1969 L-71 427/435 power steering conversion

[Kenneth K.]

1242 for the 1969 390/400 HP engines and for the 1968 435 rather than the 38711242. I think the TIMJG and JM might be in error and the correct PS pulley for the 1969 435 is also the 3871242

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Hello everyone,

I am wanting to convert my 1969 L-71, automatic transmission, non-air conditioning, manual steering to the N40 power steering option. I have found several corvette suppliers (e.g. CC) that sell “complete” BB 427 conversion kits. Does anyone know if these generic BB conversion kits will work with the L-71 option?

I have read that the conversion requires the alternator to be relocated but I don’t see this relocation mentioned in the AIM. The belt routing on pg J198 in the AIM appears to be generic for the “427 engine” and option N40 with air conditioning. Nothing specific to the L-71. On pg J427 in the N40 option area of the AIM there is a PS belt routing for the L36 and L71 so this suggests that the conversion would be the same for the 390 HP and the 435 SHP. However, I know there is a difference in pulleys for the L-71.

The NCRS Technical Information Manual and Judging Guide (TIMJG) and the NCRS Judging Manual (JM) both show that the alternator pulley for the 435 with PS is part #38711242. The pulley on my engine is 3829387 AI which is correct for a manual steering car. So as a minimum I would need to replace my alternator pulley with the 38711242. Interesting that both the TIMJG and the JM show a part number 3871242 for the 1969 390/400 HP engines and for the 1968 435 rather than the 38711242. I think the TIMJG and JM might be in error and the correct PS pulley for the 1969 435 is also the 3871242…. Can anyone verify what is the correct PS pulley part no for the 1969 435?

The other difference in pulleys I am aware of is the crankshaft pulley on the 435 is a deep groove with 2 grooves that I believe are unique to the solid lifter BB engines. So is this 2 groove pulley going to be a problem?

Any advice would be appreciated.

Thanks,
Ken

Ken------


There is no such thing as a GM #38711242 for a pulley (or,anything else, for that matter). The alternator pulley part number is 3871242. Long discontinued but available in reproduction.

If you have a cast iron balancerr pulley as you should, it will work fine with the p/s pulley system; no problem, at all.

The other specific to big block components you will need are the various brackets, braces and support as shown in the AIM. You will also need power steering pump pulley GM #3878245 which is a 2 groove, cast iron pulley. Of course, the pump, control valve, relay rod, pitman arm and hydraulic cylinder will also be required. These components are the same as small block. The hoses are the same as small block except for the pump-to-control valve pressure hose which is big block specific.

All of the above are the same for applications with or without C-60. The installation is the same for L-36/L-68 and L-71.

I assume the conversion kits available from suppliers will include all of the above. However, you best check with them before you order.

[Edward C.]

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

All the pulleys are the same for all 1969 corvette big blocks. There are no special pulleys for the L71. Power steering cars require different brackets but all use the same pulleys. The only pulley unique to power steering cars is the alternator pulley which is 3871242 as has been mentioned with the one exception being a ps and ac car having a different alt pulley.

Original brackets for ps cars are getting expensive. Not all the brackets are available in repro right now. They may get reproed again….or may not.

Edward------


Balancer pulleys were not the same for all 1969 Corvette big blocks. Most L-36/L-68 used a stamped steel pulley of GM #3921923 but some may have been equipped with a cast iron pulley of GM #3863108. L-71 were equipped with either the 3863108 or the 3921923. All L-88 and ZL-1 were equipped with the 3863108. As far as power steering goes, it does not matter which of these pulleys is installed; all other components of the system remain the same.

L-36/L-68 with N-40 and C-60 used alternator pulley GM #3883978 but the subject of the original post is an L-71 so it's a moot point regarding such a pulley since L-71 was not available with C-60. By the way, the 3883978 and 3871242 differ only in OD with the configurations being otherwise essentially identical. The 3883978 is 3" OD and the 3871242 is 3-5/8" OD.

[Kenneth K.]

Re: 1969 L-71 427/435 power steering conversion

Joe/Edward -

Thank you for your input. I found a couple suppliers that seem to have all the brackets and pulleys, etc. Prices can vary by a factor of 2 which I think has to do with original parts vs reproduction. I think this is going to be a nice conversion to make so I am going for it! Hope it is not to challenging but should be worth it.

Ken

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Joe/Edward -

Thank you for your input. I found a couple suppliers that seem to have all the brackets and pulleys, etc. Prices can vary by a factor of 2 which I think has to do with original parts vs reproduction. I think this is going to be a nice conversion to make so I am going for it! Hope it is not to challenging but should be worth it.

Ken

Ken------


It will definitely be worth it. I originally factory-ordered my 1969 without power steering. In 1986 I added power steering to the car. It was absolutely the best thing I ever did to the car.

[Edward C.]

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

I was not aware of the “108” pulley. I stand corrected.

Edward------


For info, both the 3921923 and 3863108 pulleys are 2 "deep groove" {1/2") 6-3/4" OD pulleys and can be used interchangeably. The 3863108 dates back to 1965 whereas the 3921923 was released in 1968. So, the 3921923 was never used prior to the 1968 model year.

The 3921923 was replaced several years ago by the GM #19355270 but it's discontinued now, too.

[Edward C.]

Re: 1969 L-71 427/435 power steering conversion

Edward------


For info, both the 3921923 and 3863108 pulleys are 2 "deep groove" {1/2") 6-3/4" OD pulleys and can be used interchangeably. The 3863108 dates back to 1965 whereas the 3921923 was released in 1968. So, the 3921923 was never used prior to the 1968 model year.

The 3921923 was replaced several years ago by the GM #19355270 but it's discontinued now, too.

[Kenneth K.]

