KingWalrus

Ok, so I just purchased some Absolute Speed stage 2.5 5.3L heads from a friend. I knew he had a 370 c.i. motor, but I thought it was just stroked. I just measured the heads, and it appeard that the bores have been machined out to accomodate a 3.925" bore. Would there be any problem mating these heads to my stock bore/stroke bottom end? I'm sure it's not perfectly ideal, but I figured .02" on the diameter probably wouldn't pose a problem.

Your thoughts?

I assume it will still use a stock bore sized head gasket.

Thanks!

KingWalrus

Anyone?

xfactor_pitbulls

iTrader: (16)

You should be ok. Which valves do they have? Smaller than 2.08 would be best. But even if you have 2.08s it wouldnt be bad.

Brandon

KingWalrus

The valves measured in at 2.04/1.60. I really don't think it will pose a problem, but I'm no expert. Anyone else?

PREDATOR-Z

No you'll be fine.
Just when you choose the gasket, make sure it is at least .030 bigger that 3.925 bore.

KingWalrus

30 thou bigger than 3.925? Why? I'll take your word on it; I'm just trying to learn in the process!

Thanks for the responses, btw.

PREDATOR-Z

Beacuse you do not want to shroud your chambers.

KingWalrus

Are GM replacement gaskets available in multiple bore sizes, or would I need a cometic or something similar? I have an order placed with Scoggins Dickey on some stock gaskets, but I don't think they've shipped yet. I'll give em a call.

PREDATOR-Z

GM 6.0 are 4.060
All LS1 are 3.910 (IIRC)

KingWalrus

So it looks like a Cometic is in my future unless the 6.0L gasket would suffice. Now if I could just get a hold of SD! ****, maybe I'll just bore the engine to match the heads. This makes sense...

PREDATOR-Z

Max safe bore on stock LS1 block is 3.905
Cometic makes a 3.970 bore

KingWalrus

That's interesting. Is that true for all LS1's or just the 97-98 motors? Does going beyond 3.905 require resleeving? I'm kinda surprised GM didn't put more "rebuildability" into the engine.

KingWalrus

Ok, just talked to the guys at SD. I got some Cometic gaskets with 3.930" bore and .051" thick. I can't find the stock head gasket thickness anywhere. I swear I remember reading somewhere it being like .036" or so. This gasket is a bit thicker, but it will help with P-V clearance. These heads are milled 10 thou, and I may have them cleaned up with an additional 5 thou taken off.

Thanks for the help!

KingWalrus

Found the factory head gasket thickness: .052". These cometic .051" gaskets will have little to no effect on quench, etc. So long as I still have some P-V clearance, I think I'm good to go.