Howdy all,

1968 Oldsmobile 455
​​​​Low compression pistons

I'm replacing a severely loose timing chain(1 1/4" deflection)
I ordered a Comp Cams timing set to install After removing the old chain and camshaft sprocket, I am now trying to identify what I removed. Additionally, there is a fairly substantial thickness difference between the old and new set, the old set being much thicker. The old chain reads, "Morse." Is this an original equipment chain and sprocket? Is it suggested/required to go to the thicker timing set?

Old on left. Comp cam on the right.

The next question is an attempt to identify this cam shaft. Looking through the CSD diagrams hasn't offered clues because, well I am color blind, but I can't see and colored stripes on the end.

Look ma, no stripes.

Third, if I may be so greedy, is it possible to determine if this crank is cast from the front of the crankshaft?

 

Looks like a stock type sprocket. A picture from a little further away would be better. What does the chain look like ?

I dont see any numbers on the cam. They might be on the back end. Probably not much chance of identifying it. More than likely just stock ?

The original cam sprocket would probably have had nylon teeth so it has probably been replaced.

 

"Front" hahaha

Not labeled, but I assume "back."

Old chain reads, "Morse." I kniw Morse makes aftermarket chains, OE as well?

Old chain

Any clues? Can I just slap on that skinny new set and glue everything back together?

 

To the contrary. I would say if anything it is a stock camshaft. I have 3 stock Olds cranks here and none of them have numbers on the front or the back.

The sprockets have Cloyes part numbers on them so that is probably what they are. Cloyes uses mostly Morse chains too. Someone probably replaced the stock stuff when the plastic cam gear gave up. The front cover has obviously been off before. You can see the red silicon someone used to seal it up.

You might be able to tell if the crank is steel if you turn it to get the rod throw showing through the gap in the front.

 

The sprockets have Cloyes part numbers on them so that is probably what they are. Cloyes uses mostly Morse chains too. Someone probably replaced the stock stuff when the plastic cam gear gave up. The front cover has obviously been off before. You can see the red silicon someone used to seal it up.

Good eye. Bill. The chain was so loose I assumed it was from 1968. The crank and camshaft have zero play, which makes me wonder how a replacement timing set could have become so slack? Especially for a car which has mainly been used for grabbing ice cream on the weekends for the majority of the last 20-30 years. Am I missing something?

I have a cheap endoscope, and so I'll grab some pics of the crank. I'm not sure why I care so much. I've made the call to not rebuild/upgrade the rotating assembly and top end until the piggy bank is full again. I just would like to know what I have currently while the front components are removed.

So far I have:
68 block most likely from an 88
Low compression pistons(half moon notch)
"C" Heads
"Z" headers
Cast 4bbl intake
7029251RJ 4bbl
Be great to identify the camshaft and crankshaft.

I appreciate the assist. i dont think I can return this Compcams timing set at this point. I guess I'll throw it on, button everything up, and cruise some more.

 

There is a 10-74 stamped in the crank sprocket which might be a date code. How long have you had the car ? What I can see of the rest of the engine looks like it probably has a substantial number of miles on it. You really cant tell how much "play" the cam and crank have with them installed like that. All of the valve springs are pushing on the cam and the crank has everything attached to it not to mention the torque converter / flywheel on the back. Other than the timing chain set I would bet it has never been touched since 1968. Put it back together and drive it

And sometimes short trips are worse for wear than long ones

 

Thanks for the help, Bill. I have had the car for 1.5yrs. P/O bought it in 1980. It's a true 442, but the 455 is obviously a swap. Gonna do exactly what you suggest. Thanks again.

 

Can you post a pic of the pistons?

I don’t think that’s an original cam from 68…they were still using notched identification marks on the front face in 68,,it doesn’t have any. It could have had a new stock aftermarket replacement cam and lifters installed when the replacement chain set went in

 

68 California 455 likely delta 88...based on previous posts.
Look at those cool texturized pistons! Mus5 have been a rare option.
So, from some internet research, obviously true, all early year 68 455's were given forged crankshafts(most to toros, w/30). Has anyone else confirmed the "ALL" suggestion? It seems unreasonably emphatic.

What is "early year"? Seems unreasonably vague.

