Looking for some input for this winter's project. Have a 68 J code 302 with standard .030 rebuild . Engine internals consist of a crane 260 cam (260 duration, .456 lift, 1400-4600rpm), 4v heads which should be 53.5cc This was done back in the 80's and for the life of me I can't remember what pistons were used. I'm pretty sure the compression was 9:1 max. Anyway,have a set of Thumper ported E7 heads Thumper of Orange Park and wonder if I should bolt these on? I picked them up locally for a good price and they have never been used. The E7's have a 63cc chamber vs 53.5cc on the 68 4V heads. I can probably mill the E7's to 60cc maybe even 58cc if I push it. Question is....would you do this? I'll probable drop down to 8.5 to 8.75 compression. Will the greater flow of the E7 heads justify the switch? OR Just sell these and buy a pair of AFR's and have them milled to 54cc's and be done with it. Thanks, Andrew 68 conv Mustang
Are your sure on the cc's of the 68 302 heads...I seem to recall them being more like 58ccs. Anyhow, generally speaking, .005 of material per cc on the E7s. So if you need to get them down from 63 to 58 your talking about removing .025 of material. The intake manifold would probably have to be milled too.
The Thumper heads will smoke your 68 heads, but before you mill anything, contact Thumper and see how much he's already milled em. I'm sure he did when he reworked them. Also suggest after pulling your heads to measure the piston's deck clearance and then further make a decision on milling (or not) You are correct that the 68 J code heads have 53-54 cc chambers. Milling E7's .040" will reduce the chambers from 64 to 58 cc's (these are Ford's calculations)
So I take it the small drop of .5 in compression is not that big a deal. Any ballpark costs for milling the heads and the intake? Thanks for the input....
A half point drop is a big deal if the compression ratio is too low to start with. If it's now in the 9.5 & up area, no a half point drop won't hurt. If it's anywhere less, then yea it is a big deal. Do the research I suggested before milling anything off these heads. Thumper used to or still does sell his heads here in the Classifieds on Stangnet. Contact him first to see exactly what you've got. Milling is cheap, but not if they're milled too far. Here's a link to his site: www.thumperoforangepark.com
No probem, I'll pull the heads in the next month or so. I'm pretty sure it's 9:1 though. I might have some Thumper's for sale soon if that's the case. Thanks
Is Thumper still in business, the website link is not working....Better yet does anyone have a phone number for him? Thanks, Drew
Greetings, Hope the heads work, but if they dont, I am interested in buying them. Let me know, levernegibbs@yahoo.com
Thanks for the offer....Depending on how much running around and cost of machining the heads down to 58cc, drilling steam holes...... I might just sell these heads and go for a set of AFR's. You'll be the first to know. Drew 68 Mustang
