roller rocker question
Thread Starter
Racer
Joined: Jul 2004
Posts: 468
Likes: 12
From: Pleasant Hill CA
roller rocker question
i am in the process of rebuilding 350 small block engine. i am planning on going to a 1.6 roller rocker instead of a 1.5 rocker. my friend told me not to go to a
1.6 rocker as it will not give me any benefit as he said my heads would not support the increase in lift,. He also said by going to a higher lift rocker it will put more
stress and pressure on my rocker arm assembly. Just wondering if this is true or not ? if it does not help my perfornance or dependability of the engine i will just
go with the 1.5 rockers? please give me so advice and recommendations on this thanks i already have the 1.6 rockers but i can send em back and get 1.5 rockers. thanks for all your input and help and knowledge on this.
1.6 rocker as it will not give me any benefit as he said my heads would not support the increase in lift,. He also said by going to a higher lift rocker it will put more
stress and pressure on my rocker arm assembly. Just wondering if this is true or not ? if it does not help my perfornance or dependability of the engine i will just
go with the 1.5 rockers? please give me so advice and recommendations on this thanks i already have the 1.6 rockers but i can send em back and get 1.5 rockers. thanks for all your input and help and knowledge on this.
Race Director
Joined: Nov 2003
Posts: 10,696
Likes: 3,091
From: Cottonwood AZ
C1 of Year Finalist (performance mods) 2019
What are the specs on your cam?
What heads do you have. Aftermarket or stock? If stock have they been pocket ported/ported/polished?
Are you running head? If you are running stock manifolds are the 2 1/2” ram horns?
What heads do you have. Aftermarket or stock? If stock have they been pocket ported/ported/polished?
Are you running head? If you are running stock manifolds are the 2 1/2” ram horns?
Race Director
Joined: Feb 2007
Posts: 15,468
Likes: 8,950
From: northern california
C2 of Year Finalist (track prepared) 2019
i am in the process of rebuilding 350 small block engine. i am planning on going to a 1.6 roller rocker instead of a 1.5 rocker. my friend told me not to go to a
1.6 rocker as it will not give me any benefit as he said my heads would not support the increase in lift,. He also said by going to a higher lift rocker it will put more
stress and pressure on my rocker arm assembly. Just wondering if this is true or not ? if it does not help my perfornance or dependability of the engine i will just
go with the 1.5 rockers? please give me so advice and recommendations on this thanks i already have the 1.6 rockers but i can send em back and get 1.5 rockers. thanks for all your input and help and knowledge on this.
1.6 rocker as it will not give me any benefit as he said my heads would not support the increase in lift,. He also said by going to a higher lift rocker it will put more
stress and pressure on my rocker arm assembly. Just wondering if this is true or not ? if it does not help my perfornance or dependability of the engine i will just
go with the 1.5 rockers? please give me so advice and recommendations on this thanks i already have the 1.6 rockers but i can send em back and get 1.5 rockers. thanks for all your input and help and knowledge on this.
That hardly seems like enough of an increase to be concerning. Said differently, if a force increase of 6.7% breaks valve train parts, it wasn't a very good valve train to start with.
FWIW, on the engine in my vintage racer, I run 1.6:1 rockers on the intake valves (only). Although they provide a little extra lift, my reason for using them is to give the valve spring more leverage when it comes time to set the relatively heavier intake valve back down on its seat and to get the rest of the valve train back on the base circle of the cam. It buys me a few more RPM.
Thread Starter
Racer
Joined: Jul 2004
Posts: 468
Likes: 12
From: Pleasant Hill CA
cam. AFR aluminum enforcer heads. Full length
hefman headers. Cam spec is intake duration is
299 exhaust duration is 319. Lift is 533 intake and
519 exhaust on a 1.5 rocker. Thanks for your
help
Race Director
Joined: Jan 2000
Posts: 13,019
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
You'll pick up about .035" lift on the intake side for example and add a slight amount of duration. The Thumper cams already have a fair amount of duration and overlap...so be aware the manners may not get worse...but won't get any better.
