Technical 394 Oldsmobile identification

Hey you guys, I have a 62 Olds 394 that I'm gonna put in my 56 olds 4 door sedan . I got the motor and trans from a buddy of mine . The trans is a th350 that has been made to fit a early olds engine. That's a plus ! But what I'm trying to figure out is if this motor is a high compression 394 or a low compression 394 ? I know the motor has been gone threw at one point it does have a 4 barrel intake on it and someone painted it red to look like a high compression, but the research I did is coming up nowhere. I posted pics of the casting numbers on the left side head center exhaust port and the numbers on the back of the motor as well . Any help to identify what this is would be greatly appreciated.

 

"Found this on the classicoldsmobile forum - somebody asking the same question
Assuming it's the original engine, a SkyRocket is the 330 horsepower high compression version of 394. There should be a curved "Ultra High Compression" decal on the front of aircleaner housing; looks like yours is AWOL.

It could have optionally been equipped with the 345 horsepower Starfire engine. Those engines when factory installed will always have dual exhaust.

You can also look on the left head, just below the valve cover and above the center exhaust ports. The engine ID number is there. An H prefix indicates a 2-barrel engine. A J indicates 4-barrel.

No suffix indicates standard 10.25 CR. An L indicates an 8.75 CR engine. An S is 10.5 CR Starfire engine.

As an example J001001 would mean a 10.25 CR SkyRocket 4-barrel engine. H001001 is a 10.25 2-barrel Rocket engine. H001001L is a low compression 2-barrel. Those were green and usually found only in Dynamic 88s. J001001S is a Starfire engine."

 

F should be a 1961 8.5:1 compression 394 with a 2bbl.

or a 1962 10.25:1 compression 2bbl 394.

but you never know with engines that have been worked on

 

I'm sure Tony will have better info but, I think the only difference aside from the 4 barrel intake would be the steel shim head gasket and high lift cam on the higher performance engine and composite head gaskets and milder cam on the lower performance engines

 

I agree with Mr. Squirrel: you cannot determine what an engine is, unless you know who built it and why. It *may* have been a factory low-comp, but is now a high-comp.

It's kinda like trying to determine factory tire psi by looking at wear patterns.

Cosmo

 

For what it's worth, the F prefix on the stamped number was used on the '61 250 horse and '62 280 horse engines, the lower horse engines for those years.

 

As has been stated. Once the engine has been to a machine shop all bets on being stock are off. Without documentation of what's been done the only way to be sure is to take it apart and have a look see. Joe



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...or take it for a drive, and see if it pings

 

Thanks you guys ! You all have been a great help ! I still have a ways away from driving my 56 I'm gonna start a build thread on it real soon . Thanks again !!!

 

Guys,

I was digging around and looking for info and this thread came up. I have found an Olds 394 for sale locally. Here is a quote from the seller: Have an all original rare 394 Oldsmobile motor with hydro trans from a high compression G code 1962 Olds with 10 to 1 compression and 330 HP. Original red paint complete with carb, intake, distributor, fuel lines and glass filter, finned valve covers, fan blade, water pump, all pulleys.

I have looked at the pictures the seller sent and the motor does have a 4 barrel, and under all of the grease and grime it was originally painted red. The number stamped on the machined pad on the head is G324665. From the research I've done if this is correct it should be have 10.25:1 compression ratio and was rated for 330HP. The engine comes with the hydramatic still bolted to it and the guy is asking $800.

Is it what the seller says it is? What can I look for to more positively identify it? Is the price good for the engine and trans? I have zero experience with Olds motors and know I need to do some learnin'.

Thanks in advance for any help.

Thor

 

Here are the Olds engine and casting number series. The engine number should assist to identify it.

 

Here's a bit more casting information.

 

If it is original, the hydramatic is the Roto 10 or slimjim, which is a PITA. There is a possibility that the transmission is a DC hydramatic or the old dual range single coupling type.

 

Thanks mgtstumpy. This is excellent information.

Based on the casting number I was given on the left exhaust manifold and the serial number on the machined pad, it looks like this is indeed a '62 394. The paint color (red), the four barrel carburetor, and the G code at the front of the serial number also point to the 330HP higher compression engine.

d2_willys, what can I look for to determine which transmission it is? Are there any casting numbers or physical cues I can look for?

 

Yea but if it has a decal on the air cleaner that is the determining factor.

I am really a little leery about numbers stamped on a head as well, my 394 is a '62 block and has '59 heads. My compression is up in the 13:1 range or so I have been told. I got to CC my heads and go from there.

The real question becomes if it will run on pump gas, if that is the case then one other question comes to mind, if it makes you pee when you mash the loud peddle. Now if it does the first one you are good, and if it does both then there is only one thing to remember. Depends.

 

the Roto 10 or slim jim has an all aluminum case. The DC hydramatic has a cast iron case, but aluminum tail housing and bell housing. The earlier dual range hydramatic is all cast iron.

 

Yea the early transmission is a big heavy pig. Air cooled. Well I don't know if they were all air cooled. That is more of a @d2_willys question, all of them that I have met were air cooled.

 

Please keep this post alive !

 

I second this. Just because a guy was done with his project years ago doesn't mean someone else isn't just now starting on theirs. As time goes on the old guys who figured out all of this stuff to begin with are on to other things or places, and who's left really should want to help each other learn all we can to keep this old iron old school. I would rather cut my arms off than do a LS swap a 50's car, so pages like this are very appreciated.

 

X3, great information in this thread.
I've got a 60 394 just waiting for me to get around to using. Came from running and driving 60 Super 88 flat top I parted out, so I know it's good condition. Looking back that flat top was one that should have been saved, but at least all the parts went to 2 dr projects.

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Ive got a complete 62 four dr htp in the hoard. it has a 2 bbl 394 rocket engine. Owned it for over a decade and never sold a single part from it.

 

Where can I obtain more of this information? Is this from a book or website?

 

Just picked this up a month ago. Reviving this thread. 62 88 coupe.

 

Bump!!! Cleaning up a forgotten corner of my shop. Found these I picked up a few years ago and think I also have a '56 rear end that came with them. Thinking of doing something with them. Probably need some help later on. Thanks, Joe.

 

Can't quite make out the water pump, is it iron or aluminum?
And is there a starter on it, if so is the selenoid on top or bottom?

 

I'll check tomorrow when I go to the shop. Thanks, Joe.

 

Well, the "23" heads are considered good. Let me know if you are interested in a Weiand dual quad manifold with a pair of AFBs

 

Thanks, but I have an old 3x2 with some incorrect 2 GC's that I would like to run.

 

The 23 heads were the last version of early Olds heads, '63-'64, they had a redesigned chamber that was supposed to handle the higher compression with less detonation.
Iron water pump would make the block '59-'62 and aluminum would make it '63-'64 like the heads.
I see added capacity to the pan,
And the crankshaft fitted with pilot to work with the early transmission, (flywheel should be balanced for external)
Starter switch over to gain clearance for steering,
Home made shifter.
Cool stuff

 

Picked up this motor/transmission and a '56 Olds rear end a few years ago. Supposedly was in a running '46 Ford coupe this guy in Houston inherited. So the first thing he did was pull the motor/trans and was going to run a SBC/auto.