Thinking about putting a later model automatic with OD behind my 1966 318 poly

[Bart K]

My 1966 D 100 currently has a 318 poly with a 4 speed with a granny low and a 391 rear end. The speed limits on the freeways around where I live are 75 and most people run 80. With the current set up I have, it is hard to get 70 out of the old girl. I am sure someone has done the switch I am talking about, so I was hoping to get off easy and have someone tell me what I need to pull this off. I know this is a B-Body forum, but I thought I would try here first.

 

[Darter6]

Yes you can. The early 518 non electric is good or the electric that you can wire a switch for the od.The poly block only has one bell housing bolt that won't line up. Most just leave it without.No big deal.You will have to make some cross member mods. I only installed one in a car that required floor mods, I assume that a truck will be easier. Being it's a truck the 518 is the same as a non od 727.

 

[Bart K]

Yes you can. The early 518 non electric is good or the electric that you can wire a switch for the od.The poly block only has one bell housing bolt that won't line up. Most just leave it without.No big deal.You will have to make some cross member mods. I only installed one in a car that required floor mods, I assume that a truck will be easier. Being it's a truck the 518 is the same as a non od 727.

I really appreciate the reply. I will do some homework and see if I want to go this route!

 

[Darter6]

If you do,please let us know the outcome. I've been thinking about doing that to my 88 D350. A 1 ton with 4.10 gears it is spinning up there on the roads we have out west. 3 miles in any direction the speed limit is 75.And we all know that you can add 10 mph just to keep up with traffic.

 

[Bart K]

So guys, this is the first issue I am seeing. The 518 trans is the trans I was discussing with my transmission guy. The problem is that he claims the 518 would only work with the 6 bolt flywheel arrangement of the 318 engine, I have the 8 bolt version. Also, the 518 option requires driver input to switch on and off the overdrive feature. Failure to turn it off when not needed could potentially burn-up the transmission, according to my guy. Any comments on these issues?

 

[Bart K]

If you do,please let us know the outcome. I've been thinking about doing that to my 88 D350. A 1 ton with 4.10 gears it is spinning up there on the roads we have out west. 3 miles in any direction the speed limit is 75.And we all know that you can add 10 mph just to keep up with traffic.

I would really like to find a way to make this work, so I would say to stay tuned to this channel and see what happens!

 

[Don Frelier]

A Gear Vendors overdrive might be an option, I think it can work with a manual trans?
Just an idea, otherwise look for a 46RH from early 90's Dakota or Ram.
I have a nice 46RE sitting at home, but absolutely no sense getting it to Arizona.

 

[Bart K]

A Gear Vendors overdrive might be an option, I think it can work with a manual trans?
Just an idea, otherwise look for a 46RH from early 90's Dakota or Ram.
I have a nice 46RE sitting at home, but absolutely no sense getting it to Arizona.

Thanks for the info Don. Can you add anything to my issue where the 46RH fits a 6 bolt flywheel and my 66 Poly 318 has an 8 bolt flywheel. I am open to an overdrive for the manual trans if that turns out to be the only option.

 

[66 Sat]

What about a rear end swap to 3.23? Would be a lot cheaper and easier. Or maybe a different manual box with a better spread of ratios?

 

[Bart K]

What about a rear end swap to 3.23? Would be a lot cheaper and easier. Or maybe a different manual box with a better spread of ratios?

Both good suggestions. The hope was that there would be a relatively easy swap to get to an automatic with an overdrive which would accomplish two goals, 1 to get to an automatic which would make the truck more usable to more people and 2 to fix the freeway speed issue. If an easy swap is not available, then I may just leave the truck as it is and use it in town and not on the freeway.

 

[Cranky]

With a granny low you could stick in a 2.94 3rd member (assuming the truck has the 8 3/4). Even with the 2.94, it wouldn't be all to difficult to still start out in 2nd and with a load, 1st gear would get it going without a problem. If you have tall tires on it, go with the 3.23's. Had a 1 ton with the granny gear box and 4.10 gears and installed 33" tall tires and that helped a lot. It needed tires and I got em cheap and didn't want to dig into the Dana rear for a gear change.

 

[Bart K]

With a granny low you could stick in a 2.94 3rd member (assuming the truck has the 8 3/4). Even with the 2.94, it wouldn't be all to difficult to still start out in 2nd and with a load, 1st gear would get it going without a problem. If you have tall tires on it, go with the 3.23's. Had a 1 ton with the granny gear box and 4.10 gears and installed 33" tall tires and that helped a lot. It needed tires and I got em cheap and didn't want to dig into the Dana rear for a gear change.

Good suggestions Cranky! The truck should be back on the road in a few weeks, so maybe I will do some speed tests (unfortunately no tach) and see exactly what I can get on the freeway. I was just hoping to do the trans swap while the cab and bed were off.........way easier, but it may not work out that way.

 

[Cranky]

Not hard to hook up a tachometer.....could even tape it to the steering column temporarily.

 

[Bart K]

Not hard to hook up a tachometer.....could even tape it to the steering column temporarily.

