On the heads that are mismatched on my 69 cutlass 350. The vehicle sn is 336879M163895. That does not seen to match either of the head # 5A397 742 or # 3A554 716.The block # is 3955582 located top front of block next to oil the tube. I was wondering if I would be able to use one of the heads and get another to match it. If so which one? Thanks

 

To precisely and completely answer this,we need the block VIN derivative from the block stamped just below the #1 spark plug on the BLOCK not the head. The number next to the oil fill tube is casting/part type # not the VIN derivative. Matched heads will work and probably the 5A is the best choice but get us the block VIN derivative.

 

One more time. Head casting number 397-742 is a #5 small block from a '68-'69 350 engine and has 7/16" head bolts. It is NOT a 5A head. A 5A head fits '80-'84 307 engines. The 3A head with casting number 554-716 fits a '77-'79 350 with larger 1/2" head bolts. As SugarBear and others have stated, the VIN derivative number stamped on the block is needed to fully ID your engine.

 

There is a 5A head from that time period, rare but does exist.

 

Block# 39M440544

 

I can do a pair of correct #5 heads for a 68-69

email direct lemoldsnut@aol.com

Larry

 

pgalioto1:
Your block is a '79 350, it has windowed main journals which are not are strong as the earlier (pre '77 blocks). It also has 1/2" head bolts. If you want to run earlier (pre '77) heads you will need to drill out the bolt holes in the head to fit the 1/2" head bolts. If you already have one '69 #5 head, it's had the bolt holes drilled out to fit the 1/2" bolt holes in the '79 block. You still have a compression ratio mismatch between the earlier #5 head and the later 3A head.

 

He said the block casting number is 395558 2 which is a 1968-1976 block.

 

Isn't a 3955582 casting # 1976 or earlier or is it 77 on up also? To the OP, can you tell the ORIGINAL color of your engine. Look under the block etc.

 

Guys,
I totally screwed this up. Yes this is a '69 block, please disregard everything I posted earlier about the block. The head info is correct.

 

That's good news that it is a '69 block. At least it is the correct year for the car. Now if 5A and 5 heads are identical he just needs one head preferably a 5A if not a 5. Depends on how correct he wants the car.

 

I have 69 5A heads. Everyone says they are from a 307. I know better.

 

The difference is the size of the A. On the early engines the A is small, about 1/2 the size of and offset downwards and away from the number/letter. On the later engines the A is the same size as the number.

Here's a pic of 1972 heads with the small A and 1980s 307 head with the large A:

 

Are the A as small on the 5A vs the 7A heads? I thought I saw pics and they looked more like the later 5A heads as far as lettering.

 

The A is large not small...the reason I know is because I have the 5A heads with the casting number from 1969. Believe what you see not what you hear.

 

Agreed. This is a perfect time for you to post some pictures of those heads.

 

I will. Then a video smoking the tires.

 

Chiming in due to relevance of post. I too have a numbers matching 350 engine/heads in my '69 Cutlass. Heads have a "5A" on them.

 

Can you post a pictures?

 

 

Smaller than the later 5A heads. Good for 350's in 83 or 84 H/O or an 85 442.

 

they are 69 heads. not 80;s..I posted the casting number on the heads...the casting number is from 1969.

 

I realize that, other than die hard Olds guys, no one knows two varieties of 5A heads exist. Put some grease over the block casting number and everyone else will think it is a Vin 9 307 under the hood. I wonder why they changed where the A went on the 72 7A heads?

 

I guess I can use it to my advantage next time I lift the hood.