• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Pulley sizes

Share this page

C

Cutlass

Jedi Warrior
Offline
Well, I've discovered (a bit late, I know), that my 66 BJ8 harmonic balancer pulley is for a 3/8 inch belt, as is my generator pulley. (The generator is a late model.) Water pump is new, and 1/2 inch size. My guess is that some time in it's life, the engine was replaced with an earlier model. A 1/2 inch generator pulley is no problem to find, but the balancer (which I just had rebuilt at no small cost) is a different story. Only a 3/8 inch belt will fit. It all seems to work, but for how long? Is it really worth trying to replace the balancer and generator pulleys so that all are 1/2 inch, as is apparently appropriate for this model?
 
--- /bcforum/images/%%GRAEMLIN_URL%%/savewave.gif Cutlass
-No not unless you are a purist.


If you hook up the 1/2" water pump using the 3/8" belt it will speed it up just enough to make it a bit more effective. Similarly, if you get a 1/2" pulley for the generator too it will speed it up also just enough to improve it charging at idle.--Fwiw--Keoke
 
Cutlass said:
Well, I've discovered (a bit late, I know), that my 66 BJ8 harmonic balancer pulley is for a 3/8 inch belt, as is my generator pulley. (The generator is a late model.) Water pump is new, and 1/2 inch size. My guess is that some time in it's life, the engine was replaced with an earlier model. A 1/2 inch generator pulley is no problem to find, but the balancer (which I just had rebuilt at no small cost) is a different story. Only a 3/8 inch belt will fit. It all seems to work, but for how long? Is it really worth trying to replace the balancer and generator pulleys so that all are 1/2 inch, as is apparently appropriate for this model?
Click to expand...
Sorry. I'm in a similar mess right now. I do know that a 1/2" pulley won't work for long with a 3/8" belt. It is likely near the bottom of the groove now, without even being used. Once it reaches bottom, no more grip. Likewise, a 1/2" belt will be way too high in a 3/8" groove & likely to jump out.

Since you have the most bucks in the damper, & both it & the generator are 3/8", you may wish to stay with the 3/8" belt. This leaves changing the water pump to 3/8".

Unfortunately, you have to get the whole 3/8" waterpump as they have a different pulley attachment.

If you wish to be concours correct for some reason, the only choice is to replace the damper & the generator pulley to make everything 1/2".

Personally, I would change the water pump & go with the 3/8" belt. Probably the cheapest in the long run.

Sigh, Keoke & I often have different opinions.
D
 
I don't know what kind of pulleys you have Dave, but I have been runing mine that way for 10 or 15 years and they do not bottom or wear out. As a matter of fact I rarely if ever have to adjust the fan belt. Cuz I know you like to measure things, I just went out in the cold shop and measured from the top edge of the 1/2" pulley to the 3/8" belt. It measures 0.100"--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/yesnod.gif
 
Thanks for the advice, as usual. I'm not a purist, not that there's anything wrong with that. I figured that as long as I was doing a complete tear down and rebuild, I'd do as much as I could do within reason to be "correct." What is "within reason" is of course sometimes difficult to define. I think I'll draw the line at replacing an expensive balancer just to get the right size pulley and belt, and will stock up on 3/8 inch belts. Might even consider a different water pump, but not now. Now, if I happen to see a reasonable balancer on e-bay, ....., well.
 
Well Cutlass, next time you are close to the car take look at that 3/8" belt setting in the 1/2" water pump pulley I bet you won't be able to tell its different. Be sure the belts you use say: "Gates" on em.--Keoke
 
It's at the body shop now. My practice is to find a reasonable excuse to visit about once per week. I'll look then.
 
Keoke,
I think it depends on exactly what a 1/2" pulley really measures at the top. The ones I'm having trouble with measure .520". A 3/8" belt bottoms out in the pulleys. I'll bet the grooves on yours are a bit narrower.

