[472]

Mainly to Dave, but input from anyone else who know . . .

In the 231 to 225 questions thread it was proposed that an aftermarket controller would be need to get a FWD 3.8 MPFI system running on a RWD. Why not just use the whole system from a FWD donor, computer and all? Is there something built into the FWD timing cover that can't fit into the RWD cover?

I've got a new engine going into my '68, I went 4.1 and am about ready to purchase a carb, but if I could go EFI without throwing more money into it than the rest of the engine I think I would.

 

[AndyM]

I can't answer that question, but I'm interested to hear what others say. If you want to go TBI, though, I can help you get that going on your 4.1. I even have a custom chip I could burn for you already dialed in for the 4.1 with an RV cam. The conversion isn't cheap, though. At least $500 using new and junkyard parts.

 

[SteveInColorado]

Like AndyM, I only know TBI, and that not too well. With TBI, if the donor vehicle has electronic tranny and other inputs/outputs you don't, you'll never get it to run efficiently without reprogramming the EPROM, which is the removable chip in the ECM. I happen to be dealing with exactly that at the moment on a friend's truck. We were under the impression that you could find people to reprogram them on any street corner, but haven't found anybody yet. Different sender signals advance and retard timing and dump more or less fuel based on outputs.
Seems like any injection system would have a similar setup. If that's the case, apparently SOMEONE out there could reprogram your chip to only run what you have.

AndyM- sending you a PM.

Steve.

 

[dave]

The FWD Buick 3.8 MPFI has some different changes in the front timing cover. Most RWD Buick 3.8 V6 engines have 14 bolts for the oil pan, but some RWD Buick 3.8 V6 have 20 bolts to the oil pan. The FWD Buick 3.8 MPFI has a 20 bolt oil pan. The FWD Buick 3.8 MPFI timing cover does not have a place for the distributor, heck the FWD Buick 3.8 MPFI does not have a distributor at all. The FWD Buick 3.8 MPFI has a different camshaft than the RWD Buick 3.8 V6, the FWD Buick 3.8 MPFI camshaft does not have a fuel pump lobe or a distributor gear cast into camshaft. My Federal Mogul engine bearing book shows the FWD are RWD camshaft journals are the same diameter. So would it be possible to use a FWD camshaft in a RWD block to be able to use the FWD timing cover on a RWD block?

(Maybe, but remember the difference in the oil pans 14 bolts vs. 20 bolts) The FWD Buick 3.8 MPFI has a timing cover with a cam position sensor to tell the computer when #1 cylinder is at Top Dead Center, and a crank position sensor to tell the computer the engine RPM and when the other cylinders are at Top Dead Center. The crankshaft nose of the FWD Buick 3.8 MPFI is different, to allow the use of the gearotor oil pump, thats because the FWD timing cover does not have a distributor to run an oil pump shaft. The FWD Buick 3.8 MPFI has the starter on the opposite side of the block, or another way of saying the starter location on the RWD is on the passenger side, and the FWD starter location is on the drivers side. The bellhousing bolt pattern for the FWD Buick 3.8 MPFI is not the same as the RWD Buick 3.8 V6. The FWD Buick 3.8 MPFI bellhousing is the same bellhousing bolt pattern used in the Chevy S-10 Pickup / Blazer with the 2.5 liter 4 cylinder and 2.8 liter 60 degree V6. The exhaust manifolds and heads for the FWD Buick 3.8 MPFI are very different than the RWD Buick 3.8 V6.

The only thing that I've found on a FWD Buick 3.8 MPFI engine that fits on the RWD Buick 3.8 V6 engine is the MPFI intake manifold.

The FWD Buick 3.8 MPFI can NOT use the motor mounts of the RWD Buick V6.

dave

 

[GRQster]

Howell can reburn yours or burn you a new chip.

 

[472]

Dave:

Thanks for the laundry list of differences, I was under the impression that only the bellhousing bolt pattern was changed between the FWD and RWD variants (I assumed that the HP V6 book was accurate - thats the only thing they said changed.)

