Re: Small Block Water Pump Backplates!!!!!

[William M.]

FYI and comment. Please comment on the usage of the small block water pump backplates in picture #1, picture #2, picture #3 and picture #4. Please comment on the Chevy orange paint on the water pump backplate in picture #2.
Bill Mock #93

[Joe L.]

Re: Small Block Water Pump Backplates!!!!!

FYI and comment. Please comment on the usage of the small block water pump backplates in picture #1, picture #2, picture #3 and picture #4. Please comment on the Chevy orange paint on the water pump backplate in picture #2.
Bill Mock #93

Bill------


The first photo is of a GM #3704166. I believe it was used from 1955 to ABOUT 1960.

The second photo is of a GM #3782610. It was used from ABOUT 1961.

I believe the third and fourth photos are also of a 3782610 but which was modified by changes to the GM specifications. I do not know just when these changes occurred. However, the third style was definitely in use by 1969.

I'm not sure that the fourth style (with the small "tabs" seen around the perimeter) resulted from an actual change to the GM specifications. I just do not see what functionality those would have served. So, it may just be that change was due to a manufacturing process change. When it occurred, I do not know.

As far as the paint on the rear cover in the second photo is concerned, that's very typical of waterpumps originally installed on an engine and painted at the engine plants. I've seen it on a lot of original pumps. Usually, engines with short leg pumps (i.e. all 1955-68 and 1969-82 Corvettes) will have paint only at the very top where the plate does not abut the timing cover. 1969+ long leg waterpump rear plates usually have more paint.

As far as functionality goes, I only recommend that folks use the style plates seen in your third and fourth photos. I have found that's the only style that seals RELIABLY. In fact, I'm sure that's why GM made the change to the plates seen in the difference between your second and third/fourth photos.

[Michael H.]

Re: Small Block Water Pump Backplates!!!!!

FYI and comment. Please comment on the usage of the small block water pump backplates Bill Mock #93

Bill,

Just a guess but I would say that the plate in pic #1 was used from 55 through the 61 model year?

The only reason I think that may be the case is because Joe listed the part numbers and the part number for plate #2 falls in line, numerically, with the casting number of the new 327 engine block and 3782608-9 water pump that was new for 62.

I have an original 609 here somewhere that still has it's correct tall bypass fitting used in 62. If I can find it, I'll see what back plate it has.

[Bill M.]

Re: Small Block Water Pump Backplates!!!!!

The first photo is of a GM #3704166. I believe it was used from 1955 to ABOUT 1960.

My '59 original pump has the flat plate.

[David L.]

Re: Small Block Water Pump Backplates!!!!!

Bill,

I just happen to have a "3859326" water pump (pictured below) next to me dated "L 4 7" (Dec. 4, 1967) that has a backplate like your picture #2. I believe that this water pump is original. Five bolts have "EL" logos inside 2 circles and the 6th bolt just has the letter "L".

I have an original 1963-1965 "3782608" water pump (not dated) that has the same backplate and the bolts look similar. I also a dozen or so other SBC water pumps stashed away somewhere in my garage that I collected back in the 1980's.

Dave

[Gerard F.]

Re: Small Block Water Pump Backplates!!!!!

Bill,

Here's a picture of the back of the water pump from my late 67 S/B, a June 29 67 car:



Date code on the pump is F227 which is a week before my car's assembly date.

[Joe L.]

Re: Small Block Water Pump Backplates!!!!!

Bill, Jerry, and Dave------


Well, I'd say were narrowing down when the mounting plate with the impressed "slot" between mounting holes went into use----sometime between December, 1967 (when Dave's pump was cast) and August, 1969 (when my original 1969 pump was cast).

[David L.]

Re: Small Block Water Pump Backplates!!!!!

Joe,

The backplate of Jerry's June 22, 1967, W/P is also the same or am I missing something.

I will see if I can find some of my other original (not rebuilt) pumps tomorrow. From my notes I have 3 original "608" pumps and 2 original "493" pumps.

Dave

[Gerard F.]

Re: Small Block Water Pump Backplates!!!!!

Dave, Joe and Bill,

I have another 608 water pump dated F137 which has been overhauled probably a number of times. It has a backplate with the sealing ridges, and looks like the one in Bill's #3 picture.

