hello my name is al and i am hoping you could give me a strait awnser . my father and i bought a truck thet had a moter put in it befor we bought it and we have owned it for about 10 years or so .in the past year i have been looking into what moter excatly is in it . i have looked at all you have online and still not to sure how to read some of the numbers.so far on the rear of the moter we have as follows 3969854 also A 7 70 also i found GMB or last one could be a 8 lastly on rear i see what looks like a 1upside down followed by ANO that is what i have on the back of the block . As for the frount pad as you call it pass side we have what looks like TC1551850 OR COULD BE 1C1551850 on the same pad away from the other # we have a W on it or could be a M left to right it would be a W faint but it is their .left side head reads 3964290 GM9T PASS B 27 70 RIGHT SIDE HEAD IS B 26 70 GM11T PASS 3964290 .if any one can figure this out please email me either way .also one of the big issues is we have been told two diff things for running plugs some people say short some people say long plugs .this would be a great deal of help for both of us thank you for reading .

69 396 2 or 4 bolt main same casting is a 70-72 402 2 or 4 bolt main.

Heads are 69-70 oval port closed chamber 396, 402, 427, 454 101 cc chamber.

Dave

Al have you looked at mortec.com they are the bible of numbers if someone else dosen't answer

Ok my book says 70 402 could be 3 or 4 bolt main as the block came in both types. the heads are Oval port closed chamber no listing on cc. the book say factory the motor was 10.25:1CR has different hp levels based on cam and rpo numbers. it is a car block. the book also says they came with r44t plugs for small socket plug and r44 for the flat washer plug. thats all the info I have.

oh my beat by a few key seconds lol I think we all posted about the same time lol

dave thank you for the info is there any way to tell between the 396 and 402 . as far as the heads go are these heads good for the moter or is there a better head recomended for it .

i have emailed them and they have not yet replied back thanks for the info

thank you for you for the info i see you came up with a plug size is there a big diff beetween the two you came up with and if so how do you tell for sure what should be in the heads thanks al

http://www.chevelles.com/showroom/data/500/medium/bbcast_numbers.jpg

hmm, that didn't work :o
http://www.chevelles.com/showroom/data/500/bbcast_numbers.jpg

The heads are decent pieces, to tell between a 396 or a 402 you will have to measure the cylinders.

Dave

well my book says it is a 402 but the book has been worng before lol

thank you for you for the info i see you came up with a plug size is there a big diff beetween the two you came up with and if so how do you tell for sure what should be in the heads thanks al

one the r 44t is for taper head or small plug head.
the r 44 is for the heads that take the bigger spark plugs that use a washer. the big plugs take a 13/16 socket.
The small plugs take a 5/8 socket. that is how you know the difference.

I figure a better head for it would be what came on it stock b/c I figure most BB's back then were right at 10 to 1 CR. up to 1970. So at that CR. you can run a decent sized cam and make some hp.

After 1970, CR. tanked so an early head should bring the CR. back to the 1970 CR.

A warmed over about 10 to 1 CR'd, 402 w/ no more than CC's old 280 Magnum and headers should make almost 400hp.

Excellent street engine by me.

As always, jmho.

pdq67

PS., Guys, is it a 325/330hp engine??