80 Monte Carlo updates

Glock1984

Not-quite-so-new-guy
Jan 29, 2022
15
3
Updates on the Monte Carlo. Motor is in and exhaust is sorted out. Up next will be adjusting the ride height and rebuilding the trans and rear. Anyone have thoughts on ditching the th350 and going with a 700r4. Ales was thinking of going with the UMI 2 inch drop springs. Thoughts?
 

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CopperNick

Royal Smart Person
Supporting Member
Feb 20, 2018
2,382
113
Canada
On the easy side of things, the transmission swap is almost a straight nuts and bolts exercise. The case to engine bolt pattern is the same for both versions along with the converter to ring gear bolt pattern. To be safe, you might want to take a micrometer to the hole in the crank flange and the snout on the converter to make sure the snout will slip into the crank freely. This is not a situation where, "it's snug, but i think I can use the case bolts to suck it into place", will work. The starter doesn't even need to get pulled for this, although your exhaust pipes will need to be dropped out to gain some wiggle room. If you are not planning on installing some high zoot exhaust system I even think the stock transmission crossmember will bolt up to the R4. Only thing to beware of there is that the bolts on the rear rubber t-mount can be a mix of SAE and Metric; the bolts on the member to the frame will almost for sure be metric unless someone did themselves a favor at one time or another and converted them to SAE fractional. During the 350 removal, you can disconnect the oil cooler lines at the transmission and leave them to drip. The port locations for both lines are the same on both cases.

Up on the engine, there are a few things to consider. First of all the vacuum port that feeds vacuum to the hard line attached to the modulator valve has to be plugged or capped. Since, as part of the 350 removal, the demand downshift cable was removed from its bracket, you now have to test fit the TVS cable into that same bracket and make sure the bracket is in the correct position so that the cable can be attached to its pivot point on the carb or TBI. Edelbrock does make a cable mounting bracket kit to modify the location of the cable mounting bracket is/as necessary. For mine, I just took an already modified bracket that I had fabricated some year ago and re-modified it for what I needed

The biggest hassle will be correctly tensioning the TV cable so that the transmission will shift correctly. I have already posted a summary on how to do this a while back, late spring/early summer??? so a bit of searching should bring you to that thread. Or you can go on line and YOU -Boob a video or two on the subject, or even read about it in the service manual.


Finally, while the easiest way to do this swap is up on a hoist, you can do it on the garage floor. The big secret is to get the car high enough off the ground to use a floor jack with a transmission lifting adapter mounting in place of the frame lifting saddle. Or you could hit the local "Rent a Tool" store and borrow a dedicated jack for that purpose. Again, and this time over on the Non G-Body site, I did post a picture series of the 700R4 swap I did on my Non G-Body--G-Body; my 80 G-10 Van. probably about two years ago now so it ought to be archived somewhere. After some careful measuring I found that the vehicle needed to be around 24 inches off the ground to gain enough room for the jack with the transmission sitting on the adapter plate to slide under the frame cleanly. If you have a buddy who will work for beer or food, take advantage of the second pair of hands as the combination of t-box on the jack is top heavy and hard to move around. The extra hands are useful to stabilize the whole thing.



Nick
 

CopperNick

Royal Smart Person
Supporting Member
Feb 20, 2018
2,382
113
Canada
One other item. Both the 200R4 and the 700R4 require an electrical harness to actuate the lock up. This harness is made by Painless Wiring, sold by OPGI and available as Part Number C990135, on page 146 of the OPGI 2022 catalogue. It includes the VOES switch and the -t-box internal actuator, as well as the harness. Most 700's come with the actuator already resident but parts are parts and it never hurts to have a spare.



Nick
 

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