Converting SIV automatic to a V6

By Jim Ellis
Published: April 23, 2009

Converting the SIV Automatic to a V6
Or, How I Spent My Halloween Vacation

“The SIV Automatic is the best car for the V6 conversion because of the wider transmission tunnel.”

Ever heard this statement before?  I certainly did.  It was repeated frequently on the old Forum, and it makes sense.  Widening the tunnel is one of the key steps in the conversion process, so starting with a wider tunnel should make the process easier.  The only problem is that it turns out that no one had actually done it, at least not with V6 Jose’s kit, until I inadvertently volunteered to be the first guinea pig.

I’ve been interested in the conversion since 1999, when I first found an article on Jose Rodriguez and his kit on the web.  I started corresponding with Jose a few years later and began to seriously think about it.  I decided early on that I’d leave my stock-ish SV alone and look for a second car.  I bid unsuccessfully on a few on eBay, drove here and there when I heard about candidates for sale within a 300 mile or so radius of St. Louis, but never found the right car at the right price.  At least, not until I arrived at the 2005 Invasion.

I was one of the first to arrive, but found Jim Ellis and Eric Gibeaut in the parts room and surfing the web on Jim’s laptop.  They both knew I was a Dark Side Wannabe and showed me an ad that Ed Esslinger had just posted on the For Sale section of the Forum.  He was selling a rust free, rolling shell.  Exactly the kind of a car I’d been looking for and, best of all, it was one of those fabled SIV Automatics!  The perfect car for the conversion.

A quick call to Ed and the car was mine.  All within about 15 minutes of arriving at the Invasion.  And, best of all, Ed was willing to keep it in his garage for a few more months, which gave me time to finish my new garage so that I could keep that rust free body rust free.  I started gathering V6 parts (I’d optimistically bought a 2.8 engine a couple of years ago) and peppering Jose and Jim with emails on the conversion.  I was going to be ready by the time my garage was ready!

Along the way, I learned two things about the SIV Automatic.  First, not only is the tunnel wider, but the mounting points for the cross member are different: they have three bolt holes vs. the manual’s four.  That’s not a big deal and should have been pretty easy to deal with.  However, I also learned that it had never been done before and I was going to be the first.  Fortunately for me, although I didn’t know it yet, I was also going to have some great help.

So, flash forward a few months to the week before Halloween, when I took some time off work and drove from St. Louis to Ozark, Alabamato pick up my new SIV.  This was to be no ordinary quick road trip though, as I’d also made plans to go back to St. Louis by way of Columbia, SC and Jim Ellis.  Not exactly a direct route, but Jim was willing to pause from his own projects and help me and there was no way I was going to pass up an offer like that.  More on that leg of the trip in a moment.

The car was exactly as Ed as advertised it, which is to say incredibly solid and rust free, but not much more than a rolling shell.  So far, so good.   Even though I’d paid him months ago, Ed offered to let me walk away from the deal after I’d seen the car, but like I said, it was exactly what I’d been looking for.  However, I had my first indication that the SIV Automatic may not be as perfect as everyone said when Ed showed me the eight holes in the floor.

Ed pointed out that the car had actually been converted to a manual transmission at some point in its past and that the previous owner had simply drilled holes into the floor for mounting the tranny.  Those holes, as shown in the photograph below, were well in front of the mounting points for the auto transmission.

Now, there was no guarantee that the DPO had put the holes in the right place, but I suspected that it would have been hard to be that far off.  To Ed’s credit, he gave me one last chance to back out, but I loaded the car onto a U-Haul dolly and headed east for Columbia.

Now, there is no finer Sunbneamer, shade tree mechanic or friend than Jim E.  I knew that before I left for SC, but I was about to be shown the true meaning of this.  I arrived in Columbia around 6 PM that night and headed straight for Jim’s friend Norm’s restoration shop.  Norm was out of town for the weekend and was letting us use his shop on Saturday for the V6 swap.  Jim was going to help me (actually, I helped him) install his V6 and T5 into my new car.  The plan was to do whatever modifications to the shell that were necessary, weld in the new motor mounts, take his engine and tranny back out, and get me back on the road.  That would have taken me days, weeks or months, but Jim was confident that together we could pull it off in a day.

