AFR 165 SBF Renegade heads evaluation

[bmcdaniel]

Roller lifters are taller than flat tappets. A roller cam block has taller lifter bores to accommodate. If you put a standard size roller cam in an old block with stock-type roller lifters the lifters will come up too far out of the bores exposing the oil band and loose oil pressure.

A retrofit cam has it’s lobes ground on a smaller base circle to lower the lifters. Often the small base circle cams aren’t very accurate when compared to their specs and there isn’t as much variety available for grinds. Small base circle cams have be shown to twist and whip when revved up. Somewhere online there's a high speed strobe video that shows this.

Much better to use a standard size cam of your choosing with special link bar lifters that keep the lifter oil band down where it belongs and eliminates the factory “spider and dog bone” lifter retainers.

[Indy998]

Sorry, I missed your reply due to Christmas issues...

Thanks anyway - since I never seriously got into roller cam matters, I wasn't aware of the difference between retrofit and standard rollers. What about wandering camshaft problems with link bar lifters (289 SBF)?

Back to flat tappet cams once more: if I was to achieve a certain amount of valve lift, I could do so with a higher lift cam and 1.6 rockers, or with a slightly milder cam and 1.7 rockers. In theory, the resulting valve lift would be the exact same.

Which one is easier on the lobes? Since it is the valve spring that creates the pressure, I guess there won't be any difference, right?

[GARY C]

Which one is easier on the lobes? Since it is the valve spring that creates the pressure, I guess there won't be any difference, right?

There is no free lunch...you are still dealing with a lever and fulcrum situation, the higher ratio rocker has a less desirable fulcrum point that in creases load on the push point IE: the lobe.
https://www.youtube.com/watch?v=dl0owq4xXgk

[turbo2256b]

Unless I take the roller path. What about wandering retrofit roller cams though? Any experience with it?

Instead of a retrofit cam kit you're better off using a standard full size cam with linked roller lifters. More grinds to choose from and some small base circle cams have been known to bend and twist at rpm.

Most of the link bar lifters are made out of better material than the factory style. That concern is holding me back at the moment fear of breakage of stock rollers at spring pressues currently running and RPMs able to reach.

[Carnut1]

Unless I take the roller path. What about wandering retrofit roller cams though? Any experience with it?

Instead of a retrofit cam kit you're better off using a standard full size cam with linked roller lifters. More grinds to choose from and some small base circle cams have been known to bend and twist at rpm.

Most of the link bar lifters are made out of better material than the factory style. That concern is holding me back at the moment fear of breakage of stock rollers at spring pressues currently running and RPMs able to reach.

I have pushed my luck hard with ford motorsport lifters. 7000 rpm .542 lift with bbc roller springs. Early 90's. Never had an issue, beaten like a red headed step child and still running. Thanks, Charlie

[turbo2256b]

I am running 140 seat pressure and 430 open RPM limit might be as high as 7800 not wanting to push it for now. Not sure but the motorsport lifters might be better quality that the stock ones currently running.

[tomhorn1913]

Mr. Vizard,

I have re-read this thread a couple times, & I can't find any mention of whether you used the 8017 (6500rpm) springs, or upgraded to the 7K pieces. If you kept the "stock" springs, can you offer an opinion of the effect/consequence of using the 7000rpm springs, w/o any other mods?

Much obliged,
Matt