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Tech Editor's DeskProjects, papers, writings, thoughts, musings of our technical editor Joe Padavano. To begin with, he will be making threads and can approve posts to it if he wishes. This can be changed in the future if it does not work out well.
so, perhaps the previous owner put an incorrect pump on the engine. The pulley that was on it was 3 groove, The p/s pulley lined up OK. The alternator pulley did not. It is too far in towards the engine so the belt is way out of line and sequels.
The part number cast into the pump is 31290.
3 pics attached:
pulley is 3 groove. middle groove is too far towards the engine and is the cause of the misalignment.
Both pulley 2 & 3 are have too short a "snout"
I need a 2 groove pulley like 2 & 3, but with the 1 5/8" dimension of the incorrect pulley shown on the orange ruler.
Does that exist?
If I need to get a new pump, what pulley would I need for that?
Thank you so very much for your guidance in this confusing mess I have gotten into.
The three groove pulley you have is from a 1980s 307 and was used on the 6.1" pump. Is the crank pulley original to the 1968 motor or not. Trying to mix and match pulleys will be a disaster. Get the correct pump and pulleys that match. What alternator bracket are you using? The pump, pulleys, and brackets all need to be a matched set.
I found a 5.6' pump. Would that take the black 2 groove pulley in my previous post?
The grey pulley should go on the 5.1" pump, correct?
How do I find out what P/S bracket and alternator bracket is on the engine?
Both those pulleys are in alignment as they should be.
Just the water pump is not lined up.
Your car SHOULD have a 5.1" pump. Airtex AW773 is one option for a correct new one.It will be easier to get the correct pump than to try to find a pulley that will work.
rock auto even has the GMP aluminum ones! ( at least they used to - and 2 different lengths for sure. I use the long 6" #130-1260 on my 67 with a set of 73 pulleys that hs the small diameter water pump pulley that makes the pump turn faster than he diameter of the 67 WP pulley.
its actually GMB130-1260AL ( 6" aluminum at Rock Auto
Yeah, I noted that in my most recent post. Beehall needs a 5.1" pump for his current setup. His problem is that he already has the wrong length pump and is going through the usual pulley misalignment problem.
Cool. Was there a part number on the sleeve? That might be helpful for folks needing a pump with the “other” size hose application.
Dayco 76950 or Gates 26391 or Continental 58982 is a 1.75 to 1.50 reducer bushing that works at the radiator end of the lower hose to adapt the 1970-older hose to a newer radiator (most aftermarket radiators come with the 1971-up 1.50 lower hose barb).
Dayco 76975 or Gates 26392 or Continental 58983 is a 2.00 to 1.75 reducer bushing to use the 1971-up water pump on a 1970-older car.
The three groove pulley you have is from a 1980s 307 and was used on the 6.1" pump. Is the crank pulley original to the 1968 motor or not. Trying to mix and match pulleys will be a disaster. Get the correct pump and pulleys that match. What alternator bracket are you using? The pump, pulleys, and brackets all need to be a matched set.
Joe, I found a 5.1 pump. The gray pulley fit. The original size belts fit. All is good and working.
THANK YOU SO VERY MUCH FOR YOUR GUIDANCE.
My ride is back on the road.
.Thanks also to all others for their most helpful posts.
