The Stovebolt Site Forums The Shop Area Engine Shop It ain't the distributor....

I installed the replacement distributor in my 235 and let it run for about 4 minutes. I shimmed and installed it correctly, according to Tom's instructions. While it was running, I noticed that it was 'wobbling' towards and away from the engine block. I tightened the clamp to no avail. So I shut down and pulled it. Damned if the oil pump wasn't scuffed up already after running for 3 or 4 minutes. New distributor already started to show signs of wear identical to the old dist I replaced. Same for the new oil pump.

What the hell? Bad cam?

chip

hummmm, the distributer that i designed and installed into my 5-0 (235 chevrolet)wobbled also, but after torquing the clamp bolt down tighter it stopped. i need to pull the distributer out and check it for wear. (the radiator gave up, so the pickup is waiting for a new one from american classic) The original distributer did not wobble at all. (also the dimensions for the distributer on my website are inncorrect, and lastly i would not build another like it... too much machining.. there is an easier way, and i'll find it. my 5-4 (270 GMC) needs one also.

That's very strange. I've never seen a distributor do that.

You put so much into that engine. I don't remember. Did you put a new cam in? It's seems possible, to me, that an out of round cam gear could cause a wobble.

Howard M4F. Thats what I'm thinking: That a large part of the problem has been a defective cam gear.

Time to pull engine apart? (again :mad: )
Thoughts anybody?

Chip

Pull the cam out. I feel your pain.

Huh--

wonder if the first distributor destroyed the cam?

I'm worried thats what Patrick is gonna think. But the first distributor showed signs of deflection on gear and shaft. I wrote it off as misaligned distributor or oil pump. But now I'm thinking the camshaft gear is deflecting/forcing the distributor gear into the oil pump. The wear on the new oil pump started to show up as a 1/2 circle on the cam side of the oil pump thrust face. Like the inner edge of the dist gear was deflected into the pump body.

How can I verify this short of pulling the cam???

Anybody ever hear anything about problems with Howard cams??? The HEI and the oil pump are new and installed correctly.

Please help, I'm about out of my tree here.....
:confused: :confused:

don't know how a person would measure concentricity of the cam gear with the camshaft still installed.

If the disrtibutor cam gear is out of round, it may show more or less wera on the high and low side(the part of the gear that is closer to or further away from the distributor driven gear.
Is the cam possibly bent?

Were all guessin--but I expect that Luke may be right--bent cam flopping distributor up and down--like a drill into the oil pump.

Bummer, I understand you are still using the mini HEI? Is it the same distributer you sent back? Perhaps the distributer is machined off center in a way that the distributer shaft is not perpendicular to the camshaft.Run a machinist rule down the machined part of the distributer in the same axis as the dist shaft,. Take a bunch of measurements around the dist with your verniers from different points.Make absolutely sure this distributer is not the fault. Your description of the half circle wear marks seems to imply an out of true dist? Then take of the dist cap and rotor,pull the plugs so the engine spins fast.Engage the starter and see if the dist shaft moves up and down, it does have some free paly right? Put some pressure on the center point of the shaft with a tool and see if you can feel the shaft walk up and down.

I sent the dist back to stovebolt, and they sent me another one. Don't know if they repainted the body and sent it back, but the shaft, gear & electronics are new for sure. Even has "OK" written on the underside of it.

The old HEI had uneven wear on the teeth, above the centerline of the gear. One tooth may be fine, rotate gear 180* and that tooth would be severely gouged. Shaft showed signs of hitting oil pump body on 1/2 side only. Like bang-miss-bang-miss-bang.......

I may just pull the cam and beat myself in the head with it. Cut out the middleman. :mad: :o :confused:

Check these pics out of old HEI and oil pump damage. Pay special attention to the pics of gear and shaft wear.

www.PictureTrail.com/gid1640560

Chip, my 52 five window, 235 has a howards cam in it and the mallary electronic dis (no points)
has been in over 7 yrs and no problem yet,good luck,,,Fred

Chip - I never really tried to follow your earlier discussions of all your distributor problems - I think I was too busy enjoying the morphine drip! Anyway - isn't the problem that your distributor was being driven Down into the top of the oil pump? And now you are seeing it wobble side-to-side as the engine runs?

Hopeing I remember this right . . . As you are looking at the front of the motor, the engine is turning clockwise -> cam is turning counter clockwise -> predominant force on cam gear is downward (cam is turning in such a way as to pull the dist. into the engine) . . . if the cam gear is machined off center (or the cam is bent) it is going to rub like heck on the dist gear every 180 degrees creating the wobble you see and damage to top of pump that you see. The cam is going to put a huge side load on the dist shaft and cause the damage shown on the shoulder of the dist as well on half the surface.

