On a Dodge Poly motor, the oil supply to the rockers is through the 2 hollow studs that hold down the rocker covers. The oil passage is small and prone to clogging. Unscrew the studs and check the oil passages.
I bought a car once with a low mileage "rebuilt" 315 Poly motor. The valve covers leaked, so I removed them and found the heads were clean like new. Not even wet with oil. The rockers were getting just a tiny trickle of oil. The oil passages in the studs appeared to be totally clogged with hard sludge.
Find out where the pushrods were manufactured. If not in America, they are probably inferior steel.
Dave Homstad
56 Dodge D500
----------------------------------------- From: "Matt Proske"
To:
Cc:
Sent: Wed, 18 Nov 2015 20:49:59 -0600
Subject: Re: [FWDLK] Rocker Shaft Installation in 1957 Dodge 325 Engine
So I've had 2 pushrod issues, learned a lot from both experiences.
- 360 head swapped onto a 318 block with .060" deck material removed. Caused an issue with angle of pushrod through head where casting flash (excess metal filled in between sand cores during production) scored the outside diameter of my pushrod, weakened it to the point of failure. Also due to pushrods being too long from the.060" removed from the head. Combination of the two caused pushrods to bend generating poor lift for the valves, poor performance, backfire etc.
2nd issue was a Chevy 350 with 305 heads and I was 16, installed the keepers on the valve stems incorrectly which made the pushrods fail as soon as the lifters '(hyd) pressurized.
Long story short
Check the color of the pushrod and rocker, if either are blued then they're hot from friction due to no oil. If so,
Remove 1 valve cover, cover engine bay with plastic, have someone else start car while another holds cardboard over open head. If there is an oiling problem you'll see it. Take a picture and bring car back to engine shop. Might be a clogged oil gallery.
If not,
talk to whomever rebuilt it and see if they did anything which could affect pushrod length; removed material between block and head, thinner head gasket, longer pushrods, different ratio rockers, etc. easiest way to check is with a pushrod length gauge. If pushrods are too long they'll fail prematurely.
Keep us posted.
John, its probably not the case with your car but I had a pontiac that kept trashing push rods. The problem on my pontiac appeared to be that the pushrods used for the rebuild were made of defective material. The first time I replaced only the bad ones, about 4 or 5 of them. A short while later more of the remaining ones went bad. So rather then leave in any of the possibly defective batch I replaced every one of them and didn't have any more problems. So my question in your case would be whether you have already replaced all of them and are still having the new ones go bad or whether you might still be working on the remains of the first set which simply has more and more going bad till they eventually have all been replaced.
Gary –
Thanks for the reply, and we’ve definitely checked off the items you mentioned in prior troubleshooting. Nice to know that I’ve got it right so far!
What I’m looking for is more specific detail in the orientation of the little arrow that’s at one end of each rocker shaft. Should it point to the front or the back? Is there a difference between Left or Right?
Thanks for your help!
John
I am sorry to hear of your engine/pushrods issues. There are a few items to look at and check. We will assume that the rocker shafts were properly cleaned with end caps removed and the shafts rodded and solvent rinsed till all residue was removed.
Firstly, for proper oiling to the rockers & pushrods the banana grooves in your rockers need to be facing “down.”
Have you done a visual with a valve cover off to see if oil is emanating from the shaft/rockers?
After checking for evidence of proper rocker shaft orientation and “oil” distribution, determine that the pushrods supplied in your rebuild are installed correctly with the smaller 1/4” ball in the cup of the rocker arm – the larger 5/16” ball goes into the hyd. lifter.
Subsequent items to check;
See if you can find the engine rebuild invoice for part numbers of your lifters, pushrods, and if your cam was reground. Without “adjustable” rocker assemblies you may have binding and pushrod breakage because of several factors;
incorrect pushrod ball orientation,
incorrect pushrod length (wrong pushrod or improper length of pushrod to account for head milling/smaller lobe from reground cam/block decking & head gasket thickness), or incorrect hyd. lifters – application should be Sealed Power HT812 (some older numbers are HT1812).
A lack of sufficient oil will “blue” the metal/gall or incorrect pushrod/lifters will heat and expand enough bind after warm-up/extended driving and cause breakage over time.
Keep us posted on what you find.
Sent: Wednesday, November 18, 2015 2:09 PM
Subject: [FWDLK] Rocker Shaft Installation in 1957 Dodge 325 Engine
Three years ago I had the 325 V8 engine of my 1957 Dodge Custom Royal rebuilt. Since then, I have regularly been going through pushrods at the rate of one every one to two months during the driving season. It’s a problem I’ve never experienced before the rebuild. I’m sure this is caused by improper oil distribution to the rocker arms, but I’ve been unable to confirm it.
I need a foolproof way to ensure proper rocker shaft installation so the oil gets to where it needs to be. Can anyone confirm the correct orientation of the little arrow on each rocker shaft to ensure proper installation? Any pictures of this that would be helpful?
Thanks for your help!
John Williams
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