Hey, I am new to the site, but it seems to be a great place for Camaro people, so here I am.
My ride is a 2nd Gen. 1979 Camaro.
I am currently building an upgraded version of my 400 small block.
My upgrade is a set of Keith Black .100" solid dome pistons on 5.7" rods.
Engine is standard bore at 4.125". Heads are 350 Chevy 76CC chambers.
According to the KB website, this combo will give me 10.9 to 1 compression. I have several conflicting pointers on building this setup.
Some say this combo I am looking to build will not be streetable. Some say it will do fine on pump gas.

I figure you guys might give me a straight up answer from experience, so will a SBC engine run on the street off pump gas with 10.9 to 1 compression ratio?

I already have all the parts to upgrade to this setup, but I am wanting to keep my Camaro streetable also.

Advice is greatly needed on this guys.
Thanks in advance.
Jim C.

welcome

dont forget to drill the steam holes in the heads

Any engine will run on 'pump' gas, it all depends on which pump you go to.

What are your cam specs?

Depending on timing, cam and quench dimension, imho..

I personally wouldn't go above 10 so I don't have any fuels hassle is all..

Please go over to SGCOG and look up the what compression ratio are you at thread and do some reading..

pdq67

Thanks.

10-4. Already got that in the works. This motor has already ran without the steam holes on the heads with the factory dish top pistons and low compression and did just fine in our truck, but I plan to have the steam holes drilled before I go back together with it this time and drop it in the Camaro.

440/280 Comp. Cam.

Sorry for the delay in answers back to you guys, but work sent me to Illinois this week and I just got back home last night.
My son has been talking with our local machine shop Chevy guru and this is what he told him we need to do in order to use my KB pistons and 5.7 rods.

Clearance Block for rods.
Clearance ARP Rod Bolts/Caps for cam.
Drill steam holes in the 350 heads.
Either hog out the head combustion chambers and make them larger than 76cc with a Dremmel tool, or go with thick head gaskets to get my compression down to around 10 to 1.

Cam is a 440 lift, 280 duration Comp. Cam. Hydraulic lifters.
Performer Air Gap Dual Plane Alum. Intake with Edelbrock 750 carb.

Advice is appreciated. I plan to try and run this engine on regular 93 octane pump gas.

I would go with thicker gaskets , but need to juggle round the compression and quench to find the sweet spot. Quench should be not over .040 .

Everybody seems extremely concerned with quench these days. I remember when nobody was concerned about it. I understand the theory and reason behind it but how much additional HP do you gain? Is it 1%, 2%, 10%, 0.5%, 0.10%?

The quench on my 355 is .056, it has 10.9 SCR and on the motor runs 11.30's at 120 with sluggish 1.65 short times in a 3,350 pound car. With the right converter it might run 10.90's. How much might my ET improve by going from .056 to .040 quench?

Thanks

There's more detonation resistance in tight quench than hidden horsepower because it lets you run more compression and helps ward off detonation. It's a longevity issue, not power.

OK. I did a cold compression check on my motor and it was between 215 and 230 psi. I don't have any detonation on 91 octane pump gas at 38 or 40 degrees total timing all in by 2,500 rpm.

Does quench have more influence on detonation than vehicle weight and or gearing?

What I'm really trying to get at is - Has anybody quantified the benefits of improved quench? If so, I'm interested in the results. Like, you were able to increase DCR by X amount without detonation, or you were able to use 89 octane with the same DCR that used to detonate on 91 octane?

Thanks again.

Lets try and get back to the basic question here I started with?

I am running out of time and have to build this engine next weekend. I am for sure now going to use the KB 12 to 1's with 5.7 rods.
I have 76 CC chamber 350 heads. I plan to have the steam holes drilled.
I will be using a high rise dual plane air gap style intake with a Edlebrock 750 carb.
Cam is a 440 lift. 280 duration. My previous postings on the cam size were not correct.
I will also be running headers with dual 2.5" pipes with glass packs dumping at the rear axle.

According to the KB website, this will give me 10.9 to 1 compression with stock thickness head gasket. I want to get the compression down to at least 10.5 to 1 or 10 to 1 if possible.
I just need to know the thickness of the head gasket I will need to drop the compression 1/2 to 1 point. Its either use a thicker head gasket, or try to hog out the 76 cc chambers on the heads to drop the compression.

I am wanting to keep this car a street driven vehicle, but also have some power to play with if I want to go to the local races on Saturday nights.

Guess the real question is: Will a SBC run on 93 octane pump gas with 10.9 to 1 compression ratio and not knock or rattle? I dont really want to lose power by running the timing back just to keep the engine quiet.

Can anyone tell me if a .051 thick head gasket will lower my compression enough, or would it take more? I am not familiar with the math to do this stuff so I need help?

Don, can you help me figure this out? I am old school SBC and its been about 18 years since I have played with SBC engine building due to raising 3 kids. Now they are about all grown up and Daddy is ready to play again, but things have went several levels up from when I last messed with this stuff.
I guess what I need to know is what thickness gaskets would lower my compression from 10.9 to 1 to 10 to 1 compression. And I guess I need to keep the Quench at .040 or below.
I have posted all the specs on my engine also on this thread.
I plan to start putting the engine back together next weekend, so I dont have much time between working an expected 55 hrs this coming week to do a lot of research on this.
Any help and advice is always appreciated.
Jim C.

Steve,

Have you read this thread that was just posted a bit back in Performance??

https://www.camaros.net/forums/showthread.php?t=100636

Here is the link........................

http://www.popularhotrodding.com/eng...power_squeeze/

Very good read, imho....

pdq67

Steve, for the answer to your question, static compression ratio will drop right around .5:1 for every .010" increase in gasket thickness.

Summit does list a couple of 400 gaskets at .040 and .050". stock is .030"

As much as I like talking quench, I don't think he has time.

Be sure to dummy her up and measure you piston to deck clearance before you buy gaskets. One thing I keep learning as I get older, every time you ***-u-me, murphy's law give you a chomp in the pants.