I am building a 65 nova 4dr and am finally getting around to planning the motor for an ls swap. I would like to use a 5.3l/4l6oe combo. I had originally planned on using a L33 but prices in my area seem to have gotten out of control so I will be using an LM7. I am looking for a little help to plan my build. My goals are as follows:

-400hp (flywheel)
-Decent mileage
-Runs on cheap gas
-Can use stock converter

Because of the tight engine compartment, I will be using 1 3/4 headers. I had planned on using a Comp Cams 54-424-11 cam but am open to suggestions. Will I need bigger injectors at this power level? Should I look into finding a used set of 799/243 heads? Thanks in advance for any help or advice. Happy Holidays!

 

That cam you chose their will crack 410 plus horse at the crank... good choice even with those heads. It'll be great if you could get some mild head work to the heads you already have.....

 

Would I have to have the 799 heads milled to maintain the same compression ratio if I use those? I keep seeing sets of 799 heads that have a frozen or broken off header bolts for cheap. I think that's something I would be willing to tackle. The springs are also usually worn out but I would be replacing those to match the cam anyway. Are these heads known for having guide issues? I will probably need to change the seals as well. Do you think it would make 410hp before or after swapping the heads?

 

You do need to mill the heads to maintain your compression. Stock 5.3 heads are 61.15cc and 799 heads are 64.45cc. I never heard any problems with guides. Usually those head bolts come out pretty easy because there antiseize on the threads. The bolt rusts outside the head and rots away.

Here is a good article for you to read.

http://www.hotrod.com/how-to/engine/...st-comparison/