1967 Water Pump Pulley Question

[Rocco S.]

I am a fairly new NCRS member joining about 2 years ago when I wanted to learn as much as I could about mid-year Corvettes. I have been wanting another one since I sold my NOM '64 roadster back in 1979. I always told myself that if I ever got another mid-year, it would have to be a matching number car.

After about a 5 year search I finally purchased a one owner 1967 Coupe. It took me about 3 years to close the deal. I took somewhat of a chance since the car has been parked since 1974 and has not been started since 1974. The car was garage kept and is in good shape and has some nice options. L79, TI, M21,3.70 Posi, A/C, P/W, Headrests, Tinted Glass, Offroad Exhaust, AM/FM. Color is Lynndale Blue with standard black interior.

Included with the car was a good amount of documentation including the P-O-P, dealer copy of the build manifest (similar to window sticker or tank sticker) and full maintenance history with receipts.

So far everything I have checked is original with proper date codes with the exception of the fan which is a 7 blade (date coded 72) and a big block fan clutch. For some reason the fan and pulleys were removed from the engine and were in a box of parts. The previous owner claimed they were the original.

Now to my question. I purchased a "replacement Water Pump" to be used temporarily to get the engine running. It was purchased from a major Corvette supplier. My plans are to have the original pump rebuilt in the future. When test fitting the double groove pulley to the new pump I noticed the pulley hit the pump casting ever so slightly in one place just on the inside near the outer diameter. The pulley fits fine on the original pump. Can someone confirm that I have the correct water pump pulley? The aftermarket pump casting is slightly different than the original. I could grind a bit off the housing for clearance.

Here's a list of what pulleys I have:Water Pump, 2 groove #3848904, 5.825"OD, Crank Pulley 2 groove #3858533 6.750" OD, Alternator 3.025" OD, A/C 5.662" OD. All seem to be deep groove. I would also like to know the belt lengths. It is very confusing trying to figure this out with the combination of options. The A/C compressor pulley seems larger than normal also. Maybe because of the 3.70 rear gears?

[Joe L.]

Re: 1967 Water Pump Pulley Question

I am a fairly new NCRS member joining about 2 years ago when I wanted to learn as much as I could about mid-year Corvettes. I have been wanting another one since I sold my NOM '64 roadster back in 1979. I always told myself that if I ever got another mid-year, it would have to be a matching number car.

After about a 5 year search I finally purchased a one owner 1967 Coupe. It took me about 3 years to close the deal. I took somewhat of a chance since the car has been parked since 1974 and has not been started since 1974. The car was garage kept and is in good shape and has some nice options. L79, TI, M21,3.70 Posi, A/C, P/W, Headrests, Tinted Glass, Offroad Exhaust, AM/FM. Color is Lynndale Blue with standard black interior.

Included with the car was a good amount of documentation including the P-O-P, dealer copy of the build manifest (similar to window sticker or tank sticker) and full maintenance history with receipts.

So far everything I have checked is original with proper date codes with the exception of the fan which is a 7 blade (date coded 72) and a big block fan clutch. For some reason the fan and pulleys were removed from the engine and were in a box of parts. The previous owner claimed they were the original.

Now to my question. I purchased a "replacement Water Pump" to be used temporarily to get the engine running. It was purchased from a major Corvette supplier. My plans are to have the original pump rebuilt in the future. When test fitting the double groove pulley to the new pump I noticed the pulley hit the pump casting ever so slightly in one place just on the inside near the outer diameter. The pulley fits fine on the original pump. Can someone confirm that I have the correct water pump pulley? The aftermarket pump casting is slightly different than the original. I could grind a bit off the housing for clearance.

Here's a list of what pulleys I have:Water Pump, 2 groove #3848904, 5.825"OD, Crank Pulley 2 groove #3858533 6.750" OD, Alternator 3.025" OD, A/C 5.662" OD. All seem to be deep groove. I would also like to know the belt lengths. It is very confusing trying to figure this out with the combination of options. The A/C compressor pulley seems larger than normal also. Maybe because of the 3.70 rear gears?

