What is the correct 1967 L79 water pump pulley #

[Christine G.]

I thought the 1967 L79 327-350hp engine used #3770245 2-grove pulley as stated in the 5th edition judging guide. The new 6th edition now lists #3905995 single groove for the standard L79 327-350hp engine. There is a note at the bottom of the page indicating further review is being conducted. Can anyone help with the correct #.

[Michael M.]

Re: What is the correct 1967 L79 water pump pulley #

The #3905995 is the 1-groove water pump pulley used on the base 327 engine. In all my listings of the water pump pulleys for the L-79 engine I do not see part #3905995. The only 1-groove water pump pulley part numbers I see for the L-79 are #3765427, #3883235, and #3883234. Part #3883234 1-groove pulley is also used for the base 327 engine.

[Gary B.]

Re: What is the correct 1967 L79 water pump pulley #

Richard,

I surely hope someone isn't reconsidering the correctness of the 2-belt arrangement, including a captive belt between the crank and water pump for the L79 no-option '66s and '67s. We suffered for years with people removing the captive belt for judging during the period when people didn't believe GM used the captive belt. After more research the captive belt was finally accepted. Don't tell me we're going backwards.

Gary

[Donald H.]

Re: What is the correct 1967 L79 water pump pulley #

Nolan Adam's book show two grooved pulley on an L79 engine on page 421

[Gary S.]

Re: What is the correct 1967 L79 water pump pulley #

Here is a 67 350 hp when almost brand new. I saw this picture in 2009 and saved it. Maybe someone out there wants to claim credit. If you enlarge the picture, it is pretty easy to see the two belts on the top pulley.

[Joe R.]

Re: What is the correct 1967 L79 water pump pulley #

I thought the 1967 L79 327-350hp engine used #3770245 2-grove pulley as stated in the 5th edition judging guide. The new 6th edition now lists #3905995 single groove for the standard L79 327-350hp engine. There is a note at the bottom of the page indicating further review is being conducted. Can anyone help with the correct #.

I believe there was some last-minute debate on the pulley chart for the latest '67 JG. I learned about this just before the new '67 JG went to print, so it was too late to get it sorted out.

In my view, the correct water pump pulley for the '67 L79 base engine is the 2-groove 3770245. I think it can be shown that the 3905995 simply does not align with the '533 crank pulley. This is because the 3905995 is a standard-groove pulley and the '533 is a deep groove pulley. I don't think GM would ever have used a mis-matched pair.

As I understand it, the heart of the debate relates to what the '67 AIM says (or doesn't say) and how that should be interpreted. The structure of the AIM is that it first describes the base configuration for a no-option 300 HP engine. Then, for each option (such as L79), there is a section that describes what is *changed* from the base configuration. For the L79 option, the AIM pages that we presently have available never mention changing to the 3770245 pulley. In theory, this means that the 3905995 from the base configuration is retained in the base L79.

I think this is a weak argument for saying that the L79 used the base engine water pump pulley. My understanding is that the AIM we have today is not necessarily complete. In addition, I think there are many known examples where what was actually done in production differs from what the AIM says. I have always assumed that the "gold standard" for NCRS judging is what we see on known-original cars. My guess is that known-original cars will have the 3770245 2-groove pulley, but I do not have any examples to cite.

As noted above, my main objection to the 3905995 on the L79 has to do with the fact that it would not line up properly with the '533 2-groove crank pulley. I just don't think GM would intentionally do this.

After hearing about the pulley debate in the latest '67 JG, I decided to acquire one each of all the referenced water pump and crank pulleys listed in the pulley table for the 300 HP base engine and the L79 (excluding the A.I.R pulleys). My plan was to mount these on a mock-up engine and demonstrate via photos how silly it looks to mix a standard-groove water pump pulley with a deep-groove crank pulley.

I have not yet gotten around to doing that, but if there is interest here on the forum I can raise the priority a bit and try to get it done. I've been in no rush because I figure my actual deadline is the drafting of the next edition of the '67 JG.

[Gene M.]

Re: What is the correct 1967 L79 water pump pulley #

I thought the 1967 L79 327-350hp engine used #3770245 2-grove pulley as stated in the 5th edition judging guide. The new 6th edition now lists #3905995 single groove for the standard L79 327-350hp engine. There is a note at the bottom of the page indicating further review is being conducted. Can anyone help with the correct #.

Richard,
It is a double pulley with two belts just as Gary Seymour stated and shown a photo of. Obvious the new 6th edition manual is WRONG if stating a single groove for the standard L79. The bad part of this is now members will be changing correct configuration cars to match the NCRS manual. Single pulley is correct for base 300HP engine.

[Christine G.]

Re: What is the correct 1967 L79 water pump pulley #

Thanks to all for your info. I will be looking for a #3770245 2-groove pulley. I plan on attending the Lakeland Swap Meet and NCRS Judging area and take plenty of photos.

[Gary S.]

Re: What is the correct 1967 L79 water pump pulley #

Both my early 67 #1866 and my late 67 #19567, original 350 HP motors in each, have the 533 bottom and 245 top pulleys. Both cars unrestored (very unrestored) when I bought them.

[Gene M.]

Re: What is the correct 1967 L79 water pump pulley #

The most common original finish on the double water pump pulley is not paint as most would expect. It is some kind of plate like phosphate or black oxide or possible heavy dry film. I'm not sure which. It is fairly flat no sheen finish and holds up pretty well.

[Gary B.]

Re: What is the correct 1967 L79 water pump pulley #

Gene,

The original coating on the pulley was Parkolac 30. Last year I asked Richard Fortier what he knew about Parkolac 30 and he in turn asked a plating person he knew, who told him "Parkolac 30 was a trade name for a liquid chemical that parts were dipped in post black phosphate and then baked in a 180-degree oven. The process created a coating that was 0.3 mils thick, i.e., much thinner than a layer of paint."

Gary

[Michael M.]

Re: What is the correct 1967 L79 water pump pulley #

Gary you and Gene are correct in what you are saying. Gary Seymour pictures of the finish are not correct from what I can see in the photo's. If you have seen a pulley that has " Parkolac 30 " it's as Gene describes but has a slight metallic appearance with a rough texture.

[Gary B.]

Re: What is the correct 1967 L79 water pump pulley #

Michael,

The question I've been asking for several years is, what is the best coating or process to use when restoring a pulley that originally had Parkolac 30 that will result in a comparable looking and lasting finish?

Gary

[Michael M.]

Re: What is the correct 1967 L79 water pump pulley #

Gary, I also spoke to Richard Fortier about " Parkolac 30 " long ago and as we all know that " Parkolac 30 " is no longer available. If you have a original #3770245 pulley to use as a example with today's technology you can reproduce the appearance.

[Joe L.]

Re: What is the correct 1967 L79 water pump pulley #

Michael,

The question I've been asking for several years is, what is the best coating or process to use when restoring a pulley that originally had Parkolac 30 that will result in a comparable looking and lasting finish?

Gary

Gary------

Many later SERVICE GM #3770245 pulleys were painted semi-gloss black. It's also POSSIBLE that some of those used in PRODUCTION were too. My expectation is that GM may have once specified alternate finishes for this pulley. In any event, in later years GM pretty much abandoned the phosphate/Parcolac finish for pulleys and went to painted for most, if not all, PRODUCTION and SERVICE, including SERVICE for earlier applications which were originally phosphate/Parcolac.

To restore an original finish one has to first strip the pulley completely to bare metal. Then, it has to be re-phosphate finished. To restore the Parcolac appearance, I use a very light coat of satin finish urethane. It's not perfect but, in my opinion, it's as close as you're going to get.