I will be taking the engine apart tonight. Here's my question:

The engine has had an issue with bending/spitting out the #2 pushrods from the beginning. It has been raced over 30 times and has pushed the lifters out of their bores several times I'm sure. The lifters have likely been put back on different lobes over that time...

Should I replace the cam and lifters just to be safe? Or is a visual inspection with it in the engine sufficient?

I would rather not pull the cam (I don't have the tools or experience to degree it again ), but I also don't want to assume the best and have to pull this thing apart again after a couple races.

Thanks for the advice.

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Rob

I’m Mater
The Kentucky Poser

I'm not goig to vote. I think you need to go with 3/8" pushrods on new lifters, after a careful inspection of the cam to make sure there is no damage.
If the pushrods are deflecting enough to pop out, the thicker ones may solve this problem. Smith Bros!

CJ

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Part of Tyrde-Browne Racing

You're killing pushrods? Both intake and exhaust on #2? I'd be looking for a problem of which the pushrods are just a symptom. Have the valve guides been shortened for adequate retainer clearance? Are the valves too tight in the guides and seizing when hot? Are the valves hitting the piston? If these things check out and the lifters look good I'd resurface the lifter face myself with some 600 grit wet/dry paper and a little light oil like ATF. Make figure-8 patterns and rotate the lifter frequently. This will keep the crown and refinish the lifter face adequately. I figure if David Vizard can get away with it so can I.

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Joshua

I agree - symptom of a bigger problem. Guide or valve related, as Josh described. I would not replace the cam, or even take it out. Just put new lifters on any of them that have popped out and might have gotten exchanged and leave the rest.

Whoa, I like that 600 grit lifter refinish a la Dave Vizard. Gotta try that. I have buckets of old lifters.

Motors are really very tolerant of things like this, but we usually are more careful to ensure fewer problems...

Lou

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Home of Slant6-powered fun machines since 1988

I'll see about scanning the part about refinishing lifters and post it. Obviously this quick refinish can't be done if the lifters are properly worn, but on a low-time cam and lifters I think it's great.

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Joshua

I agree that there is something else "going-on" that needs attention...

As for a cam / lifter change... not needed if the contact surface is still in good condition.

Here is a consideration: If you are running the later "peanut plug" head, that traps the lifters under it, I would consider installing a new set of lifters (or at a minimum carefully checking for the proper "crown" / sanding the current ones) to ensure that all the lifters will spin.

If it's a early head, where I can easily 'fish-out' any lifter, then just run it and check that all pushrods spin, if one does not, fish-out that lifter and replaces it with a lifter that spins.

I am somewhat sensitive to this due to a slow, almost no spinning lifter in the reincarnation of the Buster engine. (Zing)
I sanded the lifters & inspected but darn it, should have replaced them all, seeing that this engine runs a later head and the lifters are "trapped" under it.
DD

Thanks for the replies.

I will be dropping the pan and pulling the early style head this evening.

I will check all of the lifters and report back.

I'm somewhat sensitive about lifter and cam wear too. I bought a '73 Nova Custom with a 350 when I was a young Soldier (back in 1985). The engine had been partially disassembled with all the lifters removed... I didn't know any better and didn't know which lobes they came off of, so I just put the puzzle back together and drove it. It ran GREAT! ... For a couple weeks. Then it lost a lot of power...

The guy at the Auto Craft Shop said it probably wiped out the cam lobes. (He had watched the whole transaction with the previous owner and knew what was going on. He was just biding his time until I came back in with the problem... Sure enough - He made me an offer and I sold him the car) I sold it for $300, but I had only paid $75 for the Nova and a Pontiac Bonneville (that I sold for $200). So all was good. They weren't Mopars anyway.

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Rob

I’m Mater
The Kentucky Poser

It is kind of funny, but not really. When I was a teenager, I put my first Slant 6 engine together. I slapped whatever junk I could pick up cheap together; Used cams, lifters, carbs ...etc. I didn't keep the lifters all in order or anything. If they fit in the bore, they must be the right one! But I ran the livin daylights out of my car for at least 3 or 4 years, with not so much as a peep out of the engine. Then when we built Ryan's first engine and did everything right, we had more problems than you could shake a stick at!

I am by no means advocating shoddy engine building, but it is just funny how things work out sometimes.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Funny... that is how I learned to work-on engines and why I really appreciate the SL6, I was able to put together some nice running Slants for the cost of a gasket set and a can of spray paint!

After a few successes I moved away from "flipping" Darts and Valiants and tried my new found mechanical skills on some other make and model vehicles.
I quickly found-out (the hard way) that those F@%& and Chebby engines were not as "forgiving" as a Mopar SL6.
DD

Well, I'm hoping that my first Slant 6 engine build will be forgiving of this little "hiccup".

A visual inspection of the lifters don't show (to my untrained eye) anything irregular between any of the 12 lifters.

I dropped the oil pan and removed the remnants of one pushrod that had made it's way down there.

It bounced around down there for a few revolutions for sure! It's bent up like a pretzel and in several pieces.

A couple pistons have scars on the bottoms where they made contact with the errant pushrod, but it doesn't look too bad.

I'll pull a rod and main cap to check the bearings.

I'll be taking the head to the banquet to get some "professional advice".

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Rob

I’m Mater
The Kentucky Poser

Rob if it pushing out one pushrod in one cylnder something is going with either the rocker arms or different pushrod lenghs. Or one lifter that is two tall. Thanks Ron











It Aint Over Until Win

Is it bending the pushrod or just tossing it out?

If it's bent you have a guide issue, if it's just popping out you have a rocker issue.

I very seldom ever put lifters back in the hole they came out of, and have never lost a lobe.

Hell, I put a 318 shortblock together one time that had set outside and the cam was rusted. My Ford buddy laughed his ass off, right up until I took the doors off his 351 Mustang.

Motor ran for a long time until it suffered an untimely oil pan failure. It looked like someone shot out from the inside with a shotgun.

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Official Cookie and Mater Tormentor.

This Head has a different rocker assy, New pushrods (several lengths and thicknesses), springs and lifters. STILL spits number 2 pushrods after about 4 runs.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

I left the head with Gerald. He pulled the valves that were the main culprits and tested the springs. He believes that the valve springs are binding.

So, the possible scenario is this: The spring binds; which bends the pushrod. Then the lash is way off and allows the pushrod to come loose.

He's going to go through the head, clean it up and look at swapping out all the springs. There was no indication that the valves are sticking in the guides or that the guides are too high, etc. The pushrod for the exhaust valve on #2 cylinder is bent yet again.

He is also going to shim the rocker arms to prevent so much lateral movement on the rocker shaft just to be safe.

I'll have to check with Seymour to see if he still has that set of 1.5 roller rocker arms for sale. I'd like to replace the rocker arms with something better that has less variation tolerance.

I thought I had the cam card in my toolbox, but can't find it now. I'll have to go through old emails or something to find the specs for Gerald so he can spec different springs.

I may have talked him into coming up for the banquet!

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Rob

I’m Mater
The Kentucky Poser

I would not worry about rocker arms. Spring bind sounds very likely, and can only be fixed by getting the right springs or longer valves, or use a lower lift cam.

Lou

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Home of Slant6-powered fun machines since 1988