Can you turn the motor over with no plugs and put a piece of drill rod or something else straight down the dist. hole and watch the eccentricity of the cam / dist gear? Something that far outta whack should be visible with the neked eye.

just finished removing mine from my 50. the barn was too dark to see the oil pump, so i will inspect that tomorrow after work. I'm also taking the distributor to work tommarrow to take some measurements and better pictures. From your pics (i'm assuming the pics are from the first distributor and not this latest one we are discussing currently) the distributor gear has recesses it's self into the pump housing whereas mine has not (i can tell by the wear pattern on the outside of the lower part of the distributer gear). but your distributor gear has a wear pattern higher on the gear than mine does, mine only looks like the lower half has any wear to it at all. more info tomorrow

Good idea Ken... I'll spin her over and watch for cam gear weirdness. With my luck, the cam has shredded the cam bearings too.

But after the tests, I should pull the cam anyway, right?

Chip

I've been reading this with some interest, as I am headed down the same path. I don't know tons about 235s, but I do know some machining....

1. If the disti gear hole is not concentric with the base circle of the teeth, you would see wobble. IOW, the gear itself was mis-made.

2. If the disti shaft is mis-machined so that the portion where the gear is, is not concetric with the portion that rides in the disti body, you would see wobble.

3. The tongue-and-slot drive used to engage the oilpump is supposed to tolerate a lot of mismatch. But, I suppose if it were out of whack, you might get wobble.

I've also noticed that replacement oilpumps for 235s don't match originals, in all cases. Well, mine anyway. 8-) The pump that was in the motor, and which I beleive to be OEM, has a different arrangement of inlets and outlets than the replacement pumps from either Patrick's or Vintage Auto Parts. Hard to describe exactly, one difference is the angle of the fitting for the oil pickup tube, the other is whether the fittings are in the pump body or the endplate. *Maybe* the wrong oilpump is part of the problem?

Regards,
George

A mis-machined or bent cam seems highly unlikely, but did you ever try marking compound on the gears and checking the pattern?
Before tearing the engine down, try a stock distributor. If the cam is bad as you theorize, it'll show up with a stock distributor as well.

Several have suggested that, but I'm pretty sure the cam gear is ruined anyway. I saw some tooth damage when I was in the crankcase, but ignored it cuz I didnt want to pull the cam.

I'm so sick of this. I'm going to have to cancel the insurance, no sense in paying for a car that doesn't run.

Chip
I have been working on chev sixes for 40 years now and I have noticed a lot of stock distributors wobble and not thought much about it. I think you will find cam gears do not run as true as one would like.
Now with the HEI setup with the distributor clamped solid, I can easily see how a bind can occur which could pull the distributor down with force into the top of the oil pump.
I suggest using a stock distributor (maby with Pertronix if you want) for the summer and see how everthing else works and pull it apart this winter if you want to change the cam and try HEI again.
Dave

OK, I'll try the stock distributor in the driveway. If the distributor or oil pump start to show further damage, its gotta be the cam, right?

Chip

Chip - The Howard's cam that my friend put in his 261 was bent. We discovered it after he broke a rocker, never did figure out which caused what. Didn't have to replace the bearrings, either.

Chip, I hope the problem is discovered and fixed soon for your sanity and ours. This is driving me crazy not seeing or knowing what is happening :confused:

Hey Fred, I too have noticed the broken rocker/bent pushrod syndrome before as well. (2 times different engines). On each occasion rocker/pushrod was replaced and engine ran with no problems for many miles. Seems to be a Twilight-Zone thing,,, maybe an alien stuck a finger in there just to cause the problem and give us something to ponder

Chip
I was thinking you could turn the engine in small increments and try lifting up and down on the distributor to see if there is a place where it feels tighter, ie out of round cam gear.
Also by just running it with the stock distributor you should see it wobble if cam gear is out of round.
Dave

Chip is this the block that's been linebored two dozen times or another?

You can put a dowel and an indictor on it roll the motor over slowly

Was this cam ground by Donny or is this one a them
midwest 'HOWARD' cams?

I'm with Pre 68 Dave I've seen these things move all over the place....no big thing

You got me for another couple days Z is stuck in Europe til Sunday....NEVER FLY LOT(Polish airlines)
I'm not kidding!!!!Long story and I'm not into 'Chiefin' this discussion

I got the cam from Patrick. Thats all I know.
I got the dist from Tom. Thats all I know.
I got the running '60 engine from a '54 truck. Thats all I know
I'm so screwed, thats all I know.

Bought a rotor for my stock dist. I'll have to use my pencilholder for a dist cap, and steal 6 plugwires off my Scout for this experiment. I still think the cam is trashed.

