I6 to V8 Conversion and Saginaw with R10 overdrive Information inside.

[steveo3318]

Ok guys I am sure most already know this but I just want to post a little information for future reference for anyone wanting to convert from inline 6 to v8 "CORRECTLY" on their truck. It has seemed to be a hot yet rare subject with little info offered up. Maybe this will become a sticky because it took me almost a year to find all these parts and know which ones were correct.
I can post pictures if anyone needs them, but please ask quickly before I get everything back together.

My main reasons for putting the correct Cross member brackets and linkages in for is at car shows the first thing noticed is my truck was an I6 and is now a v8 because the motor is to far back and it has a spacer on the fan. Also the shift linkage is just sloppy. Lastly I have a Saginaw 7 bolt with R10 overdrive I rebuilt that's going in and I just want the truck to be as period correct as possible. "and yes I rebuilt the Overdrive and trans myself" I also rewound the solenoid myself and rebuilt it also and know the winding wrappings if anyone needs that info. Amperage pull while engaged is key on these. To many amps and it blows fuses.

All this info pertains to trucks with a three on the tree. Thats it!

First things first

1. YES the Bellhousing cross members are different and they are in different locations. The I6 is further back by about 2 inches on the frame and in the rear holes. The V8 cross member has a higher rate of twist and moves to the front two holes on the frame. The cross members ARE different.

2. The Z bar, ball stud and bracket that mounts to the block, bracket that riveted to the frame, clutch linkage from inside to the z bar, and the Linkages from the column shift to the trans are different from the I6 to the V8 models with a three on the tree. The I6 linkages are 29" and 24 1/2" long. the V8 model linkages are 26" and 22" I believe. I am still waiting on my replacements to Arrive but I am positive they are shorter.

3. Optional, the saginaw with R10 overdrive is about 2" shorter in length which requires a longer drive shaft. and its about 40 lbs heavier than the factory standard saginaw. Neither of these transmissions came with a factory cross member on the rear for our trucks and 90% of the Overdrive units I have found have a crack on the main case mounting ears where it connects to the bellhousing. I believe its from the added weight and strain of the overdrive! The OD unit has the standard saginaw bolt holes for a rubber mount which I purchased and I am going to build a rear cross member for mine for added strength.

Overdrive info for our trucks! These are important as I found this out the hard way. Our trucks that have origanal overdrives have the 1.5" plunger rod on the solenoid which is EXTREMELY rare and hard to find, If yours has the easily found 1" plunger on solinoid ITS NOT a truck overdrive. The 1" are actually repopped, but 1.5" are not, I actually found a New old stock one I paid 600 bucks for in the original box because I wasn't sure I could repair mine. It is now a spare since I fixed mine. Also if your main case on your original OD is cracked a standard saginaw 3 speed main case can be drilled to work Its only two 3/8 holes. I am about to go take some pictures for yall. Please let me know if anything special is needed. If there is no interest in this please delete it admins. I am just trying to "give back" a little since so many great members here have helped me on my truck.

[steveo3318]

Please excuse any out of place paint. I am repainting everything under the truck while I am doing this conversion Correction.

V8 Cross member on the left. Its taller, has a faster rate of twist and a little wider than the I6 on the right. Also yes I have the bottom braces off of it. Makes for an easier install.





Two rear holes are for the I6 Member. two further up are for V8





In the truck in the I6 position. notice the hole a few inches forward is for the front hole of the V8 member and the rear hole untilizes the front hole of the I6

[steveo3318]

Z bar on the left is the correct V8, the one on the right was some home made stuff by PO



correct ball stud mount for our V8 trucks

[steveo3318]

Frame mount for z bar. left I6 right V8. and how they sit in truck. They use the same bolt holes.








I6 engine stands on left and V8 stands on right. Note the V8 move to the forward holes

[steveo3318]

clutch rod difference. I am holding the V8 one in my hand for reference.



These are the I6 column to trans linkages, i will post pictures of the V8 when they arrive

[steveo3318]

Here is the Correct 7 bolt saginaw overdrive for our trucks. and the correct T pull OD lockout.







What a 620.00 dollar NOS 1.5" truck solenoid looks like lol. I keep it in my gun safe lol.

[steveo3318]

I have no idea why it will not allow me to edit my first post but it will all the rest but I forgot to say the Engine stands are different and move forward from the I6 to the V8 conversions.

I hope this helps someone else, as I had a time figuring all of this info out. Its a lot just to make it look period correct but I know the linkages and shifter will all be alot tighter and feel better. Also I can now run my headers! I cant wait to see how many RPMs she drops with the OD. I am running 3000 rpm at 65 with 373 rears. I hope to see around 2100 at 70 from my math.

