Here's my situation. I just got my motor back from being rebuilt. It is a 65 289 block, late model heads. The guy who built it used a 28oz 4 bolt dampner, where the stock ones were 3 holes. Now I can't run the stock pulley set up. I only have the water pump, crank, and alternator pulleys no other accessories. I'm kind of stumped on which way to go. He tells me to buy a billet set and buy the whole billet alternator adapter, but I'm against that. Would it be possible to redrill my stock 3 bolt crank pulley for four holes? How involved would it be to take off the dampner? I never built an engine before so this is all new to me. Also, do I need anything else in the equation, like a tensioner or would the adjustable alternator bracket handle that? Thanks
it is easy enough to pull the dampner..just use/rent a puller/installer.unless you want all that billet hanging out there off you engine.
I definetly don't want a bunch of billet **** hanging right in front of my engine. One option I thought of was to buy a billet crank pulley with four holes and v groove and paint it to match the other pulleys. I'm not sure what the difference between an early 3 bolt 1 groove pulley would be from the 4 bolt 1 groove pulley from 70' and up. I wonder if the backspacing is different. If that's the case wouldn't a water pump pulley from the same year solve that?
The good news is that both bolt patterns are on the same bolt circle, so all you have to do is drill three holes as one of them will line up. The bad news is that you will have to open the large center hole on the three bolt pulley up to match the register on the four bolt balancer. It is an easy operation on a lathe. I have converted about 10 three bolt pulleys to 4 bolt pulleys.
Ok that makes sense. I was wondering how I could do it and make it as perfect as possible. Do all the 4 bolt dampners have the same size center bore? If I can't find anyone local would you be able to do it for me? Thanks
how many grooves are you running? i'm guessing only one or two, but if you happen to need three, i can swap you pulleys. i have a 4 hole pulley i'm about to drill to 3 holes. i've been hunting a 3 groove 3 hole pulley for a bit, then i saw a picture of a pulley from a power steering kit, had a both bolt patterns, that's when i realized they could be drilled to fit the other dampers.
I would thik, unless he changed your crank configuration, you need the heavier balance anyway. You might ask the guy, he might have switched it by accident with another unit he had in for repair. I would certainly ask some questions before just using it.
Didn't all small block Fords use the same imbalance until around 1980 or 1981 or so because Ford lightened the 302 cranks and started using 50 oz imbalance on them?
Hmm, not sure. I had the same problem but the only answer I could come up with was a billet gilmer drive pulley set. Aussy laws forbade multi drilled pulleys! Get the billet one, plane dished if you can. Have it bead blasted and painted to match the others. Good point that Willy301 has though, check with the builder. May need that dampener for his set up or could be a screw up??
I think until 1980 they were all 28 oz. after that they were 50oz. I might try to find one from around 70-75 and see how it works. The prices on new stock ones are sometimes more then the billet ones but I'd rather pay more.
I went the other way & converted a 4-bolt to mount on a 3-bolt damper - I simply drilled the holes I needed - the register was the same as I recall, but it's been over 20 years. Another thing to watch for is spacing of the pulleys - depending on application, the pulley mounting surface of the balancer/damper may be different...
This is kind of a late-early balancer. They started out as 28oz 3-bolt, then moved to 28oz 4-bolt in the 70s I think. Then in '85? they went to 50oz 4-bolt. So he has the early balance, just not the early pattern. He didn't change anything besides the bolt pattern for the pulley really. Same balance as before, 28oz. The heavier balance, 50oz came way later.
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