jbbeans

I have stumbled on an apparent "virgin" 1964 L75 327cid, 300bhp engine and in verifying all the numbers, I came upon a problem. Everything matches except the passenger side exhaust manifold. Visiting websites for identification they say the manifold for this right side should be a 3750556. The manifold on it is a 3733978. I am comfortable with the number 3750556 being correct, but I am sure seeing a lot of 3733978's being offered for many different years and engines...can anyone help me sort this out?

Thanks

Bob

Frankie the Fink

The '978' side doesn't sound correct for a '64 maybe a '57...here is a 6-digit Bel Air for sale with a '978' exhaust manifold- ad says all numbers are correct:
http://cgi.cafr.ebay.ca/Chevrolet-Be...QQcmdZViewItem

DZAUTO

Is the engine for a 4sp or PG car? IT MAKES A BIG DIFFERENCE!
The 300hp engines for a PG car got 2in manifolds and the 4sp 300hp engines got 2 1/2in manifolds. AND, in addition to that, it makes a difference if the car did or did not have air cond.

kenba

BOB
1964 300/ auto LH 3846559 RH 3750556
300/man. LH 3846563 RH 3379702
The 3733978 is not used on a Corvette mid year
KEN

kenba

I don't beleave any Corvette small block had 2.5 exhaust only 1.625 & 2.0
KEN

DZAUTO

Better start bonin' up!!!!!!!!!!!!!!!
ALLLLLLLLLLLLLLLLLLLLLLLLLL solid lifter 62-65 Covette engines had 2 1/2in ex manifolds.
The 65 350hp/327 (hyd lifter L79) engine had 2 1/2in manifolds.
ALLLLLLLLLLLLLLLLLLLLLLLLLLLLL 62-65 300hp/327s with MANUAL trannys had 2 1/2in ex manifolds (PG 300hp engines had 2in manifolds).

ALLLLLLLLLLLLLLLLLLLLLLLL 62-65 FULL SIZE pass cars with 300hp/327s (manual AND PG trannys) had 2 1/2in exhaust manifolds.





In the next TWO pictures, the TOP manifold is a repo.

DZAUTO

By the way, ONLY the Corvette and full size pass cars were the ONLY Chevys to EVER get 2 1/2in manifolds on a SB. ALL other Chevy products got 2in manifolds on the SB, even including trucks.

Until about 2-3yrs ago, ALL three 2 1/2in manifolds were still available from Chev parts dept (the 4th version was NEVER available).
Now, the 901 and 902 (L&R with SIDE facing holes) are available as Chinese repos. Quite honestly, both seem to be pretty good copies, BUT, without any casting numbers. The plain ones above are the Chines repos.

NOW, IF SOMEONE WOULD JUST REPO THE 563 VERSION!!!!!!!!!!

jbbeans

Thanks everyone for all the help and responses with my exhaust manifold problem. I am a new member and am overwhelmed by the help and support you all have for each other.

Bob

kenba

I stand corrected. Got my 63-67 mixed up with 68-72
KEN

DZAUTO

All four styles that were made are shown above.
The two with SIDE facing holes for gen/alt mounts are the 901 and 902 versions.
The one with FORWARD facing alt mount holes (64-5 left side ONLY) is the 563. The one below that is the 942 style (I refer to it as the "plain" version). The plain version pictured above was NEVER available as a service replacement, it ONLY came installed on production cars. It is easy to cut off and grind down the alt bracket from a 563 to make a "clone" of the plain 942, which is what I've done below and that's what the one above is.