Straight 6 with 700r4

[SawyerBeavers]

got a 250 straight 6 with a 3 speed Muncie behind it all under the hood of a 65 c10 lwb. I want to swap in a 700r4 for the 3 speed. Has anyone done this and how did it work out? Would it be easier to just stick with the 3 speed? I didn't have too much luck trying to find a old post so sorry if this question has been asked a lot.

[lolife99]

I also think it would be cool,... but I'm not sure how to connect the 700r4 TV cable to the stock carb set-up.

[Clyde65]

Why not go with a 5 speed manual? T5 or NV3500, I believe you can get an adapter from Advanced Adapters even for the 700 to l6

[NEWFISHER]

I have a 250, 700r4 , 29" tall tire and 3:73 in my first build thread- 1950 suburban.

It works Awesome!

If you run a stock motor, you will need 4:10's. I have had just about every mod you can do to a tricked out 250 and empty it performs well. When I pull our 1960 Avion at 4500 lbs I could use 4:10's Otherwise, it's a great combo.

[NEWFISHER]

Originally Posted by lolife99

I also think it would be cool,... but I'm not sure how to connect the 700r4 TV cable to the stock carb set-up.

When you run a heated Clifford intake and the Holley 390 vs the stock intake and single bbl 3 things happen

1. The TV cable hooks directly to the Holley bracket
2. You get better performance
3. You get better fuel mileage....don't ask me how, but mine picked up ALOT!

If I was doing this swap again, the Clifford and the Holley would be on the top of my list of parts before I started in on the project. Moving the cross member, running trans cooler lines, adapted U-joint and drive shaft shortening, bolting up a floor shifted Lokar etc are all the simple stuff. getting the TV geometry and pull with the throttle, having good power for a 6 to run a 700r4 , good fuel milage and driveability are bigger concearns and are all solved by the Clifford/Holley swap

[boucher racing]

Originally Posted by NEWFISHER

When you run a heated Clifford intake and the Holley 390 vs the stock intake and single bbl 3 things happen

1. The TV cable hooks directly to the Holley bracket
2. You get better performance
3. You get better fuel mileage....don't ask me how, but mine picked up ALOT!

If I was doing this swap again, the Clifford and the Holley would be on the top of my list of parts before I started in on the project. Moving the cross member, running trans cooler lines, adapted U-joint and drive shaft shortening, bolting up a floor shifted Lokar etc are all the simple stuff. getting the TV geometry and pull with the throttle, having good power for a 6 to run a 700r4 , good fuel milage and driveability are bigger concearns and are all solved by the Clifford/Holley swap

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I couldn't have said it better. newfisher is exactly right.

I just finished swapping out a T5 for a 700r4 in my truck. I will do a thread on the process, parts list, and costs.

I am running a turbo charged inliner that puts out good power. Just a stock inliner might not have enough UMPH for that auto...

I went with a bowtie overdrive TV made EZ system. It is awesome but a little $$$. Those two usually go together anyways!

[kieth]

Originally Posted by NEWFISHER

I have a 250, 700r4 , 29" tall tire and 3:73 in my first build thread- 1950 suburban.

It works Awesome!

If you run a stock motor, you will need 4:10's. I have had just about every mod you can do to a tricked out 250 and empty it performs well. When I pull our 1960 Avion at 4500 lbs I could use 4:10's Otherwise, it's a great combo.

RAN A SPREADSHEET ON A STOCK 250 I6, THE REASON THE PERFORMANCE STOCK IS LACKING IS WITH A 700R4 & YOUR COMBINATION OF GEARS, TIRE SIZE AND TRANSMISSION you ONLY HAve 419ft/lbs of torque to the ground in 4th gear. The speed line looks good turning 66mph at 2000 rpms. My 350tbi (200 hp 350 with much the same running gear has 460 ft/lbs of torque and I consider that to be the bottom side torque limit but it is a good flat land truck. Better put the 4 barrel on, add some headers and a low restriction air filter to increase the power or go to a 292 491 ft/lbs of torque.
4:10 rear end brings you back into the 460 ft/lbs of torque range but the speed line is 60mph @ 2000rpm in Od or 42mph @2000-------63mph @3000rpm in 3rd gear.

Kieth

[RAYDAY]

I'm putting together a truck with a 250 with 700r4 and 3:73 28 in tire I was thinking 3 1 barrel carbs

[gmcdeadhead]

im going to be doing the conversion on the 292 with the 1-barrel carb this spring when i get all my parts together.

[Lowl!f3]

Didn't you guys also have to wire the solenoid switch up to a toggle or brake switch to make it kick out overdrive?