Anyway, hate to bug you brains for mostly irrelevant information, but I would like to know for either my purposes, or the next owner.

 

Learn something new every day When did they stop using the notches ? I have at least 2 Olds cams at the shop that I use for checking cam bearings and don't remember seeing any notches but they are probably newer cams.

 

not exactly sure when but I think around 73?

 

thats a big dish.

 

You've really got to get a good look at a counterweight or at the back flange of the crankshaft to tell if it's forged or not. It's clear this engine has been touched so there's no telling what may or may not be in there. It might be a crank from a '75 with pistons from '73 and a mix of rods. You just don't know until it comes back apart.
That chain is a link style. Cheap and easy to manufacture, but they stretch. Roller style, especially double roller, are much more common for aftermarket parts but cost more. Link style replacement timing sets are still available.

 

Appreciate the insight, oddball. The reality is I am going to use a similar setup with the compcam timing set I have purchased. Its a hurdle for my "perfectionist" brain...especially when we're talking about just a few more bolts to yank that whole thing out, and a few months of mostly non-driving weather ahead. However, I just don't have the ducats to rebuild the whole damn thing. So duct taping everything back together and cruising on the dry days. Fun car to cruise.
But let's just say I do finesse that hunk of iron out, is there anything I can do for under 1k that I can then feel good about putting it back in for the next couple years? Any suggestions?

 

Cheap HP adder: Long Tube Headers.

 

biggest bang for your buck is a cam change…you don’t have to pull it out for that as you’re already halfway there.

with those big dish pistons you need a short duration RV type cam to help move that thing

 

Absolutely number 1. One of the few things that typically improves power AND efficiency.

 

If you're not looking to do a full rebuild or add a whole bunch of power (nitrous or blower or other power adder) then it doesn't really matter what type of crank is in there. As long as it's running well and not knocking - just run it! Trust me, it's best if you turn off the perfectionist part of your brain sooner rather than later. I learned that the hard way over many years and many, many dollars.
Do remember that the engine has been touched so don't make any assumptions about what's in there. Rebuilds, especially in the 80's and 90's, were done with whatever was handy, which tended to be mid-late 70's parts. Or, if the original crank was in good shape, and it was forged, hopefully they kept it. But it seems like the value of those parts wasn't always well understood.
Making a good guess on real compression ratio will help with knowing how far you can go with a cam change.

 

Which is exactly what was done with this car. Might have been gone over in this car. I know only what the P/O's son told me about what his dad had told him before he passed. AND its a swapped-in 455.

I was planning to do the whole "dont get it right, just get it running" idea, but thenwhile shaking down all over tge suspension, brakes, wiring, rear dif, and various other things, the car had a miss and started over heating. So it went back in the garage for some engine and engine bay attention. Changed out the rochester 2bbl along with the manifold for an olds 4bbl cast intake, water pump, hoses, radiator, etc, etc, etc. There is an olds performer intake $300 and some long tube headers $300 locally, maybe $300 on a new cam? I just replaced rocker arms with compcam oe style. Those texurized pistons lead me to believe the heads could use a deep clean, the driver motor mount doesn't have a thru bolt. Anyway, you guys get it.

Thanks for all of the suggestions and knowledge. I really appreciate you taking the time,
Pigs

 

There is nothing wrong with the factory cast iron 4 BBL intake, cam and headers are the best bang for the dollar. If you have the time and discipline not to totally rebuild the engine if not required I would pull the engine and go through it. Change the gaskets and check the bearings. 3.42 to 3.73 make a big difference as does a shift kit if it's an auto.
Good luck.

 

I thought 455's with dish pistons (notch on front=14cc dish) were hi compression engines?

 

The "high compression" piston has a notch shaped like a "V" instead of the half moon notch as seen above.

 

I continue to learn something everyday, that's a good thing. My short block is a 70 model 455. When I looked in it with a borescope I couldn't find a notch but did find an arrow pointing forward. What piston do I have?

 

The '67 and older Olds cranks were forged. Olds shut-down the crank forging in favor of cheaper cast cranks for '68.

But some early-production 455s (probably made in '67, for the early-production '68 model year) were forged. I have one, a bonus from a batch of core engines I bought from a co-worker.

I bet no more than the first two months of 455 production got forged cranks. But I've been wrong before.