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Ok so be gentle. This 74 corvette is new to me and I am fixing a lot of bubba issues. The belt squeals when accelerating and it seems pretty loose. Almost 2 inches of play up and down. The pictures aren’t great but from what i can tell i have 1 belt that goes from power steering to the crank only. And another belt from the crank to the water pump to the alternator and that is the one that is loose. It seems my alternator mount bolt is not long enough and there is no nut on the end so ill need to fix that to even add more tension.
my big question is what pulleys the alt belt is on. It is on the furthest out pulleys which is not in alignment with the alternator pulley if i moved the belt to the back pulley slot then it would be in alingment. Is that how its supposed to be? Im guessing the previous owner just put it on those pulleys to add more tension but not the correct way.
my thinking is get a new bolt so i can tension the alternator and move the belt to the back pulleys on the crank and water pump. Do I need to change anything with the powersteering belt or is it ok only going to the crank and not the water pump?
thanks for all the help. Be gentle she is a dirty girl right now but otherwise runs well.
Hmmmm
not familiar with 74 but suggest getting aim or download this to help sort out.. https://www.corvetteforum.com/forums...ette-lonk.html
that ground cable looks hacked and even if correct missing strands..
the fan looks very strange like missing a shroud or blades strange..
Hmmm good call on the grounding wire. Guess I should replace that when i fix how it is attached to that bracket. Can I use any modern alternator grounding wire or do I need a specific gauge?
also to add not sure about the fan. Definitely missing the shroud but not too concerned. Have had it 94 degree bumper to bumper rush hour with zero overheating issues. Maybe eventually ill get one after i fix the belt/pulley issue
Last edited by sideshowbob19; Aug 29, 2021 at 08:48 PM.
Has the smog pump, ac compressor, etc. been removed?
If so, the factory routing of the belts may have to be adjusted.
V belts are real simple and also quite complicated.
Not only do you need the correct length, but you also need the correct width.
Sometimes, it is a trial and error process to get the belts to work correctly.
Most parts store will let you return a belt and get a shorter or longer one as long as you didn't actually run the engine, and the belt and packaging still looks new.
I'd suggest you read any previous threads about fan belts, so that you learn how to size them correctly.
Hey sideshowbob, welcome aboard!!! One issue - unless I'm mistaken, but I don't think I am: the bracket is on the wrong side of the alternator. Take the bolt out, move the bracket in front of the alternator, and run the bolt thru the bracket into the alternator (it should be threaded). That will enable you to get the tension you need, and likely better alignment too. :-) Best, Paul
PS: I really don't think your ground is supposed to be there.
Last edited by Hopper12; Aug 29, 2021 at 09:03 PM.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Hi and welcome
Remove the bolt (1 dot) holding the FAT ground wire, remove it and move the bracket (2 dots) in front of the alternator and replace the bolt.
Leave the FAT ground wire off.
Look at the top right drawing, does that look correct?
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
Looking at the first assembly picture in post #2 above it appears that the bolt (item 16) would have come into the rear of the alternator. Goes through the bracket (item 13) first and then into the alternator itself. Seems like putting the bracket on the front side of the alternator would move the alternator rearward and aggravate your alignment issue. Also in your picture is the bolt even clamping to the bracket? Might explain why the belt is so loose.
There is a reason why someone put an engine to frame cable on the alternator....likely the original factory one was faulty. I believe this one is normally down low on the other side of the engine. You might want to fix that first to eliminate this extra cable.
When tightening the alternator belt, I look for about 1/2 inch deflection with strong pressure on the belt. If belt is still out of alignment then move the belt to the inner belt slots on the water pump and crank pully's and see if that helps. After almost 50 years many of these cars are modified and have changes that mess up the alternator belt alignment setup. Replaced engines, different alternators and bent brackets...etc. Good luck!
Thank you all for the replies. I will be rearranging the bolt/bracket and tensioning correctly and maybe changing where the belt is based on the alignment.
