pulleys and timing cover identification
 

reason im posting this is because im having a problem aligning my pulleys

timing cover; which is supposed to be off of a 77' : 526985 is this so?

Crank Shaft pulley is 481037 YA 7 3/8, and 2" deep

water pump pulley is 481039 XF , which i believe is 8" and 2.5" deep.

anyone know my answer to the mussing piece? are the pulleys completely off?

also what is the gain of using a bigger pulley (diameter wise) vs a smaller one....

TC Cover p/n 526985 was originally introduced for late production during the '76 Model Year when Pontiac decided to eliminate the traditional Balancer Assembly. The low-po engines of that era were then equipped with a small Crank Pulley Hub in a cost cutting move. This TC Cover with a separate Timing Indicator were released to match with this new hub.

Meanwhile, your Pulleys were 1st used for '71. They are a "matching" set, should work together okay but I do not know if they will work together with the '76 up crank hub or if you should be looking for an earlier Balancer Assembly. If you swap to an earlier Balancer Assembly, the indication is that the Timing Indicator on the '76 up TC Cover will not work, likely would interfere with the larger weight of the earlier Balancer Assembly.

Perhaps you have the wrong Water Pump hub ht. You likely need to have the long snout Pump. The short snout 11 bolt '69 Pump has a 4" hub ht. (measured from the gasket mounting surface to the outer face or the hub against which the pulley mates). The long snout 11 bolt Pump (1st used on some late '69 engines) has a hub ht. somewhere around 4-1/2" IIRC.

It would help if you told us more about what you have and how it is not aligned. The '71 Pulleys were designed to work with '71 accessories like PS Pump & Alt.

The crank pulley is the drive pulley. All other Pulleys are driven pulleys.

This is where you were supposed to be paying attention in math class! Circumference of a circle is pi (3.14) x dia. of the circle. Assuming no belt slippage, the belt will be displaced the same distance as the distance travelled by a point on the circumference of the pulley. The larger the dia. of the crank pulley, the more distance the belt will travel in a single revolution of the crank.

On the driven pulleys, the smaller the dia., the more revolutions that pulley will spin for a given travel distance of the belt. If you want to speed up the water pump, you can increase the dia. of the crank pulley or decrease the dia. of the WP pulley or both.

If the crank pulley is displacing the belt about 24" every revolution, a 2.5" dia. alt. pulley will be spinning about 3 revolutions. At 2000 rpm engine speed, the alt is spinning about 6000 rpm.

On cars with A/C, you will commonly see the WP Pulley smaller than on an A/C car so that the WP spins faster. Of course, the Pump will wear out faster too.

thanks for the math lesson! haha.

well the problem i have is that the water pump pulley is about 1/2" short of lining up with the crank pulley. sounds like i need to use the water pump with a longer snout.

also, it sounds like i might have a slight overheating problem with my larger WP puley, no?

also, how do you decode the pulleys?

As John V said, the pulleys should line up.
I think the water pump is basically the same for these years.

As John V also said the crank hub is the difference.
Probably need a dampner if yours is the hub.

The larger water pump pulley will be slower than stock.
Overheating? I dunno.

Not sure what you mean about decoding the pulleys. The 2 letter codes on them are manifest codes, pulleys were identified on the build manifest by these codes, the assembler didn't need to use the p/n, he went by the manifest code. Meaningless to you today unless you are doing a matching nos. resto. The p/ns are sufficient to identify them, various references can be used to identify the original applications by pulley p/n.

The description for the p/n 481037 says it is 7-7/16", your measurement was close enough. Groove widths are also useful to determine proper belt selection.

Measure your water pump as I described. If it is 4", then the long snout pump might correct the mismatch. You might also look for the p/n on the pump body casting. If it is an original Pontiac pump and shows p/n 9796351 on the casting, that is the "true" '69 short snout pump.

What about your accessories, like Alt & PS Pump? IIRC, the '71 Pulleys won't line up with the earlier accessories, especially the PS Pump. Need to have the '71 up style PS Pump I think.

As far as cooling, that depends on a lot of things. The 8" dia. WP pulley is pretty common. Is the engine a stock build, or hi po? Stock should be okay. Is the car A/C? Auto trans? Both will require more cooling capacity generallly and you might want to find the smaller dia. '71 WP pulley to suit. Do you expect to do a lot of stop & go driving or parade useage? If not, I don't think I'd worry too much about the pulley if the pump has a good impeller.

What car and what radiator set-up? Is there a shroud? What type of cooling fan?

Lots of tricks to deal with cooling, doubt you need to worry about the pulley dia. just yet.

as far as accessories go i am going to have an alternator and power steering, so i hope you are wrong about the aligning otherwise im going to have a lot of problems.....

as long as i have the alternator pulley aligning i will be ok with the pulleys not aligning with p/s i can take care of that after i get the car running.

i will measure today after school which will be in about 2 hours so i will be back to give you an answer for that.

as far as cooling i bought an aluminum one, an i put a 16" generic electric fan, i plan on getting one of those powerfull MarkIV fans later on.... i did get the proper impellar, but if i have to get a different wp i will make sure to get the same kind again.


as far as tranny goes i have a separate cooler for that also. i do not have it running into the radiatorhttp://img.photobucket.com/albums/v4...a/DSC02180.jpg

so i think cooling would be good either way i go,


anyways, i will check on that pump

Oz

where did you get that radiator?

that is an AFCO radiator i got from summit for aorund $200ish..

ok i look at the pump and it has 2 seperate numbers one set has 5401 the other has 298


and it is a 4" long snout... what year is the correct year that is a 4 1/2" long snout...

Don't recognize those nos., probably an aftermarket unit.

'69 was the only year for the 4" snout 11 bolt pump, so that is the application for what you have.

The longer snout is '70 & up.

Ask for a water pump for a '70 Pontiac V8. Doesn't matter what model, Lemans, Catalina, Firebird, etc. although I'm sure the counter guy will think he'll need to know that. Tell him it is a 1970 Grand Prix convertible (they didn't make one but, hey, have some fun telling him it was a one-off show car if you want). Doesn't matter, they used the same pump on them all, 350, 400, 455 in '70. That should get you the dimension you want.

Bring your ruler and measure it. It should be close to 4-1/2", not sure of the exact measurement.

I've been told the original type cast iron impellers will work better than the stamped steel ones but don't have direct experience myself.

Good luck!

thanks for the knowledge.... how about i tell him a 70 Trans Am. Ram Air 455 . 4 spd. with a 4.10 limited slip from the factory show car. black on black. haha, he will probably think im a spoiled kid and my parents have given me everything i've ever wanted...

i will think of something. theres a auto zone and kragen one block from where i work. i doubt they have it but i will check.

thanks again.
Oz

thanks for the help guys i got the pump with a 4.46" snout and the pulleys align good.

Oz