67 Coupe -Gear ratio/Trans model

[Brian Buchanan]

I am looking at a 67 coupe to buy. What are the best reference books?
Can anyone tell me the gear ratio and is it posi? (AK 216 67)
Trans model M20 or 21? (Tag 3870354)I read the recent discussions.
What is engine block from? casting #3959512 I know its not the 327/350 that was originally in it.
Thank you for any help!

[Tom D.]

1967 Gear ratio/Trans model

The block must be newer than 1970. Do you have other (pad) numbers?

The AK code on the rear indicates a 3.36:1 non-posi.

I'd recommend you buy Alan Colvin's "Chevrolet by the numbers" or "Corvette by the numbers" before you buy. His books are excellent and available on this web site, or by calling NCRS.

[Tom D.]

1967 Gear ratio/Trans model

The trans should have the vin number of the car stamped on the main case. This number might be on the top, however. Look for a P7 (Muncie 1967) followed by a month code like E19 (May 19).

[Tom D.]

Re: 1967 Gear ratio/Trans model

The P number (date code) would be on the main transmission case (should have a large casting number of 3885010), plus you should look to see if the tail-shaft is correct (casting number 3857584) and the side cover (3884685. /td

[Jim T.]

Re: 67 Coupe -Gear ratio/Trans model

Brian if the 67 has the M20 IMO that is a good thing for. This 67 with a M20 will leave from a dead stop and get the car moving more efficently than a M21. If it pulls away from a stop sign and accelerates well in first it most likely a M20. The M21 when getting started on a incline requires slight slippage of the clutch to get the wheels turning.

[Brian Buchanan]

Re: 67 Coupe -Gear ratio/Trans model

I couldn't find pad numbers. According to owner (original) the short block was installed new at a chevy dealer late 60's early 70's the heads,intake ,carb,v/c appear to be original. The trans does have the original vin stamped on it. The date code is P7C22 (muncie 1967 march 22nd?)Diff also had 67 stamped on it.
This is a CA car with black plate one owner (age 86) car has 117k miles. Very few options PS,A/C,-works 327/350,Air pump. Ermine white 972 Saddle trim 420

[Jack H.]

Re: 67 Coupe -Gear ratio/Trans model

Much depends upon your objective in owning the car: (1) serious factory concours show car, (2) hybrid driver/occasional show, (3) weekend warrior use, (4) daily transporation. Only you can define the objective and it's almost IMPOSSIBLE to have your cake and eat it too (get a car that serves all use purposes)....

In addition to buying/reading Colvin's book, I suggest you get the NCRS 1967 Technical Information Manual & Judging Guide. This will outline in pretty good detail, what the judges look for on these cars.

But, beware, there's a LOT of information to read/digest/understand and you may not have that much time to inspect the car, make your buy decision and close the deal/walk away. So, if you're already an NCRS member, why not call on your local chapter folks to see if you can either hire or 'entice' someone with skill in the area to go with you for a day as your consultant?

Last, often, it doesn't matter what's embossed or stamped on this/that part because over the years the internals could have been changed to effect repair. This is true of engines, rear ends, and to some extent transmissions. Reading the 'numbers' might simply tell you what that particular part WAS when it left the factory vs. what it really is today....

[Tom D.]

Re: 67 Coupe - Heads, etc.

Did you get castings off the other parts He says are original?

Heads = 3890462 if before June. But, prob. = 3917291 if later.

Intake depends on HP rating. 3890490 is on the 350 HP, for example. (Don't remember if you referenced HP rating above) /td

[Duke W.]

Re: 67 Coupe -Gear ratio/Trans model

Axle ratio is easy to determine by dividing top gear revs at 60 by 760, then round to the nearest available ratio. This is valid for any installed tire, but assumes that the transmission has the correct speedo gears for the installed axle ratio.

CR or WR transmission can be determined by shifting from third to fourth at 3000 revs. If the revs drop to about 23-2400 it is CR; 20-2100 would be WR.

The '67 L-79 was available with both WR and CR with different axle ratio choices for each transmission.

The NCRS Spec Guide has powertrain charts that spec out the available power train combinations and information on identifying the transmission and axles.

Duke

[Brian Buchanan]

Re: 67 Coupe - Heads, etc.

I don't have head casting numbers. They are under valve cover? The heads are the "double hump/fuelie style" Yes car was optioned as 327/350 and has casting 3890490 Intake. Carb is 3886097 list 3419. Judging from receipts alt,starter w/pump and A/C comp have all been replaced over the years.
This would be my first corvette and I only know enough to be dangerous!
My intentions are to use as weekend driver and local shows. With NOM and other swapped components and low options I can't see spending big bucks to return to full show quality. My desire is to keep orginal- maybe add brake booster.
Thanks for all the responses. I am enrolling as a member now!

[Tom D.]

Castings on Heads.

Yes, under the valve cover. You will also (hopefully) find a date code ending in 6 (for 1966 casting - early cars) or a 7 (for 1967 casting) - Example in other reply.

[Bob R.]

Re: 67 Coupe -Engine

The engine number you have (3959512) was used in 1962 1963. It was not used for Corvettes. The engine had 250 hp originally.