1.7's....

casper98gt · Oct 3, 2007

Ford racing X303 heads, with 1.7's. Alot of people tell me to ditch them because i will have piston to valve problems. Whats the big difference between 1.6's and 1.7's. Should i dump the 1.7's and get 1.6's ?

Fast63 · Oct 3, 2007

What kind of cam are you running? If you have a stock cam, I would for sure keep the 1.7's if you can verify that they won't cause your pushrods to rub on the head casting. It might do that because the 1.7 is shorter overall and only on the pushrod side, so it is brought in closer to where the valve is. I had to hog out the pushrod holes on my Roush 180 heads to use them.

1.7's will give you more overall lift than 1.6's and will make your valve open and close faster. This can give you more power, but not if it makes your cam bigger than what your engine wants. If you add them to a stock cam, even on a stock engine, you're pretty safe to say that you will increase power by a little bit.

casper98gt · Oct 3, 2007

Oh cool.

Well here is the setup.

Trickflow upper and lower, F-cam, X303 heads, 1.7's and a vortech V2-SQ.

5spd GT · Oct 3, 2007

There is an extremely small difference between 1.6 and 1.7 roller rockers, and it causing an issue. It really should not be considered a problem to swap them on.

If you are going to have piston to valve contact, you probably would have had it with 1.6's anyways.

Yes, it increases lift a substantial amount in comparing terms, but the piston is well on it's way down the bore before it reaches 'peak lift'...

casper98gt · Oct 3, 2007

factory pushrods and lifters will be ok to use though correct?

5spd GT · Oct 3, 2007

As far as I know, yes many reuse their factory pushrods and lifters

bullitstang1313 · Oct 3, 2007

You will definately want to check piston to valve clearance with the F303 cam. It has a max lift of .512 already so even with 1.6's you could run into clearance issues. Mine turned out to be fine with the 1.6's and the F-Cam.

casper98gt · Oct 3, 2007

Awesome, thanks for the info.

gnx547 · Oct 5, 2007

Is there a noise difference between the 1.6 and the 1.7 roller rockers?

Maryland Stang · Oct 5, 2007

Let me jump in here a little.

Although the factory roller lifters are fine to use you really, really should check the pushrods to make sure they're the correct length. The factory pushrods are designed (sized) for the factory cam on factory heads. You're using a F cam on X heads and the valve train geometry really should be checked.

Presuming that the pushrods are the correct length is the main reason you see so many threads about noisy lifters here at Stangnet.

Additionally, with that much lift at the valve you should check for P/V clearence. If the cam timing is off by even just a little you could have problems.

Better safe than sorry.

5spd GT · Oct 5, 2007

The lift has hardly anything to do with piston to valve clearance. It is the period of overlap, when both the intake is opening and the exhaust is closing, for example.

The piston is a couple inches in the bore, when the valve is pushed all the way down. In this example, the valve will be at .512" with a 1.6, but the piston will be at 2.000" down, roughly.

In terms of tolerances, that is huge, and lift has a minimum amount to do with anything considering piston to valve clearance.

1.6 and 1.7's aren't a big difference for piston to valve clearance.

Ike83 · Oct 5, 2007

I'm runnin stock E7s with 1.7 Comp Pro Mags and a B-cam. No problems except for I have a little scarring on my rockers due to rocker to valve cover clearance.

ls1beater4eva · Oct 5, 2007

ok im going to jump in here too now, i have a friend actually 88 mouse had a set of 1.7rr s on a tfs 1 cam and it had clearence i know this isnt your set up but it turned that tfs 1 cam into about 525 / 545 or somthing like that lift wise it didnt hit but it only takes floating a valve once to do the damage as he found out. you allways want to check valve train geometry bc it will allso allow u to save the life of your valve guide's not tomention if your push rod is hitting your head those metal shavings are coming inside ur engine and friction is rubbing power. A push rod lenth checker isnt but like 20 bucks shipped save your self a head ache and check ur push rod lenth. As far as the pvc issue use a old head gasket and clay the motor you can basicly do it on just one piston after u have your push rod lenth figured out adj one intake and one exh rocker after tightening the head down with the old gasket and and clay on the piston just to save your self money in the long run, it doesnt take that much more time to do it rite the first time.

jtfairlane · Oct 5, 2007

I wish everyone on this forum thread would read 5spd GT's post...carefully.

Most of you seem to think that the cam's lift is going to be a deciding factor in whether or not you have piston to valve clearance. What everyone needs to do, is actually envision in their heads the intake, compression, power and exhaust strokes and envisions what the valves and pistons are doing during that cycle.

Like he said, it's the valve overlap between exhaust and intake strokes, not max lift, that matters.

Fast63 · Oct 5, 2007

It is true that 1.6's to 1.7's will not have much of an effect on piston to valve clearance, but it will have some. The extra lift from the 1.7's does not happen only at peak, which is a big misnomer. As soon as the valve starts opening, it is giving more lift than a 1.6 rocker. So you guys are correct that the point of overlap and duration is what affects piston to valve clearance, but the 1.7's will affect how that all works since it provides extra lift during the whole cycle. The cam's duration specs are measured at specific lifts and those will change too. But yes, going to 1.7's will not cause so much change that you will have to checked piston to valve contact again, but they are right that you should do it in the first place whenever you are changing cam/heads or anything that would affect it, including pushrod length.

5spd GT · Oct 5, 2007

The thing is, if you are borderline with 1.7's, you will be borderline with 1.6's.

Duration changes are very small.

PUNISHER RACING · Oct 5, 2007

I am running an X-cam with a stock long block that is .542 inches the F-cam with 1.7 rockers will make .546 inches and the duration is darn near the same. I have no issues, however I would replace the valve springs with better more stable ones. Your heads have a bigger valve setup so I would throw on two checking springs and do a little math at t.d.c. first!

Fast63 · Oct 5, 2007

5spd GT said:
The thing is, if you are borderline with 1.7's, you will be borderline with 1.6's.

Duration changes are very small.

Exactly.

5spd GT · Oct 6, 2007

If anyone questions p-v clearance due to lift, watch this video:

http://www.youtube.com/watch?v=ec0tczrYuYc

It's 'pot roast' in the 5.0 Talk, but I figured it could help some see what is going on.

To bad it doesn't show the overlap period

dragnazz5.0 · Oct 6, 2007

the thing about 1.7 vs 1.6 rockers is that with 1.7 rockers the valve opens much faster and closes much faster than with 1.6 rockers. so in the real world the valve is coming closer to the piston and sooner than it is with 1.6 rockers. duration does change a little but like said before very minimally.

1.7's....

Member

New Member

Member

"the 5.0 owns all"

Member

"the 5.0 owns all"

Member

Member

Member

Active Member

"the 5.0 owns all"

Member

New Member

New Member

New Member

"the 5.0 owns all"

Active Member

New Member

"the 5.0 owns all"

My "0" key d0esn't w0rk, s0 I have t0 use the zer0

Similar threads

Privacy & Transparency

Privacy & Transparency