Re: Hydraulic roller lifters !

dfree383 October 2nd 2017, 10:45 pm

SandHillsHillbilly wrote:
gt350hr wrote: Chris ( Straub)
The "issue" I read a few pages back seemed to be the raised pushrod seat in the hyd roller increasing the pushrod angularity though the guide plate and offsetting the roller tip at the valve. This is supposed to side load the rocker and the guide causing premature failure of both. This could be solved with a reduced base circle cam to allow a "standard length" pushrod to be used. ( at least as I see it)
It is my understanding the Ford test engines used a 5/16 "production" pushrod which at it's length has the integrity if a wet noodle. 5/16ths pushrods "were" 90% of the "valve train geometry" issues the Boss 302 and 351C engines had/have. A 3/8ths heavy wall ( or bigger) nearly eliminates the issue. Worse on the 429-460 and 351M-400 engines.

I don' know. Is it possible to reduce the base circle 0.500"?

Don't know about a 1/2" but they sure reduced it on the factory 5.0 stuff

gt350hr October 3rd 2017, 10:59 am

ONE inch is the practical limit on base circle diameter , even that becomes "twisty" with high spring loads. It also shortens cam timing a small amount ( at the valve).

Carl October 3rd 2017, 12:12 pm

SandHillsHillbilly wrote:I don' know. Is it possible to reduce the base circle 0.500"?

I'm gonna say no. Probably not enough material there to maintain structural integrity if you make it that small.

Hydraulic roller lifters ! - Page 4 10672259_724064410962242_9097640559963318501_n

Hydraulic roller lifters ! - Page 4 10672259_724064410962242_9097640559963318501_n

SandHillsHillbilly October 3rd 2017, 12:15 pm

gt350hr wrote: ONE inch is the practical limit on base circle diameter , even that becomes "twisty" with high spring loads. It also shortens cam timing a small amount ( at the valve).

The good part of that is the cam drive and oil pump drive are at the same end of the cam. I don't think the spring loads will be all that high with hyd rollers unless for some strange reason you are looking for higher rpms. Just browsing off the shelf Lunati Hyd Roller cams the biggest cam (20340713 61613) the recommended springs are only 402 pounds open load.

gt350hr October 4th 2017, 1:32 pm

I'll figure it out on my own.

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