Impala SS427.com Message Board

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1968 427 Motor

Posted by Mikael on 4/1/2019, 2:54 pm

Hello everyone!
I have a 1968 SS with a 427 motor. The casting number is 3916321. No stamping on the front of the block. Is there anyway to tell if it´s a L72 or maybe a corvette motor?

Re: 1968 427 Motor

Posted by 68ss427 on 4/2/2019, 8:09 am, in reply to "1968 427 Motor"

An L-72 will have 4 bolt main bearing caps and an L-36 will have 2. Look above the oil filter and see what predrilled oil fitting holes are there. An L-72 will have a 3/4" and a 1/2" tapped holes, an L-36 will have just a 1/2" oil fitting hole. If the car is original, An L-72 will have a SINGLE 3/8" fuel line and an L-36 will have both a 3/8" and a 1/4" return line. The same engine was used in both Corvette and full size, and you need to have the front pad stamping to know what trans it came with. Don S

Re: 1968 427 Motor

Posted by Mikael on 4/2/2019, 2:28 pm, in reply to "Re: 1968 427 Motor"

What about the heads?

Re: 1968 427 Motor

Posted by 68ss427 on 4/2/2019, 3:48 pm, in reply to "Re: 1968 427 Motor"

L-72 heads casting # ends in 840 and are square port. L-36 heads are oval port and end in 215. L-72 intakes are aluminum Winters snowflake. L-36 are cast iron, ends in 948. Don S

Re: 1968 427 Motor

Posted by Jeff on 4/4/2019, 4:40 pm, in reply to "Re: 1968 427 Motor"

l-72 Heads

Re: 1968 427 Motor

Posted by Nick on 4/2/2019, 9:16 pm, in reply to "Re: 1968 427 Motor"

Is there a Vin number stamped on the block by the lower rear flange of the block by the oil filter? Does the intake have a Holley carb? Is there an upper bolt between the ports? Oval ports are usually round or smaller than a rectangular port with no upper bolt. It could have an after market intake on it. The block must have been machined, "decked" to remove the stampings on the pad. It must have been rebuilt some time. You will need to remove one of the heads to make sure what piston dome height. A high dome is an L72, unless the builder replaced the pistons with lower compression domes to run on "no lead" gas. NICK L72

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