TBI350 to L31 swap. I'm told close to impossible.

[98 Nitro]

Easiest way to do this just swap short blocks but use the TBI heads, intake, FP, WP and accessories. The roller cam is probably even worth a few HP.
Have the Vortec heads checked for cracks and either sell them and the Vortec accessories and intake, or when you have time and money get a carb or gm TBI to Vortec heads intake manifold and upgrade the FP and tune.

 

[Firewood truck]

The TBI in the Yukon seems strong, just a heavy smoker at temp. The 98 L31 is a goodwrench shortblock that had zero issues.

I'm curious why you would TBI a Vortec? Seems quite a bit more involved.

I'm also curious if you know of any driveline length issues with the 3500/4500 swap.

Like I said, the L31 is just being used as a long block, I have no desire to adapt the Vortec fuel system and any of the headaches that go along with the conversion. For my personal needs, the stock TBI system will run just fine in my firewood truck. The TBI is what my '88 has for a fuel system. The only piece that I needed to change was the intake manifold, I found that GMPP made one ( stuuuupid expensive to buy one new from Summit or Jegs) Eldebrock made a similar one but no EGR provisions. There is "supposed" to be a unicorn of a OE intake on some full size vans that the engines had Vortec heads and a TBI fuel system, as well as some Volvo and Mercruiser intakes on marine 5.7's. I found the "correct" intake that I needed and didn't look back. I haven't tried to install a water t-stat neck yet as I'm not sure how the upper hose routing will be effected by the Vortec accessory drive.

I don't have any 1st hand experience ( yet) with this transmission conversion, I've read a few well documented threads on various website detailing the swap it's pretty close to as 'easy' as it gets. I believe that the SM465 rear driveshaft is a tiny bit longer then the NV4500 D/S, but the slip yoke can absorb the difference. I grabbed EVERYTHING from the donor vehicle, just in case I needed a part.

 

[tayto]

The TBI in the Yukon seems strong, just a heavy smoker at temp. The 98 L31 is a goodwrench shortblock that had zero issues.

I'm curious why you would TBI a Vortec? Seems quite a bit more involved.

I'm also curious if you know of any driveline length issues with the 3500/4500 swap.

it was an extremely popular swap 15-20 years ago. GM even had a manifold specifically for this swap as Firewood mentioned. it will most likely run on a stock calibration, but will leave a lot on the table.

 

[L31MaxExpress]

it was an extremely popular swap 15-20 years ago. GM even had a manifold specifically for this swap as Firewood mentioned. it will most likely run on a stock calibration, but will leave a lot on the table.

I never ran across one that ran even half way right without tuning the ECM. The exception being the Edelbrock MPFI TBI to Vortec conversion that included a revised chip.

 

[yeobee]

Hmm. I was under the assumption the only fuel upgrade was the pump with TBI to L31 conversion. I'm not too sure what I missed there...

I've heard about the same with the transmission conversion. I'm lucky enough to have the entire donor on hand.

 

[tayto]

I never ran across one that ran even half way right without tuning the ECM. The exception being the Edelbrock MPFI TBI to Vortec conversion that included a revised chip.

i remember a friend of a friend did the conversion. i seem to remember he cranked the fuel pressure and advanced the base timing a bunch. it definitely ran but wasn't right until he got a chip from westers garage in Alberta. i did the conversion myself, but had flat tops, cam, BB TBI, headers, etc etc. it needed lots of AE tuning and timing, I never did get it right but had valve train problems and eventually sold the long block to a friend with a boat, he put a tamer cam in it and ran a Qjet

 

[Erik the Awful]

Easiest way to do this just swap short blocks but use the TBI heads, intake, FP, WP and accessories.

Sorry, but the easiest way is to leave the Vortec heads in place and buy a spreadbore carburetor Vortec manifold, and then put a TBI-to-spreadbore adapter on top of it.

 

[98 Nitro]

get a carb or gm TBI to Vortec heads intake manifold

I actually list that as an option, my point is if he wants an easy swap and have it run correctly without tuning/buying anything swap the oil burning short block for the Vortec one but keep everything else from the old motor.

 

[ccreddell]

Its actually easier than most of the previous answers would indicate. You say that the problem with he current motor is oil consumption. If it were me, (and Ive done this before), I would swap the motor in, throw a 4-barrell manifold on it, adapt the TBI to the manifold, and drive away. Might have to fidgit with fuel pressure a little to compensate for the higher compression and the better flowing heads. No stripping wiring harnesses, not much of anything. You could actually get an Edelbrock TBI mani that fits Vortec heads, and, if you wanted, get a chip burned for the ECM. Then drive it and enjoy it. Everything pretty much just bolts up like the old motor.

EDIT: Looks like a few at the back got to it before I did.

 

[transitionbikes93]

put a carb intake on it and get an adapter plate for TBI. obviously to get the most out of it a tune is required. since you have manual trans your ecu is the older type so a prime candidate for EBL Flash

I second this!