427 engine - is it a 4 bolt main block??

[Dave E.]

I would like to know if the mid seventies NOM 427 in my 66 coupe is a two bolt or four bolt main block....without dropping the oil pan. I remember hearing once that there is some external physical machining characteristic on a Chevy big block's lower left side in the oil filter area that was an easy identifier. Any truth to that?? (the block's casting number can be either 2 or 4 per the ref books I have) Thanks

[Ray G.]

Re: 427 engine - is it a 4 bolt main block??

Hello Dave;
The machine area "boss" used for oil pressure line is different on two and four bolt(s).
A two bolt can be made into a four. Difficult to reverse.

Will get pictures today.

Hope this helps.
Ray

[Dave E.]

Re: 427 engine - is it a 4 bolt main block??

Ray.....Thank you for the quick reply.....I appreciate it.....yes, that helps a lot.....and I really look forward to the pics. Dave

[William C.]

Re: 427 engine - is it a 4 bolt main block??

Dave, there are two bosses above the oil filter, on a 4-bolt block those are drilled and tapped and have fairly large pipe plugs in them. 2 bolt are not drilled and tapped in that area. Should be pretty obvious.

[Ray G.]

Re: 427 engine - is it a 4 bolt main block??

Hello;
Bare 2 bolt.
oil line 2 bolt
oil line four bolt

[Ray G.]

Re: 427 engine - is it a 4 bolt main block??

Hello;

I should add, these are 3904351 picture.

Hope this helps.
Ray

[Mike M.]

Re: 427 engine - is it a 4 bolt main block??

Hi Dave
I can't think of any 427 Hi Perf applications from the mid 70's
(Perhaps someone can confirm) So, probably a 2 Bolt.
Mid- Year generation 4 Bolts also have an "H", "HP" or "HI PERF" cast somewhere on the bell housing flange.
HaND

[Rich P.]

Re: 427 engine - is it a 4 bolt main block??

Mike,

he did not say if it was out of a vehical with stamp and all (now that I think of it I think maybe just trucks used 427's in the 70's and they would be tall deck blocks) so it is possible it is an over the counter block cast and sold in the seventies. Just a thought.

Rich

[Joe L.]

Re: 427 engine - is it a 4 bolt main block??

Hi Dave
I can't think of any 427 Hi Perf applications from the mid 70's
(Perhaps someone can confirm) So, probably a 2 Bolt.
Mid- Year generation 4 Bolts also have an "H", "HP" or "HI PERF" cast somewhere on the bell housing flange.
HaND

Mike----


427 cid engines were not used in PRODUCTION after 1969 for any passenger cars. They were used for trucks, though, well after 1969.

[Mike M.]

Re: 427 engine - is it a 4 bolt main block??

Thanks, Guys, for jumping in.
Were the later 427 castings 351's also?
Would any of those later 427 Truck blocks have been Hi Perf 4 Bolts?
Thanks, again,
HaND

[Rich P.]

Re: 427 engine - is it a 4 bolt main block??

Mike,

off the top of my head (and the only thing that comes off the top of my head is hair lately!!) the casting #'s changed from 351 to 272(I think) then 439 and finally 512 before the 427/512 version turned into a 454 in 70. I might be wrong on the 272 but i'm sure someone will correct it if so.


Rich

OK to correct myself it is 270 not 272 and I forgot to add the 321 for 68.
Now correcting my own post would that be concidered talking to myself? Or am I just so used to being correted at home that I felt compelled to do it here???

[Joe L.]

Re: 427 engine - is it a 4 bolt main block??

Thanks, Guys, for jumping in.
Were the later 427 castings 351's also?
Would any of those later 427 Truck blocks have been Hi Perf 4 Bolts?
Thanks, again,
HaND

Mike----


Most, if not all, of the 427 blocks used in trucks after 1969 were "tall deck" blocks. These were medium duty and heavy duty applications. I don't think that any 427 "light duty" truck applications after 1969 used the "short deck" (i.e. passenger car and Corvette) blocks.

[Clem Z.]

Re: 427 engine - is it a 4 bolt main block??

what is on the stamp pad ????

[Dave E.]

Re: 427 engine - is it a 4 bolt main block??

Thanks Ray and Bill.....its a four bolt block. I think I should continue my research on this engine now - while I have some big block guys on this post.

I am trying to attach a pic of the block casting number....legible digits are 993289 (maybe the last 9 is a 0 or 8??). I can find no such big block number in the few books I have. I find 3999289...that's the closest.

The pad is completely blank....and the block itself does not look like it was ever painted.

I have spoken with the original owner of the car...he has very good recall...remembers the exact date that he took delivery of his new 1966 vette. He says he purchased the new long block from Motion Engineering (of Baldwin Motion fame) in 1973 or 1974. He ordered an exact replacement for the original 427/425 motor except that he wanted to upgrade to aluminum heads (which it has). Says he never cared about any part numbers and did not verify bore/stroke/whatever...just dropped it in and ran. He does remember that the darn motor cost way too much!!

I would think that Motion would have identified the motor in some way - in case of customer service or complain needs - or just for their own production/inventory reasons....but I don't see any stamping or paint markings on the block.

The motor has sat undisturbed in the car for about 30 years with almost zero miles during its second ownership (deceased). I am third owner.

Perhaps its a 454...anyone got some facts (or theories) for me??

[Rich P.]

Re: 427 engine - is it a 4 bolt main block??

Dave,

if the shrot block was put in as delivered from chevy, motion probably did not stamp ID#'s on it but if they went through it there usually would be something stamped on the pad, heads or bellhousing flange. Thats not set in stone but from what most motion guys tell me thats what they did.

Rich