Pushrod problem with Speedmaster heads

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dart_68

dart_68

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Problem I've got is that the pushrods are contacting the head at the bottom of the pushrod tunnel above the lifters. Anyone else encountered this? If not, you might want to check your pushrods for contact/rubbing in this area.

Problem is that I don't know how to correct it...any ideas?

360 LA, hydraulic roller cam & lifters, 273 adj. rockers, Smith Bros. pushrods. No milling of either block or head deck.
 
I went through that with edelbrock LA heads on a magnum block, my son's latest motor. What made it a pain was I had tubed the pushrod holes for porting. I had to grind the tube up about a 1/2". I had to use a dull carbide because a good one kept wanting to grab the tubes.
 
I'm thinking I'm going have to grind the bottom as well. Pull the heads, replace for mock up and check, rinse and repeat as necessary.
 
Large push rod holes roller cam engine:

1020161100.jpg
 
Not an issue, more like a situation to look for with any head and build short of all stock parts. And yes mine did this and got worse when I did a rocker geometry correction kit. Had to open the holes and used different rockers.
 
I didn't notice any issue with pushrods when I installed mine. Using factory stamped rockers from the LA heads
 
How well do the rockers line up on the valves. If not would shilling it over help??? If so does it clear now??? Thin shims available at summit.
 
I had the same issues, especially with the geometry correction kit. I have some pictures and how far I needed to machine in a thread.

Pushrod Rub (Intake side of head)

I also shimmed the rockers towards each other some to gain extra room. I had the heads off 3 times and the rockers on/off apart at least 6
 
@B3RE

Maybe Mike @ b3 can help, he is the man on valvetrain geometry
 
Heywodja said:
@B3RE

Maybe Mike @ b3 can help, he is the man on valvetrain geometry
Click to expand...

Mike and his kits are awesome. In my case the correction kit caused this issue to become worse. Not B3's issue or problem, its just where the Comp rocker lined up with my valve tips to get the geometry correct. Its just the way it goes. A different set of rockers (Hughes) lined up better than the Comps with no correction, and got rid of my push rod clearance issue (FYI we did open up the ends of my heads to help but it wasn't enough). High lobe lifts and/or lifters with taller push rod cups (i.e. roller lifters) will exasperate the problem by shortening the push rod and angling the push rod even more and you actually loose lift.

If you've ever assembled an engine with canted valves you can see this in a more dramatic way, but most of those use studs and you can move the rocker with a longer or shorter push rod to correct the geometry some (I say "some" because no two brands of rocker pivot to roller to push rod cup are the same) where as with shaft mount and cast pedestals, you can't unless raising the shafts helps the geometry in some cases.
 
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And that’s why you did not have a problem.
Had it been a roller.....
 
rumblefish360 said:
Common issue.
Click to expand...
This.
All 'LA' heads with the exception of the 308/302/714 castings all have smaller push rod hole for the flat tappet cams they used.
Grind the push rod holes top and bottom like an hour glass..basically the top toward the valve cover rail and the bottom toward the chambers. Here are my '70 J heads I run a roller cam with.

20201101_135227.jpg


20201101_135158.jpg
 
Here are before and after pictures. I drilled the holes out to 9/16" (were 1/2") and ground the bottoms out.

Pushrod before.jpg


Head clearance for pushrod.jpg
 
Yup, i have the same issue.
My question.
* I am mocking up on a stock 5.9

just to get a look at the amount I’ve ground away + push rod length.
Been chewin away at the heads and all clear. But, the engine I’m going to actually install on, the cam has a higher lift. And
* will an aftermarket cam have the same base circle for clearance and push rod length considerations?
When I go to swap out heads on the intended recipient engine, I would like no surprises.
 
I opened the pushrod holes 2 weeks ago on Eddy heads for a 408. Tilted the head 5° Ran a end mill down 1 inch. Problem solved.

IMG_1659.jpg
 
About right w me. Roller right?
But had to do by hand.
Do Anything on the top side?
i had to clear the side toward the shaft. But I’ve seen were folks have cut half way thru the valve cover rail.
Is that because of pedestal rockers? Or high rocker ratio?
Or the product they were using.
?
 
6pak said:
About right w me. Roller right?
But had to do by hand.
Do Anything on the top side?
i had to clear the side toward the shaft. But I’ve seen were folks have cut half way thru the valve cover rail.
Is that because of pedestal rockers? Or high rocket ratio?
Click to expand...
Yes roller lifters. Nothing on the top side. Yes I have comp cam roller rockers.
 
George Jets said:
Large push rod holes roller cam engine:

View attachment 1715623794
Click to expand...

From what I read from some one who claimed he knew the person who designed those ports was that the large pushrod hole was not for clearance but to induce swirl. If that is the case then that would explain the narrow port design of the magnums.
 
Large holes because roller lifters are taller. Easier for the manufacturing process to drill round and bigger, than to elongate.
My opinion.

next. I got to figure push rod length.
I have questions on how to determine. the old “stick 2 threads of the the adjuster down”. Jus doesn’t seem like the answer, w all this “china” stuff out there.

I would think the ball pivot should be below the fulcrum center, what ever threads are showing.
 
Higher lobe lift is obtained by reducing the cam BC; which may require different prods.
 
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