4.2 tbi

A 4.0 head conversion to take advantage of that improved fuel delivery.

I had my intake and Carter off preparing for a swap to TBI and noticed how tired and worn my valve guide seals are... I also happened to know of a bargain on a rebuilt 4.0 head (less than 200) so I'm in the middle of converting right now... just waiting on new crane lifters to get to me (might as well replace the 150,000 mile old ones while I'm in there).

A 4.0 head conversion to take advantage of that improved fuel delivery.

I had my intake and Carter off preparing for a swap to TBI and noticed how tired and worn my valve guide seals are... I also happened to know of a bargain on a rebuilt 4.0 head (less than 200) so I'm in the middle of converting right now... just waiting on new crane lifters to get to me (might as well replace the 150,000 mile old ones while I'm in there).

Too bad you have to pay big in gas mileage for that 'reliability'....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

Mike, fuel injection is better for mileage... That Carter isn't better than FI in any way shape or form, let alone delivering fuel efficiently.

Most TBI writeups on the web claim 1 to 4 MPG increase after TBI, and the MPI writups claim even more. One of them even claims a 6 MPG increase. Although I can't find it right now. Sure these are probably replacing badly running Carters, but then most of them never ran very well to begin with.

Assuming he's replacing a emissions era Carter his power will increase as well, JUST getting rid of that POS carter is worth a couple HP, more if it's out of tune and needing a rebuild (and they all are) when you put a higher CFM part in it's place (those GM TBI's are generally 300 CFM versus the Carter's 260), and then disable all that air flow impeding, and air density robbing heater crap and emissions equipment, things start getting interesting.

Stock that system comes with a door in the housing that mildly restricts airflow; an electric heater; an exhaust riser heater that warms the intake air; while these are supposed to only work at start up you also have the EGR pumping warm exhaust into the carb; pulse air tubes, pumping warm air into the housing (possibly constantly depending on what shape his are in); AND as if that's not enough, the coolant is sent through the intake manifold, AND the exhaust manifold is radiating heat onto it to the point where the intake can burn you.

Losing the Carter and all that heater garbage Almost all of which is there ONLY to aid fuel atomization in that horrible carb, is probably worth 10 or 15 peak HP, over a _perfectly_ running BBD.

I dumped the Ford emissions computer and regularly put the $20.00 rebuild kit into my BBD and that sucker just rocks! I have done the same for several others and got the same results. Folks forget the Carb is supposed to get a kit with every plug change...

We all pass emissions easily or with a slight lean tweak needed because the sniffer likes the idle to lean rumble slightly and I get a sweet 23 mpg running about 65-70 mph.

Killing the computer frees up about 25% power or as Jo put it, over 10 mph more per gear way faster. I also believe the gas mileage boost also come from that and running 91 octane 'gasoline', not mix. If I run mix, I drop down to 18 mpg.

Mine will light up my 33's from a stop, second hits 53 mph at 4400 rpm,

3 hauls fast to 75 mph, 4th buries the speedo easy and I have 'no' urge to find out how fast 5th goes....

I think the mpg boost the FI systems show is only because all that Ford emissions crap gets dumped, same as doing the 'Nutter' bypass.

I really like my setup.

That all said, I do like our Cherokee's FI system with nothing to have mess with too often....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)