Solid rollers with off set push rod hole issue.

-
G

gg408

Active Member
Joined
Jan 20, 2012
Messages
31
Reaction score
6
Location
Australia
Hey the peeps.
Have a set o BAM solid roller lifters in my SBM with .180"offset pushrod hole on the intake.
Recently damaged 2 intake lobes and the other 6 intake lobes have the same witness/wear marks.
Was wondering if the pushrod offset could be causing this issue.
Has anyone use offset lifters and had issues.
Thx.
1714987901654.png
 
I would think that if it was the offset, all the intake lobes would be affected. My buddy tried a set of Crane roller lifters years ago, with a R block W7 heads. The first run on the engine snapped the tie bar holding the lifters together. His thought was the offset put a side load on the lifter and tie bar and snapped the tie bar. So he put a normal set in
 
looks like the lobe is not parallel to the roller axis....cam not grinded correctly? or due to lifter bore wear the offset creates a uneven force on the cam surface?

Michael
 
Can't tell exactly if that damage is on the nose of the cam or the front or back side. From the pic, it looks like what we would call spalling which is due to excessive Hertz stresses from too much spring pressure for the material and/or incorrect or insufficiant heat treat. For example, iron core cams will spall before steel core ones, etc, etc. OEMs spend a LOT of time working to get this right as some of the cams are more aggressive than you'd think and can lead to this if the prod processes veer off where they're supposed to be.

Spalling typically occurs over the nose of the cam for engines that idle a lot (i.e. police cars, taxis, etc) but can also happen to those driven at low rpms. If it's on the front side of the lobe, the stresses go up due to the acceleration rates of the cam profile and higher rpm's and, if the stresses exceed the material strength, you get that type of spalling. If it looks like all of the damage is offset to the side where the pushrod loads would be the most, this type of failure could well be the issue.

Not saying for sure that's what it is as I can't see it in my hands to review but it looks mighty similar.
 
First thing I would check: does the offset on the lifter line up with the side of the lobe that is damaged. If so, that could point to edge loading. That can be made worse by the lifter being loose[r] in the bore ; also the roller having too much play in the brgs [ or bush ]. All of these variations in tolerance could stack up the wrong way to load just one side of the lobe. Instead of the load on the lobe being apportioned across the full 3/8" width of the roller, the load is being concentrated on a narrower, one sided, portion of the roller.
 
Thank you all for the replies.
The damage on the lifter is on the opening side of the ramp just before the top. The lifter bores where bushed for flat tappet solid lifers that measured .904"and these BAM lifters measure .903", so the clearance is about .0028" atm with the BAM's.
Spring pressure are 255 lbs on seat and 560lbs over the nose.
Cam specs are 255/262 deg @ .050", 112 lobe sep, lobe lift .399'intake .409'exhaust with 1.5 rockers.
All intake lobes have same wear pattern , runs on one side lobe , runs flat across the top then runs on the opposite side of the lobe going down. its as if its trying to turn twist the lifter.
This has me stumped
 
gg408 said:
Thank you all for the replies.
The damage on the lifter is on the opening side of the ramp just before the top. The lifter bores where bushed for flat tappet solid lifers that measured .904"and these BAM lifters measure .903", so the clearance is about .0028" atm with the BAM's.
Spring pressure are 255 lbs on seat and 560lbs over the nose.
Cam specs are 255/262 deg @ .050", 112 lobe sep, lobe lift .399'intake .409'exhaust with 1.5 rockers.
All intake lobes have same wear pattern , runs on one side lobe , runs flat across the top then runs on the opposite side of the lobe going down. its as if its trying to turn twist the lifter.
This has me stumped
Click to expand...

That’s not that low of spring load, but RPM and valve train weight matter.

Every time I’ve seen that the valve train is not happy. And the heat treat was off. Of course, the cam grinders will never say the core was heat treated wrong.

You have to send it to a 3rd party and have them test it if you really want to know.

Sometimes something as simple as lowering or raising spring pressure will clean it up. Or a stiffer pushrod. Or even a different retainer.
 
