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

Hey Chip, which way does your engine turn over when you crank the starter?

The wrong way *rimshot*

The engine would turn over better if I pushed the car sideways off a mountain. :mad:

facing the engine, clockwise... why?

Just an off the wall thought that the engine might be turning over the wrong way but that would cause a multitude of other problems like only 1 forward gear and 3 or 4 reverse
I looked at the pics again and I see that the cam gear looks loike it was riding high on the distributor,,,,,, There are two different cams for these engines large journal and smaller journal. I do not remember which is which and just got to thinking about the compatibility. It shouldn`t realy mater as the cam is stil centered in its bore. It just has different size bearings.

http://www.vapinc.com/chevy/Camshafts/main.html

Chip, I have been watching you for some time with a "keen" interest. For what it is worth I vote that you pull the cam and "eye-ball" that sucker and the gears real close. If you can't see something wrong, take it to a good machinist and ask him to. I wouldn't run it anymore as it is. You are probably gonna need to clean out all the "chips" any-ol-who.

I have often found that most problems with these engines are due to the abilities of the man with the wrench, but I don't think that is the case here. Looks to me like some machinist messed up on this one. There are some sloppy-joes out there from time to time.

First, I would check the gear mesh. Drop the pan (again [img]http://www.fradsplace.com/icons/icon17.gif[/img]) and get out the paint, grease, or whatever you want to use. That will give you a starting point. Then pull the cam, and check it. Also, get out the snap gauges and check the cam bearings. Hope y'all have skinny arms and hands, I know mine won't fit. You could have one of several problems, from a bad gear to a bent cam to a warped block. [img]http://www.fradsplace.com/icons/icon18.gif[/img] [img]http://www.fradsplace.com/icons/icon24.gif[/img]

One more vote for pull the cam....

Chiphead, you wrote.
George suggested Tony wrote NOT. I think this is where the problem lies.

And now you say.
Cam side bottom of pump body is polished.

http://pic4.picturetrail.com/VOL53/819220/1640560/19290692.jpg
Wear is on cam side.
http://pic4.picturetrail.com/VOL53/819220/1640560/19290317.jpg
Cam and pump gears will try to push away from each other. Pump bushing should support bottom of dist shaft. The "bang-miss-bang-miss" or wobble is coming from the dist shaft tang. When the tang is parallel with the crank, the flat side is holding the gears close together. When the tang is perpendicular, it will slide away. I think the pump is your problem. Pump bushing may be worn or body is tilting away from cam because body is too small or block is worn and simply isn't supporting pump properly.
From the the start, I think you suspected the pump.
One part of this I'm not sure of. I have a cut-away drawing that shows a washer or spacer of some sort on the top of the pump.

I wholeheartedly disagree. Melling does not use a thrust washer in ANY of their M45 pumps. And this engine was running before I took it apart to rebuild it. The old '54 engine did not have a thrust washer on its pump. Provided its a different pump, but no thrust washer.

Are you saying that any 55-62 motor with a current-production M45 pump will fail? That is what Tom L alluded to. He said I would have to find an old pump body with stock thrust washer and rebuild it. But see the .125" recess in my old pump in the pic above? It wasn't there when I installed it. Would any kind of thrust washer be able to survive a load like that??????

THREE DIFFERENT DISTRIBUTORS HAVE MALFUNCTIONED WITH TWO DIFFERENT OIL PUMPS!!!!!!!!!!!!!!!!!!!

Now maybe there is a chance that there is something seriously amiss with the oil pump mounting boss in the block. There is also a chance that I've gotten 3 bad dists and 2 bad oil pumps. Or it might be the camshaft. Whats more likely? :confused: :confused: :confused:

Sorry to yell, your suggestions about the drive tang are likely correct. (but not source of the bind). I'm frustrated, as this has taken 2 years and 4 thousand dollars, and its still not fixed. :mad: :o

Is that was Tom was alluding to, or is that what he said? If he is so sure I wouldn't argue. Though it seems weird. But, unless you have a bad part, you have a mismatched part problem.

The cam is the only part left. But, be prepared for it to be correct and the answer lies somewhere else.

Tom: You're likely going to have to find an older oil pump casting with the 'captured' thrust washer in the top to support the load. The Chevy M45 pumps do not have this washer. Nobody at Melling was able to tell me why the chevy pumps don't have it, and the GMC pumps they build do.

Me: What are your other customers with HEIs doing?

Tom: I don't know their setups, as yours is the first to fail like this.

