'73 Camaro Engine Questions

73CamaroSC · Jul 2, 2006

Hi,

I have posted here on a couple of occasions regarding a '73 Camaro I am restoring. Recently, the starter nose cone broke off, and while replacing it I requested a starter for a 307, which is the correct engine according to the VIN.

When the guys in the parts department handed me the starter, I inspected it visually and noticed that the bolt pattern was different than the starter that I had removed. The starter installed on the car had the 350 starter bolt pattern. To be sure, I crawled back under the car, and sure enough the bolt pattern there was a 350 also. The bolts were also equal length as opposed to the different length 307 starter bolts.
Next, when I replaced the alternator, the alternator that was taken off the car was a model for '72 and earlier; the plug was for two vertical males, as opposed to two horizontal plugs which was standard on the '73 models.

I went back and crawled under and over the car looking for casting numbers. I looked at the pad behind the alternator, but found no markings. I also looked on the block near the oil filter but saw nothing.
I'm confused, but not about to tear the heads off to measure the bore and stroke. Can someone advise me of a different location that the casting numbers might be found? Has anyone ever seen a 350 starter on a 307 block? Any advice?

Thanks,
TJ

JimM · Jul 2, 2006

it's not 350 vs 307, it's 153 tooth flywheel vs 168 tooth flywheel that accounts for the differences in the starters. Many blocks in that period were drilled and tapped for both starters, they have 3 holes.

It would be unusual for a 307 to have a 168 tooth flywheel, but then, it's been 30 years lotsa things could changed.

Can you read the casting number of the block? It on the rear driver side, just in front of the bell, facing up. On a firstgen it can be seen past the back of the hood, a lil tougher on a 73. That number would show what block it is.

As for the starter, use the one that fits

73CamaroSC · Jul 2, 2006

I know that many things could have changed in the last 30 years, which is why I was looking for casting numbers on the block, but I haven't found any. I will try looking on the block.

The flywheel did have 168 teeth; I counted the teeth from one bolt of the torque converter to the next and multiplied by 3. My block does not have a third hole for the 307 starter. I also don't have the starter bracket to connect the front of the alternator to the block; I have read about it but my father and uncle both claimed that they had never seen it in "all their years of working on small block Chevy's."

Also the block, heads, valve covers and water pump were all painted orange at some point in the past. Was that a factory job or would that indicate either an aftermarket engine, engine rebuild, or a painting of the engine?

I apologize if any of these questions seems ignorant, but this is my first time really working on one of these cars. Most of my experiences has been spark plugs, filters, oil changes, etc....

Thanks for all your help.

Sincerely,
TJ

travis · Jul 3, 2006

If there are no numbers on the pad behind the alternator, then either its buried in gunk (it is stamped and not very deep), or else the engine was decked at some point and the numbers was milled into oblivion.
Like was stated, the only sure fire numbers you will find will be on the drivers side rear of the motor, in relatively big cast numbers, right behind the head and facing up. A strategically located small mirror can help immensly in reading those numbers.
If the orange paint is relatively fresh looking, then there is a very good possibility that it is not the original engine. After 30+ years, the original paint on the engine has most likely all flaked off, burned off, etc.
You could also yank a valve cover, which would make it easier to read the numbers on the back of the block, as well as post the numbers on the heads. Assuming of course that the correct type head was used on the engine (not a 305 head on a 350 block or something like that) then those numbers can many times point you in the right direction also.

73CamaroSC · Jul 4, 2006

Hi,

Good news. I found a casting number on the rear block. It appears that the block casting number is 3970014 with a casting date of J1673.

The front pad does not have a partial VIN; the pad just states 13L1 T0104CMA.

Thanks in advance,
TJ

JohnZ · Jul 4, 2006

73CamaroSC said:
I also don't have the starter bracket to connect the front of the alternator to the block; I have read about it but my father and uncle both claimed that they had never seen it in "all their years of working on small block Chevy's."TJ

ALL Chevy V-8's left the factory with a starter brace at the forward end of the starter - that's why there's a raised boss with a 5/16"-18 hole drilled and tapped in it in every block for the 1/2"-long upper brace bolt. The starter nose (at the flywheel end) wasn't designed to carry the cantilevered load from the weight of the case and armature - without the brace installed, the starter nose will eventually crack or break. Most Bubba mechanics leave the brace off when they replace a starter because it takes extra time to re-install it, and they figure the customer will never know the difference.

:beers:

73CamaroSC · Jul 5, 2006

I will check with Classic tomorrow and see if we can get that brace. The starter that went bad actually had the nose cone ripped off; the cone is sitting on my desk as a warped gear head's momento.....

I think we have confirmed that the engine is not a 307, but rather a '74 350 2bbl confirmed by engine casting code(3970014) and the assembly code(T0104CMA). The CMA suffix was used for a '72 307 and a '74 350. The flywheel had 168 teeth and the starter had a 350 offset bolt pattern, instead of the 307/153 tooth combination. The engine casting code is for a 70-76 2bbl 350.

Interesting conundrum to be in.....

'73 Camaro Engine Questions

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