Idler Pulley For AC Belt?

DC3

DC3

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Joined
Dec 9, 2008
Messages
332
Location
Lubbock Texas
I'm just finishing up the installation of Vintage Air in my '73. The AC belt was so close to the lower radiator hose that I ended up fabricating a belt/hose guard. When I test ran the engine before charging the compressor, the clearance was fine.

After charging the compressor a problem developed with the belt slapping the new guard when the compressor was engaged. Clearance was still fine when the compressor was not engaged. The belt slap was bad enough that I could not run the AC.

I then went to the absolute shortest belt I could install (NAPA/Gates 7555). I had to completely remove the compressor from its mounting bracket in order to install the belt and barely got it back on the bracket.

This gave me more clearance and initially solved the problem. But, the belt stretched a bit and the belt slap is back although minor this time.

I have an email into Vintage Air inquiring as to the possibility of another compressor bracket that would mount the compressor higher in the engine bay. I have at least 2" of room from the compressor to the hood now.

I'm wondering about the possibility of using an idler pulley under the lower part of the belt. This would allow me to run a longer belt and gain the clearance I need without having to run a different mounting bracket.

Has anyone else ran into this issue? Anyone have any ideas on fabricating a bracket to mount an idler pulley? Would a bracket using just one of the water pump bolts be okay or would it really need two mounting points? Any other suggestions?

Other info that may be relevant:

Small block w/ power steering
Inner belt - crank to water pump to alternator
Middle belt - crank to water pump to AC
Outer belt - crank to power steering pump
Mechanical fan and clutch replaced with dual Spals
Tall valve covers

Appreciate the help.

DC
 
raising the compressor seems to be the easiest solution, what does that bracket look like ? Could it be as simple as elongating bolt holes to raise it ? Is the bracket weldable material or cast ?

I think with the aluminum bracket from Summit you can use a longer threaded rod and raise the compresor, unfortunately not cheap....

http://www.summitracing.com/parts/MCH-20171/?rtype=10

hope the link works.....

I have a Hooker header AC bracket somewhere in the garage, came with my sidepipes.... if that bracket is of any value for you I'll see where it is and you can have it.... it's steel and can be welded to relocate the holes and raise the compressor....
 
IF you are running a R4/later shark compressor, you will have belt slapping problems, ever late shark I have ever seen with a R4 has the issue to a certain extent, it's the pulsing of the compressor, the A6 styles don't have the issue... or I have never seen one that did, anyway....

I would go the idle pulley route, and use at least two points to mount the needed bracket....maybe use some of the fuel pump bolt holes??

:nuts:
 
MYBAD79 said:
I have a Hooker header AC bracket somewhere in the garage, came with my sidepipes.... if that bracket is of any value for you I'll see where it is and you can have it.... it's steel and can be welded to relocate the holes and raise the compressor....
Click to expand...

Appreciate the offer. Vintage Air is going to send me a different bracket to try. It should raise the compressor up some but I'm still thinking an idler pulley will be the best solution to prevent problems.


mrvette said:
IF you are running a R4/later shark compressor, you will have belt slapping problems, ever late shark I have ever seen with a R4 has the issue to a certain extent, it's the pulsing of the compressor, the A6 styles don't have the issue... or I have never seen one that did, anyway....

I would go the idle pulley route, and use at least two points to mount the needed bracket....maybe use some of the fuel pump bolt holes??
Click to expand...

It's a new Sanden compressor that came with the Vintage Air kit. You can watch it pulse when engaged and thus the belt slap. I'm liking the idler pulley solution but was hoping someone had already fabricated something I could copy.

I'm wondering if I could mount a flat bracket for an idler pulley to the cross member in front of the lower part of the belt? Anyone know of any issues with drilling holes in the cross member? I would have to figure out how to get the pulley lined up vertically under the belt.

I was on the fence about a serpentine belt system. This may get me off the fence. Maybe I can buy some time with the new compressor bracket until I can figure out how best to go serpentine.

DC
 
Serp is the way to fly, no doubt, a '88-91 vette setup is the best, it's a bolt on swap, but use the reverse rotation water pump....you can bolt in your p/steering pump regulator to the later pump....that large brass bolt the output line fastens too....

:mobeer:
 
mrvette said:
Serp is the way to fly, no doubt, a '88-91 vette setup is the best, it's a bolt on swap, but use the reverse rotation water pump....you can bolt in your p/steering pump regulator to the later pump....that large brass bolt the output line fastens too....

:mobeer:
Click to expand...
Yep I have to agree any 85-91 vette serpentine drive system is a excellent mod for any C3. Just buy some electric fans, few hours of work to install and you won't ever want a V-belt design ever again.

heres my 82 with a 84/86 system.

DSCF0796.jpg
 
How many holes are required in the passenger side head for mounting the serpentine setup? My passenger side head has only one hole located in the upper outside corner of the head.

DC
 
DC3 said:
How many holes are required in the passenger side head for mounting the serpentine setup? My passenger side head has only one hole located in the upper outside corner of the head.

DC
Click to expand...

some very early SBC heads only have holes on one end, so on the pass side have NO holes for accessories, the ones I had were early 70's and had two of the 3 necessary for the a/c bracket....so I devised a L bracket from the front intake bolt to behind the a/c bracket....if you don't that bracket WILL fail....

don't ask, mine has been TIG'd as a result....

NOW I have aluminum later L98 heads, so no issue....
 
DC3 said:
mrvette said:
. . . two of the 3 necessary for the a/c bracket
Click to expand...

Wonder if the other 2 holes I would need could be drilled without pulling the head?

DC
Click to expand...

Sorry, can't help....no clue...much less if there is any machined smooth surface on which to spot the holes....I know the one on the top most near the intake flange was not possible due to casting on heads I used to have....I THINK the castings were 998 or close....
 
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