The Pontiac OHC Six

[TheSilverBuick]

Re: The Pontiac OHC Six

Did a little more work tonight. Picked up a harmonic balancer puller, and the threads on the balancer were rusted/stripped, go figure :P So I tapped them a bit larger, and the balancer came off relatively trouble free from there.

Check out what came with the engine.


Popped the water pump off, the water jackets are relatively clean. I've certainly seen worse.


The front of the engine with all the covers removed, as well as the belt and water pump.


Decided to slide the lower sprocket and balancer onto the 292 crank. Fits nicely.


Front of the 292 Crank with the balancer on there.


Interestingly enough, the distributor cap, rotor and points are brand spankin new. Never been ran new. Not even a hint of an electrical arc.


How I left it for the night.


Plugs don't show anything special. Shows the same carboned up look as the ports, no wear on the electrodes.



This weekend I should get some big stuff done. Accessory block, head and bottom end!

[squirrel]

Re: The Pontiac OHC Six

tease!

[milner351]

Re: The Pontiac OHC Six

Progress is good!

[TheSilverBuick]

Re: The Pontiac OHC Six

tease!

:D

[Junk Whisperer]

Re: The Pontiac OHC Six

I can't BELIVE I missed this thread! Oh,wait a minute.............. :P ;D :D. Nice work Randal,I've got two of those burried someware in my Engine 'stash'(1 4-BBL & a 2 BBL...plus LOTS of Rocker Covers....about 7 of 'em actually. Plus,some Manifolds & Q-Jets...). Nice work. ~J/W.

[TheSilverBuick]

Re: The Pontiac OHC Six

I can't BELIVE I missed this thread! Oh,wait a minute.............. :P ;D :D. Nice work Randal,I've got two of those burried someware in my Engine 'stash'(1 4-BBL & a 2 BBL...plus LOTS of Rocker Covers....about 7 of 'em actually. Plus,some Manifolds & Q-Jets...). Nice work. ~J/W.

In referring to your other thread, if you ever would like to do buisness with a fellow Bangshifter, let me know! Welcome back, hope all is well.

[Junk Whisperer]

Re: The Pontiac OHC Six

Hey,Randal! Besides the Rocker Covers,the Quadrajets(I think there's 4 of them,all NOS in their origional Boxes......the Boxes themselves say,'service replacements',but WTH...)and the Manifolds,I really don't know what other stuff you might want,CARDONE (in Phila...)makes all sorts of replacement parts like Rad Hoses,those Belts,Carb re-build Kits(2 & 4 Barrel..)for these Engines. But,if yer interested in a spare Rocker Cover,just let me know.......it'll take a month or two(!?!?!)to dig it out ;D! ~J/W.

[TheSilverBuick]

Re: The Pontiac OHC Six

I would definately like to have at least one spare cover, I'm in no hurry. Holler when you come across one.

[TheSilverBuick]

Re: The Pontiac OHC Six

First sign of trouble. The intake lobe and rocker on the #1 cylinder is flat, the rest look practically new. Pictures later.

[TheSilverBuick]

Re: The Pontiac OHC Six

Got the top end pulled apart, I'll hit the bottom end tomorrow. The highlights are, cam lobe and cam follower on the #1 intake valve are worn flat, something is up with the valve keeper on the exhaust valve on #2 cylinder allowing the cam follower to rub the spring retainer and lastly, interestingly enough, it has two different types of pistons in it too, cylinders 2 & 5 are a matched set that don't match the rest. Picture time!

Took the accessory drive block off first. All looks good there.


A picture of the cam in the cam housing/valve cover. Notice the lubrication holes. I'm thinking this set up will really like the properties of synthetic oil. You can see the funny wear patter on the second lobe, I have a better picture coming up.


The cam follower arraignment on the head.


Here is a picture of the number one cam followers, you can see something wasn't working right.


Yup, wore down.


To show the lash adjusters under the cam followers. The valve springs and the lash adjusters push up and the cam pushes down.


Looks just like a lifter with an added piece to the top. The whole body of the thing does not move up and down, but it is fed by a hole in the side of the body like a lifter, then the top part hydraulically takes up the slack. I'll be taking one apart later.


The bottom side of one of the cam followers. It centers/locks itself onto the valve stem with that groove. Hench how the #2 exhaust started hitting the spring retainer.


Here is the #2 cylinder, the difference is obvious. At first I thought there was a valve tip height issue, but then realized the retainer is off...


