235 Engine question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

scrapy1949 · 08-12-2005, 02:16 AM

These is my first rest. and I'm learnig along the way, I have a 49 and I wan't to put a 55' 235 engine do I have to make some modifications like one would be on the mounts? these one has them on the side not in the front. My next ? would be what's the difference between a open drive line and close one and I could keep my oringinal rearend? Well I hope someone can help tnks

3100 special · 08-16-2005, 10:17 PM

1st of all welcome to the board! Where are you located? We need to see pictures of your project!
If you go here...
http://groups.msn.com/Jons54/54panel...oto&PhotoID=71
...you can see (kind of) a pic of an enclosed drive shaft. The is a tube that is attched to your rear end that the drive shaft spins inside of. Open drive shaft, is exposed (you can see it spin when the vehicle is in motion.
as for the engine swap, you will definitely need new mounts...and a different transmission...and a new rear end to handle the power.
Keep us posted!

scrapy1949 · 08-17-2005, 08:18 PM

Tnks for the help . I'm located in La Puente Ca. is about 20 mn. from LA. I would put some pictures up soon. What would be better to put on my truck a enclosed or open drive shaft and around what year should i get the rear end. tnks again.

3100 special · 08-17-2005, 08:41 PM

What are you going for? Original or later model drive train?
Are you also listed as 49chevybomb???

Fred T · 08-18-2005, 01:23 AM

The side mounts were used in cars. You should be able to bolt on a front mount, if you want to go that route, but you have to use the bell housing with side mounts for stability. If you're useing a tranny crossmember, you need side mounts on the engine.

Closed drive shafts work great, but they will always drip at the ball joint. 50 years ago people got fed up and GM switched to an open shaft. On the closed shaft, the universal joints ride in gear oil, and rarely wear out, if the oil is maintained. On the car and the 1/2 ton, the driveshaft was inside of a tube connecting the tranny and the differential. If you're wanting to swap either the tranny or the differential, you just about have to go with an open shaft.

What to choose for a rear end? Depends on what you're doing with the truck. If you're leaving on the 6 bolt wheels, you need to locate a 6 bolt rear from another pickup. Best to figure out what you want for gears, then locate a rear the proper width with the gears you want.

You'll find most 6 bolt rears have ratios of 3.73, 3.90, 4.10, 3.42 and 3.07. For highway driving a 235 with a 1:1 tranny ratio, I would recommend the 3.42. For hauling loads, the 4.10. GM made the 3.73 standard behind the six for years, and it is a good, all around ratio, but your milage will suffer. 3.07 gears are to tall for a 235 if there are any hills, wind or loads involved. Just not enough power in the right place on the curve. Tire size also comes into play, smaller diameter tires allow you to use taller gears.

If you're switching to 5 lugs, then you can find a car rear end that will work. Nova and Camaro body sizes are popular, but hard to find with the gears low enough for a pickup.

Phat · 08-31-2005, 01:32 PM

Fred dont tell my 235 its got a six lug 2:73 under it........

It will go and quit on me. LOL But it does have a 5 speed in it. Never tows anything but does haul crate motors now and than.Top 2 gears dont get used in town for sure.It pulls all them bumps on I-80 across PA or the NH white montains in the top gear or 4th.
I think Fred is right though, if i had to buy a rear it would be the 3:42 and slow my sorry butt down on the highways. Sure do like the milage with that 2:73 haulin sail boat fuel

08-12-2005, 02:16 AM	#1
scrapy1949 Registered User Join Date: Mar 2005 Location: So Cal Ca. Posts: 2	235 Engine question These is my first rest. and I'm learnig along the way, I have a 49 and I wan't to put a 55' 235 engine do I have to make some modifications like one would be on the mounts? these one has them on the side not in the front. My next ? would be what's the difference between a open drive line and close one and I could keep my oringinal rearend? Well I hope someone can help tnks

