Pushrod help

motoheada1 · 07-05-2023, 09:20 PM

Hey there

I'm currently finishing up a Gen 1 SBC for my Chevy II. When I went to measure for pushrods, I decided to try a "new to me" method called the half travel method. That method gave me a longer than expected dimension, and tip wear pattern out on the exhaust side of the stem. So I tried the other two methods I've used in the past, the plastic rocker gage, and centering the wear pattern, all with different results. Both the wear pattern and the and the half travel method seem logical, but end up with very different results. Looking for some feedback from the one's that are in the know!!!

Chuck

curtis reed · 07-06-2023, 10:54 AM

Did you change procedures because you had valvetrain problems from the method you were using before?

motoheada1 · 07-06-2023, 11:36 AM

Curtis
Its not that I had any known issues in the past, but once I tried the half travel method and found out it produced the smallest sweep pattern, I have more questions than answers. It leaves me wondering what is more important in term of HP and wear, a centered pattern, or the smallest sweep regardless of its location on the lash cap. I know class racers leave no stone unturned looking for HP, and was hoping to find come help here.

Chuck

curtis reed · 07-06-2023, 12:00 PM

Gotcha, thanks Chuck

I know which I prefer but there is so much more knowledge on here I don't feel like I should throw my hat in this ring. I just wondered why the change.

Rich Biebel · 07-06-2023, 12:35 PM

If you're talking about a Stocker....you'll find the total lift at the valve will change with different pushrod lengths. Not a lot but a measurable amount

I look at the overall picture and try to get the wear pattern centered and also no interference issues like rockers hitting retainers underneath the arch.

Use an adjustable length pushrod and try different lengths

I never used the 1/2 lift method but I'm sure it's valid and some do.

Small blocks have poor geometry with stud mounted rockers....as do big blocks on some locations....

Shaft rockers corrects those problems but are not legal on a stocker unless it came with them I believe....

motoheada1 · 07-06-2023, 03:06 PM

Rich

Stud mounted rockers are a budget decision, and there are no clearance issues with any of the three length's I came up with.

1. pattern centered on lash cap- .657 valve lift, rocker short of 90 degrees to stem, and the largest sweep width. 7.975 pushrod length.

2. used plastic Moroso rocker ratio tool. .662 valve lift Pattern slightly towards exhaust side of cap, but much narrower than #1. rocker still slightly short of 90 degrees to stem. 8.060 pushrod length.

3. Rocker 90 degrees to stem [half lift method] .660 valve lift. Smallest sweep, but pattern still slightly towards exhaust side of lash cap. 8.100 pushrod length.

Chuck

dragracerray · 07-06-2023, 03:12 PM

Quote:

Originally Posted by motoheada1

Hey there

I'm currently finishing up a Gen 1 SBC for my Chevy II. When I went to measure for pushrods, I decided to try a "new to me" method called the half travel method. That method gave me a longer than expected dimension, and tip wear pattern out on the exhaust side of the stem. So I tried the other two methods I've used in the past, the plastic rocker gage, and centering the wear pattern, all with different results. Both the wear pattern and the and the half travel method seem logical, but end up with very different results. Looking for some feedback from the one's that are in the know!!!

Chuck

Chuck,
I don't know if I am "in the know" but here is what I do. I always to rocker geometry measurements with the intake off. First thing I do is make my own adjustable pushrod. If you have fancy ends on your race pushrods you would have to cut up a fancy pushrod to make an adjustable pushrod. Cover the end of the valve with Sharpe. Install the adjustable pushrod with the adjustable end near the lifter where you have more room. Lash the valve. Rotate the engine from zero cam lift to max cam lift back down to zero cam lift. If you can not see the witness mark clearly in the Sharpe than rotate engine again. When you have a good image remove the rocker and inspect the witness mark. If the the witness mark is not centered on the valve readjust the pushrod and repeat. When you are satisfied borrow a dial vernier that is big enough to accurately measure the pushrod you want. As others have said make sure you have no interferences rocker to retainer, rocker to stud etc. Ray

Adger Smith · 07-06-2023, 04:06 PM

Don't get the pushrod so long that it is pushing on the rocker cup at an odd angle and increasing the load and stress on parts. I would sacrifice a pattern or few thousands in lift to keep the pushrod and cup in the right position.
as that cup goes up and in toward the stud the load on the cam, pushrod and lifter increases. IMHO too much attention to the valve side can create other issues when compromise is necessary.
I always used my Cam Pro Plus to plot valve movement.
I always considered the real issue getting the geometry where the cam profile is transferred/duplicated at the valve.
There you go Curtis Reed.....
Well said, Rich

07-06-2023, 10:54 AM	#2
curtis reed Member Join Date: Jul 2011 Location: Kiefer, Ok. Posts: 139 Likes: 46 Liked 89 Times in 50 Posts	Re: Pushrod help Did you change procedures because you had valvetrain problems from the method you were using before?

