opinions on block wanted

[68scott385]

Someone asked about the thermostat in the 307. Last night I tested it. It's a regular, replacement style, 180* thermostat. It cracked open at 180* but wasn't completely open until 200*. I tossed it as I like my junk to run at 190ish or at least below 200* in traffic.

[68scott385]

These are pictures of the block. Notice the windows in the main webs and how little material is there to be worked with, this was one way Oldsmobile tried to reduce weight of the car.

[68scott385]

The rod journals from 1/2 -7/8 and again the pictures aren't very good.

[68scott385]

The mains, in order 1-5 hopefully. The pictures aren't all that good, partly because I was too close and mostly because I could hold still.

[68scott385]

Autopsy of a 307

This is the motor I wanted to replace, just not yet or in this manner. I had hopes that it would live until the new motor was ready to be transplanted. After measuring the crank and all the inner diameters of the bearings it is obvious that the crank got eaten and the bearings didn’t give up much metal, just enough to mirror the crank’s surface. The mains gave more than the rods. Mains 1-4 were at least .001 too small while all the rods were within .0003 of their minimum dimension. Two rods were in the middle of their oil clearance spec, everybody else was either right on the edge of too much or bigger. The ultimate demise of this motor, IMO, was me turning the idle speed down to 700rpm. The sticker on the core support says something like 1000rpm but being a Chevy guy that is usually too high for a stock engine. When I swapped in the Pertronix distributor, to have an advance curve because the computer was dead & removed, I also set the idle speed. I don’t know if the idle air bleeds on the feedback Q-Jet are staked behind plugs or not. I tried to look at it once it came off the car but there is so much oil based grime caked on it, and everything else, that it is just indeterminable at this time and it’s not like I care about this carb anyway.

The oil in the filter case. No glitter, all metal.



No wonder there's so much oil grime all over this thing, this bolt was laying here when I took the motor mount off.


The plugs.


Valves fit for a lawnmower.


Piston dishes the size of small bird bathes.


The bottom end with spider-sized webbing in the block.


And my typical marking of parts; front to rear for mains or the outside of the rods, facing the side they're on.

[Mater]

yup 80 and 81 had a change in appearance

1980



1981-86

[68scott385]

It very well could have been that. I don't know. Didn't ask many questions, as he didn't have many automotive logical answers anyway. Seems like it could have been in the year range you specified. I don't recall the body specifics as there were minor changes between 80 & 81 right? I do remember it having an Olds motor and being yellowish.

[Mater]

it's rare but some 81-83 montes had the 350 diesel it was probably one of those with a gas engine swapped in

[68scott385]

That sounds like a cool engine combination. I like when things get out of the box and work as well or better than the normal trend. I have seen an Olds motor in a G-body Monte Carlo but only one and it's been nearly twenty years ago. The owner bought it that way and knew nothing of cars but where to add gas.

[Mater]

the car was really clean (under the dirt still had the yellow grease pen markings ont he black frame including the rear frame horns) the hydroboost brake system was also pretty nifty unless the PS belt failed or the pump did both of which happened LOL

i sort of want to swap it into a monte carlo

just to pick at the swap a SBC into every g-body crowed by removing a SBC LOL

the full plan for the engine is to bore it out to 4.125 (i had it sonic checked it has plenty of meat and could even go another .030 over) this is the stock bore of an olds 425 issue is the 425 pistons are expensive but the chevy 400 has the same bore and is cheap so i plan on getting those and 6" chevy rods just need to grind down the crank .010" when i do this i will have it off set to give it a 3.395 stroke. this will give it a zero deck height and 9.2:1 compression with the C heads (9.8:1 with the eddy heads) and have a size of 363 ci and have a tiny stroke but a huge bore so the engine will rev and the 6" rods are cheaper then then a set of factory 6" olds rods

still deciding on a cam but that will wait until i have a home for it and how i plan on driving it will probably splurge on a hydrolic roller as stock 7.3L PSD roller lifters are the same size and fit in the lifter bores just need to get a retainer

[68scott385]

That was a sharp car. Sorry to hear of its demise. I think it would be real cool if you could find a decent G-body to replace it and accept that Olds motor. Probably have to make a road trip to get one though.

[Mater]

the car was a 1982 Pontiac Grand Prix LJ Brougham Mexico export (it was not meant for sale int he US) it was an interesting car as it was ordered with the diesel but also with the F41 perfomance handling suspension and 3.73 posi rear. people say the GPs never had the same 8" rear as the GNs but this car did form the factory not sure about eh US sold cars but this mexican sold car did. it also had the checkerboard monte rims form the factory but with a pontiac center cap. but being a brougham it had every luxo options GM had, slow fade interior lights, power driver passenger pillow 40/60 bench, rear coat hangers, premium sound system, antenna in the windshield, and factory dark tint



and no i do not have a new car to put it yet it's one of those "someday" builds

[Beagle]

Interesting. Deleted, found the Rockauto part number to be for a SBC.

[68scott385]

the stock 350 olds diesel exhuast sounds pretty throaty on a gas engine

I bet it does.

Please, tell me again what car this came from. It puzzled me to think that there was a diesel version of that car in the year it was made but I do not recall what make/model you said. Grand Prix?

Do you have a place (recipient) to put the Olds motor once it's built? You said the car was stolen years ago but have you decided to put it somewhere else? (besides storage)

[Mater]

the diesel version is simular but larger. my 82 was 3" all the way form the manifolds to the single muffle (no cat do to being a diesel)

the stock 350 olds diesel exhuast sounds pretty throaty on a gas engine