Cadillac & LaSalle Club Discussion Forum

Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: Geoff 34cad on April 17, 2012, 04:48:26 PM

Title: Inter-changeable flatheads??
Post by: Geoff 34cad on April 17, 2012, 04:48:26 PM
Hi All,

Does anyone know if 37-48 heads fit on 34-35 Blocks? There seems to be the same amount of head studs but I can't find the answer. No one here in Australia that I know can tell me so any info would be great.

Thanks

Geoff White
Title: Re: Inter-changeable flatheads??
Post by: John Washburn CLC 1067 Sadly deceased. on April 17, 2012, 07:13:55 PM
Geoff,

As you probably already know the 1936 was a new block, which is even different from the 1937 and later. So 1934 and 35 used the older blocks and heads (event the cylinder numbering is opposite of the 37 and later.

So would "guess" they are not interchangeable.

John Washburn
Title: Re: Inter-changeable flatheads??
Post by: Chris Davis on April 17, 2012, 07:22:48 PM
I don't know the specifics on what makes the heads unique, but the Master Chassis Catalog shows two different part numbers for each of 1937 models (4 total when you account for the left and right side heads); 39 models (4 total); and 40 models (4 total). 

41-48 have a single part number for each head (2 total).

My catalog only goes back to 1937 so is not that helpful in what would work on an earlier model year.  An educated guess is no.
Title: Re: Inter-changeable flatheads??
Post by: tozerco on April 17, 2012, 07:41:41 PM
Geoff,

My Master Parts List says they are completely different part numbers so I'm also guessing no. Then again, it shows different part numbers for '37 to 42 and we know the later heads will interchange so that in itself proves nought. For the reasons the wise John Washburn (demolished that bottle of red yet John?) describes, I'm also going to go with "No".

I have '37 and later heads if you are anywhere near Canberra and if eye-balling them would help.

Regards,
Title: Re: Inter-changeable flatheads??
Post by: John Washburn CLC 1067 Sadly deceased. on April 17, 2012, 08:47:58 PM
John, John, John,

We don't celebrate with wine till the fat lady sings... So when Mr. Crank is released from the machine shop then red wine will be inhaled.

The Johnny

I assume you got my response on the electric choke for the 37. The parts numbers are different from 37 to 38 but I believe that is due to the parts, especially the spring. I think the coil unit is the same.

Title: Re: Inter-changeable flatheads??
Post by: harry s on April 17, 2012, 09:14:08 PM
Here is a picture of a 1930 V-8 which is the same up through 1935 and you can see the head bolt configuration and shape of the heads is completely different.
Title: Re: Inter-changeable flatheads??
Post by: Bob Schuman on April 18, 2012, 10:01:33 AM
The 1937 through 1940 models with V-8 engines had different compression ratios on different models, which is why there are different part numbers. 1941-48 all had 7.25/1 compression ratio, so same heads for all. I believe the heads will interchange for 37-48 engines, but compression ratios will vary and the appearance of the heads also vaied from year to year.
Bob Schuman,CLC#254