Motor advice

[6daze]

I would like to do a stock type rebuild on a CL roller 302. I have fuel injection on my current motor (RJM harness, A9L computer, explorer manifolds, etc.) so that will carry over.

I have some iron GT-40 heads from an explorer. I am also running JBA shorty headers and a 2-1 exhaust.

The bronco is 75% trail, 25% street. Specs are ZF, Atlas 4.3, 35" tires and 4.56 gears. It is an all around driver/crawler/ some sand dune wheeler.

Looks like I don't need to overbore, just oversize rings..

What pistons?

What cam?

thinking of the Comp Cams 35-308-8.

My builder wants to 10.1 compression ratio. Is this ok for pump gas?

Thanks for any help!

[Mcdobson]

Re: Motor advice

If you are getting this info from a true engine builder, you may want to look for a new one.
There are no over sized rings to fit std. pistons, you would need to bore and hone.
10 : 1 with cast heads is really pushing it on pump gas.

A good engine builder should be able to put together a good combo for you.

Let me know where you are at, I can probably point you to a good builder.

[6daze]

Re: Motor advice

Looks like I am going with a forged piston, 9.5 CR. I can always go with 89 octane if needed.

Block is at the machine shop, getting cleaned up and a line bore.

I will post info on the rings when I get it...

I think that cam will work, trying to see if I can get one ground for me. Schneider and Crower are here in San Diego.

Someone mentioned milling the heads where the springs sit. Anyone have to do this with GT40 heads?

[TRAILBOUND]

Re: Motor advice

You shouldn't have to mill the heads. But you will need new spring retainers on the exhaust side. It's all a part of putting things together. Since your building an engine, you should buy the complete cam kit ( cam lifters springs etc)

[NOTPRETTY]

Re: Motor advice

I bet you'll need premium at 9.5:1 unless you use alluminum heads. Maybe not...

What pistons exactly are you buying? I had a hard time finding a stock bore piston that got me to 9.5:1. Over .030 has many more options. Keith Black pistons? Are you/your builder sure the valves will clear these pistons?

Marlon

[6daze]

Re: Motor advice

Actually I could use some help finding pistons.... I will need to bore the block afterall.... I think .030.

I am having some trouble figuring out my CR. I have used various calculators but I am unsure on my deck clearance. It appears most people are using .015 in the calcs.

Where do I get this number?

Do I need forged pistons?