ported j heads

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1970 La

1970 La

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just wondering what kind of numbers others have run with the ported j head. i have a .030 340 with 13.1 trw pistons. the heads do have 11/32 valves in them. i run 1 7/8 headman headers. has a small comp solid camshaft .560 lift. 273 adjustable rockers. my car weighs 3360 with me in it 9.5 lbs/ci . i leave @ 6800 shift @ 7200. 5.13 gear 29.5x9 mt. with a stick. best pass 1/8th mile 7.17 @95 mph 1.50 60' on super stocks springs. i have got the camshaft in @ 106 thinking about advancing it to 103 now that it is hooking. upping seat pressure to 150lbs and 400lbs open.
 
What do they flow? What happens when you tighten the lash .010"?
 
My 67 Barracuda that weighed 3200 with me in it and a 13:1 360. Ran around 11.20 with a best of 11.14. I had a 4400 stall converter, 2.74 low gear, 4.30's, super stock springs and 28x10.5 MT slicks. My cam was 296 and 244 @ .050. Lift was .620. When I went to CalTracs, it dropped to 11.08 & 119.81 with a 1.50 60'. I had J heads that I ported and had 2.055 intakes and 1.625 exhaust valves with 11.32 stems The valves were the result of several freshenings. I think 2.02's and 1.60 are just fine.
 
i have never tighten the lash up that tight cam calls for .018 and .020 i did tighten both up .002 and didnt see any differance. theese heads flow 258 @ .550 on the intake 180 on the exhaust by memory. i also get to do lots of valve jobs. next time i will stay with 2.02 on the intake also. as far as seat pressure i was just trying to squeze a little more horsepower thats what seatpsi i found for the 400lbs open.
 
Have you tried launching and trapping at lower rpms? Was the engine dyno'd? Do you have the full specs (or part number) of the cam?
The heads and cam would seem to support something that peaks around 6500. Did the dyno say otherwise?
 
If you are not plagued with valve float now, more spring won't help you. Too much spring will just cost HP and increase stress on the entire valvetrain. A better course would be to decrease the load on your current springs by lightening valvetrain components. Titanium retainers perhaps.

What are the specs/RPM range of that "small" cam? 7200 is "big" cam territory. Are you going through the traps at 7200? If so you may be under-cammed for your gearing.

Never hurts to call the cam manufacturer for spring and intake CL recommendations.
 
moper, i had to do some digging but i came up with my cam card. lobe seperation is 105 recomended @ 103. intake duration @ .050 is 264 exhaust is 272. 294 / 305. .567 intake lift and .578 exhaust lift with a lash of .018 and .020. with cam in at 106 i have got 205lbs of cranking compression. when i had it in at 103 i had 225-230lbs but it hit the tires so hard running high 7.20s @93.45 mph with only a 1.60 60'. our track didnt open back up. then i retarded it to 106 went to a another track and my 60' times came down from 1.60 - low 1.50s and ran 7.19 @94.5 mph leaving @ 6600 and a best of 7.17 @ 95 mph leaving @ 6800 with a 1.50 even 60'. our track was a heads up racing track lbs/ci. it has closed so now i have to drive further to a another track that is a bracket racing track. but seems to hook harder. should i put the cam back in @ 103 and leave the spring pressure where it is @ 135 seat and 350 open and try it? i do have a set of closed chambered w2s for a flat top motor but would like to see this car run a 7.00 with j heads am i crazy? thanks for any help. i have not had it on a dyno guessing 425-450 hp!
 
going to take the dart to the track this weekend sat night. i pulled the comp cam and put in a old racer brown cam with more duration and lift. we will see what happens with the same spring pressure.
 
well it was a lot of work changing camshafts & degreeing but my new best time is now a 7.13 @94.75 mph. 60' was consistant 1.52's. had to jet the crap out of the carb 86-90's set timing @ 34 degrees total and shifted @ 7000. still not a 7.0 but with a new set of slicks i think i might make it.
 
With SS springs, I had a best of 1.53 60'. Cal Tracs made it much more consistant especially if the track was edgy that day.
 
i still think i am going to step up the pressure. the cam is broke in i am going with 150 lbs seat over 400lbs open. i have seen others do this and nothing else and pick up a tenth and not turn much more rpm.

yea they sure get crazy with the roller spring pressure any more also. and seems to help. i have kinda been one for liability and longivty but u cant go faster if you do not experiment!
 
Mt cam was 265@.050 with .620 lift. I had 130 on the seat and 330 at full lift. I don't see how you will gain anything by upping the spring pressure. It may cost HP. If you are not floating the valves DON'T CHANGE IT!!!
 
this car has not seen over 95 mph. so it does not look like there is nothing left in it. my heads are a pretty good set of heads but fall off @ .600 so i have always kept the cam around .550 after lash. it did pick up a little bit with the racer brown but it probably has more duration @ .050 than it needs. it is 345 ci @ 3360lbs maybe i'm looking for something thats not there. it does have all steel wheels on it and i know there is some to be gained there but it looks so good!
 
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