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Author Topic: 302 Crank Pulley not working on 350 LT1  (Read 6915 times)
69Z28freak
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« on: May 28, 2013, 02:47:38 AM »

I started to mock up my motor with all of the accessory brackets and hardware and discovered that it looks like the 302 harmonic balancer pulley will not line up with the power steering and water pump pulleys. It appears that the 350 harmonic balancer is not as wide as the 302 harmonic balancer, which means that the crank pulley sits about 1/4 inch back out of alignment.



Should I use a LT1 350 crank pulley?



The water pump pulley is a 302 Pulley as is the power steering pulley.



The alternator and brackets are all stock 302 parts.



It looks like the everything lines up except the crank pulley. I used all stock 302 parts thinking that everything would like up ok, but, that is not the case.



Has anyone come across this situation before. Would the 350 LT1 pulley solve my dilemma?
« Last Edit: May 28, 2013, 03:53:17 AM by 69Z28freak » Logged

Mike 1969 Grandma Camaro
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« Reply #1 on: May 28, 2013, 08:23:24 AM »

It probably will help line things up, but there is still the spector of mixing deep groove and shallow, LP groove pulleys - you might have to change belt lengths slightly to compensate for the change in pitch (alternator adjustment range ?). You didn't picture it, but are you using a 3.2 DG alternator pulley as well ?

If you don't have your original 302 balancer, or a good used one, I could see where it's easier to change the pulley rather than pick up a (correct) balancer - I spotted a couple on eBay recently headed into the stratosphere in price - talk about speculation -

Regards,
Steve
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1968 Z28 BRG/W
1969 Z28 X77 LeMans/W
1969 X66 L78 Cortez/BVT
1969 Z11 L48
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« Reply #2 on: May 28, 2013, 08:45:58 AM »

Would part of the problem be the long water pump?
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68Z28
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« Reply #3 on: May 28, 2013, 09:33:58 AM »

With stock '69 302 pulleys, the forward belt track (closest to the radiator) drives the crank, A.I.R. pump, alternator, and water pump. The rearward belt track (closest to the engine) drives the power steering pump; see the "Base" diagram in the Assembly Manual, section N40, sheet A7, and the V-8 installation on sheet A4.
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'69 Z/28
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« Reply #4 on: May 28, 2013, 09:39:31 AM »

It's not real clear in your photos, but it appears your crankshaft pulley may not be fully seated. Make sure the back of the pulley is completely flush against the damper.

Bob
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69Z28-RS
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« Reply #5 on: May 28, 2013, 11:22:07 AM »

And there is also the possibility that the harmonic damper is not fully seated on the crankshaft...?
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
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60 Corvette white/red, 72 Corvette coupe (2), 
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69Z28freak
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« Reply #6 on: May 28, 2013, 02:16:39 PM »

It probably will help line things up, but there is still the spector of mixing deep groove and shallow, LP groove pulleys - you might have to change belt lengths slightly to compensate for the change in pitch (alternator adjustment range ?). You didn't picture it, but are you using a 3.2 DG alternator pulley as well ?

If you don't have your original 302 balancer, or a good used one, I could see where it's easier to change the pulley rather than pick up a (correct) balancer - I spotted a couple on eBay recently headed into the stratosphere in price - talk about speculation -

Regards,
Steve

Thanks Steve. All of the pulleys will be deep groove. I still need to find a power steering pulley, but all other are correct deep groove. My understanding is that the motor is balanced to that harmonic balancer. I am not 100% sure, but I thought it was the correct balancer for a 1970 350 LT1. Perhaps I should by finding if I can change teh balancer and what balancer I do have. Obviously my main goal is to have all of my pulleys line up correctly.
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Mike 1969 Grandma Camaro
69Z28freak
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« Reply #7 on: May 28, 2013, 02:18:20 PM »

Would part of the problem be the long water pump?

Is my water pump not the correct water pump?
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Mike 1969 Grandma Camaro
69Z28freak
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« Reply #8 on: May 28, 2013, 02:19:26 PM »

It's not real clear in your photos, but it appears your crankshaft pulley may not be fully seated. Make sure the back of the pulley is completely flush against the damper.

Bob

Thanks Bob I will check that. It is currently not tightened all of the way. I was just mocking up and it looked way out.
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Mike 1969 Grandma Camaro
69Z28freak
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« Reply #9 on: May 28, 2013, 02:21:26 PM »

And there is also the possibility that the harmonic damper is not fully seated on the crankshaft...?

Thanks Gary I will check to see if the balancer is seated all the way. It appears the crank pulley is sitting back towards the motor 1/4 of an inch, so it actually needs to move forward. That is assuming that the water pump is correct of course. Something is out and causing the belts to not line up correctly. I want to sort it now before the motor goes into the car.
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Mike 1969 Grandma Camaro
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« Reply #10 on: May 28, 2013, 02:29:08 PM »

Your other pulleys (alternator, WP, smog) should line up with the outermost crank groove (see John Z's post), so actually your crank pulley is too far away from your engine for that to happen... and *the crank pulley* needs to go back towards the engine (per the photos)..  Only your PS pulley should line up with the groove closest to the engine.   

I'd suggest making sure your outer groove of the crank pulley first lines up with the water pump pulley, and then make everything else lines up appropriately after that.
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
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69Z28freak
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« Reply #11 on: May 28, 2013, 02:36:10 PM »

Your other pulleys (alternator, WP, smog) should line up with the outermost crank groove (see John Z's post), so actually your crank pulley is too far away from your engine for that to happen... and *the crank pulley* needs to go back towards the engine (per the photos)..  Only your PS pulley should line up with the groove closest to the engine.   

