I have a set of 241 heads that Im porting out. I also have an f13 cam (230/232, .595/.585). Id like to bump up the compression a bit. Would I be better off milling down the heads and then flycutting the pistons to clear the cam? Or should I just weld in a little extra aluminum back into the combustion chambers on the side of the spark plug boss? What are the pros and cons of each?

 

Welding can get you a better shape if you know what you are doing.... problem is you need to put new seats and guides in the heads most times. If you keep the heat out of the heads then you might get away with it, but I wouldn't trust it.

Milling too much can get into the valve seat which will hurt your flow, so there is always a comprimise.

Bret

 

Well, depending on how much chamber polishing I need to do, Ill probably have to mill a max of .040. Ill use a thinner gasket to recoup some compression, and Im shooting for milling around the .030 area and aiming for a 11.33 static compression ratio. I could possibly get away without even flycutting, but I dont want to chance it. As per alan futral, my f-13 has .095 P to V clearance on the intake. Reducing that to a mere .050 clearance is getting a little close for comfort.

 

Seems to me like a pair of 243s would put you
a lot closer to your goal (CR, flow) with less
work? These pop up for barely insane prices
from time to time esp. locally from non-Internet
people who don't know pricing.

The Patriot welded-up heads, I seem to recall,
had some problems that got people riled up a
year or two back. Welding up on a pressure
vessel takes better than shade-tree metallurgy
(heat control, filler) I reckon. Not to mention a
bunch more grinding, by hand, to identical
volume in the chamber. At least shaving them,
you keep the original integrity.

 

Id love to do the 243 castings, but im on a dirt cheap budget right now. Ive already bought 3 pairs of 241 heads (one guy ripped me off and never shipped, and another set I bought from bo as practice heads as one was already compromised from the previous owner before bo). Anyway, im tired of spending money on heads. The whole Idea was to do this on the cheap for the cost of a carbide burr and some cartridge rolls...

As far as the welding goes, I wouldnt do this myself after seeing my awful beads on my exhaust

 

I'm pretty sure the company known for welding chambers sends them out to be re heat treated afterwords.

 

Good to know.

I think im pretty well decided ill just mill em and be done with it. Thats what I had planned on doing from the start.

Thanks for the helpful info guys!

 

Just got my 241 heads back from TEA and I got Stage 1 Milled 0.030, CNC ported and A valve job. I'd say get them milled it will bump you up and then get some Cometic 0.40 gaskets and you should be close to where you want for compression. I think the Chambers end up being 63cc after the heads are milled from what TEA told me.

 

Cool... Every .006 is approximately 1 CC of chamber volume. So milling them .030 will drop you 5cc. If the heads started out untouched I believe they are 66.67cc - 5 gets you to 61.67...

I think your F13 is +4, so you should have a static of 10.9ish and a DCR of 8.5, damn good numbers... assuming something like a .045 Cometic head gasket and a 1cc fly-cut on the pistons…

 

We are able to weld our chambers because we start with raw GM castings which are +.050" on all surfaces. We preheat the heads, weld, and then send the heads out for heat treating.

 

X2 for the TEA stage 1 treatment. Also ,from what I've read, their 59cc 5.7 chamber will give you better PTV clearance than their 1.5 5.3L head.

 

Really? That is an interesting tid bit there. I knew the 5.3's had their seats a little lower, but I didnt know it was that much.

How tight do you think I can run my P to V?

 

I don't know , I'm just regurgitating info from this thread....
https://ls1tech.com/forums/showthrea...ight=tea+stage

From Pg.2 (flow #'s on pg. 3)