6066 (1960-1966) GMC Truck Club

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-   -   1960 Gmc 305 v6 (https://6066gmcclub.com/showthread.php?t=51179)

ZDADDY July 28th, 2021 04:42 PM

1960 Gmc 305 v6
 
Picked up this beauty a few weeks ago, started to tear into her, found this site, and I'm getting excited about this Truck and this engine! I need some feedback from you gearheads on going forward. My plan is to drive this Truck.I want it to drive 70mph on the interstate with no problems, without rpms redlining. I am pulling engine, and taking to machine shop for complete overhaul. Need advise.......I'm not big on loud *** trucks that can do burn outs. Would like my daughter to learn how to drive a stick in this truck.It was a 3 on the tree, but somebody changed it to floor shift before I got it.Questions..........

Do they make different gears for rear end? Or do I have to replace rear end with something more newer? Its the granny tranny.

Disc brakes?

Suspension?

Holly carb rebuild?

Any comments would be great Thanks

Zdaddy

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Ed Snyder July 29th, 2021 06:58 AM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by ZDADDY (Post 74404)
Picked up this beauty a few weeks ago, started to tear into her, found this site, and I'm getting excited about this Truck and this engine! I need some feedback from you gearheads on going forward. My plan is to drive this Truck.I want it to drive 70mph on the interstate with no problems, without rpms redlining. I am pulling engine, and taking to machine shop for complete overhaul. Need advise.......I'm not big on loud *** trucks that can do burn outs. Would like my daughter to learn how to drive a stick in this truck.It was a 3 on the tree, but somebody changed it to floor shift before I got it.Questions..........

Do they make different gears for rear end? Or do I have to replace rear end with something more newer? Its the granny tranny.

Disc brakes?

Suspension?

Holly carb rebuild?

Any comments would be great Thanks

Zdaddy

https://uploads.tapatalk-cdn.com/202...5edfc17586.jpghttps://uploads.tapatalk-cdn.com/202...28ff8b49a8.jpghttps://uploads.tapatalk-cdn.com/202...fdd95a29d1.jpg

Sent from my P027 using Tapatalk

Welcome to the forum, Zdaddy! We may be a little slow answering all your questions, but don't give up. I'm sure most of your questions will get answered eventually.

You don't say whether your truck is half or three-quarter ton. The half ton rear ends lend themselves to taller highway gears of course. Stock half ton ratios were 3.07, 3.54, and 3.92. Quickest way to find out what you've got is to roll it slowly forward for one revolution of the rear wheels while having a second person count the number of times the driveshaft goes around.

If you've got a three quarter ton, most likely it's got a 4.10 or 4.56. If I remember right, the tallest ratio you can fit is a 3.73. That's what I did to a truck I bought several years ago that came with a 4.56 rear end -- changed to a 3.73. With 32" tall tires, freeway cruising was no problem.

Looks like you're off to a good start! Keep us informed of your progress.

jbgroby July 29th, 2021 12:56 PM

Re: 1960 Gmc 305 v6
 
1 Attachment(s)
Welcome to the Wonderful World of V-6's PLEASE CHECK AND ENJOY THIS LINK, it has every single thing you'll ever want oe need to know about our trucks. It was created by Jolly Goodfellow.

http://6066gmcguy.com/


I have a 1/2 ton GMC V-6 with a factory rear differential DANA 44 and that originally had a stock 3.92 ring and pinion. I swapped it down to a 3.23 from Precision Gear, that helped a lot but I had no overdrive, so I stayed on the low roads.....

I recently swapped out my worn out 4 Speed hydramatic to a 700R4 - if you consider that you'll need the factory or aftermarket trans adaptor to mate up an automatic. Once I made the swap and the truck had OD, I can cruise at 70+ and only turn 1500-1900. I tested at 80 mph and was only turning 1750-1800. See screen shot

Finding parts will sometimes be a quest but they are out there, reach out to both Kanter and EGGE Auto.

Jim A July 29th, 2021 05:51 PM

Re: 1960 Gmc 305 v6
 
I have owned and appreciated a 1960 3/4T, 4 spd GMC 305 for over 50 years.
It has literally done every thing I have asked of it and done them well.
I never have asked it to cruise on the interstate at 70 MPH, however, and never would.
Your new truck has great potential for many years of satisfaction and reliable service, but it was not designed or built for speed.

