1.7s with Tfs stage 1 cam?
- Thread starter fastfox90
- Start date
skunk21
Active Member
I was actually gonna ask the same question myself. I think i've heard people say it works, but still would like verification.
I have a set of Crane 1993 Cobra RR's i want to use...as my only other option is the stock 1.6's. I'm installing GT-40P's and have a TFS1 cam..so i hope it will work togehter, otherwise i will just use my stock 86-88 SD cam which is apparently a half decent cam to begin with.
I have a set of Crane 1993 Cobra RR's i want to use...as my only other option is the stock 1.6's. I'm installing GT-40P's and have a TFS1 cam..so i hope it will work togehter, otherwise i will just use my stock 86-88 SD cam which is apparently a half decent cam to begin with.
skunk21
Active Member
I think it will work or may be close but I would feel like crap If I said "yeah no problem" and then he had a problem. even when it works for others who have the same or close setup we all know how things can be different. so it's always a safe bet to verify it.
Yeah, i'll prob clay it.
Gonna prob pick up a stock short block and do a 306 or something..so i'll have plenty of time to play with it on the stand.
Gonna prob pick up a stock short block and do a 306 or something..so i'll have plenty of time to play with it on the stand.
is it thet easy, throw some clay on a piston put it together and spin the motor? Its still in the car so it will be a little harder than if it was on a stand ,but I guess your right its the only way to know for sure. I just hate to buy the rockers only to find out they dont work and have to try and sell them.
skunk21
Active Member
not exactly. I could type it all out but read this post they explain it and it will help out, also explains degreeing a cam which I'm a big fan of when installing an aftermarket cam...
Checking Valve Clearance?? - Corral Forums
liljoe07
5 Year Member
Posted via Mobile Device usually when the valve lift changes, everything needs to be considered. Pushrods, PtV clearance. With 1.7's and the TFS stage 1, I'd be worried about the spring coil bind. I forget the exact specs, but I'm sure its close. Also max lift has nothing to do with PtV clearance. At max lift the piston is about 1.5" away and traveling away from the valve. The valve events are the most important part of any cam.
How can i calculate max lift with the TFS1 and 1.7rr's?
I've been trying to decide on a set of springs for the last few weeks and still can't decide.
That's what TFS claims with factory 1.6's. How can i calc it out with 1.7's?
I've been trying to decide on a set of springs for the last few weeks and still can't decide.
That's what TFS claims with factory 1.6's. How can i calc it out with 1.7's?
liljoe07
5 Year Member
.499/ 1.6= .311 lobe lift
.510/ 1.6= .318 lobe lift
.318 x 1.7 = .540 valve lift
.311 x 1.7 = .528 valve lift
.510/ 1.6= .318 lobe lift
.318 x 1.7 = .540 valve lift
.311 x 1.7 = .528 valve lift
skunk21
Active Member
I come up with .499lift (figured with 1.6 rockers) so go .499/1.6=.312 round up(lobe lift@cam) .312x1.7=.530
.510/1.6=.319 .319x1.7=.542
pretty much the same
.510/1.6=.319 .319x1.7=.542
pretty much the same
liljoe07
5 Year Member
Just in case your wondering, all you do is mutlipy the lobe lift by the rocker ratio. That gives you total valve lift. I divided at first, because I didnt know the actual lobe lift of the TFS 1.
I didnt round up, thats why my numbers are a tad lower.
I didnt round up, thats why my numbers are a tad lower.
skunk21
Active Member
skunk21
Active Member
liljoe07
5 Year Member
Also depends on the rest of the valve events. You could keep the same duration, but open the Intake valve sooner and end up with clearance issues.
liljoe07
5 Year Member
It's not so much PTV i'm concerned with. I need some springs for m GT-40P's. I was gonna go with the Crane kit, but it's no longer made. The TFS kit is right at the border with .540 max lift so i am trying to find a decent spring/keeper setup to run that will handle the lift and not go into coil bind.
I'm also wondering if there is any benefit in going with a 1.7rr vs the 1.6rr.
liljoe07
5 Year Member
Call TFS and ask them what the Coil bind Hieght is for the springs you want to use. Usually the Max lift thats advertised for springs is not the Coil bind hieght. The max lift is just what they suggest you use to keep it what they consider a safe distance from coil bind, and not actual coil bind. They usually have a .80 to .100 safezone after max lift is reached.
Ive always been told you rather run closer to coil bind than farther away. Closer works the springs harder, and good oiling up top needs to be better. Plus everything needs to be paid close attention when setting up. Just so you know exactly where you are in terms of coil bind distance.
Farther from coil bind and the spring needs to be stronger, to help reduce the harmonics generated in the valve train. All things equal, a spring closer to coil bind will control the valve and lifter better than one farther away from coil bind.
Ive always been told you rather run closer to coil bind than farther away. Closer works the springs harder, and good oiling up top needs to be better. Plus everything needs to be paid close attention when setting up. Just so you know exactly where you are in terms of coil bind distance.
Farther from coil bind and the spring needs to be stronger, to help reduce the harmonics generated in the valve train. All things equal, a spring closer to coil bind will control the valve and lifter better than one farther away from coil bind.
skunk21
Active Member
looking at this cam and the gains yor are getting are the heads going to benefit from the added lift from the 1.7's at this point vs the 1.6's. I know there is some but is really worth it is the question.
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