700 R4 Swap

Right now I have the I6 with a TH350 Auto in Tammy's 66 Sporty. Looks like the head is warped or gasket out or something and getting water in the cylinders. Plus the thing is leaking really bad out the rear seal and the rear seal on the tranny.

I am contemplating doing the V8 and 700R4 swap.

Mechanically I have seen posts about the drive shaft needing to be shortened when using a 700R4 due to it being longer than a TH350. The 350 V8 should be shorter in length than the I6 and since I am going to be redoing the whole dog house anyways I am thinking instead of shortening the drive shaft, just moving the motor ahead a couple of inches. Since I am going to make a new tunnel anyways I would make it accommodate a better radiator further forward than the current mounting position.

Using the V8 out of the donor van I have would be awesome to have all the A/C components and the fuel injection with cruise not to mention a better gearing from the 700R4.

Even with rebuilding the 350 and the materials for the interior redo I will save over half of what just the Vintage A/C unit would cost me.

Thoughts?

look in our archives- explains all that ur contemplating doing!! Motor , tanny & all. it gets specific as to what u will need to do .

Thanks TP. Was looking for opinions if the motor could be moved forward instead of shortening the drive shaft. If someone has done or seen it done and what it did to their ride one way or the other. (since there would be more weight moved forward)

I have read others posts on doing it with the shorten drive shaft method.

It would be a whole lot easier shortening the driveshaft Matt. You will find that there really isn't as much room up front as you would think between the engine and the radiator to play with. You still have to make the tranny X-member anyway. Keeping the engine on the original mounts lessens the number of changes you have to do. Moving the weight forward to me on these would be a bad thing.

Yeah I talked to Greg about shortening the drive shaft and I can make up a lathe type holder for the drive shaft to make sure I have it straight to cut and re-weld.

I would have been moving the radiator forward also. Since I am redoing the dog house and tunnel in the front I have plenty of room but I think I will just shorten it.

Matt, To have a drive shaft cut and balanced is usaually under $50 bob

The "Ifs" on moving the rad forward would be, Are you going to have to put in a different radiator for the V8? The slot the rad sits in, is or can be limited by Swaybar and a dual MC upgrade. Swaybars run very close to the front of the radiator as they are. A dual MC will eat up space also if you ever go to a X-flow. Even with all the alterations on mine , the radiator sits nearly the same on the fore and aft measurements.

Yeah I thought about all that too.

Like I said, just going to drop the motor a couple inches and shorten the drive shaft I guess. I got a lot of work coming with pulling all the wiring and ECU from the donor van. I want everything. Going to be fun finding a place to put all that wiring with cruise and such.

Matt, Do a little search with the 4wd guys alot of rock buggys are running tbi chevy motors. Also checkout affordablefuelinjection, they make a new harness without all the bs for under $300. I know it sound like alot but, most are getting $500-$600 for the harness Bob

performance wise ... u want a 50/50 weight ratio when it comes to the weight on the front and rear tires or as close as you can get ... moving the engine forward will obviously put more on the front and lighten the ass end up .... hence little traction back there. id leave it in the stock position ... im also about to do this but with a hi-po small block puttin out about 350 horses and a built 700R4 .... good luck and post pictures as you go please

There is even a company now making a FI setup thats =WIERLESS!!!

remember - Manuf's designed these to be safe & work well - we can improve on some things .

Moving the engine forward = not a good idea. These vans already have way too much weight up front.

Selling the 700r4 and buying a 200r that is the same length as the th350 and fits without driveshaft modifications = very good idea!

Changing the engine location, moving it down or forward, will alter the driveshaft angle and possibly create bad driveshaft vibes... ask M1dadio!

If it were me, I'd do it the simple way and try to use parts that fit. I know you already have the 700r4 in hand, but the 200r is shorter and fits better in the 1st gen vans.

Here's another idea.. what about just doing the engine install for now, and leaving the th350 for now? Save the transmission swap for a later project.

will the manual 3 speed bolted up to a 230 or 250 bolt up to a 350 ?? first gen 350

It should, you might run into some issues with having the right exhaust manifolds or something to keep the linkages in place?

I got the motor tore down and taken in to Napa. They are going to Acid bath everything, put in the cam bearings, ridge ream and take the glaze off the cylinders, clean and put the rings in the pistons.

The tranny looks in great shape without any leaks so we are going to use as is.

The heads got a cleaning, a valve jobs and checked for warp.

I have a question about the heads. They asked me if I wanted to get the heads ground and told me they had a slight variation in the flatness of the heads. I asked how much and they said .003" and so I asked what the tolerance was on them and they said they dont know. To me this doesnt make any sense. I understand you want them flat, but there HAS to be a tolerance, this is what a gasket is for otherwise it would be metal to metal, or at least gaskets that had NO GIVE in them. They charge $40 per head to grind them and I could find a better way to spend another $80 if the flatness of heads has a tolerance of .010" and it is far below but I dont know what it is.

Does anyone know what is acceptable for the flatness of the head deck?

See what the other guys say, but if your not getting the block decked flat also I don't know if I would worry about it.

003 thou isnt anything shop is likely after ur pocket -gasket will take care of all that too.

What twin said.

A new set of bolts and proper torque will pull about 10 thou straight, and a gasket will make up for another 10 thou.

3 thou over three feet!! Most shops cant machine it closer then that.


They did say .003" and not .030" right?
M1D

I program a CMM all day long and deal with tolerances, measuring Aerospace and Medical parts. I told the guy that I was the lead programmer for the fuel delivery system inspection for the AuX tank on the shuttle and those fittings were .005 flatness over 4 foot diameter surface. He was just like, I hmm maybe .003 is ok then. Lol

Yes it was .003. I dont see how they could measure this accurately. He told me they used a straight edge to measure it from end to end but not sure their process. I think I will call and talk to the machinist on Monday, they were gone and this was a sales guy that told me. He had it written down for him though so he was just reading what the machinist left for him and I seen it on the paper saying .003.

Standard machine shop practice uses a straightedge and feeler gages.

.003 isn't bad, when I was circle track racing with a friend we used .004 as the cutoff- but that was on engines running 8000 rpm for an hour.

IMO, if I was going through all the work to rebuild I would get a cleanup cut on the heads and deck, line bore, cleanup on bores, etc, but then I tend to go overboard on some things. Most rebuilders just replace bearings, hone the cylinders, reassemble and call it a day.

350 rebuilt and ready to install... and man she looks pretty... Thanks to all for their information on this. Cost me about $600 total for the rebuild.

This included...

Machine shop work
Clean
Ridge ream
Glaze scuff of cylinders
Valve job

Gasket set

New Oil Pump

New Water Pump

New timing set

New Flex Plate

Think that was it...