[RichardJ]

Excellent. Nice of you to take the time. Not information that everyone can use, but those that do will be very grateful. Thank you.

[jjzepplin]

I'm in as I want to find an overdrive and put it on a four speed Saginaw. Just curious about wiring and the cable.

[steveo3318]

Wiring is easy. When you get the overdrive let me know and I will help you. There are two 4 speed saginaws on eBay that's been converted already to both Warner OD. they are a bit pricey but the hard work is done and they have a one year warranty. If it wasn't for my solenoid I only paid 500 for my original Saginaw with overdrive. But it had a crack in the case I didn't see. I used my Saginaw in my truck and got a master rebuild kit and rebuilt it. They do still sell the master rebuild kit for the Borg Warner OD

[ghalperin]

Thanks for starting this awesome thread. I'm in the parts collecting stage for this conversion for my plain Jane '67. I'm also going with an original 396. I found a very nice Saginaw OD transmission, but the governor has been replaced with a very large bolt. That bolt looks as if it has been there a long time. I'm wondering how it would be if I ran it as is without the governor.

I did find a source for a replacement governor. I still need to find a nice cable and then configure the wiring.

[steveo3318]

I am in love with my overdrive. I run 75 at 2100 Rpms all day. Your welcome. I am glad it's helping at least one person. Please ask any questions but I doubt your conversion is identical to mine with that big block. I have put my trans to the test and it's amazingly strong. Just don't let it hook up. Lol. Your trans will operate without the governor you will just have to engage it with a switch and disengage it with the same switch when you stop or start. I strongly suggest finding a governor. The correct governor for out trucks has the rare black plastic cap. Only found on 67-68. But a older model with the steel cap will work just fine. The governor is a must have in my opinion. Ask if you need anything.

[faribran]

Please note that you must be a supporting member to post classified items. This includes but is not limited to What Its Worth, Want To Buy, Want To Trade, and For Sale. Please consider supporting the forum by subscribing. Further information on the subscription levels available are located here

If you need any further assistance with that please contact any Admin for help.

[ghalperin]

Originally Posted by steveo3318

I am in love with my overdrive. I run 75 at 2100 Rpms all day. Your welcome. I am glad it's helping at least one person. Please ask any questions but I doubt your conversion is identical to mine with that big block. I have put my trans to the test and it's amazingly strong. Just don't let it hook up. Lol. Your trans will operate without the governor you will just have to engage it with a switch and disengage it with the same switch when you stop or start. I strongly suggest finding a governor. The correct governor for out trucks has the rare black plastic cap. Only found on 67-68. But a older model with the steel cap will work just fine. The governor is a must have in my opinion. Ask if you need anything.

Thanks to you, I knew what crossmember and shift likage to find. Thanks for the tip on the governor, I already found it but now I'll order it. Herm is old school and seems to know overdrives. http://hermtheoverdriveguy.com
For the wiring should I get an O.E. type relay or use a modern relay?

[steveo3318]

I used a modern relay with a fuse and push button. I wanted to be able to turn mine on and off. T handle is just the mechanical lock out

[jfnar]

Do you have any info on the passenger side engine stand for a 292? I bought a '68 GMC with no engine and according to the VIN it was an I6 truck originally. I have a 292 I'd like to put in it but the info I've found seems to point to a special engine stand that is almost impossible to find. I can get a special engine mount that uses the the standard perches but it eliminates the mechanical fuel pump. It appears to me that I can drill the frame and move the passenger side stand forward 4" but I'm reluctant to do that unless I'm sure it'll work ok. Thanks for any info. [IMG][/IMG]

[Boyd67]

Thanks for the info steveo

[steveo3318]

I honestly have no idea on the 292 mounts. The mounts in the picture are for a regular i6 like my truck came with. I am sorry I don't have any info on the 292. I would of though the 292 used the same stands as the smaller i6

[ghalperin]

Can you please tell me where you routed the cable, specifically where it went through the firewall?

I finally got my overdrive installed. I'm having no luck finding the correct governor, but I'm still searching.

[spspspspoon]

so what about drive shaft?
ur truck Was I6 with 3spd?
now V8 with 3 spd n OD?

mine is 65 put 83 V8 in it
now have (car) 7 side bolt 3 spd with OD
and wanting to swap trans out

where can I find gearing and numbers On this trans I have?

[jjzepplin]

Man I want one of those 3 speed overdrives!