The one in my picture above (F227) is original to my 67 327/300, and was taken off the car for the first time, about 3 years ago.

So I think we have a service replacement issue for the backplate. How long the plain backplate was used in production I don't know, but I would assume from the data above that they went to the backplate with the sealing ridges after 1967.

[Bill M.]

Re: Small Block Water Pump Backplates!!!!!

My '59 original pump has the flat plate.

Here's a picture of the '59 pump; never been apart. The paint is not OE, just very old:

[Clem Z.]

Re: Small Block Water Pump Backplates!!!!!

chevys had problems blowing out the water pump cover plate gaskets in the NASCAR races so i wonder if that is why they change the backing plate to grip the gasket better by putting the ridges on the backing plate.

[Joe L.]

Re: Small Block Water Pump Backplates!!!!!

Joe,

The backplate of Jerry's June 22, 1967, W/P is also the same or am I missing something.

I will see if I can find some of my other original (not rebuilt) pumps tomorrow. From my notes I have 3 original "608" pumps and 2 original "493" pumps.

Dave

Dave-----


Yes, Jerry's is a June, 1967 and it's the same as yours, but yours is later being a December, 1967. So, that's why I figure that the change to the cover with the "ridges" happened between December, 1967 and August, 1969 (when my pump with a cover with the "ridges" was manufactured).

[Joe L.]

Re: Small Block Water Pump Backplates!!!!!

Dave, Joe and Bill,

I have another 608 water pump dated F137 which has been overhauled probably a number of times. It has a backplate with the sealing ridges, and looks like the one in Bill's #3 picture.

The one in my picture above (F227) is original to my 67 327/300, and was taken off the car for the first time, about 3 years ago.

So I think we have a service replacement issue for the backplate. How long the plain backplate was used in production I don't know, but I would assume from the data above that they went to the backplate with the sealing ridges after 1967.

Jerry-----


Once a pump has been through a commercial rebuilding operation it's pretty much impossible to say what components are original to it. Commercial rebuilders "mix-and-match" components.

[David L.]

Re: Small Block Water Pump Backplates!!!!!

Here are 3 more water pumps. I believe that all are original (not rebuilt).

photo #1
"J 30 7" (CORRECTED), "GM 7, "T", "3782608", all 6 bolts have a waving flag logo.

photo #2
"GM 12", "3782608", all 6 bolts have the letter "E" inside 2 concentric circles.

photo #3
"GM 1", "3736493", "T X", with boss on top but WITHOUT a threaded hole, flat backplate with screws (for flat head screwdriver). This backplate looks like Bill Mock's photo #1.

I assume the "T" is for Tonowanda, NY.
Does the "X" (3736493 pump) mean that it is a new type of casting during that time frame?
I believe that the 3736493 pump was used on 1957-1960 models.

All my rebuilt pumps have the backplate in Bill Mock's photo #3.

Dave

[Joe L.]

Re: Small Block Water Pump Backplates!!!!!

Here are 3 more water pumps. I believe that all are original (not rebuilt).

photo #1
"L 08 9", "GM 7, "T", "3782608", all 6 bolts have a waving flag logo.

photo #2
"GM 12", "3782608", all 6 bolts have the letter "E" inside 2 concentric circles.

photo #3
"GM 1", "3736493", "T X", with boss on top but WITHOUT a threaded hole, flat backplate with screws (for flat head screwdriver). This backplate looks like Bill Mock's photo #1.

I assume the "T" is for Tonowanda, NY.
Does the "X" (3736493 pump) mean that it is a new type of casting during that time frame?
I believe that the 3736493 pump was used on 1957-1960 models.

Dave

Dave------


Usually, the "T" casting mark indicates Tonawanda. You can confirm this on this pump since "608" pumps cast at Tonawanda have two reinforcing ribs on the driver side of the pump. The date on this pump indicates a pump manufactured in December, 1969. That's after my pump, but this pump rear plate doesn't have the sealing "ridges". Maybe Tonawanda didn't use that rear plate until later.

The "waving flag" headmark is Elco Industries, the same manufacturer as indicated by "EL" and "E".

I'm not sure what the "X" casting mark signifies.