5.3l with 4.8l pistons
 

Hey guys im building a 5.3 Lm7 and am installing flat top 4.8 pistons. Is there any need to balance the engine now since it will have new pistons?

how are you going to install 4.8 pistons? the CD is different, more than likely it will stick too far out of the hole.

it wont stick out the hole, they ar just flat tops as apposed to the dished 5.3 pistons. I just wasnt sure if it needed balancing since the piston weight would be different

.178 out of the hole to be exact.

4.8 pistons wont work.

they will stick out of the hole. the compression depth is different for the shorter stroke of the 5.3

the compression depth of the 4.8 piston is 1.498 and the compression depth of the 5.3 piston is 1.328 ish.

they do work, dont come out of the hole either

Attachment 619979

check out the build sheet on this thread...
http://www.pro-touring.com/forum/sho...ht=4.8+pistons

alrighty, i stand corrected. the rod length is different. search>me.

to address your balancing issue, i would have it balanced. but keep in mind stock engines are no where near 0 balance...i would still have it done just for peace of mind.

yeah i know the balance was not perfect from the factory, but i do know that the 5.3 pistons have a 7cc dish and that has to change the weight some from using flat tops now. Not sure if its enough to worry about though

wow, i saw what i need to build in the garage for a couple hundo.. to a grand

Pistons
 

70 two Nova, What pistons did you go with ?

I've searched for forged 4.8 pistons = nodda ?

I bought a set from speed pro, h855cp
they arent forged though

Try putting the 4.8 pistons on the drivers side then install the 5.3 pistons on the passenger side. This should balance well if my math is correct. Just make sure to mill the head with 5.3 pistons to even out the compression ratio.

so 4 heavier pistons and 4 lighter pistons = balanced? what kind of math you doin boy?

aahhh why didnt I think of that!!!??? Mitch youre a genius! lol

i've heard it all now, what next if i use the power ball/mother's wax on my heads i'll have a port /polish

:D just teasing my buddy

If anybody needs some stock 4.8 piston/rods I have a nice set of stockers from a donor motor I have. Make me an offer.

ahh now you tell me lol. I could have used those about 2 weeks ago... lol

Just saw this thread. What a great idea. I have a stock 5.3 LM7 sitting on the engine stand and this looks like a great thing to do. Looks like I'll be doing this when I'm ready to drop the engine in my '78 Z28.