BBC Alternator Tension
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 779
Likes: 1
From: Minneapolis MN
BBC Alternator Tension
I would pull my hair out but I'm already bald.
I added PS to my BBC this summer. Since then I have been beating my head against the stock-style power steering pump and alternator bracket.
First I wasn't able to get tension on the PS pump but that was easy to solve with an adjustable rod. Now I can't get enough tension on the alternator for love or money. Part of the problem is that there's no good point to lever on it and tighten it down.
How have you guys solved this?
I added PS to my BBC this summer. Since then I have been beating my head against the stock-style power steering pump and alternator bracket.
First I wasn't able to get tension on the PS pump but that was easy to solve with an adjustable rod. Now I can't get enough tension on the alternator for love or money. Part of the problem is that there's no good point to lever on it and tighten it down.
How have you guys solved this?
Pro
Joined: Nov 2008
Posts: 542
Likes: 3
From: Bloomfield Hills MI
You should be running the alternator from the PS pump - I gather you are? You should not have too much tension on the alternator. If you have the right sized belt (and it took me several trips to NAPA to get the right one) you should be able to use your hand to put enough squeeze pressure on the alternator bracket and alternator body to get the belt tight enough, then tighten. I tend to wear a heavy duty leather glove when doing this - it helps.
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 779
Likes: 1
From: Minneapolis MN
That's how I've got it setup but I can't even get it tight enough (after a warm-up run-in) that the I can't slip the alternator pulley right under the belt.
Needless to say I have some pretty aggressive belt squealing at start-up.
Needless to say I have some pretty aggressive belt squealing at start-up.
Drifting
Joined: Jul 2009
Posts: 1,534
Likes: 14
From: Dallas-Fort Worth TX
ddn, post some detailed pics of your set up. Someone here might find/see the problem. Could be the brackets configuration. I know the original bbc vettes had the offset alt pulley which then ran to the ps pulley in order for it to line up. I learned this from other folks who have done the bbc conversions in there cars.
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Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
I believe your '68 bracketry should look the same as my '69. I don't have the smog pump installed. Ended up going with a 31" alternator belt which is almost too short, but at least I am not at the end of the adjustment. Adjust the PS belt first, then the alternator. Both can be held tight with a second set of hands. I would not be prying anywhere.
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
I know, my original had a hole in it when I bought it unbeknown to me. I found it when I went to have the alternator rebuilt.
Fortunately the hole was in the back half of the case and the shop I took it to had an exact match in their parts pile. I had them transfer over the battery bolt and insulator to keep everything the same.
cc
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Sorry, you guessed wrong....alternator belt is 1 alt, 2 waterpump, and 3 crankshaft
....
L-72, 427 iincluding air too
L-78, 396
LS7, 454
and there is one more, 73 El camino 454, the only way a Vette goes to the PS/Alt is PS without AC.. belt # 7435 Gates
....
L-72, 427 iincluding air too
L-78, 396
LS7, 454
and there is one more, 73 El camino 454, the only way a Vette goes to the PS/Alt is PS without AC.. belt # 7435 Gates
Last edited by Ironcross; Jul 14, 2010 at 10:23 AM.
Drifting
Joined: Jul 2009
Posts: 1,534
Likes: 14
From: Dallas-Fort Worth TX
I believe your '68 bracketry should look the same as my '69. I don't have the smog pump installed. Ended up going with a 31" alternator belt which is almost too short, but at least I am not at the end of the adjustment. Adjust the PS belt first, then the alternator. Both can be held tight with a second set of hands. I would not be prying anywhere.
As mentioned try and post some pics of your set up....,.
Pro
Joined: Jan 2010
Posts: 533
Likes: 18
From: Boca Raton Florida
I would pull my hair out but I'm already bald.
I added PS to my BBC this summer. Since then I have been beating my head against the stock-style power steering pump and alternator bracket.
First I wasn't able to get tension on the PS pump but that was easy to solve with an adjustable rod. Now I can't get enough tension on the alternator for love or money. Part of the problem is that there's no good point to lever on it and tighten it down.
How have you guys solved this?
I added PS to my BBC this summer. Since then I have been beating my head against the stock-style power steering pump and alternator bracket.
First I wasn't able to get tension on the PS pump but that was easy to solve with an adjustable rod. Now I can't get enough tension on the alternator for love or money. Part of the problem is that there's no good point to lever on it and tighten it down.
How have you guys solved this?
The probem may be the pulley on your alternator. Faster Rat's picture in post #9 shows the correct one quite clearly. According to the AIM, non-ps cars have the second belt sheave driving the alternator.
When you add power steering, the second sheave drives the power steering pump and the power steering drives the alternator, effectively from the third sheave. If you didn't change the alternator pulley it is still aligned with the second sheave.
Of course, if you have AC, you are supposed to have an idler pulley on the first sheave belt...
Last edited by Bob Heine; Jul 14, 2010 at 11:17 AM. Reason: Posted after Rebelrob provided same info.
Pro
Joined: Nov 2008
Posts: 542
Likes: 3
From: Bloomfield Hills MI
Bob Heine wins the prize for posting the AIM setup - which is absolutely correct BTW.
Faster Rat - agree completely, second set of hands are great when getting the PS pump tight (what a PITA that is) first, followed by alt. nice orange manifold to WP hose there, BTW
Ironcross - mine was originally set up by PO like the ones you show - which was incorrect. It also prevents you easily seeing the timing marks.
Faster Rat - agree completely, second set of hands are great when getting the PS pump tight (what a PITA that is) first, followed by alt. nice orange manifold to WP hose there, BTW
Ironcross - mine was originally set up by PO like the ones you show - which was incorrect. It also prevents you easily seeing the timing marks.
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
I was told by a former NCRS regional chief judge the '69 BB was originally painted that way...clamps and intake manifold overspray included...in about 15 seconds. I hated to do it, but I'm trying to go the original route as much as possible on whatever restoration I do.
Thread Starter
Burning Brakes
Joined: Oct 2000
Posts: 779
Likes: 1
From: Minneapolis MN
As you can see I am right in the middle of the adjustment range:
There are spacers because my crank trigger wheel brings the crank pulley out about 1/8".
Other than the spacers, the setup should be pretty standard.
There are spacers because my crank trigger wheel brings the crank pulley out about 1/8".
Other than the spacers, the setup should be pretty standard.
Drifting
Joined: Jul 2009
Posts: 1,534
Likes: 14
From: Dallas-Fort Worth TX
DDN, hard to tell from the pic if you have the offset alt pulley.
Also I noticed that your lower alt bracket/strap (last pic-above) is bolted to the upper alt bracket. In the original bbc vette config, this strap is bolted to the water pump via top bolt right side if your standing in front of engine looking at it.
Not sure, but that might give you more tension, or try a shorter belt.
Also I noticed that your lower alt bracket/strap (last pic-above) is bolted to the upper alt bracket. In the original bbc vette config, this strap is bolted to the water pump via top bolt right side if your standing in front of engine looking at it.
Not sure, but that might give you more tension, or try a shorter belt.