68 L79 power steering

[Jeffrey C.]

Trying to put the PS pump on my 68 L79 and things are just not lining up right. The balancer pulley is #3850838BG and the water pump pulley is 3890419CT. These two pulleys line up perfectly. However, I can't seem to finf a PS pulley with enough offset to line up with the front grove on the other pulleys. Ecklers sent me a 3 spoke cast pulley that comes close but it isn't close enough. Also, its a 6 inch diameter and hits on the lower A arm support. Bairs sent me stamped pulleys that are 3/8 inch smaller but don't have near the offset. My assembly manual shows a 2 groove pulley on the balancer and a add on pulley on the water pump for the air pump on a non air car like mine and the PS pump runs off the front groove. What am I missing here?? It almost appears that my PS pump shaft extends farther than it should but it corresponds with everything I have read. The front casting extends 2 inches from the front of the reservoir tank and then the shoulder on the shaft is another 1/4 inch. My motor mounts are not original and I am wondering if original style mounts might have raised the motor enough that they give addition clearance for the pulley against the A arm support. I know my mounts aren't correct as my lower ignition shielding will not fit right and I am ordering original mounts. Any advice would be greatly appreciated as I have been trying to figure this out for the past 2 months!!!

[Joe L.]

Re: 68 L79 power steering

conner-----

The 3 spoke cast pulley, GM #3834720, and the stamped steel pulley, GM #3770509 were the only 2 power steering pump pullies used on any 68 small block. So, if you have both of those, then you have the correct pulley.

I think that your problem lies in the crankshaft and waterpump pullies that you are using. The GM #3850838 crankshaft pulley and GM #3890419 water pump pulley were used for 300 hp engines, not the L-79.

The L-79 used crankshaft pulley GM #3858533 which is a 2 groove pulley and is still available from GM. The L-79 waterpump pulley was GM #3770245, a 2 groove pulley which is still available from GM, OR GM #3848904, also a 2 groove pulley. Early cars used the former pulley and later cars used the latter pulley. I can't tell you when the change occurred, though. The GM #3848904 pulley is discontinued, but replaced by GM #3995641 which is still available.

No add-on crankshaft pulley was used with the L-79. One belt went around the waterpump, crankshaft pulley and power steering pump. The other belt went around waterpump, crankshaft, and alternator. There were only 2 belts for this application.

All this assumes that you DON'T have A/C.

[Joe L.]

Addendum

conner-----

By the way, are you SURE that this engine is an L-79. If so, it should have an 8" OD balancer which is 1-11/16" thick. Besides the balancer being about the only outward indication that the engine is an L-79, or not, the thickness dimension is very important to the pulley system utilized. In fact, that's why the 300 hp and 350 hp (L-79) use different pulley systems.

[Jeffrey C.]

Re: 68 L79 power steering

Joe; My balancer is 8" diameter but 1-5/16 inch thick. I had the motor built from a correct casting # block with high compression pistons and high lift cam but apparently he didn't put the right balancer on it. Will this balancer affect performance and/or longivity?? What specifically does the balancer do? Also, on Page 389 of my assembly manual it shows the belt and pulley configuration for the L79 and it shows the water pump pulley as 3890419, the balancer pulley as 3850838. The stamped steel PS pulley I have, #3770509, only has about a 5/8 inch offset and hits the a-arm support while the cast pulley has a 1&1/8 inch offset but with its larger diameter also contact the support about 1/3 of the way in the belt tension adjustment travel. I am still confused as it seems neither one of my PS pulleys will work but the assembly manual indicates they should.

[Joe L.]

Re: 68 L79 power steering

conner------

I don't know what balancer that you have on the motor. The only balancer that I know of that was 1-5/16" thick is the 69-71 350 cid 300 hp/270 hp balancer. While this balancer will fit on your engine, the timing mark will be way off. 69+ small block balancers have a timing mark/key way which is 9 degrees off. Plus, the pulley system would be different for this balancer and would not conform to any used for the 68 model year.

The part numbers shown on the page you described in the AIM (page 390 in my 68 AIM), are for the L-79 with C-60 and A/C. Although the L-79 with just N-40 and no A/C belt configuration is shown on the page, no part numbers are provided for the pullies (note that there are no boxes with numbers in them for the bottom (L-79 with N-40) configuration. A/C uses a completely different pulley system. That's why I mentioned in my previous post that the information which I provide assumes NO A/C (you didn't mention in your post that your car had A/C so I assumed that it didn't).

As far as the p/s pump pullies go all I can do is reiterate what I said before: the GM #3770509 stamped steel pulley and the GM #3834720 cast iron pullies are the only p/s pump pullies ever used for ANY 1968 Corvette small block. In fact, with just a few minor exceptions, they were the only pullies used for any 63-74 Corvette small block. The 3834720 pump pulley is likely the one that would be correct for the L-79 pulley system I described in my previous post.

Given the possibility that your engine may have the incorrect balancer, then I'm going to make a GUESS at what would work. That GUESS would be to use the current crankshaft pully and water pump pulley that you have. Then, use add-on crank pulley GM #3751232 and use the GM #3770509 p/s pump pulley that you have. In this configuration, the p/s belt will route only between the crank add-on pulley and the p/s pump pulley. To be honest, I wouldn't do it that way, but it will be the least expensive route from where you're at. But, as I say, this is just a GUESS as to what might work.

My real recommendation would be to get all the correct parts and install them. You're lucky as they're all still available. For how much longer, who knows?