When I was in the planning stages of building my 434 in one of our conversations Brett told me not to run an offset seat roller lifter. I didn't ask why and took his advice.
 
gg408 said:
Thank you all for the replies.
The damage on the lifter is on the opening side of the ramp just before the top. The lifter bores where bushed for flat tappet solid lifers that measured .904"and these BAM lifters measure .903", so the clearance is about .0028" atm with the BAM's.
Spring pressure are 255 lbs on seat and 560lbs over the nose.
Cam specs are 255/262 deg @ .050", 112 lobe sep, lobe lift .399'intake .409'exhaust with 1.5 rockers.
All intake lobes have same wear pattern , runs on one side lobe , runs flat across the top then runs on the opposite side of the lobe going down. its as if its trying to turn twist the lifter.
This has me stumped
Click to expand...
Lack of lube?? What is the oil hole size in the lifter bore bushings?
 
gg408 said:
Thank you all for the replies.
The damage on the lifter is on the opening side of the ramp just before the top. The lifter bores where bushed for flat tappet solid lifers that measured .904"and these BAM lifters measure .903", so the clearance is about .0028" atm with the BAM's.
Spring pressure are 255 lbs on seat and 560lbs over the nose.
Cam specs are 255/262 deg @ .050", 112 lobe sep, lobe lift .399'intake .409'exhaust with 1.5 rockers.
All intake lobes have same wear pattern , runs on one side lobe , runs flat across the top then runs on the opposite side of the lobe going down. its as if its trying to turn twist the lifter.
This has me stumped
Click to expand...
Also, even tho' Your pic presents the lift side of #8 intake, I can see #7 looks bad as well. Could You post a pic of the lift side of #7 for Us?
 
Killer6 said:
Lack of lube?? What is the oil hole size in the lifter bore bushings?
Click to expand...
Oil hole size is .059””
Killer6 said:
Also, even tho' Your pic presents the lift side of #8 intake, I can see #7 looks bad as well. Could You post a pic of the lift side of #7 for Us?
Click to expand...
Have taken the cam back to the grinders. All intake lobes have the same markings , only#2 & #8 intake lobes are damaged.Maybe I caught it in time before they all become like that.
 
Any exhaust lobe wear indications?
 
gg408 said:
Oil hole size is .059””

Have taken the cam back to the grinders. All intake lobes have the same markings , only#2 & #8 intake lobes are damaged.Maybe I caught it in time before they all become like that.
Click to expand...
I was curious to see the position & progression of the spalling pattern on a 'mirror offset' lobe. That's not a ton of lube, I'd run that past the grinder for input, best of luck & keep Us posted...
 
Maybe the lifter bore bushes are not perpendicular to the cam. Side loading, post #6.
 
Bewy said:
Maybe the lifter bore bushes are not perpendicular to the cam. Side loading, post #6.
Click to expand...
That’s getting checked now but I would have thought if that was the case why all intakes have same witness marks and exhaust are ok.
 
Killer6 said:
I was curious to see the position & progression of the spalling pattern on a 'mirror offset' lobe. That's not a ton of lube, I'd run that past the grinder for input, best of luck & keep Us posted...
Click to expand...
Plenty oil going to lifter. If I could up load vid you would be amazed out how much oil flows past the lifter.
 
Killer6 said:
gg408 said:
Plenty oil going to lifter. If I could up load vid you would be amazed out how much oil flows past the lifter. Here is another pic of the cam. Also a pic of oil flow to lifter.
Click to expand...

I was curious to see the position & progression of the spalling pattern on a 'mirror offset' lobe. That's not a ton of lube, I'd run that past the grinder for input, best of luck & keep Us posted...
Click to expand...

IMG_9750.jpeg


IMG_9767.png
 
gg408 said:
No just the intake.
Click to expand...
Assuming valve springs are set up the same, spalling on the intake only suggests it's an issue of the larger forces involved due to the heavier intake valve. I doubt the heat treat or core is any different intake vs exhaust so we're back to an insufficient heat treat or material for the stresses involved.
 
gg408 said:
View attachment 1716247041

View attachment 1716247042
Click to expand...
They do appear to be getting plenty of oil, but I am concerned about how close the intake pushrods are to the lifter bore wall with the offset lifter. That's got to be creating a bunch of side load on the lifter. On the 72 Dart I had previous I was running W2 heads with a solid roller cam, but the lifters I used had no offset. You may want to look into no offset lifters, as they will help get the pushrod away from the lifter bore wall and center up the load on the lifter itself.
 
I have never seen anything adverse from running offset lifters.

Like I said, when I see that I look at spring load and heat treating.

One other thing it could be is pushrod flex. The incredible loads generated by pushrod flex is real.
 
You must log in or register to reply here.
-

Back
Top