My opinion is that is has to be the camshaft. This is based on the assumption that the majority of these 235 rebuilts are using Melling M45 replacement pumps and the owners/builders are totally unaware of the issues I'm dealing with. If its the engine block, I WILL sell this car and go into '60 Pontiac muscle.

chip

Chip, I have rebuilt one 235 and two 261's in my own trucks in the last 6 years.None of them had any sort of thrust washer between the oil pump and distributer when they were disassembled. I also had a few other 55-57 235's laying around here, no thrust washers on them either.On the 3 engine, I replaced all the oil pumps with the M-45 pump which had a Sealed Power name on the boxes, all bought from the local machine show at different times.No thrust washer on them either.All these engines are in trucks driven on the road and none of them have any problems like you are experiencing.I'm no expert here, maybe I have time bombs ticking away too.
None of my several old Chevy parts book show any sort of washer, but it may be captive like Tom Says? Anyway the GM part number for a 55-62 Chevy oil pump is 3815635

Richard emailed me a pic from an old shop manual that shows a thrust washer 'captured' in the top of the oil pump casting. (thanks richard). Nobody seems to know why this washer was omitted from the replacement pump design. I can only guess that mech engineers figured that the washer was not needed in the replacement pump design.

Anyway, the cam comes out soon. Pics to follow. I hope you guys look at them closer than the warren commission looked at the Zapruder film. I have a feeling that my cam is firing from the grassy knoll.

I'll let you guys chicken and egg if cam ruined distributor or vice versa.

chip

Richard found the smoking gun .The parts manual list two oil pump part numbers, one for a 54 and another for 55-64. Do you think GM eliminated the washer in later years, a design change?How many 235/261's are running washerless pumps with no problems?

Don't misunderstand my opinion on that thrust washer. I can't think this would have any connection to the wobble problem. It would possibly hold the dist shaft up high enough to put the wear pattern in the middle of the gear. This alone could cause a new problem. The shaft would ride too high inside the HEI. This would require spacing the HEI body higher by the same amount. I can't think this would solve the wobble. But,But, the stock dist doesn't wobble?? This still takes ME back to the pump.
You never have mentioned one thing. Is the shaft diameter for the orig and the HEI exactly the same? How much clearance does the shaft have in the pump bushing?

Here is another thing you might want to check, that none of us have given any thought to.
Chevrolet Inline SIX-CYLINDER, by Leo Santucci, page 128. He notes.
"Distributor Pad Machining
Many 250 CID engines wore out the lower distributor bushing due to an inaccurately machined mounting pad for the distributor "collar". The pad was not machined perpendicular to the axis of the distributor bore, so when the hold down clamp was tightened, it twisted the distributor out of alignment. Always check this pad for squareness and remachine if necessary, or you will risk wearing out your "new" distributor. It is also possible to use a shim under one side of the distributor collar instead of machining. "
I know you don't have a 250, but this could explain a lot and would be easy to check with feeler gauges. You could even set up an indicator and see what happens as you tighten the dist clamp. You could even use two gauges. Side to side as well as fore and aft.
You haven't run it long enough to get the bushing wear he talks about, but it sure seems like it might cause the problems you have.

Hi

Sorry you didn't understand

Take the motor out Take it apart AND fix whatever it is.

I'm not trying to be mean or rude but till you do these steps it will not be right

It's sad that everything seems to be falling on your project here but a Pontiac is not going to be much better unless it's in a GMC truck HONEST

I bet that if you strip the motor you'll find something none of us has addressed as the problem

OK. Dunno if I can diagnose the whole thing, but here's a hint. There are two different oil pumps for early pressure-feed 235s. I've mentioned this before. I posted pix at the website below:

http://homepage.mac.com/grenley/PhotoAlbum3.html

The pumps seem to interchange OK, except that the different pickup angles make the stock pickup not clear the crank. I decided, after *two* trys at a new pump, to keep the old one.

As noted, this is a K103 block, i.e. November 1953, or 54 production model. Chevy used to let raw castings 'age' for a number of months, so it may have gone into production in late '54 or even '55. I don't know for sure, but I suspect the OEM pump is original. The engine is on its first rebuild. 8-)

Kind Regards,
George
53 3600

hmmm

Maybe so. What a mystery. I still think something's goofy with that cam somehow....

Hey Chip,

Where is the original cam now? Is it gone?

The original cam is long gone. I do remember that it had a fiber cam gear and hyd lifters. I stripped the engine years ago, and used the bare block as a TV stand in college. Then I had to rebuild it. The engine is a '60 model 2nd series 235.

I started the teardown last night. Pulled radiator, radiator support, balancer and timing cover. Then I realized that I'll have to pull grille, bumper and gravel shield to get camshaft out. :mad:

Hey JH, Just keep talking crap, how you gonna beat a P350/T350 in a '67 LeMans?

chip

Is that common with these engines? Sure doesn't sound like it would last....

The fiber gear was common in the passanger engines. The HEI does use a smaller diameter dist shaft. The stock dist has a larger dia shaft that fits tighter in oil pump drive passage. So any deflection will show up as a wobble, as the HEI shaft is supported by its shaft bushings and the top of the oil pump. The stock dist is supported by the same thing, but is a 'closer' fit in the oil pump shaft passage. But since I saw wear on the stock dist gear after only a few minutes of running, I assume that the cam gear is trying to chew it up.

