BillK

Hey guys,


First of all, nice forum you have here. I will try to visit every once in a while and if anyone ever has an engine related question feel free to PM me. See my signature


My Wife's 84 Riviera stopped right in front of the house the other night when she was coming home from work. 307 Olds engine. Looks like the timing chain has jumped a few teeth. Distributor is still somewhat turning but definitely not right.


My main question is whether you guys know if these engines typically bend valves when the timing gears strip ? I cant remember ever seeing an Oldsmobile head with bent valves in my shop but figures I would ask. I should probably pull the engine and go through it but for right now I will probably just do the timing chain and leave the rest till I am not quite so busy at my shop.


Thanks in advance !!

joe_padavano

I suspect you'll be fine. The 307 isn't really an interference design, given the large dish on the piston. I threw the chain on my 1984 Custom Cruiser and it ran fine once I installed the new chain and gears.

olds 307 and 403

Had one skip, valves should be fine. They are a non interference motor.

Sugar Bear

Valves probably will be OK, oil pump intake from the old nylon gear eh???

MDchanic

The older high compression models can bend valves (ask me how I know...), but yours should be fine, as the others have said.

Just excavate the timing cover from under all those tubes and hoses, change the timing set, and drive on.

Also, there will be a handful of nylon in the sump, but in general, it should not impede oil flow enough to do any damage, especially in a stock, conservatively-driven car.

Welcome to ClassicOlds.

- Eric

oldcutlass

Welcome to the site. As the others have said you should be ok with a new timing set.

joe_padavano

Note that if you don't intend to replace the water pump while you have the front cover off (though you may want to consider this "MIGHTASWELL" since you have to pull all the accessories off anyway), then you don't need to even separate the pump from the front cover. Simply leave the four 1/4-20 bolts that hold the pump to the front cover in place and remove the pump and cover as a unit.

BillK

Ok, Here is my update. Got it down to the front cover. All that is left is to try to get the dowel pins out so I can get the cover off. Any thoughts ? Anyone have any hints on getting them out ? I have a dowel pin puller at the shop but I don't know if there is enough room for it unless I pull the radiator which I might just do anyway.

joe_padavano

You don't need to pull the dowel pins. Just carefully pry the cover off of them.

BillK

Joe,
I am doing this in the car and I am not dropping the pan because it is almost impossible to get to in the Riviera. I have pried on the cover as much as I feel comfortable with and it is not going to come over the dowel pins. I will bring my dowel pin puller home this evening, that should get them out but I will probably have to pull the radiator. No big deal and should probably have it checked out anyway

joe_padavano

Yes, it does come off and go back on without removing the dowel pins. I've probably done two dozen of these. Never pulled a dowel pin - at least not intentionally. One did get stuck in the cover one time and came out on its own.

BillK

Figured I would post an update. Decided with 210K miles I would go ahead and pull the engine and trans out and freshen everything up.


So far it looks like every single valve tapped the pistons I haven't taken the heads apart yet so I have not refaced the valves to see if they actually bent or not.


The rest of the engine has surprisingly very little wear. Cylinders maybe a half thousandths at most Crankshaft measures absolutely perfect and bearings look like new. Same with cam and lifters.

I really attribute this to the fact that the engine has had nothing but 5W30 Mobil 1 since its first oil change back in 1984.

I am probably going to bore it .030 anyway, cant leave well enough alone and I happen to know a good machine shop


Also plan on switching to a hydraulic roller cam.


This has been Olds week at the shop. I haven't seen an Olds engine in probably a year and all of a sudden I have a 350 that is getting supercharged, 2 455's and my own 307.

MDchanic

They can do that lightly with no harm done.

But you're basically doing a complete rebuild anyway, so it's not that important.

Since you are doing a complete rebuild, have you considered just getting a 350 block and spending the same money to build a 350 instead?

- Eric

BillK

Famous last words I should have the heads apart Monday and then the valve facer will tell the truth


I seriously thought about it but then decided to keep the original engine in the car. We have had it since new and the little 307 actually does real good in the heavy Riviera. I am going to upgrade the cam a little bit but that is it.

Destructor

Was the timing gear nylon? that's a lot of miles on a nylon gear. My 88 Caprice's 305 was a factory all steel set.

BillK

It was at one time Not much left of it. I cant believe it was actually running as bad as it was. I drove the car about a week before it died and it actually felt pretty good !

Olds64

That's a bummer that the engine had a valve strike.

At least you get to rebuild the engine though! The car will be good for another 100k miles when your done.

BillK

Yup, just need to find a good machine shop

olds 307 and 403

The early 307's were incredibly durable if taken care of. My 81 Delta 88 came with a stack of bills from when she bought in 82. Many regular oil changes and maintenance including one timing set done. The second timing set skipped at 405,000 km. As you said it ran great still right before it happened, I had transplanted it into my 78 1/2 ton. One day it wouldn't start at work. I just swapped in another 307 but that one would have made 500,000 km with a new timing set. It still used almost no oil but oil pressure was only acceptable, I guess with that many miles.