I parked the SIV next to the OGM and we inspected those floor board holes.  We took some careful measurements on them and on the mounting points on Jim’s car and confirmed that mounting points on the AT and MT are, in fact, very different.  The AT brackets sit about four inches back of the MT brackets and they are also about ¾ inch shorter (closer to the floor board).  Clearly, this was not going to be the piece of cake everyone thought.  Fitting the transmission into the Alpine body is a critical first step in the conversion, as it is used to help position the engine properly in the engine bay.  Jose’s custom mount makes this easy (once the tunnel is modified), but that mount is based on the MT.  We tucked the car in for the night and went home to ponder the situation.

I met Jim back at the shop the next morning, and he had a solution waiting for me.  Eric, who conveniently lives just up the road from Norm’s shop, had been cutting up a very rusty Alpine and disposing of the pieces.  He was down to part of the floorboard, which had one transmission mount left.  It’s hard to recognize the mess in the following picture as anything that was once an Alpine, but trust me: It was.

An air hammer made quick work of the last remaining salvageable bit on the car, and we were able to get a pretty exact fitting for it by snugging it up against the frame.  Knowing that it would work, Jim set about fabricating a mate for it out of sheet metal, being careful to do it as the mirror image of the original.  Working mostly with a hammer and vice, Jim proved himself a master of fabrication and the result is shown below (the original is on the right in both pictures), alongside the original.

With both brackets done, it was a relatively simple matter to weld them in place and get the car to the point where we were ready to start the installation process.  We’d already removed the original engine mounts and opened up the back of the transmission tunnel (it’s wider, but not longer, so that is still required), so we set about fitting the T5 in place.  The cross member handles that nicely.

With the transmission supported by the cross member and a jack, we then attached Jose’s custom engine mounts to Jim’s V6, lowered it into my engine bay and began orienting it left/right.  This is the most critical part, as there is only a fraction of an inch to spare on each side.  Interestingly, I seemed to have just a hair more room in my bay then Jim did, as he needed to heat and dimple one spot where the headers rubbed and I had enough room there.  We did have to open up the mounting points in Jose’s bracket a bit to get the engine centered, as shown below.  Jim had to do this to his too, but I’m sure mine required more because the two mounting brackets we welded in weren’t exactly lined up.

Once we (well, Jim actually) were satisfied it was correct, we carefully marked the spots where the mounts sat on the front suspension and pulled the engine back out.  We (Jim, again) welded the mounts in place, fit the engine again, did a little more fiddling with the cross member to get it just right, and called it a day!  It was about 7 pm and we’d been at it since 7 am.  We were dirty, tired and I had to explain lots of interesting scratches and bruises on my back from crawling around under the car when I got home, but the worst was over.  As much as I hated to remove Jim’s engine and transmission, I know my rust free rolling shell is ready for the V6.  There is a lot more to do and lately I’ve had no time to do it, but the worst is over and I’m well on the way on my journey down the path that leads to the Dark Side.

So, is “the SIV Automatic is the best car for the V6 conversion”?  It’s hard to say.  It certainly would have been easier if we’d had a pair of transmission mounts from a donor car, but the decision isn’t a no-brainer.  The trade off is between having to widen the tunnel on an MT car and installing the mounts on an AT car.  I’ve only done it one way.  Jim’s done it both, but he’s still not sure which way is easiest.  I certainly wouldn’t pass up an SIV AT as a V6 candidate, but I wouldn’t recommend going out and looking for one either.

But, there is one other option:  Now that it’s been done, it should be possible to use my car as a model to design a cross member made for the AT.  After all, we now have one car with both AT and MT mounts in it!  If such a mount were made, then the choice would be a no-brainer: The SIV Automatic would, in fact, be the best car for the V6 conversion!

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