT1 pink rod 11:1 short block that will be used. It’s stock bore never been apart super low mileage short block. If I do use the original 64CC 302 heads and a 30-30 or LT1 cam, I might consider shaving the tops of the pistons.

Question: What amount of shaving should/could be done to the top of the piston domes?

Just a guess, but flat tops might not have enough compression. And it might be difficult to find flat tops with full floating pins.
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Or maybe this is a better way to go about it:

I’ve been reading that aluminum heads allow a higher compression ratio to be used. I guess another option would be to use aluminum heads. Trick Flow has a DH series head that has a nostalgic appearance with double hump castings (and bolt holes for the 69) They only come with 60cc chambers.

As far as pinging is concerned, does anyone have input on how the 60cc chamber aluminum heads might work on my application? Or might compare to 64CC stock heads? I’d like to maintain a stock engine appearance.
 

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Unless you have a machine shop in your garage, you’ll be talking to a machine shop/engine builder. My machine shop knew what to do with the pistons, pin rod ratio block and head shaving and milling,quench.... you need to talk to your local competent machine shop
 

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I would personally say in a street car don’t get hung up on compression ratio, don’t push it, run conservative and you will never notice the difference. I’m running a small cube large port motor with 9:1 compression an I bet you would never know riding in it.....ha. I messed with pushing compression etc., but you will never feel 1 point, maybe more, on the street.

Also I get the nostalgia of a 30/30 cam, but I see no reason saddling yourself with 50+ year old cam technology. Lots of modern designs that will give better performance, or the sound if that’s what you want.

Just my .02
 
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You can easily get by with that compression if you use more cam - I'd look at a hydraulic roller cam for that build myself.
 

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i am running 10-9-1 and mine is very much border line on 93 octane. depending where i get gas, SO i mix gas and come close to 101 octane which is fine for my engine. your Ping may vary 😁
 

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My 11:1's run fine on 93 pump gas.
 

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10.8:1 but alum heads and temps kept on the cooler side too.
91 octane and no issues seen.
If/when I ever plan to hit it with some giggle gas....I plan on some 100+
 

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Ben - Delaware - 67 Camaro
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11.4:1 aluminum heads and i can run 34* of timing on 93 octane before i get into detonation. at the track i run 110 and 36-38 degrees. runs fine one the street at 34*
cam choice and overlap has a lot to do with how much static compression you can run as the increased overlap will bleed off some cylinder pressure.
 

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Man I wouldn't shave em...Personally speaking, I've run the old GM 140 solid cam in a 69z28 and a 70z28 and never had a pinging problem with either. Both engines had factory pistons and heads. It'd be great with your 4 speed too.
 

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You can easily get by with that compression if you use more cam - I'd look at a hydraulic roller cam for that build myself.
What roller cam do you think would be a good option? I've tried several different solid lifter cams in my 69 302 that I've had for over 30 years and currently running the 140 offroad.
 

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What roller cam do you think would be a good option? I've tried several different solid lifter cams in my 69 302 that I've had for over 30 years and currently running the 140 offroad.
unfortunately Windows 10 upgrade broke my Camquest software which worked great. I would call a comp cams Monday and talk about it with them. For a 302, you definitely don't need to worry about rod interference on big lift.
 

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Call me old fashioned/old school/stubborn or whatever but you’ve got a really nice old school couple of motors there with 11 to 1 pistons that are likely original. There are old GM solid cams like the 140 or even the 754 that you could run with great results without shaving the pistons or really changing the integrity of you original-ish build.
One thing too consider as well. If those pistons are actually original 11 to 1s they’re likely “troughed” on top with not much valve relief, much like the TRW 2304 LT-1 replacement. Even if you shaved them you may have an issue with piston to valve with a high lift hydraulic roller. Maybe not but it’s worth checking.
The old school cams mentioned have a ton of overlap so they’re premium pump gas friendly even with 34-36 degrees of total timing.
Just my opinion, for what it’s worth.
 

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Discussion Starter #13
I bought my LT1 brand new at the Chevy dealer back in the late 70's. It's only been ran maybe 500 miles in a vehicle that was on the road a very short time. I think I'd rather not shave pistons or put flat tops in it. It does appear and old school cam with lots of overlap will be my best option if my heart is set on running an LT1 on 93 octane. It's the route I'm going to take.
Thanks for all advice. I acknowledge there will be less torque and a little less HP by not going with a modern cam, but just trying to avoid octane booster and mixing fuel.
 

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What roller cam do you think would be a good option? I've tried several different solid lifter cams in my 69 302 that I've had for over 30 years and currently running the 140 offroad.
Even IF you went to a roller with the same specs as the 140 there would be a "slight" increase in power just due to the roller cam lobe design.

BUT !!!
As always.... CHECK THE PTV to be sure you're good ANYTIME you swap a cam.
 
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