Thank you so much for taking the trouble, out in the cold & all,
D
 
Keoke said:
I just went out in the cold shop and measured /bcforum/images/%%GRAEMLIN_URL%%/yesnod.gif
Click to expand...
Does that mean you had to change out your shorts for long pants? /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
 
I didn't measure the width at the top Dave, I will take a look at that and let you know. Yeah these stock Healey pulleys seem to be a bit narrow. I have some spares but it too cold to fiddle around looking for them. When you measured was it across the out side or inside of the pulley?--Keoke

Yep, I guess you have a wide one. On my generator measuring from the face of the fan to the outside edge of the pulley measures 0.500" so its a bit less inside. About 0.430" at the point the belt rides.




Oh! I just heard some noise comin over from somewhere

around Santa Monica I gotta go checkit out.- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
 
My pulleys measure right at .510" inside to inside the groove at the top. A "3L" belt, 3/8", goes clear to the bottom. I'm going to look for a "4L" belt or an "A" belt which should be close to .500".

What's all this "cold" talk, I thought you were in sunny LA?
It's been running in the 20's at night & 40's day here.
D
 
I did save the old water pump. It was working at teardown, but I decided on a new one anyway, same for new oil pump. The old pump has a 3/8 inch pulley. But the pulley is not just a take off and replace item. Isn't it integral to the pump shaft in some manner, making it impractical just to switch?
 
Have you any idea what cold steel feels like in 15 degree temps? When I lived in Santa Monica (north of Montana Blvd)a very cold night was in the 50's. Are you trying to sell us on global cooling? And I'll bet you got a heated garage, too. I've got to put on a down jacket and glovess just to get to the garage. (But I do get to ski the choicest days)
 
Cutlass said:
I did save the old water pump. It was working at teardown, but I decided on a new one anyway, same for new oil pump. The old pump has a 3/8 inch pulley. But the pulley is not just a take off and replace item. Isn't it integral to the pump shaft in some manner, making it impractical just to switch?
Click to expand...
The way I understand it is that it takes a good press to remove the pulley & is likely to cause enough damage to require a rebuild. Maybe Keoke can clarify.
D
 
tahoe healey said:
And I'll bet you got a heated garage, too. I've got to put on a down jacket and glovess just to get to the garage. (But I do get to ski the choicest days)
Click to expand...
You're right. I do have a heated, insulated, attached garage. It seldom goes below 45 degrees, & only takes about an hour to bring it up to 60.

Long ago I worked outdoors & had to use a torch to warm the tools so that they didn't stick to my fingers. I know what cold steel feels like. I'm not that addicted to misery any more.
D
 
So has anyone switched pulleys on a water pump? I was advised against rebuilding, for the cost of a rebuild approaches the cost of new.
 
Cutlass said:
So has anyone switched pulleys on a water pump? I was advised against rebuilding, for the cost of a rebuild approaches the cost of new.
Click to expand...

Would you believe it can exceed it!!---Keoke


I will note that a shop with a proper puller and a press can remove the pulley from a pump and replace it on another one. There is a very small risk factor here. replacing the pulley on the pump can reduce the friction fit to the point where it might fail in use. However, as noted, this is not a known prevalent failure mode.--Happy now!- /bcforum/images/%%GRAEMLIN_URL%%/banana.gif
 
Dave Russell said:
My pulleys measure right at .510" inside to inside the groove at the top. A "3L" belt, 3/8", goes clear to the bottom. I'm going to look for a "4L" belt or an "A" belt which should be close to .500".

What's all this "cold" talk, I thought you were in sunny LA?
It's been running in the 20's at night & 40's day here.
D
Click to expand...


Just a big thissy here I guess Dave. /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

I think you are victim of tolerances on the pulley and the belts . Cumulatively, there can be about 0.050" deviation between Original pump pulleys, British aftermarket belts and American replacements. The aftermarket BJ8 pump pulleys are narrower inside than the original Ripton UK made items. For example a 3/8" Quinton Hazzel belt will ride about 0.125" from the top of the pulley but not bottom in the UK Pump. Contrastingly, that same belt will ride about 0.020" from the top of an aftermarket pump pulley. This does not say that other aftermarket pumps may not be wider it just reflects what I had available to measure. Keoke-?
 
So the pulley is a press/interference fit on the shaft? It would be nice if it had a keyway and retaining bolt, such as the balancer or generator. Probably cheaper to find a new 3/8 inch pulley pump.
 
Back
Top