You can see four spots were the cam follower was rubbing the spring retainer around the valve stem and lash adjuster side.


Here is the whole head. It had a steel shim head gasket. I didn't notice any issues with the valves from the bottom side.


Here are the two piston designs. Cylinders 1,3,4 &6 had the pistons on the right, and cylinders 2 & 5 had the ones on the left. 2 & 5 are a paired set, where one is on the compression stroke, the other is on the exhaust stroke.


None of the combustion chambers stood out as different from the others, so here is a picture of one. I checked the head numbers, and they match for a low compression '69 1bbl head.


Thought I'd take a picture of the rod cap and bolt through the accessory drive opening.


Think the 292 would need a shorter piston and rod? Does that look like a forged rod parting line?


So you inline six chevy guys, comparisons??? ;D

[squirrel]

Re: The Pontiac OHC Six

cast crank, forged rods

[67pete300]

Re: The Pontiac OHC Six

Chevy pics for comparison:





Note different firing order/cylinder combination:





The Chevy has smaller valves (1.72 and 1.5 if I remember correctly in stock form



No similarity here:



Or here:



No need for side covers on the Pontiac:

[TheSilverBuick]

Re: The Pontiac OHC Six

cast crank, forged rods

I'm going to call that "CONFIRMED"


Thanks for the pictures Pete! I'm not sure what you mean by the the different firing order/cylinder combinations. Mine are paired: 1&6, 2&5, 3&4. Am I not seeing that properly in the pictures? And yup your valves in the head are way flatter than mine.

[67pete300]

Re: The Pontiac OHC Six

cast crank, forged rods

I'm going to call that "CONFIRMED"


Thanks for the pictures Pete! I'm not sure what you mean by the the different firing order/cylinder combinations. Mine are paired: 1&6, 2&5, 3&4. Am I not seeing that properly in the pictures? And yup your valves in the head are way flatter than mine.

You're right, I guess they could be the same. If you look at the pictures your 5 and 6 are opposite each other and mine are both at BDC. That threw me off at first.

[TheSilverBuick]

Re: The Pontiac OHC Six

Pulled the bottom end apart. A few interesting things. All the bearings are standard bearings and look practically new. The rod and mains on the crank look great. Interestingly enough, the two cylinders that had the different pistons look like they had recently had a dingle ball hone on them. The others seemed to have a what I'd consider a normal wear pattern. No grooves that I could catch my fingernail on. Couldn't really tell if the top of the cylinder had a real ridge or if it was just carbon build up. All the pistons came easy enough. Also I was surprised to see the oil pan had a baffle on the sump. On to the pictures.

The oil pan removed. Definately a deeper skirt block from what Pete posted.




Some moisture definately got to the oil in the pan and the oil was a bit thick, but nothing shocking except I didn't expect the baffle.


The bearings looked pretty good.


I noticed all the flat surfaces had that hatch marking on it, and the curved bearing surfaces look like they've been cleaned up with something. Thoughts? OEM? Machine shop work? Dude at home? Also on the right, the bearing has a hole in it, that feeds a grove around the rod bolt. With the exception of the rod by the accessory drive block, they seem too low to be spraying the piston or cylinder wall. More thoughts?






The two styles of pistons. All and all I thought the pistons were shorter than I figured they'd be.


All the bearings looked really good. I still have to get the mic out to check their sizes.


All the rings looked good. No broken or stuck rings.


The mains pretty much all looked the same.


Seven, ha ha ha, seven mains.


The crank ready to come out.


The 292 crank on the left and the 250 crank on the right.


The 292 crank in the block.


It didn't hit or rub anywhere, but got dang close to some of the baffling, and probably would have issues with a rod/rod cap.


The main bearings I thought were interesting. I'm not entirely sure they are correct. I heard the chevy 250 bearings were different, makes me wonder if these are chevy 250 bearings....


The oil baffle for the oil filler and diptstick.


The oil baffle for the PCV port.


The window for the accessory drive and the oil pick up tube port.


Thought I'd take a picture down the mains.


The rear main/thrust bearing (the thrust was tight), showing the bearing ID.


The rear main, it's bearing shell had two holes in it.


Cylinders 2 and 5 looked like this.


Cylinders 1,3,4 and 6 looked like this.


And as the block sits now. I still need to remove the oil filler tube and a few other miscellaneous things.


And my pile of parts. All the bolts are in labelled bags in the postal box.