More questions!

[johng]

I put a few more bits back on the car today and came up with another couple of questions.
1) does anyone know what this hole is for? It goes through the firewall just above where the throttle pedal is bolted on and just below the grommet where the vacuum hoses go through the firewall



2) When I got the car it had air con fitted, but as there was no gas in it and I think there is a hole in the evaporator, I'm not going to replace it at the moment.
Looking in my AIM it shows 3 belts for the setup I've got now. My question is how are you supposed to tension the Track 2 belt? Am I missing some sort of tensioner?

 

[Oneball]

Loosen/remove the water pump pulley, put the belt on the pit back together, 1st belt needs to be in place before and the second belt needs to be spot on the right size.

I think the hole is for a plastic rivet for the firewall mat inside the car. But not 100% sure which hole you’re looking at.

 

[johng]

Wow I didn't think anyone would design a belt drive with no adjustment.
Could be to hold the mat, although the throttle pedal attachment is very close and that holds the mat in place pretty well.
I did take a picture with a view of a wider area, but I managed to hide the hole behind a vacuum tube!

 

[Oneball]

Ha, weirdly enough I’ve got a photo too but the vac pipes are covering the bit you need to see.

 

[kentvette]

John

With teh car in the garage and the drivers seat in place I don't have the contortional ability to get up inside the footwell! But, it does seem to be a rubber grommet of some sort. This is what it looks like from the engine bay...




The A/C on ours gave up teh ghost many years ago - my fault, I should have used it regularly and didn't, the gas level dropped, it stopped working and I forgot about it - living here now I really wish it was working, but re-commisioning is a major excerside beyond my skill level! But, I have left the compressor and its belt in place (and in fact renewed it last year) for no other reason that it gives the adjustment and to some extent, evens the force exerted on the w/pump pulley, as well as probably making the drive of same more reliable.

I ran the belt number in the AIM (3935420?) through Google and Paragon listed it as:
GM Part Number: 3935420
Idler / water pump belt, GM #3935420, 32.46" length, 3/8” top width.
1969 w/350 h.p., w/o P/S and /or A/C.
1970 w/LT-1.
1970 w/350 h.p., w/o P/S and /or A/C.
1972 w/250, 255 h.p. w/o A/C and /or P/S.

I thought it might at least give you the dimensions, but then came across these guys:

3935420 GMC GENERAL MOTORS CORP OEM Equivalent Cogged Automotive V-Belt

Buy 3935420 GMC GENERAL MOTORS CORP OEM Equivalent Cogged Automotive V-Belt Today! Huge Belt Sale. Fast Shipping. 100% Satisfaction Guaranteed!

www.vbeltguys.com

They claim to have a French supplier, which may be better than getting it from the US?

 

[johng]

Brilliant Steve, I can get that size belt for £5 on EBay. The photo was perfect as well. I've got the same thing in a hole on the passenger side and it is a grommet. It's easy to see with everything out of the car!

 

[Oneball]

Those are the rubber rivets that hold the sound mat in place.

 

[Forrest Gump]

I wonder how many cars are actually running that 2nd track belt. Not all for sure.
When I first got my car it didn’t have that belt and I did snap the 1st track belt, although that could well have have been because the clutch on the fan was locked so putting a lot of strain on the belt. The stock fan is a heavy lump so can see why the 2nd track belt was required to share the loads.

 

[johng]

Those are the rubber rivets that hold the sound mat in place.

Funnily enough I've looked at the bit sticking out of the firewall on the passenger side several times wondering what it was, I thought it was a previous owner's bodge to fill the hole. Driver's side hole is now sealed up.

 

[johng]

I wonder how many cars are actually running that 2nd track belt. Not all for sure.
When I first got my car it didn’t have that belt and I did snap the 1st track belt, although that could well have have been because the clutch on the fan was locked so putting a lot of strain on the belt. The stock fan is a heavy lump so can see why the 2nd track belt was required to share the loads.

Looking on the US forum several people say you don't need it, but if the alternator belt were to break then you could probably still get home if you have another one to run the water pump. Seems like good insurance for the price.

 

[Forrest Gump]

Looking on the US forum several people say you don't need it, but if the alternator belt were to break then you could probably still get home if you have another one to run the water pump. Seems like good insurance for the price.

Good insurance definately. The first belt is only contacting a quarter of the water pump pulley...thats fine to spin the water pump but a bit more of an "ask" to accelerate the large fan blades.