The diagram in the upper right is NOT what i have. My second belt is only going from power steering to the crank. Not to the water pump. Should i change this and get a longer belt and have it go to all 3? Pros and cons?
i have looked up a lot of random photos of c3 engines just to compare my setup and none seem to have that giant grounding wire. I will check the engine mount on the right side and see if that ground is still there. Although this is a weird grounding wire on the alternator, i have found mention of other people doing this on the forum. I mean it cant screw anything up being there can it? Granted it does look like it needs to replaced.
also for info. No ac and no smog pump
Last edited by sideshowbob19; Aug 29, 2021 at 11:35 PM.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Originally Posted by Redvette2
There is a reason why someone put an engine to frame cable on the alternator....likely the original factory one was faulty. I believe this one is normally down low on the other side of the engine. You might want to fix that first to eliminate this extra cable.
Good advice above, check that the engine to frame ground is connected in the spot that GM put it.
And YES! Ignore my bad advice about the bolt and bracket, the bracket and bolt should be behind the alternator.
Fairly certain my photo is clear. one belt from crank to power steering pump. one belt from crank, over water pump to Air-Con. and third belt crank, over water pump to Alternator. ( 3 belts. )
First (outer front) belt. power steering. second belt, air conditioning. 3rd belt Alternator.
Last edited by 4-vettes; Aug 30, 2021 at 05:51 AM.
I lost the pulleys when we replaced the engine on my '74, and could not find the correct pulleys to get it all in proper alignment, so the Hell with it I got a serpentine setup from a 1995 Chevy truck, and with very little trimming it worked great. I am using electric fans however. Just a thought.
I agree with previous posts. The alternator bolt is on the wrong side. I don't see it maintaining any belt tension on the side it is currently on.
Question: Did your car have A/C at one time and Bubba removed it? I ask because your engine photo shows 3 pulleys on the crank.
Three pulleys on the crank indicates A/C (C60) and power steering (N41).
According to the AIM for '74 your alternator belt is on the wrong pulleys.
The alternator belt should be on the inner most pulleys. Your photo shows it being on the middle crank pulley/outer water pump pulley, hence your alignment problem.. Check the Power Steering belt location as well.
Man, Bubba did not do you any favors!
Last edited by '73and'75; Aug 30, 2021 at 12:24 PM.
Idk if it ever had ac. There are no ducts for it under the dash. Its possible all of it has been removed by a previous owner.
so i moved the belt to the proper pulleys and changed the bracket/bolt arrangement to be correct but then i found out why bubba created this mess in the first place. Either the alternator is incorrect or the bracket it. It does not line up AT ALL with the mounting hole on the alternator. I was able to force it (bend slightly) to get it to attach but it can not be tensioned. The alternator moves to low for the bracket to be able to stay attached. The curve on the bracket is not enough. Thoughts?
Some possibilities I can think of: wrong belt; wrong bracket; wrong alternator; need spacer between the bracket and alternator (please see pic below - I know the pic is a bb, but you can see what I mean here).
Idk if it ever had ac. There are no ducts for it under the dash. Its possible all of it has been removed by a previous owner.
Do you have 2 vent outlets above the gauge cluster? Do you have vent levers and ***** on the console?
Your alternator appears to have the correct case. Can your post the numbers on the alternator? No spacer needed on a small block, Hopper12. It appears to be the correct bracket correctly mounted with a bolt through a water pump bolt hole.
Use a shorter belt. The alternator bracket is supposed to pivot to provide alignment with the bolt..
Last edited by '73and'75; Aug 30, 2021 at 04:40 PM.
A shorter belt will allow the alternator case to clear the alternator bracket. Your longer belt is causing the alternator case to interfere with the bracket here:
Last edited by '73and'75; Aug 30, 2021 at 04:34 PM.
Car with AC Originally should have 3 crank pulleys. one closest to the engine block is for Alternator. also water pump pulley is the one closest to the engine block. try to get your Alternator about in the middle of the adjustment slot. to close to the valve cover and you won't be able to remove the power steering resivor cap. reference the photo I posted above (the one with the red alternator).
Alternator belt issues
