Roller rockers, difference between brands?

[skinny z]

I did get an email from Harland Sharp today. Here is what Randy said.

"Our standard Chevy rocker is 1.440 long
We make a short version that is 1.344 Long.

Let me know what you think. If you need something in-between we can do that too.

Randy Becker Jr.
Harland Sharp / Custom Speed Parts"


Sounds like they have us covered, all we gotta do is ask.

Sounds about as vague as you could get.
Shorter?
I've not a clue as to what's meant by that although I can guess.
As far as the Crower's go, it clearly described that the only difference in the rocker arm assembly is that the hole for the stud mount in the trunnion is located "x" distance offset from their traditional offering.
I'll be watching for your "product review"!

[smokie]

I'm going to try to try one these this weekend and see how it goes.
The way I'm reading the email is the difference between the standard and backset is .100". I assume that's center of the trunion to the center of the roller. Being that I'm so far out on the edge of the valve, this will probably work out fine. Probably just to the inside of the center, but who knows untill the shit is bolted on and adjusted.

Someone turned me into these. They have the same heads and ran into the same problem. The box does say for afr, so that may be the afr enforcer which is the same heads I have, just under a different brand name. Again, who knows.

[Tom68]

Sounds about as vague as you could get.
Shorter?
I've not a clue as to what's meant by that although I can guess.
As far as the Crower's go, it clearly described that the only difference in the rocker arm assembly is that the hole for the stud mount in the trunnion is located "x" distance offset from their traditional offering.
I'll be watching for your "product review"!

It'd have to be an offset trunion, otherwise the pushrod will be moved to far to keep the ratio.

[skinny z]

Sounds about as vague as you could get.
Shorter?
I've not a clue as to what's meant by that although I can guess.
As far as the Crower's go, it clearly described that the only difference in the rocker arm assembly is that the hole for the stud mount in the trunnion is located "x" distance offset from their traditional offering.
I'll be watching for your "product review"!

It'd have to be an offset trunion, otherwise the pushrod will be moved to far to keep the ratio.

Hey Tom. You'd think that would be the case. But with the stack of evidence here demonstrating the thread's question of differences between brands, it seems you just don't know what you're getting.
The Crower trunnions are clearly drilled off centre. Let's see what smokie gets.

As a follow up, I approached Crower once again about rebuild kits for their rocker arms, and again they went silent.

[smokie]

Sounds about as vague as you could get.
Shorter?
I've not a clue as to what's meant by that although I can guess.
As far as the Crower's go, it clearly described that the only difference in the rocker arm assembly is that the hole for the stud mount in the trunnion is located "x" distance offset from their traditional offering.
I'll be watching for your "product review"!

It'd have to be an offset trunion, otherwise the pushrod will be moved to far to keep the ratio.

Not necessarily. It could have a shorter nose and the pushrod cup could be relocated to adjust for keeping the ratio. I'll try to pull one out this evening and check it out. The trunion may be offset, but it doesn't look like it in the packaging.

[Tom68]

Sounds about as vague as you could get.
Shorter?
I've not a clue as to what's meant by that although I can guess.
As far as the Crower's go, it clearly described that the only difference in the rocker arm assembly is that the hole for the stud mount in the trunnion is located "x" distance offset from their traditional offering.
I'll be watching for your "product review"!

It'd have to be an offset trunion, otherwise the pushrod will be moved to far to keep the ratio.

Not necessarily. It could have a shorter nose and the pushrod cup could be relocated to adjust for keeping the ratio. I'll try to pull one out this evening and check it out. The trunion may be offset, but it doesn't look like it in the packaging.

It could be but that's around 150 thou further outboard for the top of the pushrod instead of 100 thou further inboard for the offset fulcrum.
It also means a tighter arc for the roller tip making a wider seeep.
It also means more pushrod cup angularity, with a highlift cam that could end up dictating your rocker height.
Also if Jesel is right about rocker length you'll add more drag to the engine, can't see that myself.

[smokie]

I tried a backset Harland Sharp out tonight. I used the mid lift method and came up with needing a 7.450" pushrod. However, the sweep pattern was about .072" wide.

IMG_20230121_185926424.jpg

Then I tried a 7.550" pushrod and the sweep got smaller, around .045".

IMG_20230121_192550743.jpg

I'm not sure exactly what to do. I'm going to check it again tomorrow and double check my measurements. Just so everyone knows, my pushrod length checker is to fat to fit in the guide plate, so I had to remove it, but I used it as a spacer to keep the stud from bottoming out.

[Tom68]

I tried a backset Harland Sharp out tonight. I used the mid lift method and came up with needing a 7.450" pushrod. However, the sweep pattern was about .072" wide.

Then I tried a 7.550" pushrod and the sweep got smaller, around .045".

Sounds like your 7.55 is closer to mid lift, did you measure actual valve travel with each pushrod length ? and ideally you'd be plotting that against crank degrees.

[smokie]

Sounds like your 7.55 is closer to mid lift, did you measure actual valve travel with each pushrod length ? and ideally you'd be blotting that against crank degrees.

No I didn't. I don't have a dial indicator or degree wheel. I need to get both.

[HQM383]

This might add to this thread discussion.

Pulling an engine down today and it thought I’d measure the effect of different length pushrods on actual ratio of lifter rise v valve lift. Comp cams 1.6:1 rocker used, valve lash set at .018” per cam card for each test. Theoretical peak valve lift should be .544”.

Lifter rise @ tdc measured at .107”
Peak lift .316”

With 8.000” pushrod valve lift @ tdc .137” = 1.28:1 actual ratio. Peak lift .504” = 1.59:1 ratio
With 8.150” pushrod valve lift @ tdc .142” = 1.32:1 actual ratio. Peak lift .522” = 1.65:1 ratio

[bobmc]

my ignorance wonders why you measure valve lift at TDC? what do you learn from this number?

[HQM383]

my ignorance wonders why you measure valve lift at TDC? what do you learn from this number?

1. In this instance an easily repeatable reference point using confirmed balancer timing mark.
2. I’ll be changing cams soon and my engine has low pcv clearance. Using comp cams lobe catalog I can now look at tappet lift @ tdc and multiply it by 1.28 if using 8.00” pushrods and not multiply by theoretical 1.6
3. Although it’s not at the valve, tappet lift @ tdc is an easy way to dial in cam.