AZKen July 29th, 2021 07:46 PM

Re: 1960 Gmc 305 v6
 
It is a VERY LOW RPM motor. Built for torque. To buy one you must realize that. If you want a hiway truck, there are many choices. Many are very expensive. I don't know how much you can do. I don't know your skills, tools, experience. The suggestion are coming in from members. It all takes work and some time. Maybe just a rear diff gear change will work. It worked for ED. That would be your first step. If you are going to take it to have it done, it will be way cheaper to find a 12 bolt Chevy donor to swap in. The only way to be sure of any ratio is to take off the cover and read the numbers on the ring gear. Please state if it is a 1/2T or 3/4T.
My 1960 GMC 1/2T had a Dana 44, Jakes 1960 GMC 1/2T has a Dana 44. Yours does not. Don't know what it is yet, corporate 10 bolt? or a drop out? or other. 1/2 T or 3/4 T? Could be stock or could have been swapped already. I can't see your lug nuts to tell if yours is 1/2T or 3/4T.
Your truck seems to have some custom cab features.

ZDADDY July 29th, 2021 10:59 PM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by Ed Snyder (Post 74406)
Welcome to the forum, Zdaddy! We may be a little slow answering all your questions, but don't give up. I'm sure most of your questions will get answered eventually.



You don't say whether your truck is half or three-quarter ton. The half ton rear ends lend themselves to taller highway gears of course. Stock half ton ratios were 3.07, 3.54, and 3.92. Quickest way to find out what you've got is to roll it slowly forward for one revolution of the rear wheels while having a second person count the number of times the driveshaft goes around.



If you've got a three quarter ton, most likely it's got a 4.10 or 4.56. If I remember right, the tallest ratio you can fit is a 3.73. That's what I did to a truck I bought several years ago that came with a 4.56 rear end -- changed to a 3.73. With 32" tall tires, freeway cruising was no problem.



Looks like you're off to a good start! Keep us informed of your progress.

Hey Ed!!!! Thanks for the reply......I think my truck is a halfton it has 6 lugs. Pulling engine tomorrow.I am going to take pumpkin off and see what I got. I posted a pic under rear end disscussion and havnt figured out what I have yet.Someone posted a chart with diffrent rear end pics, but mine does not look like any of them. I really appreciate the feedback.I may take the advise of everyone here going forward on what to do, since most have done it before.

Zdaddy

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ZDADDY July 29th, 2021 11:05 PM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by jbgroby (Post 74409)
Welcome to the Wonderful World of V-6's PLEASE CHECK AND ENJOY THIS LINK, it has every single thing you'll ever want oe need to know about our trucks. It was created by Jolly Goodfellow.

http://6066gmcguy.com/


I have a 1/2 ton GMC V-6 with a factory rear differential DANA 44 and that originally had a stock 3.92 ring and pinion. I swapped it down to a 3.23 from Precision Gear, that helped a lot but I had no overdrive, so I stayed on the low roads.....

I recently swapped out my worn out 4 Speed hydramatic to a 700R4 - if you consider that you'll need the factory or aftermarket trans adaptor to mate up an automatic. Once I made the swap and the truck had OD, I can cruise at 70+ and only turn 1500-1900. I tested at 80 mph and was only turning 1750-1800. See screen shot

Finding parts will sometimes be a quest but they are out there, reach out to both Kanter and EGGE Auto.

Jbgroby,

That's exactly what I want!!!!!! Low rpms going 70/80...........How does that work with a manual 4speed? I would like to keep the floor shifter......is that doable or to much a pain in the ***?
Got any more pics? I need inspiration. Do you have to change tranny and rear end? What trannies bolt up to the v6?

Thanks for the reply
Zdaddy

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ZDADDY July 29th, 2021 11:12 PM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by Jim A (Post 74410)
I have owned and appreciated a 1960 3/4T, 4 spd GMC 305 for over 50 years.

It has literally done every thing I have asked of it and done them well.

I never have asked it to cruise on the interstate at 70 MPH, however, and never would.

Your new truck has great potential for many years of satisfaction and reliable service, but it was not designed or built for speed.

Jim,

Thank you for the response. Your right, they were made to work. And now that she is retired, its time to do some modern upgrades so she can still show everyone she's still got it going on. I know I'm treading a fine line with keeping these pieces of American history intact, but a part of me really wants to drive this truck around, I live off an interstate, and it must be able to drive on it. That's all I want no more no less. Hopefully with this forums guidance, I can make that happen. Thanks you again for the comment.

