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Thinking about milling my heads to get the compression up on my southern sportmod. But dont want to go too much, I want to keep it around 160 to 165 on cranking compression. Engine currently has 130 lbs of cranking compression mainly due to a 110 lsa on the cam that is currently in it.Could anyone give me an estimate on how much to have milled to get it up around the 160 mark.
for best results , have them angle milled by a reputable machine shop...there is a calculator on wallace racing that will help you decide how much you want to cut them to achieve the CR you want...
Cranking compression has very little to do with how much static compression you have.As you stated the camshaft is what affects the cranking compression.How much overlap the camshaft has and where it is installed is what either kills or makes compression.On static compression .007 angle mill will usually equal one cc.
Have you considered changing the camshaft instead of milling the heads? Once you mill them, you cant un-mill them.
Would think you are giving up some mid-range with that 110 LSA cam anyway. Do you know your quench? You can work with head gasket thickness to up the static if the quench doesnt get too tight.
sure you can change cams and make gains , but nothing like what angle milling those heads on flat tops will do..but thats just me....
Its obvious the OP is not trying to get everything out of the combination. Southern Sportmod cranking pressure can be up to 175 legally.Quote:
Originally Posted by fastford
Was just thinking that he could improve his static compression and gain some with the camshaft change at the same time without going the angle mill option.
If he knows his quench, he can bump up with thinnner head gaskets also.
Just giving him other options to think about.
i agree , but his original question was about milling , thats all i was answering , but you are right , there is a lot to be gained with the cam , and probably a lot cheaper , I charge 250 to 300 to angle mill the deck and correct the intake face........
I'm not really interested in changing the cam in this shortblock. I know I'm sacrificing tq. In the bottom end but it does make good smooth power. I'm just looking to get a little more out of it. The block isnt decked and it has untouched eq heads on it. Is angle milling legal per imca rules on a sportmod?
Excerpt below :
CYLINDER HEADS: Steel only. May use Stock Replacement (SR) cylinder heads: Engine Quest (EQ) GM part number CH350I, (EQ) Chrysler part number CH318B, World Products Ford part number 53030 - 1.250 inch (± .015 tolerance) maximum O.D. valve springs. All SR heads must remain as produced, seat angles and valve sizes can not be changed: three angle valve job only (absolutely no casting removal in valve pocket of EQ or World Products head, for any reason). No porting, polishing, or unapproved alterations allowed to ANY cylinder head or intake, disqualification and $250 fine if illegal.
A little further down it says flat milling allowed. Our track techs every night, and I just dont want to be illegal what so ever we are already a top 4 car every weekend. Just looking for that little extra to help in the moisture.
I would try to keep the quench .035 - .038 if it was mine and I was spinning it very high.
Throw a shim head gasket on it and let it rip. 175lb cranking pressure rule is easy to check so be sure about what you do.
Not sure how much you're looking for but, we had Wildcat Performance in Adel,GA build us a llm engine using the same heads. We provided the short block.. stock decked block,Mahle flat tops, 575 lift Crane cam.., and it made 504hp. For a carb, we had a Quick Fuel 3310.
More compression is cheap HP... get her up to 12-1 and have Mike Jones grind a cam for you next season and you'll be pulling your competition all the way down the straight...
www.jonescams.com