I'd suggest making sure your outer groove of the crank pulley first lines up with the water pump pulley, and then make everything else lines up appropriately after that.


Thanks Gary. Looks like this situation requires more investigation. I guess I also need to confirm that I have the correct water pump and power steering set up as well as harmonic balancer. However I do need a starting place for reference and them work from there.
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Mike 1969 Grandma Camaro
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« Reply #12 on: May 28, 2013, 07:37:30 PM »

The FRONT face of the 302 and the LT-1 pulley should be identical spacing from the engine block.

Yes they are different thicknesses, but start out as the same casting (at least the later 302) and the back side is machined differently.

You have another problem.  Not any repop pulleys in that group are there?  They are crap.
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69Z28freak
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« Reply #13 on: May 28, 2013, 07:53:25 PM »

The FRONT face of the 302 and the LT-1 pulley should be identical spacing from the engine block.

Yes they are different thicknesses, but start out as the same casting (at least the later 302) and the back side is machined differently.

You have another problem.  Not any repop pulleys in that group are there?  They are crap.

I am not using any repop pulleys. Only original 302 oulleys at this point.
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Mike 1969 Grandma Camaro
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« Reply #14 on: May 29, 2013, 12:13:32 AM »

Here's a little reference you can check - hard to see in the pics, but the width of the balancer is slightly more than 1.50", plus the area around the hub (front face) projects another .250" to give it a total width of 1.750 from the back edge to the pulley mounting face. The inner hub should stop on the crank camshaft gear when fully seated - it's real tough to get it too deep, unless for some reason the crank gear is thinner than spec. If your current balancer measures up, you can eliminate that from the puzzle and start with the crank gear, and work out from there.

I have my original balancer hidden somewhere in the Black Hole of Calcutta (my garage), but I'm sure it is identical to the NOS House/Bedroom Closet Stock pictured here. If you need any additional measurements, let me know.

Regards,
Steve
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1968 Z28 BRG/W
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« Reply #15 on: May 29, 2013, 12:19:53 AM »

Compare my Pic #1 to the original shot of yours - I don't see that front ledge/projection that appears on mine - that's a good .250" difference right there, unless I'm looking at it wrong (maybe it's there, and just not visible - it sure doesn't look like it. You'll have to verify if it's present).

Regards -
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69Z28freak
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« Reply #16 on: May 29, 2013, 02:01:13 AM »

Hey Steve Here are some updated pictures. All of the pulleys currently on the car are stock 302 pulleys and the harmonic balancer on my '70 LT1 Motor is the same as the '69 302 motor. All of the Pulleys, Water pump, Power Steering Pump came off of a '69 Z/28. The crazy thing is that all of the pulleys lined up perfectly on the 302 motor. All I did was transfer the parts from the 302 to my 350. It would appear however that all of the pulleys are out by 1/4 inch from the crank pulley. This would lead me to believe that for some reason the 1182 350 crank is 1/4 longer than the 1178 302 crank.

Here the crank pulley is seated all of the way.



Here is the the crank pulley part number



Crank Pulley seated all the way



Water pump and power steering set up. Both of these units were on the 302 motor before mine and lined up perfectly.



This is a better shot showing the pulleys not lining up



And from the other side



Power steering pulley part number



Water pump part number


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Mike 1969 Grandma Camaro
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« Reply #17 on: May 29, 2013, 08:15:52 PM »

Great pics -

I'm like you at this point - looks like the balancer is seated all the way back; I surmise that if this setup was the same on the 302 all the way around, it's got to be the crank, or the block seating surfaces for the water pump and pads for the power steering pump. What approximate production dates for the current 350 block and crank ? Later production ?

You will probably have to shim the water pump pulley, and the power steering pump at this point if the balancer has no more room to seat, or try another water pump and/or pulley combination IMO. Bummer.

Regards,
Steve
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1969 X66 L78 Cortez/BVT
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69Z28freak
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« Reply #18 on: May 29, 2013, 09:35:35 PM »

Here is an update on the pulley situation. Looks like the crank pulley currently on my motor is 3-1/4 inches deep compared to the one on the original Z/28, which is 3 inches. That would explain the situation and solve the mystery, as was suspected. This should fix the problem. Now all I have to do is find a correct pulley and make sure it is the right depth.

Here is the one on my motor that may be a repop



Here is the original pulley on the 69 Z/28

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Mike 1969 Grandma Camaro
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« Reply #19 on: May 30, 2013, 10:22:00 PM »

I'll try to get to mine and measure the depth. Glad you found the problem -

Regards,
Steve
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1968 Z28 BRG/W
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« Reply #20 on: May 30, 2013, 10:47:50 PM »

I'll try to get to mine and measure the depth. Glad you found the problem -

Regards,
Steve

Thanks Steve. I appreciate it. My guess is that if I go with all original pulleys I should be in good shape. I wonder if other repop pulleys are different dimensions than original as well. I have not heard of such a problem before, but I have seen first hand on many occasions, that some repop parts I have tried, do not work very well unfortunately. Gives a whole new meaning to the word "Close". In this case, close is not close enough, however.
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Mike 1969 Grandma Camaro
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« Reply #21 on: May 31, 2013, 06:46:06 PM »

I just measured the 69Z pulley I have and its 3 ".
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68Z28
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« Reply #22 on: June 02, 2013, 05:34:48 PM »

I just measured the 69Z pulley I have and its 3 ".

Thanks
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Mike 1969 Grandma Camaro
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