Zdaddy

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ZDADDY July 29th, 2021 11:31 PM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by AZKen (Post 74411)
It is a VERY LOW RPM motor. Built for torque. To buy one you must realize that. If you want a hiway truck, there are many choices. Many are very expensive. I don't know how much you can do. I don't know your skills, tools, experience. The suggestion are coming in from members. It all takes work and some time. Maybe just a rear diff gear change will work. It worked for ED. That would be your first step. If you are going to take it to have it done, it will be way cheaper to find a 12 bolt Chevy donor to swap in. The only way to be sure of any ratio is to take off the cover and read the numbers on the ring gear. Please state if it is a 1/2T or 3/4T.
My 1960 GMC 1/2T had a Dana 44, Jakes 1960 GMC 1/2T has a Dana 44. Yours does not. Don't know what it is yet, corporate 10 bolt? or a drop out? or other. 1/2 T or 3/4 T? Could be stock or could have been swapped already. I can't see your lug nuts to tell if yours is 1/2T or 3/4T.
Your truck seems to have some custom cab features.

AZken,

Thanks for the response, I traded a 54 Pontiac for this truck that ran and drove, for a 1960 gmc 1/2 ton, 6 lug, big block v6......that doesn't run.........That's about all I know about it.......That's why I'm here, for guidance from people like you, who have one, or have had several.I am going to post pics of the rebuild as I go, I got the money, and the time, just need the dos and donts from people who done it before. I live off an interstate, and would like to have it drive down it. With low rpms. I rebuilt a 63 falcon in my 20s, (strait 6) and it always had high rpms when driving it, and don't want to reapeat that.
Iv never replaced gears in a rear end, but that don't mean I can't do it.I can take apart **** and put it back together, but that don't make me an expert. The truck had a column shift In it, but currently has a 4 speed floor shifter in it. If I would have noticed that when I traded for it, I probably wouldn't have bought it.I'm pulling engine tommorro, and off to the machine shop.Already have new gas tank, and will do brakes and brake lines while being bored and honed.Any advice would be appreciated.

Thanks for the comment.

Zdaddy

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Ed Snyder July 30th, 2021 12:37 AM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by ZDADDY (Post 74413)
Hey Ed!!!! Thanks for the reply......I think my truck is a halfton it has 6 lugs. Pulling engine tomorrow.I am going to take pumpkin off and see what I got. I posted a pic under rear end disscussion and havnt figured out what I have yet.Someone posted a chart with diffrent rear end pics, but mine does not look like any of them. I really appreciate the feedback.I may take the advise of everyone here going forward on what to do, since most have done it before.

Zdaddy

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With six lugs, yours is definitely a half ton model. I'm guessing your rear end is not original to the truck though. You might be able to figure out what you've got by looking at this page --- https://m.roadkillcustoms.com/differ...ication-chart/ For the best highway cruising, you probably want a ratio somewhere between 3.00 and about 3.50. If you need to change your rear gears, I highly recommend getting a professional shop to do it for you. Changing the rear gears is a simpler, less expensive project than changing to an overdrive transmission. Tall rear tires will help with highway cruising too.

Funky61 July 30th, 2021 12:51 AM

Re: 1960 Gmc 305 v6
 
Welcome ZDADDY! :welcome:


Glad to hear you are sticking with theV6. :upyes:


Here is a link to a GMC V6 build-series on YouTube that you may enjoy.

https://www.youtube.com/watch?v=FXPKRjzxRTo


Post some photo's of the interior and side view mirrors when possible

:coolphotos:

LEWISMATKIN July 30th, 2021 01:21 AM

Re: 1960 Gmc 305 v6
 
welcome to the group!!! anything part # wise that isn't on Jolly's original site, I can furnish. and i agree with ed, keep the sm420 and change the ring gear anf pinion. spicer/dana 44 series. 3.07 is the lowest gmc offered, however fmc had a 2.73 version as an option to the 9" chunk style and with the low 1st gear, it will still pull, while giving you highway speed. good luck, and junk them bowtie motors!!!!!!!!!!!



Lewis Ellis Matkin, Jr.
Ridge Manor, Florida
1965 1002 305e-V6 (soon to be 401M powered)

FetchMeAPepsi July 30th, 2021 03:15 AM

Re: 1960 Gmc 305 v6
 
Don't forget brakes. A lot of nuts start gearing it up for speed (making it a very heavy, badly aimed bullet) then forget that you need to stop. Beef up the master cylinder, brakes, steering, heck you'd probably be better off getting a newer truck for driving on the highway then using your sweet piece of history here for sunday driving, toodling around town, and taking panoramic pictures of beautiful spots around your area.

jbgroby July 30th, 2021 01:29 PM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by ZDADDY (Post 74414)
Jbgroby,

That's exactly what I want!!!!!! Low rpms going 70/80...........How does that work with a manual 4speed? I would like to keep the floor shifter......is that doable or to much a pain in the ***?
Got any more pics? I need inspiration. Do you have to change tranny and rear end? What trannies bolt up to the v6?

