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On a 351w stock bottom end with a non roller block are roller cams, link bar lifters and roller rockers worth it if your on a with in reason penny pinching build?
By penny pinching I mean if its worth it I will get it.
Roller rockers may not be required with the heads you get, so you could save money there, and spend it on roller cam, roller lifters and springs.
Check the manufacturer of the heads.
Edelbrock 60399 heads recommends:
Rocker geometry should be checked making sure that the contact point of the roller or pad on a stock rocker remains properly on the valve tip and does not roll off the edge.
You still have to check everything as you build it.
Pedestal rockers can be shimmed, and different pushrod lengths may be necessary to get correct geometry and preload.
When I put a compcam in a roller 351w block, the stock cam base circle is 'large', and compcam standard size is smaller than the stock 1994 351w roller cam, but not a small circle.
From another thread:
Check the head manufacturer for what type of rockers work.
Here is a quote from Edelbrock with 60399 heads:
With machining the heads, you could probably adapt stud mounted rockers.
Also, I think with a small circle cam and link bar lifters, is safer, in that the lifters will sit in the hole lower, if using a non-roller block.
Non-roller blocks lifter bores are not as tall as a roller block. You don't want your lifters popping out of the bores!
So, with that statement, that should guide you to what cam circle size you should get.
A small base circle cam loads the lifters heavier in the bores because it increases the pressure angle on the rollers. It isn't really "safer". Also when the same master is used the cam shrinks(loses duration) when ground on a smaller base circle.
One time I had a 351C block that had really big chamfers at the tops of the lifter bores, a full size hydraulic roller cam and I think with a Crane lifter it could almost get into the oil band of the lifter. It was probably within about .040 but it worked fine and didn't spill a bunch of oil.
A small base circle cam loads the lifters heavier in the bores because it increases the pressure angle on the rollers. It isn't really "safer". One time I had a 351C block that had really big chamfers at the tops of the lifter bores, a full size hydraulic roller cam and I think with a Crane lifter it could almost get into the oil band of the lifter. It was probably within about .040 but it worked fine and didn't spill a bunch of oil.
Good ol' compromising.
- pressure angle on lifters
- lifters sitting in bore
- cam base circle, strength of cam
I suppose, with link-bar lifters, if the cam base circle was really small, the link bars could hit the top of bore.
I shouldn't have said 'safer', should have said 'depends'.
Good ol' compromising.
- pressure angle on lifters
- lifters sitting in bore
- cam base circle, strength of cam
I suppose, with link-bar lifters, if the cam base circle was really small, the link bars could hit the top of bore.
I shouldn't have said 'safer', should have said 'depends'.
I doubt that you could ever get it small enough that the bars could hit because the hydraulic lifters are already .400 or so taller. I usually use a full size cam with the Morel lifters in a Cleveland build and in a Windsor I use a cam ground on a factory non HO core whenever possible. The design base circle for the DM lobes that I had designed is 1.312 which is usually pretty easy to hit on a full size core.
If I go with a roller cam and link bar lifters in a 1990 351 block do I have to use a small base circle cam?
OK just read somewhere that you can use any cam as long as you use linkbar lifters. So confusing when your learning.
I'm learning right along with you. Found the following helpful info during research:
If using a stock roller 351w F4TE block, has taller bores, has dog bones, and spider/spyder to hold the dog bones.
If using a stock non-roller 351w, earlier than 1993(non F4TE), converting to a roller block you have 2 choices:
1) link bar lifters, and whatever cam you want
-- "crane linked hydraulic roller lifters"
-- "standard old- style large lobe base circle diameter cam"
2) factory spider and dog bones
-- must drill and tap block to hold spyder
-- must use small circle cam
You do not need small base circle cam, nor is it recommended with link bar lifters. Probably stick with the crane setup. I believe its called the "retro fit cam and lifters".
If not using link bar lifters, and using factory dog bone and spyder, you MUST use small base circle cam with HO roller lifters.
I chose the XE-258-HR.
Have Edelbrock truck intake, and pacesetter long tubes.
I'm running tuned Speed Density (SD) EFI.
dyno build, like this, .... yes, ...I'd rather run on a real dyno, but all that is available in my area is $800 for an hour, non-EFI. Stock EFI, Speed Density(SD), XE-258-HR.
Thats nice numbers, I noticed in your thread that you had over 500 lift so that's ok for SD?
So can you get away with bigger lift on a roller cause its graduated.
Honestly, I've never posted the desktop dyno results, I'd really like to compare to real dyno. I might have a chance to take it down the drag strip next year.
The only issue I have had with that cam and SD, is a little bit of a hunting idle, and has stalled out on me a few times backing into my driveway.
Idle tuning on SD is whole nother learning curve, can be done, takes time.
Think of it this way, if a flat tappet lobe looks like > more pointy, and a roller lobe looks like ) rounded, the time of max lift will be more on the roller, and many other attributes.
The amount of lift is not dependent on roller or flat tappet type of cam.
Many variables with what you can get away with "bigger lift": valve geometry, valve stem length, piston to valve clearance, compressed spring height, head design, just to name a few.
Honestly, I've never posted the desktop dyno results, I'd really like to compare to real dyno. I might have a chance to take it down the drag strip next year.
The only issue I have had with that cam and SD, is a little bit of a hunting idle, and has stalled out on me a few times backing into my driveway.
Idle tuning on SD is whole nother learning curve, can be done, takes time.
Think of it this way, if a flat tappet lobe looks like > more pointy, and a roller lobe looks like ) rounded, the time of max lift will be more on the roller, and many other attributes.
The amount of lift is not dependent on roller or flat tappet type of cam.
Many variables with what you can get away with "bigger lift": valve geometry, valve stem length, piston to valve clearance, compressed spring height, head design, just to name a few.
The same exact profile can be ground as either a roller or a flat tappet. The finished cams will be shaped differently but produce identical lifter motion with the roller looking more rounded and the flat tappet more pointy. In other words they aren't as different as they appear.
Did you know that the centerlines of the holes are different on the pedestal vs the stud mount heads? I ran into this when I converted a set of GTP heads to use the old style 289 rockers with guide plates. Jomar makes a special girdle for the application.
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