07-06-2023, 11:36 AM	#3
motoheada1 Junior Member Join Date: Mar 2023 Posts: 8 Likes: 5 Liked 4 Times in 2 Posts	Re: Pushrod help Curtis Its not that I had any known issues in the past, but once I tried the half travel method and found out it produced the smallest sweep pattern, I have more questions than answers. It leaves me wondering what is more important in term of HP and wear, a centered pattern, or the smallest sweep regardless of its location on the lash cap. I know class racers leave no stone unturned looking for HP, and was hoping to find come help here. Chuck

07-06-2023, 12:00 PM	#4
curtis reed Member Join Date: Jul 2011 Location: Kiefer, Ok. Posts: 139 Likes: 46 Liked 89 Times in 50 Posts	Re: Pushrod help Gotcha, thanks Chuck I know which I prefer but there is so much more knowledge on here I don't feel like I should throw my hat in this ring. I just wondered why the change.

07-06-2023, 12:35 PM	#5
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,275 Likes: 25 Liked 510 Times in 200 Posts	Re: Pushrod help If you're talking about a Stocker....you'll find the total lift at the valve will change with different pushrod lengths. Not a lot but a measurable amount I look at the overall picture and try to get the wear pattern centered and also no interference issues like rockers hitting retainers underneath the arch. Use an adjustable length pushrod and try different lengths I never used the 1/2 lift method but I'm sure it's valid and some do. Small blocks have poor geometry with stud mounted rockers....as do big blocks on some locations.... Shaft rockers corrects those problems but are not legal on a stocker unless it came with them I believe.... __________________ Rich Biebel S/C 1479

07-06-2023, 03:06 PM	#6
motoheada1 Junior Member Join Date: Mar 2023 Posts: 8 Likes: 5 Liked 4 Times in 2 Posts	Re: Pushrod help Rich Stud mounted rockers are a budget decision, and there are no clearance issues with any of the three length's I came up with. 1. pattern centered on lash cap- .657 valve lift, rocker short of 90 degrees to stem, and the largest sweep width. 7.975 pushrod length. 2. used plastic Moroso rocker ratio tool. .662 valve lift Pattern slightly towards exhaust side of cap, but much narrower than #1. rocker still slightly short of 90 degrees to stem. 8.060 pushrod length. 3. Rocker 90 degrees to stem [half lift method] .660 valve lift. Smallest sweep, but pattern still slightly towards exhaust side of lash cap. 8.100 pushrod length. Chuck

07-05-2023, 09:20 PM	#1
motoheada1 Junior Member Join Date: Mar 2023 Posts: 8 Likes: 5 Liked 4 Times in 2 Posts	Pushrod help Hey there I'm currently finishing up a Gen 1 SBC for my Chevy II. When I went to measure for pushrods, I decided to try a "new to me" method called the half travel method. That method gave me a longer than expected dimension, and tip wear pattern out on the exhaust side of the stem. So I tried the other two methods I've used in the past, the plastic rocker gage, and centering the wear pattern, all with different results. Both the wear pattern and the and the half travel method seem logical, but end up with very different results. Looking for some feedback from the one's that are in the know!!! Chuck

07-06-2023, 04:06 PM	#8
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,348 Likes: 434 Liked 677 Times in 261 Posts	Re: Pushrod help Don't get the pushrod so long that it is pushing on the rocker cup at an odd angle and increasing the load and stress on parts. I would sacrifice a pattern or few thousands in lift to keep the pushrod and cup in the right position. as that cup goes up and in toward the stud the load on the cam, pushrod and lifter increases. IMHO too much attention to the valve side can create other issues when compromise is necessary. I always used my Cam Pro Plus to plot valve movement. I always considered the real issue getting the geometry where the cam profile is transferred/duplicated at the valve. There you go Curtis Reed..... Well said, Rich __________________ Adger Smith (Former SS)