08-16-2005, 10:17 PM	#2
3100 special Street Rod Dreamin' Join Date: Feb 2004 Location: Work:Batam, Indonesia/ Home:League City, Texas Posts: 1,243	1st of all welcome to the board! Where are you located? We need to see pictures of your project! If you go here... http://groups.msn.com/Jons54/54panel...oto&PhotoID=71 ...you can see (kind of) a pic of an enclosed drive shaft. The is a tube that is attched to your rear end that the drive shaft spins inside of. Open drive shaft, is exposed (you can see it spin when the vehicle is in motion. as for the engine swap, you will definitely need new mounts...and a different transmission...and a new rear end to handle the power. Keep us posted! __________________ 1954 Chevy 3100 Panel Truck 2004 GMC Yukon 2007 GMC Sierra 4X4 "I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it." Benjamin Franklin, On the Price of Corn and Management of the Poor, November 1776

08-17-2005, 08:41 PM	#4
3100 special Street Rod Dreamin' Join Date: Feb 2004 Location: Work:Batam, Indonesia/ Home:League City, Texas Posts: 1,243	What are you going for? Original or later model drive train? Are you also listed as 49chevybomb??? __________________ 1954 Chevy 3100 Panel Truck 2004 GMC Yukon 2007 GMC Sierra 4X4 "I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it." Benjamin Franklin, On the Price of Corn and Management of the Poor, November 1776 Last edited by 3100 special; 08-17-2005 at 10:19 PM.

08-18-2005, 01:23 AM	#5
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	The side mounts were used in cars. You should be able to bolt on a front mount, if you want to go that route, but you have to use the bell housing with side mounts for stability. If you're useing a tranny crossmember, you need side mounts on the engine. Closed drive shafts work great, but they will always drip at the ball joint. 50 years ago people got fed up and GM switched to an open shaft. On the closed shaft, the universal joints ride in gear oil, and rarely wear out, if the oil is maintained. On the car and the 1/2 ton, the driveshaft was inside of a tube connecting the tranny and the differential. If you're wanting to swap either the tranny or the differential, you just about have to go with an open shaft. What to choose for a rear end? Depends on what you're doing with the truck. If you're leaving on the 6 bolt wheels, you need to locate a 6 bolt rear from another pickup. Best to figure out what you want for gears, then locate a rear the proper width with the gears you want. You'll find most 6 bolt rears have ratios of 3.73, 3.90, 4.10, 3.42 and 3.07. For highway driving a 235 with a 1:1 tranny ratio, I would recommend the 3.42. For hauling loads, the 4.10. GM made the 3.73 standard behind the six for years, and it is a good, all around ratio, but your milage will suffer. 3.07 gears are to tall for a 235 if there are any hills, wind or loads involved. Just not enough power in the right place on the curve. Tire size also comes into play, smaller diameter tires allow you to use taller gears. If you're switching to 5 lugs, then you can find a car rear end that will work. Nova and Camaro body sizes are popular, but hard to find with the gears low enough for a pickup. __________________ Fred There is no such thing as too much cam...just not enough engine.

08-17-2005, 08:18 PM	#3
scrapy1949 Registered User Join Date: Mar 2005 Location: So Cal Ca. Posts: 2	Tnks for the help . I'm located in La Puente Ca. is about 20 mn. from LA. I would put some pictures up soon. What would be better to put on my truck a enclosed or open drive shaft and around what year should i get the rear end. tnks again.

08-31-2005, 01:32 PM	#6
Phat Registered User Join Date: Sep 2003 Posts: 105	Fred dont tell my 235 its got a six lug 2:73 under it........ It will go and quit on me. LOL But it does have a 5 speed in it. Never tows anything but does haul crate motors now and than.Top 2 gears dont get used in town for sure.It pulls all them bumps on I-80 across PA or the NH white montains in the top gear or 4th. I think Fred is right though, if i had to buy a rear it would be the 3:42 and slow my sorry butt down on the highways. Sure do like the milage with that 2:73 haulin sail boat fuel



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