[SawyerBeavers]

Originally Posted by NEWFISHER

I have a 250, 700r4 , 29" tall tire and 3:73 in my first build thread- 1950 suburban.

It works Awesome!

If you run a stock motor, you will need 4:10's. I have had just about every mod you can do to a tricked out 250 and empty it performs well. When I pull our 1960 Avion at 4500 lbs I could use 4:10's Otherwise, it's a great combo.

When someone says "3.37 gears" does that refer to the tranny or the differential? how would you change the gears if you needed to? does tire size play that big of a roll in the performance of the engine? If you cant already tell I'm pretty new to all this.

My 250 isn't completely stock, I've upgraded the carb to a 2 bbl holly and the intake is a 4 bbl with dual headers.

Im totally open to using a different tranny just not sure what else is out there. I have a 3 speed Saginaw out of a 67 (but im not a big fan of the long stretch from 1st to 2nd) that I would use if it works better than the 700.

[NEWFISHER]

Originally Posted by RAYDAY

I'm putting together a truck with a 250 with 700r4 and 3:73 28 in tire I was thinking 3 1 barrel carbs

Think about a camshaft, lump ports and some headers and you will beok with the 3:73s. The 28" tire will help a little.

Check out Tom at .......12bolt.com

[NEWFISHER]

Originally Posted by Lowl!f3

Didn't you guys also have to wire the solenoid switch up to a toggle or brake switch to make it kick out overdrive?

Yes.
You can go with bowtie overdrives system which dials in the rpm and speed at which lock up happens all the way down to a simple "wire it yourself" solution that allows lock up when 4th gear comes on. No toggle switches. I have used TCI set ups on the last few and it also recieves input from a simple adjustable vacuum switch which unlocks the tq when you let off or apply the throttle.

[NEWFISHER]

Originally Posted by SawyerBeavers

When someone says "3.37 gears" does that refer to the tranny or the differential? how would you change the gears if you needed to? does tire size play that big of a roll in the performance of the engine? If you cant already tell I'm pretty new to all this.

My 250 isn't completely stock, I've upgraded the carb to a 2 bbl holly and the intake is a 4 bbl with dual headers.

Im totally open to using a different tranny just not sure what else is out there. I have a 3 speed Saginaw out of a 67 (but im not a big fan of the long stretch from 1st to 2nd) that I would use if it works better than the 700.

3:73, 3:08,4:10 refer to rear diff ring and pinion gears. The size of the rear tire plays a role in overall gearing too. Think of it like grandpas drill press and changing the belt to different pully diameters to get slower or faster drill speeds.

With just a carb and exhaust upgrade I would use 4:10 rear gears with a 700r4

If you don't want to change rear gears to accommodate a 4 speed auto, use a TH350 trans.

[AcampoDave]

As far as trannys go, don't rule out the good ol' 4 speed saginaw. It's a less costly option and lacks overdrive, but it's plenty strong for a warmed up 6. You can even keep your stock clutch and bell housing too. They came in 4 different gear spreads which are usually denoted by "rings or grooves" on the input shaft. They go from zero rings up to 3 rings. Three ring shafts work great with a more hyway friendly rear end like a 3.08. I've seen rebuilt ones on Craiglist for as little as 150 bucks. Just something to think about if you're a low budget trucker like me.

[Ozzy2013]

Originally Posted by NEWFISHER

When you run a heated Clifford intake and the Holley 390 vs the stock intake and single bbl 3 things happen

1. The TV cable hooks directly to the Holley bracket
2. You get better performance
3. You get better fuel mileage....don't ask me how, but mine picked up ALOT!

If I was doing this swap again, the Clifford and the Holley would be on the top of my list of parts before I started in on the project. Moving the cross member, running trans cooler lines, adapted U-joint and drive shaft shortening, bolting up a floor shifted Lokar etc are all the simple stuff. getting the TV geometry and pull with the throttle, having good power for a 6 to run a 700r4 , good fuel milage and driveability are bigger concearns and are all solved by the Clifford/Holley swap

So the Holley made that much difference?I have the Offenhauser intake and have just been reluctant to buy the holley (Cant find a used one).Thanks Oz

[NEWFISHER]

Originally Posted by Ozzy2013

So the Holley made that much difference?I have the Offenhauser intake and have just been reluctant to buy the holley (Cant find a used one).Thanks Oz

I didn't have the chance to run the mods by themselves. I ran a worn 250 for a year and then installed a .60 over, milled head, ported, cc'd, lump ported, 194 valve, z28 beehive sping, camshafted, cast landon headered, clifford intaked and 390 Holley balanced , blue printed 200+ tire fryer. Then added the 700r4. Then went from 3:08 to 3:73 the next weekend or week prior I can't remember. It was a busy Decemeber, each weekend was a major compont exchange.

