Trying to find out what motor I have in my '72 chevy. How can you tell the diff. between a 307, 327 and a 350. I think I have a 350. Can anyone help?:7
If you are standing in front of your truck look to the left of the timing cover and there is a little step and there should be some numbers stamped into that step. Now if you give me those numbers i can decipher them and tell you as much as I can about the engine you have.
those numbers are not working out for me. if there are any other numbers in that area give them to me also. look above the timing cover and also to the left of the timing cover there are two different spots that have numbers on them.
Hello again, Assuming that the engine is not original and that you just want to know for g.p. on the back of the block above the bellhousing where the trans bolts up, on the drivers side are a series of numbers(large)cast into the block. example; 3900010 These numbers will tell you what the block casting was intended for. Either 350, 327, 305, 400,...etc. If it is the original engine the casting should be 3900010 and it would be a 350 casting for 72 and earlier. Don't let anyone tell you that the "010" casting blocks are 4 bolt mains. That's not what it means. Some were, but not all. However they all had a high content of nickel in the metal which makes them stronger compared to the later castings. These blocks are consequently more desirable with the performance engine builders. As far as outside physical differences in the 307, 327, 350 and only if they retain the original parts, this is how to tell at a glance. First the balancers on the crankshaft. the 307 and the 327 use a very small diameter balancer. I don't remember exactly, but I recall the 307 being externally balanced. Which would make the balancer on the 307 to have a weight on the inside making it not symetrical. The 327 has an equal thickness and is internally balanced. The 350 used two different balancers one 6" in diameter and rare toa find, the other and most common is 8" in diameter and about an 1 1/2" thick. Also internally balanced. The 400 has a large balancer that has a partial notch in the back side making it have an uneven thickness. also the 400 has bosses for 3 freeze plugs. 70-72 have the three freeze plugs and the rest have two, the middle one is blank. Next the heads. The 327 until the last year 1968, stock did not have accesory bolt holes. In fact I don't believe any small blocks before late 67 had them. These holes are for the alternator bracket and a/c brackets that bolt to the head. There are more diferences but I don't remember them all. Your best bet is to get the numbers of the back of the block and find out what casting those numbers go to. They won't tell you exactly what vehicle and horse power rating like the front stamped ones will, but they will tell you the intended cubic inches. GOOD THINGS, BRANT.