Thanks for the reply
Zdaddy

Sent from my P027 using Tapatalk

I already had the factory Hydramatic and wanted to keep an automatic - so I dropped in a 700R4. I'd already changed the rear gear back about 7 years ago which DID HELP the non OD hydramatic greatly - the trans was just too expensive to rebuild
(3500 plus shipping to MI) so I found the needed OEM adaptor and a 700R4 and made the swap. I have no clue how you might go the route of a manual and make it OD. First thing is to figure our what you have.. IF you're on Facebook, send me a friend request and I can send you pictures of my various swaps (rea gears, trans, intake, carb, etc.

ZDADDY August 2nd, 2021 12:54 AM

Re: 1960 Gmc 305 v6
 
Weekend update
Pulled 2 piece driveshaft, slid tranny out, pulled engine without taking hood off.
Couldn't believe how easy it was. I'm lucky to have an old timer best friend that helps too:-)

Engine and heads heading to machine shop this week.

Going to pull pumpkin cover to see what I got this week too.

I took off the floor shifter ( push down, and turn counterclock wise) for first time without messing it up:-)

If anybody is interested there is a huge autoswap meet at ozark empire fairgrounds Aug 20-22. In Springfield MO. Acres and acres of car stuff, people come from all over the country to get their hard to find auto parts, its something to see. Ill be up there looking for some 6066 brethren lol. I can't wait to get this thing on the road.

Zdaddyhttps://uploads.tapatalk-cdn.com/202...9cc9f1f28b.jpghttps://uploads.tapatalk-cdn.com/202...42ae50f546.jpg

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ZDADDY August 2nd, 2021 12:56 AM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by Funky61 (Post 74419)
Welcome ZDADDY! :welcome:


Glad to hear you are sticking with theV6. :upyes:


Here is a link to a GMC V6 build-series on YouTube that you may enjoy.

https://www.youtube.com/watch?v=FXPKRjzxRTo


Post some photo's of the interior and side view mirrors when possible

:coolphotos:

Funky61

I watched the whole series as soon as I bought the truck:-) That's what got me so excited to do the rebuild.

Question is....... should I do it, or let machine shop do it..........hmmmmmmmm

Zdaddy

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Jim A August 2nd, 2021 05:08 PM

Re: 1960 Gmc 305 v6
 
Perhaps I am mistaken in the impression I have gotten over the years that parts (especially rebuild ones) for GMC 305's have become quite hard to find and very expensive.
I hope your machine shop is on top of the situation.
The decision to let them do the reassembly or to do it yourself needs to be based in your experience and confidence in your knowledge and skills.

ZDADDY August 3rd, 2021 02:15 AM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by Jim A (Post 74434)
Perhaps I am mistaken in the impression I have gotten over the years that parts (especially rebuild ones) for GMC 305's have become quite hard to find and very expensive.

I hope your machine shop is on top of the situation.

The decision to let them do the reassembly or to do it yourself needs to be based in your experience and confidence in your knowledge and skills.

I was under the impression this engine is a 454 with two missing cylinders, which has readily available parts. But not sure.

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ZDADDY August 3rd, 2021 02:34 AM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by jbgroby (Post 74422)
I already had the factory Hydramatic and wanted to keep an automatic - so I dropped in a 700R4. I'd already changed the rear gear back about 7 years ago which DID HELP the non OD hydramatic greatly - the trans was just too expensive to rebuild
(3500 plus shipping to MI) so I found the needed OEM adaptor and a 700R4 and made the swap. I have no clue how you might go the route of a manual and make it OD. First thing is to figure our what you have.. IF you're on Facebook, send me a friend request and I can send you pictures of my various swaps (rea gears, trans, intake, carb, etc.

I took my driveshaft up to shop and they said somebody stuck a small shaft into a larger one and welded it.........So now I'm gonna have to buy a rear end, and drive shaft. Have any ideas on what can bolt up with 3.20ish gears? New ones are pretty expensive, any suggestions?

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Ed Snyder August 3rd, 2021 02:36 AM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by ZDADDY (Post 74436)
I was under the impression this engine is a 454 with two missing cylinders, which has readily available parts. But not sure.

I'm not aware of any parts shared with the 454. Check out http://6066gmcguy.com/gmcv6a.html

George Bongert August 3rd, 2021 08:14 PM

Re: 1960 Gmc 305 v6
 
Quote:

Originally Posted by ZDADDY (Post 74436)
I was under the impression this engine is a 454 with two missing cylinders, which has readily available parts. But not sure.

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Greetings, ZDADDY!

This engine was specifically designed to be a true V-6 engine having no relationship to any other GM V-8 engines, and was engineered long before Chevy even thought of manufacturing the 454 V-8 engine. The internal parts are much beefier than the 454 internals, and are not interchangeable.


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