Cam is coming out. We'll see what condition its in. But did cam kill dist or what?

chip

Hey Chip,

Probably just another one of my dumb questions, but could you go back to a cam with the fiber gear?

Wouldn't make any diff. The fiber gear is the cam gear that is driven by the crankshaft gear. The gear that is machined on the cam that drives the distributor is made out of whatever the camshaft is made out of.

I'm thinking the dist drive gear on the cam had the wrong tooth angle, wrong material, wrong hardness, machined wrong, or bent. I'll get pics when I get it out.

Chip, is there any possibility that some foam insulation from the space shuttle hit your truck upon take off?

Thats not out of the realm of possibilites. Unfortunately, the chevy 'black box' burned up on re-entry. The debris field streaches some 800 miles, from Michigan to Mississippi. Failure analysis is ongoing. A team of highly tanned shadetree specialists are reconstructing the damaged vehicle in my hanger. :rolleyes:

Seriously, if it isn't the cam, dist, or oil pump, what else could it be????


chip

You say that like it doesn't mean anything. THIS IS THE PROBLEM. Or at least what started the problem. The gears have been pushing away from each other to the extent, the gear teeth are only making partial contact. As for replacing the cam. You'll have to make the call or get really good pictures of the cam gear.
I've seen one of the 6cyl HEI with the smaller shaft. The shaft is the same size from the top to the bottom of the gear. The bottom is turned smaller to fit a different bushing. On a 250 the bushing is in the block, not the pump. Are you sure the guy that sold you the dist knew what engine it was for? The dist I saw was in Pontiac Ventura (Looks like a Nova) with a 250.

Chiphead,,,, was the oil pump mount removed on your engine block at any time? (the one secured with the rivet looking bolts)

BOTH OF MY DISTRIBUTORS SHAFT'S MEASURED .490IN IN DIAMETER AND THE BOTTOM DRIVEN GEAR WAS IDENTICAL IN SIZE. 100% INTERCHANGABLE.

Desist in your basic propaganda! I have the camshaft removed!

Uneven wear on dist drive gear. Identical to what I've seen on the distributor gears.

Uneven wear on the cam journals. Rear cam journal was the worst, 1/2 was fine, 1/2 was scored bad enough to catch my fingernail on. My buddy is bringing it to the machine shop today to have it checked for anything wrong with it.

But its all moot: The cam bearings are ruined. :mad: :confused: :o

So,,, who dropped the cam :confused:

You named the problem. That danged tv set has polarized the block. The only way to fix it now is to disgronificate it. I think Tony has one he'll sell you. Just be sure to wear your tin beanie, ya'll don't want to get your brain destroyed in the process.

chip, pull that sucker apart. The whole engine will be trash if ya keep going like this. If all the parts are good, check the block. Bent cam? If it was bent enough to cause this problem it would never go in. Could it have been twisted after installation? I don't see how. The gear teeth could be machined wrong. But I would think the mistake would be constant in all the teeth, not just some of them. Mike

Yeah, whatever it was it killed the motor. Even if I put a new cam in, the engine won't have a long life. The front cam bearing has some serious scoring at the 7 to 9 o'clock position. I can only imagine what the others look like. A couple thousand miles, she'll lose all her oil pressure.

The machine shop will tell me if anythings wrong with cam. But now the motor is ruined. What parts can I safely re-use?

Seriously, should I just sell this car? :confused:

my vote, NO. Do a complete teardown, salvage what you can and get another block, or complete engine. Find out what is wrong and move on. Can you walk away from this and forget about it? My $.02. Mike

IMO, if the cam bearings are ruined that was caused by the cam and not debris. I think the tolerances between bearings and cam is too tight to let anything but the smallest debris in. So, whatever killed the cam bearings did not necessarily kill the rest of the bearings in the motor.

So, the whole bottom end could be reused as long as you are sure it is clean of additonal debris. You may want to disassemble to make sure of this and to do the cleaning.

At that point you would be able to reassemble using new cam bearings and cam. This and gaskets would be the only new parts you would need unless you find additional damage during your tear down.

If the cam is found to be the problem you might get a new one from whoever you bought it. Maybe a gasket set too. So, you would be out a few thousand hours, big deal... :rolleyes:

Am I qualified for the 'Saga' section yet?

Wasn't Methusela a young man when we started this one?

I seem to recall that someone else here had a 235 "block from hell". I would vote for another block, oversize the bores to the same size, and use your pistons, rods and crank in it.

I think we all need to chip in and send chiphead a good 235 block.

Listen guys. After dragging that block around his whole misspent youth there is no way he could just junk it now. Unless he wants to start using it as a coffee table again. Imagine the stories that block could tell...
:p

Uhhh Fred, that other block from hell was mine too. It was the original '54 block that ate two cranks before it was diagnosed with a fatal main cap crack. That took about a year and three machine shops to find.

The motor in this car has been gimped up since June '01.

Seriously, anybody got a KNOWN good 235 block??? I'll pay for delivery and dance at your wedding!