1.6 rockers on relatively low lift cams usually helps a little...depends on the heads. How much does flow increase between .500-.550 or so lift?
They won't help reliability...but not really hurt anything either. Make sure pushrods clear as they will get moved inward somewhat.
JIM
1.6 rockers on relatively low lift cams usually helps a little...depends on the heads. How much does flow increase between .500-.550 or so lift?
They won't help reliability...but not really hurt anything either. Make sure pushrods clear as they will get moved inward somewhat.
JIM
Race Director
Joined: Nov 2003
Posts: 10,696
Likes: 3,091
From: Cottonwood AZ
C1 of Year Finalist (performance mods) 2019
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Thread Starter
Racer
Joined: Jul 2004
Posts: 468
Likes: 12
From: Pleasant Hill CA
Roller rovkets
You'll pick up about .035" lift on the intake side for example and add a slight amount of duration. The Thumper cams already have a fair amount of duration and overlap...so be aware the manners may not get worse...but won't get any better.
1.6 rockers on relatively low lift cams usually helps a little...depends on the heads. How much does flow increase between .500-.550 or so lift?
They won't help reliability...but not really hurt anything either. Make sure pushrods clear as they will get moved inward somewhat.
JIM
1.6 rockers on relatively low lift cams usually helps a little...depends on the heads. How much does flow increase between .500-.550 or so lift?
They won't help reliability...but not really hurt anything either. Make sure pushrods clear as they will get moved inward somewhat.
JIM
so for reliability maybe I should just go with 1.5?
what would u do? I think I would rather have the
reliabilty and less stress on the rocker assembly??
what would u do?? Should I use the 1.6 on intake
and 1.5 on exhaust? I like the performance but
also like and want reliability? This is all new and
dont want the engine to break down in 6 months?
i am no racing it just. Drive it on the street but
maybe take it to the strip once or twice a year
mostly drive it to the car shows and it’s not a daily
driver so I would like it to be dependable and last.
Thread Starter
Racer
Joined: Jul 2004
Posts: 468
Likes: 12
From: Pleasant Hill CA
Roller rockers
Jim
one other question . I do have a 4 spd do u think
that this cam is too big for the street and will cause
any drivability? I drive mostly on the freeway but
also to the car shiws locally. Thanks for your help
and knowledge and advice.
just don’t want any drivability problems.
one other question . I do have a 4 spd do u think
that this cam is too big for the street and will cause
any drivability? I drive mostly on the freeway but
also to the car shiws locally. Thanks for your help
and knowledge and advice.
just don’t want any drivability problems.
Team Owner
Joined: Nov 2005
Posts: 28,226
Likes: 2,872
From: Beach & High Desert Southern California
When I put 1.6 rockers on my ported Bowtie Phase 6 heads with the 0.352 lobe lift Isky cam (0.563 valve lift) in my 350, I found major pushrod rub, and had to machine the head's pushrod passages larger. I was sweating the potential to break into an intake port, but each pushrod hole machined clean.
You never know what to expect, so check everything.
Race Director
Joined: Jan 2000
Posts: 13,019
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Jim
one other question . I do have a 4 spd do u think
that this cam is too big for the street and will cause
any drivability? I drive mostly on the freeway but
also to the car shiws locally. Thanks for your help
and knowledge and advice.
just don’t want any drivability problems.
one other question . I do have a 4 spd do u think
that this cam is too big for the street and will cause
any drivability? I drive mostly on the freeway but
also to the car shiws locally. Thanks for your help
and knowledge and advice.
just don’t want any drivability problems.
The cam uses relatively mild/soft opening lobes so longevity should be fine..
The 1.6's aren't going to be bad for reliability. You're not going to be pushing things too far out of the envelope. Not sure which new rockers you have but if comparing to stockers....they don't actually come in with a true 1.5 ratio...usually much less....more in the 1.40's...so adding 1.6's will get the true lift the cam is supposed to produce.
There are better cam choices for overall street performance especially if a roller cam comes into the picture.
JIM