LS1 5.7 heads on a 5.3

[twobit]

I have a set of 5.7 heads Im wanting to put on my 5.3 When using 5.7 heads on a 5.3 motor what head gasket would you use? The one for the 5.7 or the 5.3 or are they the same? thx

[farmtruc]

I've seen both and compared them and just from looking at them , they are identical, if you're going with the 5.7heads, i'd go with the thinner gasket. Did you mill them, what kind of compression you getting?

The ls1 head has a 64.45cc chamber, with 2.00/1.55 valves
The 5.3L head has a 61.15cc chamber, with 1.89/1.55 valves,

did you get bigger valves or ported, just wondering what made you get those, and what kind of power is expected


thanks, keep us updated,

allen

[twobit]

These were a set of heads (241 casting)I got cheap b/c two of the rocker arm bolts were broken off in the threads. So I figure I would have them milled down .040 and have a performance valve job (5 angle)done on them since they only had about 6500 miles on them. I was told these heads have a 66.7 combustion chamber so milling them
.040 should get me close to the stock cc ratio. I have them at the head shop now having them checked out.

[Hit Man X]

Do not go any bigger on those 5.7 intake valves, if ya do you'd shroud the combustion chamber as your bore is only 3.78"...meaning you will lose some power.

Hell AFR's heads for the 302 5.0 'Stang come with 1.9" intake valves and that has a 4" bore...

You going to get these cleaned up at all?

[twobit]

Hit, Im keeping the stock 5.7 valves. I was just planning on having them heli coiled, cleaned and blasted and a 5 angle valve job. Also milling them at least .040.
Do you know how much I could mill them without having any intake alignment issues?

[Hit Man X]

Hell if you have some extra cash I'd get the valve throats cleaned up, maybe open up the runners a tad, clean up the combustion chamber, etc.

Nothing too exotic but that should help flow a bunch.

[twobit]

If I had that done would it hurt my low end? How much do they usually charge for that? thx

[Hit Man X]

Originally posted by twobit@Sep 23 2003, 07:58 PM
If I had that done would it hurt my low end? How much do they usually charge for that? thx

It will not hurt your bottom end power at all, it will make it better. Just don't widen the runners too much or that will hurt low down power.

Um...light port work maybe $400?

[farmtruc]

Originally posted by twobit@Sep 23 2003, 12:34 PM
...on them. I was told these heads have a 66.7 combustion chamber so milling them
.040 should get me close to the stock cc ratio. I have them at the head shop now having them checked out.

I pulled that data out of the LS1 Performance book, i'm pretty sure it's right, if you have them milled that much, you might be right on with the compression, a little more or less wont hurt performance that bad.

do like Hitman said and try to clean them up, at least smooth out the bowl and exhaust area.

btw, anyone have a spare ls1 head, i want to practice porting.

[twobit]

Thanks for all the help guys. I'll keep you posted on what i end up doing.
I'll check arouind with a few people and see If I can find an extra head from someone.

Clint