1.7 Roller rockers on a 1986 GT?

[Performancestone]

I have a set of 1.7 roller rockers and a B303 cam. Will this work in a 1986 GT. I am using stock heads.

Thanks

 

[HemiRick]

Yes you should be fine a b cam only has .444 lift w 1.6 rockers. With 1.7 it will increase only a little. The limit is about .544

 

[96pushrod]

Lift means almost nothing when it comes to ptv clearance. The piston chases the exhaust valve up, so how long the valve stays open is far more critical.

 

[MustangIIMatt]

If the engine is stock, piston to valve clearance will probably be an issue. The '86 pistons didn't play nice with a lot of cam/rocker combinations.

 

[Performancestone]

If the engine is stock, piston to valve clearance will probably be an issue. The '86 pistons didn't play nice with a lot of cam/rocker combinations.

Thats what I'm worried about. I might just get some 1.6 rockers.

 

[mikestang63]

not worth the hassle for the 15hp IMO

 

[KRUISR]

Yes you should be fine a b cam only has .444 lift w 1.6 rockers. With 1.7 it will increase only a little. The limit is about .544

No that is incorrect. Stock cam is .444 with 1.6 rockers, .472 with 1.7s. B cam is .480 with 1.6 rockers and .510 with 1.7s.

From the specs on the B-cam shown on American Muscle website

Based on the valve timing info, I would say install it straight up (not advanced on multi keyed timing set) and you should have no problem (with 1.6 or 1.7 rockers).

Why... The above says intake starts to open at 5 deg. before TDC and exhaust closed at the same time. Basically when the piston hits top they are essential closed. Would be no interference there. The more advanced the cam gets installed the greater the chance intake valve has opened too much when piston gets to top that would cause interference.

 

[Mustang5L5]

Might want to consider a spring upgrade, for added insurance

 

[Performancestone]

I called Summit Racing and they I'm good to go with the 1.7. I'll give it a shot.

Thanks for the help.

 

[96pushrod]

I called Summit Racing and they I'm good to go with the 1.7. I'll give it a shot.

Thanks for the help.

The summit help line isn’t going to be checking ptv clearance for you, so I don’t know why they would blindly tell you you’ll be alright.

Check ptv before running.

 

[MustangIIMatt]

The summit help line isn’t going to be checking ptv clearance for you, so I don’t know why they would blindly tell you you’ll be alright.

Check ptv before running.

This.

You're dealing with an assortment of mass-produced parts produced to different standards, some of which are used or reconditioned and were possibly altered over time. They can't tell whether you're going to have an issue over the telephone.

 

[Fox86]

I also own a 86GT with GT40 heads and original cam. Not quite sure if this will work with the 1.7 roller rockers. Do you have a idea? My 86 has no valve reliefs/full flat tops.