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Discussion Starter #1 (Edited)
Are Howards pushrods p# 95012 (7.9") correct for a Howards Cams p# CL110245-12 in a chevy 400 small block?
These are what were installed in my 67' Camaro but the mechanic thought he was working on a 350.
The rods he removed were measured at 7.75".
I now hear a clacking noise when accelerating.
Any info or tips will be greatly appreciated.
(Side note; I think he used 350 head gaskets and not 400's with the steam hole)
20200703 adder,
I was able to pull my pushrod and measure. It appears to be 7.2 inches…
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Most important is you should be using the steam holes if it's a street engine. I just spent hours reading on that subject the other night. Second , you really need to measure what your rod length should be. Chris Straub's site has a link to a video on how to measure pushrods correctly.
 
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As for the steam holes.... still up for debate IMO.

And for the push rods.... ALWAYS measure. Too many variables ;)
 

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As for the steam holes.... still up for debate IMO.

And for the push rods.... ALWAYS measure. Too many variables ;)

This /\/\. Steam holes are debatable and definitely need to check for correct pushrod length. It's easy to do.
 

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I listened to Sean (68rs406) went without the steam holes....it was not a cruiser, had a 3000 stall, didn't idle a lot, did see some street time to cruise-ins, driving to the track, and street "fun"....never an issue.

Your result may vary
 

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I listened to Sean (68rs406) went without the steam holes....it was not a cruiser, had a 3000 stall, didn't idle a lot, did see some street time to cruise-ins, driving to the track, and street "fun"....never an issue.

Your result may vary

To steam or not to steam, it's definitely a contentious debate, lol. I usually just say do whatever makes you feel better, but as Doug describes the way we use our cars typically doesn't require them.

One thing I see in the original post is the reference to "350 head gaskets", you don't want to do that because the bore is different. They make several 4.125" bore gaskets (actually I think they usually run 4.200" if memory serves) some with steam holes some without.
I never ran steam holes personally.

The stock pushrods for a 350 are the same as a 400 (7.8"). But they need to be checked. Variables like finished deck height, head gasket, aftermarket cylinder heads, etc. etc. etc. change things. That's why they should always be checked, and it's really an easy procedure and checkers are pretty cheap.

It's been several years now but I think with my 406, zero decked, aftermarket aluminum heads and a small(er) base circle cam I ended up with 7.9".

More likely than not the noise you are hearing is from poorly adjusted valves, and pushrod length could add to that.

On another note, I don't think I'd let that "mechanic" work on the motor anymore...;)
 

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I have not finished putting my engine together yet, but on the recommendation from the Edelbrock tech, I drilled mine. I figured what the hell since they are already off of the engine. Will see.
 

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I have not finished putting my engine together yet, but on the recommendation from the Edelbrock tech, I drilled mine. I figured what the hell since they are already off of the engine. Will see.
It will be fine either way, so I wouldn't worry. The manufacturers just like to follow a CYA approach and I totally get it.
 

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OP

Buy a PR check tool and confirm what length you need. Blocks and heads that have been decked, thinner head gasket, etc, all affect PR length. You want a narrow sweep pattern centered on the valve tip. If the pattern is to far towards exhaust side you need a shorter PR and if closer to intake a longer. PR come in .025 increments so set your PR check tool +/- .025 one way or other if pattern not centered and narrow and get that length once you are happy with the pattern

IMHO correct valve train geometry is critical to a well running LONG lasting motor
 

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I have not finished putting my engine together yet, but on the recommendation from the Edelbrock tech, I drilled mine. I figured what the hell since they are already off of the engine. Will see.
I always do steam holes on SBC 400s. Very simple to do.
 

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Ben - Delaware - 67 Camaro
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on the steam hole issue, it's perplexing. i have always drilled them or had machine shop drill them. i recently installed a set of AFR heads and i ordered them with the steam holes. i was supprised to see the holes that AFR drilled were much smaller than the holes in the block or the holes in previous heads i have drilled and/or had drilled. i believe they call for 1/4" & 3/16" holes or somewhere around there. the holes provided by AFR were much smaller, like little pin holes and both the same size for each location. i went ahead with it and haven't had any issues at all.
 

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on the steam hole issue, it's perplexing. i have always drilled them or had machine shop drill them. i recently installed a set of AFR heads and i ordered them with the steam holes. i was supprised to see the holes that AFR drilled were much smaller than the holes in the block or the holes in previous heads i have drilled and/or had drilled. i believe they call for 1/4" & 3/16" holes or somewhere around there. the holes provided by AFR were much smaller, like little pin holes and both the same size for each location. i went ahead with it and haven't had any issues at all.
1/8" is all you need
 

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Or none... ;)

I believe some manufacturers call for just one of the 2 holes even.
 

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Ben - Delaware - 67 Camaro
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mine seems to be holding up just fine with the small holes. looks about 1/8". its just odd that the holes in the block are two different sizes and the head manufacturers don't do that. guess it goes to show how much good the holes do, or don't do, in the first place. OP sorry to highjack your post, measure for correct pushrod length
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