350 to 6.2 conversion

[MechanicMike]

Any advice on swapping out an 87 350 gas Suburban with a 6.2 out of an 84 Suburban?

[catmandoo]

well for one thing the diesel uses a hydraboost power brake instead of a vacuum booster, diesel has no vacuum.

[britannic]

Some other thoughts:

If you don't have a fuel return line to the tank, you'll need to run one.

You'll also need an ignition switched 12v feed to run the shutoff solenoid on the inj. pump.

The torque convertor will need to be changed for one with a lower stall speed suitable for the diesel's low down torque.

You'll need two batteries to run the high torque starter (the 350's starter won't have enough welly to spin the diesel to starting rpms).

If you don't have an engine oil cooler, that will be needed as well.

[arveetek]

Do a search. Several members, including myself, have gone down this road, often more than once. Swapping a gas-guzzling 350 for a fuel-saving 6.2L is a wonderful idea. I went from a 9 mpg 305, to a 20 mpg 6.2L. I've put 100,000 miles on my 6.2L since I rebuilt it and installed it in 1996. I wouldn't have anything else under my hood.

Here's a link to some more help:

http://www.thedieselpage.com/members/swap.htm

Casey

[NH2112]

Some observations on swapping...

My C1500 is a former 4.3L truck that a friend dropped a diesel into. He ran a single 1000CCA Deka battery that gave him no problems during winters in Gloucester MA, Arlington MA, or Tyngsboro MA. Right now I have a single 1000CCA or so Wal-Mart battery in it and haven't had any problems.

The gasser + coil wire is perfect for energizing the fuel shutoff solenoid.

As far as power brakes go, if you don't want to fork over $175 or more for a hydroboost unit you could always do like my friend did during the swap and run without power brakes.

If you can get the 6.2L fuel filter(s) with the engine, go for it. If not a Racor is nice but will set you back $100 or so. My truck had a cheap little John Deere fuel filter on it when I got it, which I replaced with a Racor.

A manual glow plug switch will be the easiest way to go. Plus, it's also a mild form of theft prevention. Just run 12V directly from the battery (actually tapping from the starter solenoid or "junction block" on the firewall would be better) to one side of the relay, hook your 2 glow plug leads to the other side, and wire a momentary toggle switch to energize the relay's coil. The seatbelt buzzer or light makes a good glow plug timer [img]smile.gif[/img]

[mhagie]

You say you can get a 6.2 from a 84 burb,do you have access to the entire vehicle?
If so it makes it a hole bunch easier. [img]smile.gif[/img]

[MechanicMike]

Thanks for the replys my 87 sub has a th350 trans with a 4x4 transpher case. the 84 diesel has a fresh
th400 will this trans mate to the 4x4 case

[catmandoo]

don't know about the new stuff but 400 tailshafts used to be bigger than 350's and they are longer so you would need to move the transfer case back and shorter rear shaft and longer front shaft

[mhagie]

Is the diesel Sub a two wheel drive? if so bad luck the 400 won't hook up to the transfer case if it is by chance a 4x4 use all componets from diesel unit, its pure bolt in, no fab no nothing.

[NH2112]

A transfer case bolted to a TH350 will only bolt to a 700R4 due to shaft diameter, spline count, etc. TH400s and SM465 transfer cases are also interchangeable. You'd have to change the input shaft in order to use the donor transfer case on your truck.

[britannic]

In order to use the TH400 with the transfer case, you would need a transfer housing adaptor that is specifically for that transmission and t-case. I know this for a fact as I'm swapping a TH400/NP208 to a TH700R4/NP208 myself.

[imported_]

I have an idea to simplify your brakes. any gas truck usally has some type of vaccuum resivoir. but on ford trucks you can find a large round resivoir, I have never tried it but maybe with some extra vaccuum resivoir you might be able to make your vaccuum brakes work, unless your stock vaccuum pump is in poor shape. just a thought!

[arveetek]

I've been using vacuum brakes on my '81 6.2L diesel since 1996. With a good vacuum pump and reservoir, it does work. However, you have to wait a few moments after initial startup to build up enough vacuum for the power brakes to work. I would suggest swapping in the hydroboost. One of these days I'll get around to doing it on mine!

Casey

[big swifty]

Do you have any specific questions? I did the gas to diesel conversion in my 1988 Sub. I also added a factory tach from a big block to where the fuel gauge sits, and relocated a factory fuel gauge to where the (useless) clock resides.

As stated, having a COMPLETE donor vehicle SIMPLIFIES things greatly. As Casey says, a search might reveal a lot of info.

I just finished an SVO conversion on this truck and am running on grease! The whole conversion process was well worth it for the feeling I get everytime I pass the the gas station.

If I can answer any specific questions- Just ask.

[JeepSJ]

Great info here. I'm in the beginning stages of a gas to diesel swap, and there is great info throughout this site. I just need time to sit and read it all.

As for the brakes, Stainless Steel Brake makes a vacuum pump especially for power brakes - the application is for gas engines with radical cams or superchargers, but it is a stand-alone electric pump so it should work fine for a diesel swap.