1970 LT1 Belt Routing

[James H.]

I am putting my 1970 LT1 back together after an engine re-build. In the Assembly Manual, it shows the fan belt routing on page K185 and it shows the belt for the A.I.R Pump going around the pulley on the water pump and the alternator belt going around the crank pulley and also the water pump pulley. It seems to show another belt wrapping around the crank pulley and the water pump pulley. I don't believe my car, when I took it apart, had this last belt that I mentioned on it at all.

If that routing I mentioned above is correct, how would you tighten that last belt, if it actually did go around the crank pulley and the water pump pulley? There would be no adjustment for it. Do I have this correct, would there be 3 belts on my car?

Thanks

Jim

[Joe L.]

Re: 1970 LT1 Belt Routing

I am putting my 1970 LT1 back together after an engine re-build. In the Assembly Manual, it shows the fan belt routing on page K185 and it shows the belt for the A.I.R Pump going around the pulley on the water pump and the alternator belt going around the crank pulley and also the water pump pulley. It seems to show another belt wrapping around the crank pulley and the water pump pulley. I don't believe my car, when I took it apart, had this last belt that I mentioned on it at all.

If that routing I mentioned above is correct, how would you tighten that last belt, if it actually did go around the crank pulley and the water pump pulley? There would be no adjustment for it. Do I have this correct, would there be 3 belts on my car?

Thanks

Jim

Jim-------


It depends whether the car has power steering or not. Without power steering, it's as you describe. There is a 2 groove pulley on the crankshaft of GM #3858533 and a 2 groove pulley on the waterpump of GM #3848904. In addition, there is a single groove add-on pulley on the front of the waterpump pulley. The rearmost pulley grooves include a belt which also drives the alternator and adjusts at the alternator.

The second set of grooves has a belt called a captured or captive belt. This belt has no adjustment and, thus, must be the EXACT correct length. Installing this belt can be difficult.I recommend doing it by first removing the balancer pulley, installing the belt in the proper grooves and then (mightily) pulling down on the pulley until it "snaps" into place on the balancer. You can also do it by removing the waterpump pulley, removing the studs from the waterpump flange, installing the belt in the proper grooves and then (mightily) pulling up on the pulley until you can get it to "snap" onto the waterpump pilot shaft. Either way is difficult but I have found the former way to be the easiest.

The GM #3883235 pulley then "sandwiches" onto the waterpump pulley. A belt runs between it and the AIR pump pulley and adjusts at the AIR pump brace.

If your car has power steering everything is way easier. In that case, the captive belt is eliminated and the grooves occupied by a belt which drives the power steering pump and adjusts at the power steering pump.

If you don't have power steering, you might want to add it. If nothing else, it makes your belt installation so much easier.

[James H.]

Re: 1970 LT1 Belt Routing

Thanks Joe.

I have a NON power steering car so I will go with the captive belt. The engine is on the stand, so do you think I can install the alternator belt (and let it hang) and then the captive belt and crank and water pump pulleys and it sounds like that would be easier than doing it all after I have the engine in the car. What do you think?

Thanks

Jim

[Terry M.]

Re: 1970 LT1 Belt Routing

Jim-------

If you don't have power steering, you might want to add it. If nothing else, it makes your belt installation so much easier.

To add power steering Jim will need a CTK coded block with the original smaller oil pan. If he has a CTU block with original oil pan there will be a clearance issue with the power steering ram. The CTK smaller pan holds 4 quarts (+1 gt in the filter). The CTU pan is 5 quarts (+1 for the oil filter).

Years back someone on this board measured the front to rear dimension for both oil pans, but I wouldn't risk my memory of those dimensions.

[Joe L.]

Re: 1970 LT1 Belt Routing

Thanks Joe.

I have a NON power steering car so I will go with the captive belt. The engine is on the stand, so do you think I can install the alternator belt (and let it hang) and then the captive belt and crank and water pump pulleys and it sounds like that would be easier than doing it all after I have the engine in the car. What do you think?

Thanks

Jim

Jim-------


It will definitely be easier to install the captive belt on the engine stand. However, the addition of the pulleys and belt might make installation of the engine into the chassis more difficult.

[James H.]

Re: 1970 LT1 Belt Routing

Thanks again Joe. I am going to keep the car as original as possible, and keep it with the manual steering. I have the radiator and radiator frame removed so I don't think the couple of extra pulleys on the front of the engine should cause an installation problem... at least that is what I will be telling myself when I get the engine up on the hoist

Thanks

Jim

[Leonard M.]

Re: 1970 LT1 Belt Routing

CTU pan. With no ruler, looking at the deep sump of the pan, it's length is roughly 5 side edge bolt holes for the "6 qt" vs 4 bolt holes for "5 qt".
pan r.jpg