Chip, you got to write a book on your engine , be a best seller.This is gonna drive you to drink or consume large quanties of laughing tabacco, or both.
I would think cams are cast in lots, ground on production machines, one right after the other, I doubt the machine operator grinds each one on a custom basis, maybe someone here knows for a fact how they are made.It's a possibility that Howards has them made by a large cam grinder to their specs.If your cam is bad, then there must be a few others out there with similar problems.The stock distributer, whether it's Chevy or GMC, is free to float around a little ,unlike your mini HEI which is clamped down tight.Perhaps the stock type distributer won't cause a problem, they have about an 1/8 inch of up and down play on the drive gear as does the big head HEI found on 250 6 cylinder engines.You have eliminated the oil pump,oil pump retaining bracket as the problem, so the cam and dist are the likely suspects.

Does a cam get hardened at the end of the process? I could easily see how a cam gets dropped when it is still soft and then goes through the hardening process already out of round?

Here in So Cal we have a bunch of cam grinders...
many of them I've known for years.
Isky is the biggest and best I know.There is a ROOM
full of ladies straighting cams.They bend in the
hardening process.
Next part...You got this from Patrick...Is it a 'HOWARD'ground by a big company.A Howard ground by
Donny Johanson...The guy who's father was named
Howard....
OR
a 'HOWARD GRIND' copied by someone else like Joe Bray

What did the box say on it

Donny's cams a custom ground one at a time and fine
just the way you'd think a Howard Cam shouldbe

Joe's got a bigger operation but also good

Howard Cams inc I don't know

It is pretty hard for them to be bent to the extent that this sounds like and TURN...OR EVEN GO IN

If the end play is bad or the motor has been lineborde poorly I guess that could do this

I guess you could have gotten two bad motors but
you must be very lucky in something cause this isn't it

Over the years I have had motors that really gave me fits building,but they were usually messed up by someone before me that didn't know squat except that everyone beat him.Remember I work on old race stuff.

Take it apart...find what's wrong....you mustbe learning a bunch....that's good but it sounds like
if it were me I'd be at the top of the water tower
spitting 1/2 at the ground

Sorry this has gotten too Chiefed for me

What the hell is JH talking about???

Anyway, I installed a stock distributor and let it run for a couple of minutes. Pull distributor and examined. The dist teeth showed accelerated wear, and the oil pump showed additional contact, but not as bad as with HEI. This dist didn't wobble, but it did fit pretty tight in the block. Dist shaft was 'shined up' after just 2 or 3 minutes runtime. 35 PSI oil pressure cold at 800 RPM.

Should I call Patrick, or pull the cam first and call him to say the cam is on its way?

Chip

I would call first.

What Jim was saying was that Howard's is no longer making these cams. Another company is grinding them to Howard's specs, and the quality might not be as good. But the one in my friend's 261 was a Howard cam, and it was not straight.

If you have access to a lathe or fixture, I would pull the cam and check it with a dial indicator. I would also be on the horn to Patrick.

Chip . . . as a sign of my insanity - I kinda understand about everything JH sez except the part about spitting from the tower . . . unless the tower was in Italy or something like that.

Sounds like the cam gear relief might not be ground sufficiently - could be straight as can be, yet if the roots of the gear teeth are not ground correctly, their is not enough room for the dist. gear teeth to seat and run on the gear crown - instead they run on the pointy ends of the gear teeth face and you will get a big thrust load, lots of little chips (hey . . . your name is Chiphead . . . this might just be normal for you!) ha ha ha . . . How much lash is their in the gear engagement when it is all fitted up. Should be a little to indicage gear clearance. Rotate motor in half rev increments and check dist gear lash at each point. Kinda like setting up a pinion/ring gear without the white grease stuff. . . .well, I am supposed to get some work done today. Big secret project involving microwaves, composites and round automotive products in mass quantities. :o

Ha. Ha. Ha. Its Chiphead for electronics, not metal shavings.

Guess I'll go call patrick.

Patrick says to run it more with the stock distributor and see how it does. Thoughts?

If the cam gear is screwed up . . . your new dist gear will be too and your motor will be a chip generating machine! :o

I'm with Ken on this thing ,, I think the distributor drive on the cam has not been ground deep enough and is binding on the distributor .
I cannot see the point in running it further just to confirm what you already know , that is , the dist gear gets worn real fast .
Pull it and measure it against another cam .

Chip--

You've been thru 3 distributors--right? and replaced the oil pump. Gotta be the cam--bent, off center, or now maybe bad gear--but cam is the only thing left.

Ok Chip ,I just pulled the distributer on my 261 to replace the points.The engine Has a Howards M4F cam I installed about 5 years and 15 thousand miles ago.Looked down the hole of horrors, I can see a shiney area on the top of the pump. My big thick finger can't feel any wear though. The distributer gear has very slight wear right in the middle of the gear.All is well I guess. Sherlock Holmes says "eliminate the impossible and what is left must be the truth"

Thanks Tony, I needed a laugh. So I was going to start a poll, but its been disabled (figures)... So here is the impromptu poll, please vote:

Should I pull the cam out and examine & post pics for you guys????

OR

Sould I take more measurements and run the engine more with a stock dist and see what happens???