With the 268H and your heads and pistons, you're going to run into problems with pump gas. Unless you have flat tops with a shorter pin height, then you may be OK, but on the edge with the 268H. It's designed for motors with a comp ratio in the 8 to 9 to 1 range. If you've got a near zero deck and 54 cc chambers, you're looking at a 10.5 to 1 comp ratio. If that's the case, you'll need a cam with more overlap to bleed off some of the pressure.
I ran that same cam in the first motor i ever built (a 10.5.1 1970 351W) had the stock studs and used the matching lunati springs turned it 7k on more then several occasions and never had a problem using the stock 1.6 rockers with polylocks .I was always told around .530 is were you start to have retainer/guide issues on stock heads
heads had a valve job,surfaced,new seals and matching springs for the cam with the bumps removed from the exhaust ports. was the shortblock was .040 over with 2 eyebrow cast speedpro flattops stock rods,sealed power moly rings,crank machined ,hi volume oil pump and the lunati cam and double roller chain.topped by a performer intake and 750 holley. nothing special really but it was very reliable I probly put 50k miles of beating on it ,and got decent milage 15ish I had this motor in a couple differant cars I originally built it for my old 70 torino It went 8.30's on street tires in my old cobraII (3k pnds) and was fun to drive around was my only car back at that time (late 90's)
first off what's the condition of your bottom end? More cam and heads with higher RPMs means trouble in bearing and piston slap. Timing gears/chain, oilpump drive shaft, then there's exhaust. Or is there more to all this then you've told us, like the stock 68 heads, then E7s out of the blue. Not to mention your trans going south on your. Been ther done that. Ujoints etc. Personally, build a solid drive train first and then build the engine.
bottom end is fine.engine ran great with 74k orig.miles before being pulled.nothing more to this than what i've said.the stock 68 heads is what came off the engine.the e7te heads is a pr. that i have laying around.trans going south,you lost me on that onei'm just trying to find a combo that will work. thanks
Going with the E7's will allow you greater choices in cam profiles over the 68 heads. Take the E7's, open up the exhaust ports (roof and walls, leave the floor as is, other than polishing) to match your header flanges, remove the thermactor bumps completely, blend all this work down into the bowl area under the valves. Next, remove any rough spots in the intake sides, and blend the bowls. Then polish the chambers and smooth any sharp edges. Have a valve job done with a machineshop that has a "Serdi" machine to face the valve seats. With this done you'll have a good set of mild street heads, and if you do the port work, you'll have all of $250 in em with new valve springs. I've done two sets like this. One set I bought at a junkyard for $50, they've been on the 5.0 in my Ranger for about 8 years now. Can't give you flow numbers, but they're no doubt better flowing than they were when they left Ford. Top em off with a set of pedestal full roller 1.7 rockers. I've got a used set of Cobra 1.7's on mine that had over 100K miles when I bought em 8 years ago, they're still going strong today. I've run em with both the F4TE roller and a B303 roller. The F4TE is smooth as silk, the B303 has a nasty-wicked lope , but runs great with high rise dual plane intake (as does the F4TE)
very good advise ,baddad457 ,i have a 78 351w ,with 70 351w heads with screw in studs stock porting,510 lift cam, dished pistions,victor jr intake,good oil pump,timing chain,my motor had 54,000 miles the timing chain was so sloppy it came off with out loosing the cam bolts when i removed the cover, 3500 stall maybe 3800 stall ,c4 ,4.11 gears ,i run 7.60s 1/8th ,also e85 fuel,12.00s 1/4 mile ,i shift at 5200 rpm, 750 double pumper, with 15/8th headers and 3 inch exhaust to rear with flows
With the heads and cam you have, you'd do better to swap to an RPM intake(or any other high rise dual plane) and swap the converter to something closer to a 1500-2000 stall. Your fuel bill would be cut in half and you wouldn't loose much if any in the 1/4 mile.
we built it to go faster its just right now,my son is using it for highschool drag class cut off is 7.50 1/8th ,after next year racing were going to a big cam alum heads,and hoping to get in the 6s or maybe 10s 1/4 mile
