I recently bought a truck and the previous owner said it had a 305. I was just trying to verify it were true or not. I found the cast block #, which is 3970010. I couldn't find anything else. Least for the time being. I do know the time key is behind the water pump. (12:00). Ive heard that all 350's key tab is at 1:30 position, which makes me believe its a 305. I'm just trying to find out exactly what I have. Help would be appreciated!
305 or 350?? 3970010
- Thread starter jay
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Hi Jay,
The position of the timing key has nothing to do with the size of the engine. You could either have a 327 or a 350, depending on the year. The casting number was very common for blocks that could have been either a 302,327 or 350. The 302s were very scarce and 1969 was the last year for 327. If your engine is 1969 or later I am saying that you have a 350.
Now, since you mentioned the "timing key', assuming that you mean timing mark on the balancer, The 350 up to the year 1973 was typically at around 1:00 Oclock. In 1974 when they came out with the HEI distributor, the timing mark indicator was moved to about the 12 Oclock position. Even this is not 100% because the timing cover and balancer could have been changed at one time or another.
Does the engine have HEI ignition? If so, probably 1974 or later. I would be comfortable saying you probably have a 350. Any idea what year engine you have?
The position of the timing key has nothing to do with the size of the engine. You could either have a 327 or a 350, depending on the year. The casting number was very common for blocks that could have been either a 302,327 or 350. The 302s were very scarce and 1969 was the last year for 327. If your engine is 1969 or later I am saying that you have a 350.
Now, since you mentioned the "timing key', assuming that you mean timing mark on the balancer, The 350 up to the year 1973 was typically at around 1:00 Oclock. In 1974 when they came out with the HEI distributor, the timing mark indicator was moved to about the 12 Oclock position. Even this is not 100% because the timing cover and balancer could have been changed at one time or another.
Does the engine have HEI ignition? If so, probably 1974 or later. I would be comfortable saying you probably have a 350. Any idea what year engine you have?
Thanks for the information. It does have a HEI, and I'm gonna guess its a mid to late 70's model. Does the side of the dipstick matter? Everyone that I've talked to has said the 350's will be on the left, and mines is located on the right. I'm hoping its a 350, but I don't wanna get my hopes up yet. I'll have to find the numbers behind the alternator sometime tomorrow for more NFO.
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Jay, as I recall, the 70s model was on the drivers side and the 80s and 90s was on the passenger side. The number on the pad underneath the alternator would tell more. But in reality, it makes no difference as far as the basic engine goes, they are all the same specs until late 86, early 87 when they converted to a one piece rear main seal and roller cam and lifters. Hope this helps.
We have another guru on her that is a whiz at the numbers, but that is not me. I am more concerned with what I can do with it.
We have another guru on her that is a whiz at the numbers, but that is not me. I am more concerned with what I can do with it.
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There is a small machined pad on the top surface of the block just below the front of the head on the passenger side. If your alternator bolts to the passenger side head with a long bolt going through the pivot point and into the head, it will be just below that. It is sometimes hard to see. Sometimes you may need to scrape or sand it and use a light. Look straight down behind the alternator and it will be there.
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If you see the raised markings 010, you have a V8. If it is a V8 engine, it could have been a factory crate engine, or the engine has been down and the deck machined. I still need to know for sure if it is a straight inline 6 or a V8?
And the casting number is the back. (3970010) I'd say there's more numbers behind the flywheel. In fact I remember when I saw the engine on a hoist. I just never wrote them down. With the block cast number being 3970010, does that officially eliminate it being a 305?
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The numbers 3970010 indicates a block casting with a 4.000" bore. It could have been used in 302, 327 and 350. The 302 is not likely because it was in the Z-28 Camaro with aluminum intake and Holly carb, very collectable and people are not going to put one in a truck.
The last year for the 327 was 69 and the first year for the 350 was 69. I think you are safe assuming it is a 350.
The last year for the 327 was 69 and the first year for the 350 was 69. I think you are safe assuming it is a 350.