[Sharps40]

From Langdons tech tips.....referenced to the earlier generation babbit bearing motors but likely very applicable to our 194/230/250 motors since they are much the same.

Mr. Langdon, one of the senior GM engineers for our engines recommends:

"We strongly encourage the use of a 200 4R in combination with a 3.73 or 4.10 axle ratio so your efforts will result in a satisfying combination of low speed performance and highway cruising at modern speeds up to 70 MPH. The THM 350 could be used at a substantial loss in low speed and highway cruising (both). The use of the Powerglide is strongly discouraged."

Worth an email to Mr. Langdon at Stovebolts Engine Company for straight scoop w/o clutter....Seems you are very new to it, I figured since you were asking about gear ratios. Peruse his site, send an email or two and don't worry bout hopping up the motor to 1 million inyerdreamshorsetorque. With proper trans selection and rear gear a sound and stock I6 will send the truck down the road just fine with a slushbox.

[sigshooter]

Who ever invents a bracket to connect the tv cable to a stock one barrel carb will be a millionaire! Everyone has asked how to do it and no one has an answer for the one barrel.

I think every other kind of carb has been mastered but no one has attempted the stock carb! Bummer

[Lowl!f3]

Originally Posted by sigshooter

Who ever invents a bracket to connect the tv cable to a stock one barrel carb will be a millionaire! Everyone has asked how to do it and no one has an answer for the one barrel.

I think every other kind of carb has been mastered but no one has attempted the stock carb! Bummer

im going to when I get to that point. It will be a 200 4r tho.

[fs64]

I too had looked into this but have since gone with a 4.3 and 700r4.
(Sorry I cant provide picts but my laptop with all of my saved images and sites is currently dead )

I did find a setup that utilized an arm extended out from the top of the first fulcrum { toward driver side with a downward bend on the end}that was attached to the end of the tv cable.

The cable base bracket was a fabricated piece that was attached to the firewall.
A similar one had the base bracket attached to a "clamp" around the intake manifold.

And this creative setup from a forum member:
http://67-72chevytrucks.com/vboard/member.php?u=54960

There are many post on the Nova sites covering this with similar solutions.

Google 700r4 tv geometry and you will find the critical dimensions that are needed for proper operation of the trans.

I found a lot of information and parts from the following site:

http://www.transmissioncenter.net/


GOOD LUCK with your project,
Todd

[gmcdeadhead]

Who ever invents a bracket to connect the tv cable to a stock one barrel carb will be a millionaire! Everyone has asked how to do it and no one has an answer for the one barrel.

I think every other kind of carb has been mastered but no one has attempted the stock carb! Bummer
__________________

i to am going to figure it out when i get to that point in the project.

[Mikes66ChevyC10]

Sorry to hijack but what is the Th350 like behind the 250? Mine is currently a 3spd column shift but we want to convert it to an auto.

[ACK]

Originally Posted by Mikes66ChevyC10

Sorry to hijack but what is the Th350 like behind the 250? Mine is currently a 3spd column shift but we want to convert it to an auto.

I have a 250/TH350 combo with 3.73 rear and I like it for the most part. It's good for driving around town and can handle most hills with ease. The down side, it doesn't like to go much past 65 on the PA Turnpike and when you're at a stand still on wet or snowy days, it tends to spin the tires unless you tap it very, very lightly. Gas mileage isn't bad, but it would be great to have OD.

[kieth]

Originally Posted by Mikes66ChevyC10

Sorry to hijack but what is the Th350 like behind the 250? Mine is currently a 3spd column shift but we want to convert it to an auto.

The 350 automatic and the 3 speed std will have the same speed line......
.you need to go to a 700r4 to drop rpms and let the engine loaf. What we have to watch out for though is the drop in torque (1:1 final drive leaves your truck with torque like it came from the factory, but the OD actually reduces available torque by the amount of the OD ratio (.70) this is why along with a lot of other factors (tire diameter, rear axle ratio) that we have to watch out for this loss of torque. This is why I made up a spreadsheet that is customize able and it looks at all of these factors and especially torque within a usable range of speed.
By keeping a eye on torque and speed we can build a truck that will not only drop the rpms, get better fuel mileage, reduce cab noise, and still be able to get out of its own way.......If we only look at one variable then we can end up with a truck that does not perform correctly......Kieth