My bad on posting the wrong numbers. The duration on my cam at .050 is 214/220. Wasn't paying attention when I looked at my info that I was reading the wrong line.

 

You probably know this but I'll post it just in case you dont... The 243 heads have 64.xx cc chambers stock and the 4.8/5.3 (706 and 862 I believe) heads have 61.xx cc chambers.. So if you mill them .030 that will give you approx 60-61 cc's... In other words you wont gain much if any compression, unless you do the thinner head gaskets as well. Just though I'd mention it in case you didn't know. Keep us posted, I'm curious what numbers you can get out of that lil 4.8

 

ahh got ya... i thought the 243 and 706 had the same size chambers. i gotta get ontop of this stuff! hmm ill just have the current heads worked over then. thinking gasket matching with polishing. gonna run a felpro gasket. undecided on what thickness. thinking .043 gasket guess im gonna have them custom make one and take off .035 of the heads which should put me a tad over 10.5:1
and im thinking of doing the NNBS intake so everything looks stock and the heads match up stock wise so people cant argue with me on my setup sorry im a street racer at heart thoughts? suggestions?

 

If you could handle the down time, take your heads off and send them into Texas Speed and the can put bigger valves in them and CNC port them to flow about 315 cfm for like $800. And then get them milled My brother milled his .030 on his old setup and just hand ported them a little (more like cleaned them up a little) and put them back on and we could definitely tell a power difference. And that was with stock gaskets too. If you mill them .035 and go with say a .040 cometic gasket, you should get a total of about .050... You'll need shorter pushrods though... And you might ask a few people on here about weather or not the stock manifold will line up with that much mill. Oh and also PTV clearance could start to become an issue also..

 

what size pushrods did you end up using with the .030 off and stock gaskets? seems that with the thinner gasket ill be cutting it waay too close. unless someone can chime in with exactly how how much can be milled, which gasket will yield what compression, have everything line up with a stock manifold, wont run into ptv issues with my cam, and what pushrods? looks like im gonna be calling some machine shops for some answers.

 

Well the guy that my brother bought his new heads from (dirt track racer 81) had the heads milled .030 and had .040 head gaskets and he ran the 7.35 inch push rods... But when my brother milled his stock heads .030 and was running stock gaskets he was running the stock pushrods. But I would recommend the 7.375 if you run the milled heads with stock .055 gaskets.