Yes, I was considering doing that, at least temporarily!

 

[1 Wild R/T]

First comment, has he torn it apart to confirm the eight bolt crank? Chrysler changed the 318 poly to a six bolt crank in 63.. 62 & earlier is eight bolt 63 & newer should be normal...

Second you can control O/D & L/U automatically with a few simple components, if your interested I can provide links for the parts... Pretty cheap & easy...

 

[Bart K]

First comment, has he torn it apart to confirm the eight bolt crank? Chrysler changed the 318 poly to a six bolt crank in 63.. 62 & earlier is eight bolt 63 & newer should be normal...

Second you can control O/D & L/U automatically with a few simple components, if your interested I can provide links for the parts... Pretty cheap & easy...

View attachment 877463

Yes, he removed the inspection cover and used a flashlight and mirror to verify 8 bolts on the flywheel. This is a 66 Poly 318 original to the truck as I understood it, so not sure what is up here. I am aware of the automatic OD, but is a 46 RE required for the automatic OD, or are you speaking of making the mod to a 46 RH?

 

[1 Wild R/T]

Yes, he removed the inspection cover and used a flashlight and mirror to verify 8 bolts on the flywheel. This is a 66 Poly 318 original to the truck as I understood it, so not sure what is up here. I am aware of the automatic OD, but is a 46 RE required for the automatic OD, or are you speaking of making the mod to a 46 RH?

First
If he can see the crank flange with the clutch cover/disc/throwout bearing/trans in place he's got Superman type vision.... Or one very special mirror....
So....
If you have an eight bolt crank I would expect it to have the same pattern as the eight bolt Hemi crank.. Not sure of that so it would require some research...

If it is in fact the same thats an easy fix... The Hemi flex plate will bolt to the 518 T/C...

Next
46 RE requires electronics to control every shift and to control pressure based on a few inputs... Much more elaborate than the circuit I posted above...

What I posted is for the 46 RH... It uses a pressure sensor in the governor test port to determine vehicle speed which is the first input to control the shift into O/D

Then the timer built into the first relay whats to see the speed stay above the preset speed for a preset amount of time before it shifts into O/D.. The reason for the time is to prevent O/D kicking in & out repeatedly....

After the O/D timer is satisfied power is fed to O/D & to the L/U relay where a second timer needs to be satisfied before it sends power to the L/U...

 

[Cranky]

First
If he can see the crank flange with the clutch cover/disc/throwout bearing/trans in place he's got Superman type vision.... Or one very special mirror....
So....
If you have an eight bolt crank I would expect it to have the same pattern as the eight bolt Hemi crank.. Not sure of that so it would require some research...

If it is in fact the same thats an easy fix... The Hemi flex plate will bolt to the 518 T/C...

Next
46 RE requires electronics to control every shift and to control pressure based on a few inputs... Much more elaborate than the circuit I posted above...

What I posted is for the 46 RH... It uses a pressure sensor in the governor test port to determine vehicle speed which is the first input to control the shift into O/D

Then the timer built into the first relay whats to see the speed stay above the preset speed for a preset amount of time before it shifts into O/D.. The reason for the time is to prevent O/D kicking in & out repeatedly....

After the O/D timer is satisfied power is fed to O/D & to the L/U relay where a second timer needs to be satisfied before it sends power to the L/U...

Is it possible to set it you to where the driver can control both the OD and the LU? There have been lots of times where I'd like to shut off the LU and not downshift out of OD. There's a bridge near me where my V6 Dakota will go over it without much of a problem as long as the LU doesn't engage....and that takes some light brake pedal pressure.

 

[1 Wild R/T]

Is it possible to set it you to where the driver can control both the OD and the LU? There have been lots of times where I'd like to shut off the LU and not downshift out of OD. There's a bridge near me where my V6 Dakota will go over it without much of a problem as long as the LU doesn't engage....and that takes some light brake pedal pressure.

Pretty simple to do it that way..

The rear wire to the three wire plug is L/U, simply add a switch to that wire...

 

[Bart K]

First
If he can see the crank flange with the clutch cover/disc/throwout bearing/trans in place he's got Superman type vision.... Or one very special mirror....
So....
If you have an eight bolt crank I would expect it to have the same pattern as the eight bolt Hemi crank.. Not sure of that so it would require some research...

If it is in fact the same thats an easy fix... The Hemi flex plate will bolt to the 518 T/C...

Next
46 RE requires electronics to control every shift and to control pressure based on a few inputs... Much more elaborate than the circuit I posted above...

What I posted is for the 46 RH... It uses a pressure sensor in the governor test port to determine vehicle speed which is the first input to control the shift into O/D

Then the timer built into the first relay whats to see the speed stay above the preset speed for a preset amount of time before it shifts into O/D.. The reason for the time is to prevent O/D kicking in & out repeatedly....

After the O/D timer is satisfied power is fed to O/D & to the L/U relay where a second timer needs to be satisfied before it sends power to the L/U...

Thanks Wild R/T. The cab and bed are off, I will ask then about just pulling the trans, the driveshaft is already off, so should be easy to confirm.