[GreasedPiggy]

Hi Emievel,

I've only done gas conversions but have just about got everything together for the 4BT conversion, so my view is in the midst of conversion. Would this be a full-time 4-week effort?

Also, how far into the driveline do you need to modify? (I've had to re-fit driveshafts, axles and brakes).

I've you've got the time, then the hard part will be collecting the parts. Also, how well-equipped is your workshop? Is pulling engines/trans fairly routine and easy with what you've got? Are your welding skills up?

IMHO, if everything fell into place perfectly and you had the time for full
attention it would be very hard and close at best. Also assume at least a week of "shake down" after the install, especially prior to an 8,500 mile trip.

The conversion is not just popping in the motor, but re-fitting your brakes, steering, fuel, electrical, driveline and cooling systems. Vehicle safety is dependent upon all of these.

Might be good to get a calendar of events going with time estimations, then pad your times a bit. My personal calendar is much, much longer than yours but I've come in way under my estimates. (I've also come in under budget quite a bit. This is with a bit of luck, I scored a complete 4BT set-up for only $1500, but the HD tranny and torque converter was higher than estimates).

Curious to see what other more experienced members have to say...

Best Regards,
George

 

[GreasedPiggy]

Hi Chris,

That paints a better picture, and a fab guy no less!:happyfinger: I re-read in your post about the non PB/PS and that will super-simplify everything.

The 4BT's typically come with a mechanical fuel pump. You might be able to grab the filter mounts/types from the truck.

The integrated hydraulic PB pump can be pulled from the back side of the front cover and some kind of patch fabbed for the remaining hole or you can let it spin and loop the line. There may be a bracketed vacuum pump below the Alt, that can be pulled.

Making the alt bracket is easy, the pulley style/shaft fit may be an issue- consider the alternator from a '94 Caprice which Andre said is a direct bolt-in (105 amps, about $60).

The hard part of fabbing the exhaust will be acquiring the elbow out of the turbo and dealing with the close/tight fit at the firewall/pass-side footwell.
Gas temps are typically 1000F so some distance is always good.
Elbow is available online but you may have one from the truck.

The transmission will be a bit of searching. The TH400 can take the loads, but they have city gearing. The 700R4 has wide ratios (big jumps in-between which should be addressed with the shift points vs. ideal rpm). The 700R4 has a great range but beware of pre-'87 models not yet rebuilt (not likely) and be certain the trans is rebuilt with the increased torque mods in mind. It will also need to be a "diesel" trans, and will also need the diesel governor... ...amongst other little things. The 4L80 has the strength and ratios are fairly good but you will have electronic shifting as part of your plans.

If you go with the auto trans, you will need to get a custom Torque Convertor. DarylB has that sourced here, not sure if you can get that in less than 4 weeks...

Axle strength may/may not be an issue. If you have stock sized tires it is less of an issue. If you drive pavement-only it is less of an issue.

Drivelines that hold up with high-horspower gas engines can break with the 105hp Cummins. Off-idle torque is phenomenal, and this puts undesigned-for stress on the system. If you tow, you may need to address the rear susp for axle wrap while underway. Front susp needs to handle the added (usually 200 lbs) weight of the Cummins.
The driveshaft will require dynamic balancing so find a shop with a quick turn-around time (driveshaft gets done toward the end of your conversion so you've got less time).

Can you clear the tallness of the 4BT? If the van has an engine crossmember then you may be able to lower it as stated.

Better start guttin' that thing!

Best Regards,
George