1961 GMC 5500 Tilt Cab Project

[DanDizzo]

I'm not sure the final destination of this truck yet.
But, I;m going to put some pictures and stuff here.
I am thinking a ramp truck for my 46 ford 1 Ton, but not sure.
I will probably need air bad rear suspension, to drop the rear for the ramp.
I was thinking a motor swap to something more economical...
Everything is still up in the air at this point.
It has a 401V6 with the 5 speed and 2 speed axle.

Thoughts?

[DanDizzo]

The brake and clutch masters were not working when i got it, but it starts and runs great. (still needs a tune up, though)

I rebuilt both masters, and the clutch is working.
The brakes still need more bleeding though.
I used the 1-1/4" master rebuild kit from powerbrake-drivetrain website. $110
The 1-1/8" master, i used a kit from macs that was for a 50's GM car. $30

[DanDizzo]

The frame has a support plate that runs most of the length.
It wraps under the frame as well.
The is a ton of rust scale in between the the frame and plate.
I cut a section of it out, and found holes in the frame.
I am going to 1/4" plate the inside (box it) then replate the outside once i clean it up a little.

[FetchMeAPepsi]

Thoughts?



Yes, keep that 401! It's a historical longwinded powerhouse that will stay running long after anything else you could put in it if you just keep the oil pan full. Gas is cheap and you'll never know the thrill of pulling up to a gas station and the conversation starts - "Whatcha got in that thing?"
"A V6"
"Really? How does it even move?"
"The pistons are as big around as your head. It was a GMC only thing in the '60s. That little V6 has enough torque to change the earth's rotation if she can get traction"
:thumbsup::thumbsup::thumbsup:

[DanDizzo]

I would like to keep the motor.
I really enjoy keeping those kind of conversations.
Also, i know it's all relative, but what kind of MPG would i be looking at?
I'm hoping to haul my '46 with it, and want something "reasonable" on fuel.
Although, i have no long distance trips planned...


The ramp would have to get real low to be able to drive the '46 onto it.

[TJ's GMC]

Upgrade the carb and get an HEI and that will help. You will not get good mileage with Any gas engine. Only a diesel swap would do it. Matter a fact a bragged about big block chevy would get just as bad a mileage as this v6 for a little power gain. :pullinghairout: I'd keep the 401, big and sought after motor; but if you do decide to part you can send it my way. lol

[DanDizzo]

So, I pulled 1 plug. It was a champion j8c. Is that correct?
Also, which hei would fit the 401?
Thanks in advance.

[bigblockv6]

No stock HEI will directly bolt in without modifications unless you by a custom unit from HEIDIZZY on ebay that will drop right in. Or you can use an even fire late 70's Buick 231 V6 HEI distributor with a custom machined collar and the existing distributor gear from your V6, I first built this setup back in 1991 for my 68 KM2500 with 305E, now the distributor is residing in a 478M V6 in the same truck. I'm using corresponding AC HEI spark plugs designed for .060 gap, AC number R44XLS6 which is one step hotter than stock are the plugs I'm using. You would have to do some cross referencing to find out if the J8 plugs are correct, most of us stay away from Champion plugs and if you're going to HEI it's preferable to use an HEI plug to get the full benefits with the larger gap as well. I do remember many years ago using Champion N11Y plugs in the 305E V6. If you want to build an HEI from the Buick distributor the go to Jolly's 6066gmcguy website, all the info for the conversion can be found on the V6 Performance Upgrades page.:upyes:

[DanDizzo]

ok, found the dizzy hei and this carb.
is this the carb model that will work? if you know...

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[bigblockv6]

Yes the 4412 is the right carburetor, looking at the condition of this one if I were you spend the extra money for a brand new carb, you don't know what you're getting when it comes to an old carburetor. You will also need an adapter for the trapezoid base like the one I'm including in this pic of an original TransDapt 2140 adapter specific for these engines. They don't make these adapters anymore but you can easily build one from a TransDapt spacer plate just by drilling the proper holes and countersinking them:thumbsup:

[TJ's GMC]

I would do a 4 barrel for that engine. :thumbsup:

[FetchMeAPepsi]

ok, found the dizzy hei and this carb.
is this the carb model that will work? if you know...

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Swapping out for the HEI and the carb won't improve your mileage by more than 1-2 mpg. You'll see 12-15mpg on average, which was pretty decent for the time.

The HEI and carb will make cold starts easier and will make the engine run smoother though, provided it's running not-so-smooth now. If that ain't broke, you can keep it as a rotor/points system and drive it like you stole it. These engines are very tough.

