1.7s with Tfs stage 1 cam?

fastfox90 · Dec 12, 2009

Ane one know if I will have any p.t.v. clearance problems with 1.7 rockers on gt-40 heads and tfs stage one cam ? I think cam specks say a max lift of 510 I know 1.6s are ok, but came across a great deal on the 1.7s, thanks for any help.

skunk21 · Dec 12, 2009

I it might be close but....when in doubt clay it. verifying will always give the right answer!

Mustang5L5 · Dec 12, 2009

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.

skunk21 · Dec 12, 2009

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.

Mustang5L5 · Dec 12, 2009

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.

fastfox90 · Dec 12, 2009

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 · Dec 12, 2009

fastfox90 said:
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.

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 · Dec 13, 2009

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.

Mustang5L5 · Dec 13, 2009

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.

Valve Lift with Factory Rocker Arm Ratio: 0.499 int./0.510 exh. lift

That's what TFS claims with factory 1.6's. How can i calc it out with 1.7's?

liljoe07 · Dec 13, 2009

.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

Mustang5L5 · Dec 13, 2009

Ah thanks. Now to find a good spring

skunk21 · Dec 13, 2009

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

liljoe07 · Dec 13, 2009

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.

skunk21 · Dec 13, 2009

Mike remember duration is the main issue for ptv vs lift.

skunk21 · Dec 13, 2009

liljoe07 is was just busting

liljoe07 · Dec 13, 2009

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 · Dec 13, 2009

greensvt21 said:
liljoe07 is was just busting

Its cool.

Mustang5L5 · Dec 13, 2009

greensvt21 said:
Mike remember duration is the main issue for ptv vs lift.

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 · Dec 13, 2009

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.

skunk21 · Dec 13, 2009

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.

1.7s with Tfs stage 1 cam?

fastfox90

New Member

skunk21

Active Member

Mustang5L5

That is…until I whipped out my Bissell

skunk21

Active Member

Mustang5L5

That is…until I whipped out my Bissell

fastfox90

New Member

skunk21

Active Member

liljoe07

Mustang5L5

That is…until I whipped out my Bissell

liljoe07

Mustang5L5

That is…until I whipped out my Bissell

skunk21

Active Member

liljoe07

skunk21

Active Member

skunk21

Active Member

liljoe07

liljoe07

Mustang5L5

That is…until I whipped out my Bissell

liljoe07

skunk21

Active Member

Similar threads

1.7s with Tfs stage 1 cam?

New Member

Active Member

That is…until I whipped out my Bissell

Active Member

That is…until I whipped out my Bissell

New Member

Active Member

That is…until I whipped out my Bissell

That is…until I whipped out my Bissell

Active Member

Active Member

Active Member

That is…until I whipped out my Bissell

Active Member

Similar threads

Privacy & Transparency

Privacy & Transparency