Ok, I I recently acquired a L76 short block. Stupid cheap. Needs a rod bearing. Originally, guy though it was a L92. Oh well, still stole it.

So, my question is. How much would I leave on the table, potential wise? This will most likely be going in a 5100lb Yukon. Cam and stall are a must. I'd like to see 12s.

Cathedral or Rectangle heads? I see boost in the future as well.

Should I get this short block refreshed and sell for a 6.2 or am I not missing much.

 

You arent missing all that much... especially if boost is in your future.

12's at 5100 lbs will take a fairly aggressive build NA, but it will be a cake walk with boost. You will need north of 450 to the wheels to accomplish 12's.

I'd probably go square port. I have a new respect for them after doing some research and talking to experts that have built careers around cyl heads... I'd also put a maggie on it... but I'm biased.

For what its worth my race weight is 250# more than that and I just went 11.43 with a 6.0 and a maggie.

 

I figured I'd need 450+. I also was thinking 821 heads. Probably do a port job on the exhaust. And if I have to. Maybe a 150 juice shot, until I can go turbo. Not like I'm going to be thrashing it on the daily.

 

Does the 4" 6.0 bore have to be bored for the larger l92 valves to work?

 

No, they fit.

 

They "fit" but it is not optimal to run the larger valves on the small of a boar. I think Skeet got it to work pretty well but he had to do a lot of work on the chambers of the head I believe to take care of shrouding from the valves being so close to the cylinder walls. I will see if I can find the thread..........

 

Here is the thread......

https://www.performancetrucks.net/fo...3-swap-522931/

See posts 5 & 6. Can be done and may have good results but without extensive head work like what Skeet had done cathedral port head may be better for a 4" bore application.....

 

Should be a whicked grocery getter lol