Looks like for now I look for a good carb, though with the weather we've had in New England (-6 this morning) and the trouble I've had starting my fuel injected car, I shudder to think how much fun I'll have next winter when I'm starting my Jeepster each morning.

 

[AndyM]

Dave: that's good info. So if the MPFI manifold fits on the RWD block, then you could probably use that with a fuel-only ECU and let the stock distributor handle the ignition duties, right? This would be a cheap and effective way to convert to FI using a Megasquirt ECU (that's the "build it yourself" one - do a google search on it). I have one of the Megasquirt kits in my garage. I just don't need it since I'm running TBI with spark control.

 

[472]

Wow - the MegaSquirt looks like it just may be the ticket. I've gotten the manual, it may justify a little investment.

 

[1832]

1985 BOP fwd with a 3.8 was fuel injected and still used a dist. It used the 14 oil pan so other than fuel pump drive on cam it should fit a rwd block.
Also in 85?-87 they used 20 bold pans on rwd, A wrecking yard by me has 2 two core rwd motors that are 20 bolt pan.

 

[AndyM]

The Megasquirt is pretty cool, isn't it. The only downside I saw with it is that it doesn't have a very well-developed idle compensation system. In the interest of developing a simple system, they didn't incorporate an idle control valve or a true cold start/warm-up enrichment system. You can still get a fast idle circuit by using a simple on/off valve to bypass the throttle body. I haven't built mine yet since I don't know what I'm going to use it on, but I was going to incorporate a thermo-time switch off of an old VW or BMW to handle the cold start/enrichment duties. If you go that route, let me know how it turns out - I may try to locate a MPFI manifold myself.

 

[dave]

Hello John,
I've not yet seen a FWD Buick 3.8 MPFI that has a distributor. I'm not a Buick V6 expert, so I'll start doing some research with the Mitchell's Manuals at my local public library. I'm very optomistic that maybe the 85 distributor will solve some of the problems associated with a RWD MPFI conversion. I'm thinking that the FWD MPFI intake manifold will need to be installed with the throttle body pointing at the firewall if a distributor is used in the MPFI conversion. The Buick V6 intake manifold (carb or MPFI) is a mirror image design. This means the Buick V6 intake manifold can be installed forwards or backwards and still work. I'm also wondering what the 85 FWD Buick 3.8 MPFI used for a water pump?
dave

 

[dave]

Hello Andy,
I looked at the MegaSquirt system, and in many ways is similar to the Simple Digital System (SDS). I favored the SDS system because it could be used to control both fuel and spark engine management, and is programmed without a laptop computer. SDS offers a system that would allow for fuel management only; with the reference pulse coming from the ( - ) post of the ignition coil, similar to the MegaSquirt system. I'm wondering Andy, what type of pricing does the MegaSquirt system have?
dave

 

[AndyM]

Dave: I can't remember the total cost of the circuit board and the assorted parts, but I believe it was right around $200, if that much. I also bought the "stimulator" to test it, as well as the very, very cool relay board to help with wiring chores. I haven't assembled it simply because I changed plans and don't need it right now (I was going to use it on my old BMW, but wrecked it). I may still build the relay board and use it with my TBI on the Jeepster.

 

[472]

With the Simple Digital System prices starting over $800.00, guaranteed "NO!" on requests for specialize software and no source code I think I'll be investigating the Megasquirt exclusively. I can't imagine that anything is going to work on an oddfire without some effort (I'm now thinking beyond the 4.1)

 

[dave]

Hello Mike,
Electromotive http://electromotive.com offers a fuel injection system for an Odd Fire V6. I've printed and read the 175 page Acrobat Reader file for the Electromotive TEC3 system. http://www.electromotive-inc.com/pdf_files/tec3.pdf
dave

 

[472]

Nice unit, but I don't think I can afford it $2000 is 10 times what I paid for my last complete engine. Time to break out the osciliscope and soldering iron at that price. At least with all this discussion I've been able to find some usefull information on how EFI works.