.530/.544 Lift... hard to say on .050 duration, depends on the profile of the cam.

 

sorry to jack your post but can you run a stage 2 cam with stock pistons?

 

I don't have stock pistons.

 

I want to know if my tfs stg 1 will benifit with the 1.7s too... altho i have stock psitons:crying:

 

I had a good friend that was running a set of TW heads,stage 2 cam,1.7rockers on a stock shortblock and ran damn good before he parted it out

 

not without the stock pistons notched he didnt

 

Doesn't really apply to stock 302 shortblock situation, but I've got
a TF Stg 1 with 1.72's for .538/.548. Got it in a basically stock
95 Lightning shortblock. Dial indicator w/checking springs showed
plenty of p-v clearance.

I'm a tad low on static compr ratio at 9.2 w/the Ebrock heads, a little "softer" under about 3k than I'd like, I'm really considering advancing the cam 3 or 4 degr to trap a little more compression pressure by closing that intake valve a little sooner. I don't have the heads to carry the rpms very high anyway.

 

i'm running the TFS-1 cam with 1.7's on a set of GT-40s all on top of a 9:1 342, and it runs great. only thing i'd advise is to steer away from the Crane rockers... mine sounds like a damn sewing machine.

as far as the lift goes.. it's a simple equation ot figure out..

.499lift (figured with 1.6 rockers) so go .499/1.6=.312 (lobe lift@cam) .312x1.7=.530
.510/1.6=.319 .319x1.7=.542

not too sure on the duration though. shouldnt make a very big difference as far as that goes.

 

Your duration should not change. Yes you are making more lift and the valve are open a very short time longer but the cam profile was not changed and all. As for TFS-1 with 1.7 that is what I am runing on my turbo car and I love it.

 

TFS 1 and GT40's here too. As mentioned, .530, .542 is the correct lift numbers for 1.7's. Runs pretty good in my mind...not to mention on the track.

 

So from what I see here, I would benefet greatly to go to 1.7RR???

 

If your heads benefit from the additional lift (which they should), its worth a try.

 

I run a Stage 1 cam w/1.7 "Cobra" rockers in GT40P heads (better springs) and an otherwise stock '99 Explorer motor. Runs very strong.

 

I have the same combo minus the explorer intake. I'm very happy with mine.

I changed my explorer intake to a performer RPM. It runs ever better now.

 

I am running a carb with a Victor Jr intake. I meant that the long block was stock.

 

i know mine is different, i'm running a e-cam with svo gt40's and 1.7 rockers and the car halls ass, a few people say i should run 1.6 on the intake, but i have know idea if i would notice any difference

 

1. Rocker ratio does NOT effect camshaft duration.
2. Its affects duration at the valve.
3. It is going to take TQ away.
4. P-V. If it clears with a 1.6, then it'll clear with a 1.7.

After everything that has been said about this, I still cannot believe it when I see someone saying how duration (at the cam) is affected by rocker ratio.

 

Nobody cares about duration at the cam. They are talking about duration at the valve. There is significantlly more lift with 1.7 vs 1.6 rockers. If you are near P-V minimum clearance with 1.6, you could be below minimum with 1.7 rockers.

 

I think the assumption would be the duration at .050 would be more because the valve has more lift it must be getting to .050 sooner, and going below it later.

Because if you take .050 lift and divide it by 1.6 and then multiply it by 1.7 you get .053. So the duration at .050 must be larger by at least the amount of degrees it took to get to from .050 to .053.

So instead of 232@.050 you get 232.003@.050. So technically yes it got bigger.

THE ONLY PROBLEM IS the duration at .050 is of lifter rise not valve distance from the seat, so the rocker arm does nothing. You could have a 1.9 ratio or a 1.3 rato and the lifter rise at .050 is the same.

I think what Jay might be trying to say is while lift does have an impact on piston to valve clearance the bigger issue is cam profile, and timing. If you had .100 clearance with a .490 and a 1.6, going to a 1.7 doesn't mean you end up with .07 directly.