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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old March 27th, 2023, 07:03 PM
IdahoFarmboy IdahoFarmboy is offline
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Smile 401M - HEI and Holley carb upgrade

Hi all, I was hoping to get a little info on upgrading my 401M in my Hyster forklift we use as a hay squeeze. I found a bunch of good info on 6066gmcguys website a few years back but can't seem to get on those pages now. I've read a bunch of good threads here but haven't found my exact situation.

Will the Holley 500 #4412 carb and #1937 adapter plate work on my 401M?
It currently has the Stromberg.

Also planning on doing the HEI conversion with the EvenFire Buick V6 HEI distributor. As far as the bushing needed, I am going to check with WE7X to see if he still has any in stock. Or, we can build our own quite easily once I know the specs.

Thanks in advance for any info,
Wade
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  #2  
Old March 28th, 2023, 02:26 AM
BobBray BobBray is offline
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Default Re: 401M - HEI and Holley carb upgrade

Unfortunately the Stromberg WWC has a unique bolt pattern and the 1937 adapter will not work. Balkamp made a Stromberg to Holley adapter years ago, unless you find one you will have to fab one up. Since your 401 is in a forklift, I am not sure you would get much benefit from the Holley. Can your Stromberg be rebuilt? HEI would be a worthwhile modification, your 401 will run better and start easier.
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  #3  
Old March 28th, 2023, 01:08 PM
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jbgroby jbgroby is offline
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Default Re: 401M - HEI and Holley carb upgrade

I have the Buick V-6 distributor, I bought it to make the switch but changed my wmnd, If you need one I don't mind selling it. $75.00 plus shipping

Quote:
Originally Posted by IdahoFarmboy View Post
Hi all, I was hoping to get a little info on upgrading my 401M in my Hyster forklift we use as a hay squeeze. I found a bunch of good info on 6066gmcguys website a few years back but can't seem to get on those pages now. I've read a bunch of good threads here but haven't found my exact situation.

Will the Holley 500 #4412 carb and #1937 adapter plate work on my 401M?
It currently has the Stromberg.

Also planning on doing the HEI conversion with the EvenFire Buick V6 HEI distributor. As far as the bushing needed, I am going to check with WE7X to see if he still has any in stock. Or, we can build our own quite easily once I know the specs.

Thanks in advance for any info,
Wade
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  #4  
Old March 28th, 2023, 04:08 PM
IdahoFarmboy IdahoFarmboy is offline
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Default Re: 401M - HEI and Holley carb upgrade

Thanks for the info BobBray..... that's good to know and saved me a hassle. I'll look into the Stromberg adapter plate or build one unless I can find a Stromberg carb. We had this Stromberg off a few years ago to put a kit in it and found some pitting and a little flaking if memory serves me right so was thinking it needs an upgrade. It currently seeps a little and makes me exremely nervous to go through another season as is..... gas fumes, heat, hay..... not a good combo. I've owned this thing since 2006 and is a crucial piece of equipment and has moved 10s of thousands of tons of hay over the years.... its a real work horse.

We just ordered the distributor last week jbgroby so will plan on going with that one. I should have joined the club a little sooner!! Thanks for the offer. WE7X still has the adapter bushings so I have one of those on order from him.

Thanks for the help
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  #5  
Old March 29th, 2023, 02:21 AM
IdahoFarmboy IdahoFarmboy is offline
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Default Re: 401M - HEI and Holley carb upgrade

Quote:
Originally Posted by BobBray View Post
Unfortunately the Stromberg WWC has a unique bolt pattern and the 1937 adapter will not work. Balkamp made a Stromberg to Holley adapter years ago, unless you find one you will have to fab one up. Since your 401 is in a forklift, I am not sure you would get much benefit from the Holley. Can your Stromberg be rebuilt? HEI would be a worthwhile modification, your 401 will run better and start easier.
We did a little measuring and checking specs on the 1937 adapter and they seem to match up. My Stromberg base measures 3 1/4" x 1 7/8" just as the specs for the 1937 adapter does and it doesn't appear to have any other conflicts. So I think I am going to cross my fingers and hope for the best and if all fails it looks fairly easy to build our own or modify this one. For the $25 at Summit Racing I think it might be worth the shot. I'll update the forum with what I find. Thanks
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  #6  
Old March 29th, 2023, 10:51 AM
Prowbar Prowbar is offline
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Default Re: 401M - HEI and Holley carb upgrade

These forklifts originally came with the 305 ci V6, right? Did you swap in the 401M? How does it compare to the 305?
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  #7  
Old March 31st, 2023, 08:48 PM
IdahoFarmboy IdahoFarmboy is offline
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Default Re: 401M - HEI and Holley carb upgrade

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Originally Posted by Prowbar View Post
These forklifts originally came with the 305 ci V6, right? Did you swap in the 401M? How does it compare to the 305?
I'm not sure Prowbar, all I know is I bought it this way in 2006. It wouldn't surprise me if it was swapped at some point. Originally it ran off of propane before my time with it. The serial number on the engine is 401M021200. She runs pretty good but don't know how to compare with the 305. It's no powerhouse that's for sure if you compare with the diesels of today.
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Old April 1st, 2023, 06:16 AM
BobBray BobBray is offline
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Default Re: 401M - HEI and Holley carb upgrade

I wonder since it's a 401 industrial engine it may have the smaller Stronberg WW on it. If so, the 1937 adapter might just work.
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  #9  
Old April 1st, 2023, 09:54 PM
Prowbar Prowbar is offline
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Default Re: 401M - HEI and Holley carb upgrade

Quote:
Originally Posted by IdahoFarmboy View Post
I'm not sure Prowbar, all I know is I bought it this way in 2006. It wouldn't surprise me if it was swapped at some point. Originally it ran off of propane before my time with it. The serial number on the engine is 401M021200. She runs pretty good but don't know how to compare with the 305. It's no powerhouse that's for sure if you compare with the diesels of today.
Yes, the modern turbo diesels are unmatched. But these are the 'diesels' of the 1960's, low RPM high torque truck engines. Gas engines with a diesel behavior.
At least that is how I view them.
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