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Discussion Starter #1
I have a mark Iv 454 big block with cast iron o49 heads, 3/8 pushrods and guide plates and Steel 1.72 roller rockers. I can't center the roller rocker tips over the valve anymore without the pushrods running into the outside edge the intake ports of the heads.

My one thought would be to buy 5/16 pushrods to give myself a little bit more room, but I want to keep the same wall thickness of .083".

Could I run it like this until I have the funds to buy new pushrods and guide plates?
 

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Check your guide plate placement. You can loosen the studs and move the guide plates a bit.

If that doesn't work out I would question the guide plate accuracy.
 

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Discussion Starter #5
Check your guide plate placement. You can loosen the studs and move the guide plates a bit.

If that doesn't work out I would question the guide plate accuracy.
I can't adjust them any more without the 3/8 pushrods touching the wall of the pushrod hole in the head.
 

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Discussion Starter #7
You should verify all your valve train geometry

The roller tips are center over the valves as far as intake side and exhaust side and have a narrow sweep. It's just that the roller tips do not sit in the middle of the valve tip as far as the front of the motor to the back of the motor.
 

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What does it do when you rotate the engine around? Does it change position at all when loaded?
 

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Oops.Missed the "hitting the head" aspect.I did a bunch of research for my friend when he had this problem but that was with aluminum heads and I think the holes may have been a bit bigger.Guide plates were way off though.If your pic is the worst one,from what I read and heard from BB guys I would say that's acceptable.I wouldn't go back to the weaker 5/16" pushrod for sure.If it really bugs you,maybe clearance the hole in the head a bit.
 

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That little tidbit of having to open the hole up to align the rockers for the 3/8 pushrods should have been brought up PRIOR to selling them to him.

I have a SR and am using .080 5/16" rods with zero issues to 7k+ rpm.
Are 3/8 stronger...yes, is it worth grinding the heads IDK.
Do or should you pull the heads off to do this?

You can get .120 5/16 rods too.
 

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I have a mark Iv 454 big block with cast iron o49 heads, 3/8 pushrods and guide plates and Steel 1.72 roller rockers. I can't center the roller rocker tips over the valve anymore without the pushrods running into the outside edge the intake ports of the heads.

My one thought would be to buy 5/16 pushrods to give myself a little bit more room, but I want to keep the same wall thickness of .083".

Could I run it like this until I have the funds to buy new pushrods and guide plates?
The answer to your primary question is YES you can run that until you can save up some money to get the adjustable guide plates and new pushrods. It really isn't too uncommon to see the rocker not centered on the valve on most "stock" rebuilds. That doesn't make it right, but still livable.

It looks to me that you are running a stock type valve spring and possibly a hydraulic flat tappet cam? If that is the case, you would have what we would consider to be on the light side of spring pressure. I'm not a fan of going to a smaller diameter push rod but with the lighter spring it may not be an issue. I'm from the school that a stiffer pushrod is always the best way to go so if you do move to the 5/16, the suggestion to use the .120 wall is a good one. This conversation will be different if you had greater spring pressures or racing.

I have had to fix pushrods that rub the intake port on engines I have assembled (oops!), but mostly with aluminum heads. A new and crisp rat tail file and some controlled filling typically makes short work of it. Of course taping in some rags to keep her clean is key.
 

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If it makes you feel better I recently had the exact same issue with a 496 I built, has Brodix heads that were all set up for my roller valve train by Straub Tech. I panicked when I saw the roller off center on 1 valve tip, sent Chris pics right away figuring I was going to be pulling the head at the very least. Chris responded to me almost immediately after he got my pics and said there is absolutely nothing to worry about, so I'll take his advice, he said don't waste my time messing with adjustable guide plates, anyway just my .02 worth
 

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Been there a couple of months ago with iron Merlin heads. Bought the Comp Cams adjustable pushrod guides and with a bit of careful attention I got all of the roller rocker tips to line up properly on the valve stem. Before that it was WOAH NELLIE.... three of them were WAY OFF. When I took apart my engine it stood out big time! I'll post pics once I can find them...
 

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Discussion Starter #14
Thank you guys for all your advice. This motor is fresh from the machine shop and still on the engine stand. I told my Machinist and sent him the pictures. I'm bringing the motor back to him since he supplied the roller rockers, guide plates, 3/8 pushrods and assembled to motor.
I'll fill you guys in on what the out come is.
 
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