[TJ's GMC]

Swapping out for the HEI and the carb won't improve your mileage by more than 1-2 mpg. You'll see 12-15mpg on average, which was pretty decent for the time.

The HEI and carb will make cold starts easier and will make the engine run smoother though, provided it's running not-so-smooth now. If that ain't broke, you can keep it as a rotor/points system and drive it like you stole it. These engines are very tough.

He'd be lucky to see 10 in a truck that size. The bigger carb and HEI swap with dual exhaust on my 305 was quite an improvement. More power over anything.

[FetchMeAPepsi]

He'd be lucky to see 10 in a truck that size. The bigger carb and HEI swap with dual exhaust on my 305 was quite an improvement. More power over anything.

He's got a two speed rear end and a 401.

As for your truck, you had issues with yours before you dropped the HEI in, remember? I won't argue that exhaust though. GMC choked the trucks with a single tiny exhaust.
:thumbsup:

[TJ's GMC]

He's got a two speed rear end and a 401.

As for your truck, you had issues with yours before you dropped the HEI in, remember? I won't argue that exhaust though. GMC choked the trucks with a single tiny exhaust.
:thumbsup:

Still...that is a heavy truck. lol Nope, never had fuel issues with mine even with the 4 barrel and points setup. The old dizzy on mine had a sticky advance.

[bigblockv6]

I would do a 4 barrel for that engine. :thumbsup:

A 4bbl would definitely be even better as long as Dan doesn't mind the extra fabrication which really is no big deal as long as a Magnum manifold is used:thumbsup:

[TJ's GMC]

A 4bbl would definitely be even better as long as Dan doesn't mind the extra fabrication which really is no big deal as long as a Magnum manifold is used:thumbsup:

And with a Mill you can get the perfect job. :upyes:

[DanDizzo]

will the 4bbl be much different than a 2 bbl on that motor?
Also, it runs a little rough, but the plugs and wires look way old.
gonna do a normal tune up and then plan on an HEI, and holly.
I don't believe a have a Magnum manifold...
Are those hard to find?
Also, if i would see big gains in the 4bbl, which one would be the "best"?
Thanks again for the advice, i truly appreciate it.

[bigblockv6]

I have done a 4bbl but have not tested it yet. I've heard from others it is a noticeable difference the bigger cubic inch V6 engines. GMC actually did offer a dealer installed option 4bbl conversion. The Magnum 2bbl manifold is based on that 4bbl manifold design it's just cast with a different top base and that's why it's so easy to convert it to a 4bbl. 600-650 cfm would be a good choice for the 401. TJ is the one to talk to about his 4bbl experience though it's on a 305 V6:upyes:

[TJ's GMC]

Your 401 should be a Magnum, if it's not I will be a little surprised. There are numbers stamped on the block just forward of the right head. If yours is a Magnum it will say 401M.

As for my 305, much better over the 2 barrel. :upyes:

Mileage is decent if I can keep my foot out of it and it has no problems lighting the tires in 2nd. I went with an HEI and dual exhaust(recommend, especially for a larger engines).

Ed Snyder would be the one to talk with as he has a 401 with a 4 barrel. :thumbsup:

[DanDizzo]

Ill check the casted number on the block tonight.
Looking at Jolly's site, it says the 401 magnum was used in '66 and later trucks.
Mine being a '61, I think I may not have a magnum...

[bigblockv6]

The Magnum engines were introduced in 1966 so a 61 would just be the smaller port 401

[TJ's GMC]

Blast, I'd do the 2 barrel holley then. Unless you like fabrication. Only one of us that I am aware of that fabbed a non-magnum intake for a 4 barrel.

[DanDizzo]

2bbl might be the way to go, since I won't be "racing" it.

[TJ's GMC]

2bbl might be the way to go, since I won't be "racing" it.

I don't race mine at all. lol Engine is built for torque...Id lose to a 4 cylinder ricer. haha But when towing, it seems the extra barrels help. I towed 10,000 pounds up a grade and accelerated from 1500 RPM in 4th. :thumbsup:

[DanDizzo]

No racing here, just trying to look cool, and maybe haul my '46 with it.
I got numbers from the block. 40103079
I included a shot of the vin also.

I got all the running lights working. Left blinker still doesn't, but i think that's in the switch.

Did some spark plug searching today...
Didn't find much.
I'm planning on using a AC 44xls? I think that's what I bought. either way, it's long reach. That's correct right?

Next is to see if any of you guys are trying to part with a magnum intake?

[TJ's GMC]

Getting a magnum intake will be a bit of a chore. haha Many don't want to part...I got mine and will never part with it because it took darn near a year to get it. lol

Probably a ground issue on the blinker. Really common.