"Do not allow over clearancing for the pushrod. This may cause the pushrod to move around or deflect more than needed. Clearance of .010 at the closest point, wherever that may be during its complete cycle is sufficient. The cylinder head and engine block can often be utilized like a big guide plate and dampening device, which stabilizes the pushrod. Just make sure that there is no interference problems when turning the engine over on the engine stand."

http://www.mantonpushrods.com/Pushrod-Info.html

 

I have some that are running right on the head. As long as they are not removing aluminum, a little rub isn't an issue. I'm sure there are going to be people that are going to say its bad to have them touch but use some common sense and you will be fine. When I fit mine I used Prussian blue to check for clearance and at least half were just removing it. I had to grind a bunch on my heads for clearance and I didn't want to break through so I left them like that. No issues. I use Manton pushrods and they said using the head as a guide (within reason) is perfectly fine.

 

As long as the side loading from rubbing isn't trying to push the tip of the pushrod out of the rocker or lifter cup, it's OK to have some contact.

 

X2

 

simply look at guide plates----There very close for sure!

I do like to leave .010 or so on aluminum heads

 

Least amount of clearance possible without side loading.

 

I am not saying this is right just sharing what I did and felt comfortable with. I wraped a piece of paper around the push rod it was about .003 thick, and clearanced it until it did not rub on the paper.

 

Ya probably used a $100 bill didn't ya?

 

No I don't believe any of them will rub hard enough to try and deflect it to the side. Couple I can see daylight between but it can't be more than a couple thousandths at best.