Rocco------


Does this car NOT have power steering?

[Rocco S.]

Re: 1967 Water Pump Pulley Question

No, it does not have power steering. I know that would make a difference. The engine is "HT"

[Leif A.]

Re: 1967 Water Pump Pulley Question

Rocco,
Your crankshaft pulley and water pump pulley are the correct part numbers for a L79 with C60 only (no power steering). The alternator pulley sounds to be correct, also. Might I recommend (if you haven't done so already) that you purchase both the Assembly Instruction Manual and the Technical Information Manual and Judging Guide from the NCRS store. They are a treasure trove of invaluable information that will answer most of your questions. Welcome back to the wonderful world of C2 ownership (especially a L79).

[Chris D.]

Re: 1967 Water Pump Pulley Question

Check your pulley hub placement along the pump shaft. Compare original pump to the replacement pump for the distance from the hub face to the block mounting surface. The much more common 300hp and lower pump is set up 1/8" closer to the engine block. Could be a rebuilder error.

[Douglas L.]

Re: 1967 Water Pump Pulley Question

Rocco,

I'd be willing to bet the contact is due the pump and not the pulley. I had a similar experience with the 68 L36, bought aftermarket pump and pulley rubbed. I ended up using 1 shim under the pulley. When I finally got around to rebuilding the factory pump I found that you have to be real careful when pressing everything together to maintain correct pulley mounting hub offset relative to the pump body to be sure the pulley wont rub. Since the corvette pulleys already sit pretty close to the engine it seems pretty likely that during assembly someone could easily set the distance on the close side of things and run into a rubbing problem.

[Richard M.]

Re: 1967 Water Pump Pulley Question

I agree that the culprit is likely a rebuilder error whereas the hub was pressed on too far onto the bearing mainshaft. Probably just took a measurement from the old hub to the housing snout, replaced the bearing assembly and pressed the hub back on. This is NOT the way to get the reference for the hub.

Their is a specification for the hub face to pump mounting bosses. This is the way it should be checked. It's hard to check it when the pump is mounted on the engine and much easier on the bench. Typically, when pumps are rebuilt the mount bosses could be a bit corroded form age. Many times rebuilders will lay them on a flat table belt sander to clean the faces. Over time, after many rebuilds, the distance between the face and the hub face can get shorter. This now becomes the installers problem.

Adding a additional water pump pulley reinforcement may kick it out enough and you'll be all set. The reinforcement is about 0.040" thick so 1 or 2 of them may do the trick. BTW, there was a Service Bulletin which addressed Water Pump pulley cracking issues. It stated to add this reinforcement whenever a cracked pulley was discovered. The reinforcement was added when the new pulley was installed.

Their is another more preferred method to resolve this when the hub is too far in. When I run into this I use a 3 jaw puller to pull the hub out just enough to gain the needed pulley clearance and meet spec. But be careful because if you pull it out TOO far you then have to completely disassemble the pump to press it back on properly by supporting the impeller side of the shaft.

Below is a webernet-info-article I made about C1 Engine accessory pulley alignment. It discusses water pump pulleys and hubs with some data that may help. Much applies to the C2 engines, with the exception of the Generator versus Alternator, and the infamous Harmonic Balancer Spacer which the Ci engines require due to their "different" front engine mount arrangement. Kudos to fellow member Dave Zuberer for his conversion editing and PDF magic.

Rich

[Rocco S.]

Re: 1967 Water Pump Pulley Question

Thanks to all of you who responded.

After some thought and careful measurements it was determined that the aftermarket pump was at fault. The pulley mounting flange was pressed on too close to the pump casting. I compared the height of the original "326" pump to the new unit and noticed a small difference in the "distance from the block mounting surface to the outboard surface of the pulley mounting flange". I used a puller with 2 puller bolts attached to the flange and moved the flange outboard about .020" which was just enough to prevent the interference.