Re: 1969 L-71 427/435 power steering conversion

Joe-
You mention the PS alternator pulley 3871242 is 3-5/8" OD. The manual steering alternator pulley 3829387 AI is also 3-5/8 OD. The judging manual says “On machined pulleys the space between the back of the belt groove and the back of the pulley varies to allow for belt positioning. This distance is either 1/16 inch (thin) or 1/2 inch (thick).” The 3871242 is thick and the 3829387 is thin. If the distance increases when I replace the thin pulley with the thick pulley it seems like the belt would not line up with the crankshaft pulley…

Joe/Edward
The following items are included in the conversion kit I am thinking on purchasing. Since I don't plan on judging the car and my tank sticker does not included the N40 option I am not to concerned if theses parts are reproduction. They say it takes almost 60 days to ship so it does sound like they don’t have all the parts available. I am in no hurry so I can wait as long as the kit contains all the parts I need. Does the list below look complete to you?

Installation Instructions
1965-1974 427/454 Power Steering Hoses w/Clamps
1965-1974 Alternator Strap with Power Steering 396/427/454
1965-1969E Alternator Brace w/396/427
1965-1974 Alternator Bracket with Power Steering396/427/454
1965-1974 Alternator Adjuster & Power Steering Pump Mount Bracket
1963-1982 Pitman Arm with Power Steering
1963-1982 Steering Relay Rod with Power Steering
1963-1974 New Power Steering Pump(Less Pulley)
1965-1974 Power Steering Pump Pulley (2-Groove Cast)
1965-1974 Power Steering Pump Mount Bracket Big Block
1963-1982 Power Steering Cylinder (New)
1963-1982 Power Steering Cylinder Frame Bracket
1963-1982 Power Steering Valve (New)
1963-1982 Power Steering Pump Cap
1963-1982 Power Steering Pump to Valve Clamp
1963-1982 Power Steering Cylinder Frame Bracket Reinforcement
1965-1974 BB Power Steering Pump & Alternator Mount Bolts

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Joe-
You mention the PS alternator pulley 3871242 is 3-5/8" OD. The manual steering alternator pulley 3829387 AI is also 3-5/8 OD. The judging manual says “On machined pulleys the space between the back of the belt groove and the back of the pulley varies to allow for belt positioning. This distance is either 1/16 inch (thin) or 1/2 inch (thick).” The 3871242 is thick and the 3829387 is thin. If the distance increases when I replace the thin pulley with the thick pulley it seems like the belt would not line up with the crankshaft pulley…

Joe/Edward
The following items are included in the conversion kit I am thinking on purchasing. Since I don't plan on judging the car and my tank sticker does not included the N40 option I am not to concerned if theses parts are reproduction. They say it takes almost 60 days to ship so it does sound like they don’t have all the parts available. I am in no hurry so I can wait as long as the kit contains all the parts I need. Does the list below look complete to you?

Installation Instructions
1965-1974 427/454 Power Steering Hoses w/Clamps
1965-1974 Alternator Strap with Power Steering 396/427/454
1965-1969E Alternator Brace w/396/427
1965-1974 Alternator Bracket with Power Steering396/427/454
1965-1974 Alternator Adjuster & Power Steering Pump Mount Bracket
1963-1982 Pitman Arm with Power Steering
1963-1982 Steering Relay Rod with Power Steering
1963-1974 New Power Steering Pump(Less Pulley)
1965-1974 Power Steering Pump Pulley (2-Groove Cast)
1965-1974 Power Steering Pump Mount Bracket Big Block
1963-1982 Power Steering Cylinder (New)
1963-1982 Power Steering Cylinder Frame Bracket
1963-1982 Power Steering Valve (New)
1963-1982 Power Steering Pump Cap
1963-1982 Power Steering Pump to Valve Clamp
1963-1982 Power Steering Cylinder Frame Bracket Reinforcement
1965-1974 BB Power Steering Pump & Alternator Mount Bolts

[Kenneth K.]

Re: 1969 L-71 427/435 power steering conversion

Joe-

Can you help me understand the belt routing. The diagrams in the AIM are hard to decipher. But I think I will need at least 2 belts. One belt from the alternator to the PS pump as you mention above and one belt from the water pump-balancer pulley-PS pump. The AIM shows a 3rd belt from the balancer pulley to the water pump. Do I also need this belt?

[Kenneth K.]

Re: 1969 L-71 427/435 power steering conversion

Joe-

The conversion kit I am looking at does not include the 3871242 alternator PS pulley. They sell a GM 3829193 that says will work. Do you know if the GM 3829193 will work for the L-71?

Thanks,
Ken

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Joe-

The conversion kit I am looking at does not include the 3871242 alternator PS pulley. They sell a GM 3829193 that says will work. Do you know if the GM 3829193 will work for the L-71?

Thanks,
Ken

Ken------

The GM #3829193 was actually the original part number for the pulley. The GM #3871242 superceded it in January, 1973. There is very little difference between the 2 pulleys. So, a reproduction of the 3829193 should work just fine.

[Joe L.]

Re: 1969 L-71 427/435 power steering conversion

Joe-

Can you help me understand the belt routing. The diagrams in the AIM are hard to decipher. But I think I will need at least 2 belts. One belt from the alternator to the PS pump as you mention above and one belt from the water pump-balancer pulley-PS pump. The AIM shows a 3rd belt from the balancer pulley to the water pump. Do I also need this belt?

Kenneth------


Theoretically, I suppose, the belt between the water pump and the balancer pulley is not absolutely necessary (this is called a captured or captive belt since there is no point of adjustment). Would I do without it? Absolutely not! In fact, I was faced with this exact decision with the "ZL-1" engine I built for myself. I installed the belt and, I might add, one needs to install a belt of the exact required length and it's an absolute BEAR to install this belt.