1990 XJ, AMC 360 swap, MPI fuel pump?

I'm putting an AMC 360 into my XJ and was wondering if anybody had any suggestions on how to handle the fuel? Will the mechanical pump on the 360 pull through the stock dead in-tank pump on the XJ? Would I be better off going with an adjustable fuel pressure regulator and run the 360 directly off the in tank pump and block off the mechanical unit? Some combination there-of? Or should I just tie a jerry can to my roof? :dunno:

Thanks for any ideas.

Are you going to run the 360 on a carburetor? A carb wants about 7 psi ... the electric pump in an XJ puts out about 40 psi. I think you need an external pressure regulator, and then you can by-pass the mechanical fuel pump on the engine.

Right, as a start I'm going to be using the stock carb. I do have an adjustable fuel regulator handy, however, I'm not certain it can do down to 5-7psi. Otherwise I know Summit has an inexpensive one that is setup specificly for carbs.

Down the road, I have many of the parts for a TBI conversion using a Megasquirt so I like the idea of being able to easily bump the fuel pressure up to the 15-20psi or whatever TBI likes.

However, in the event my adjustable reg doesn't go low enough, WOULD the mechanical pump pull through the non-running in-tank pump? If for no more than an interim solution?

Thanks.

Wagons,
Have you tried to fit the V8 in the engine bay yet? I was also going to do the AMC V8 in one of mine,but had issues with the passenger side manifold(connects with frame).
I tried a couple diffrent styles of manifolds and neither worked.Things were just a little too tight and the motor was too high for my comfort.My solution was to cut out the uniframe and build a 2x3x.180 frame.
If you have found a way to get one to clear could you post some pic's of it?
To see if the stock pump will work why not try a 12v in line pump to see if it'll draw through the intank one?
OlyWa

I've never disassembled a stock fuel pump. Don't know if a mechanical pump could suck through it or not. What about getting something like a Mighty-Vac and just attaching that to the fuel pump output to see if it'll draw. If you put a tee in the line you could also connect a gauge to see how much vacuum is required to pull the fuel. The old mechanical fuel pumps don't geneate a lot of vacuum, because they're typically fairly low on the engine so there's not much "hydraulic head" to overcome. They pull the fuel mostly horizontally, and then push it up to the carb.

Might want to take a look at a early Dodge setup, had an inline filter, close to the carb, with a return outlet on the filter, to dump the extra fuel, back into the tank.
Not a Jeep, but on one Dodge, I ran an inline 30 PSI electric, that pushed fuel through the engine mechanical (I beleive in redundancy) and through a filter with a return line, with no issues. Installed a regulator, that was mostly not needed, just insurance.

8Mud said:

Might want to take a look at a early Dodge setup, had an inline filter, close to the carb, with a return outlet on the filter, to dump the extra fuel, back into the tank.

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Thats exactly how the fuel filter on this particular engine is setup. Its worth a second look, and I'm sure I will have to do some testing once I get it all hooked up.

OlyWaXJ said:

Have you tried to fit the V8 in the engine bay yet?

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Not exactly, the moment is coming soon. I certainly hope I don't have the same issue as you did but I'm going to giver heck. I'm not totally against chopping out parts of my frame - but I'm also not against building some new manifolds if I can find blank flanges. We'll see what I come up with in a couple weeks.

Eagle said:

What about getting something like a Mighty-Vac and just attaching that to the fuel pump output to see if it'll draw. If you put a tee in the line you could also connect a gauge to see how much vacuum is required to pull the fuel.

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I like this idea a lot, but since I don't have a mighty-vac or know anybody who does I may have to come up with something else. Also, the vacuum reading would be kind of arbitrary. What I may do in all my high-tech wonder is just put a couple tubes into a mayonaise jar and put one end on the fuel line and the other in my mouth. :roflmao: Or actually I'll probably get lazy and forgo the jar anyway and take a mouthful.

I guess this all may be for not if my adjustable reg can go low enough. But thanks for all the suggestions - now onto engine cooling...

A friend of mine put an AMC 390 into a 1947 Hudson pickup. IIRC to clear the Hudson steering mechanism he had to run two passenger side exhaust manifolds. The one on the driver's side dumped at the front of the engine and had a long pipe back to the exhaust. A 1947 vehicle was exempt from catalytic converters and had no O2 sesnors to worry about, so he ran dual exhausts ... no Y pipe to mate up to.

Eagle said:

A friend of mine put an AMC 390 into a 1947 Hudson pickup. IIRC to clear the Hudson steering mechanism he had to run two passenger side exhaust manifolds. The one on the driver's side dumped at the front of the engine and had a long pipe back to the exhaust. A 1947 vehicle was exempt from catalytic converters and had no O2 sesnors to worry about, so he ran dual exhausts ... no Y pipe to mate up to.

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I'd have to double check, off the top of my head I don't recall. But can you flip the exhaust manifolds on the AMC v8s upside down? That may be a feasable way to clear stuff also with a 180 degree bend or two... Keep the ideas coming.

I did just find a 258 flexplate that will bolt up to the TH400 I'm using behind the 360. I wonder if it would just be a better idea to hold off on the 360 and get the 258 bolted in and running around... Would definately make my cooling system woes slightly less tragic too. Feedback is welcome on this as well.

Never done it on an XJ pump but on an earlier vehicle where the pump "appeared" identical to the XJ one, I couldn't afford a new one and merely bolted an external one on. Took an extra minute or so to get it primed and going but then it ran great for the next two years until I sold the truck.

Sarge

Up side down? Definitely not with the newer heads and manifolds with the "dogleg" ports, maybe with the older ones that had rectangular ports. Don't recall if the bolt holes were located on the vertical centerline of the ports. My friend didn't flip them upside down, he just ran two passenger side manifolds.

Ahh yes the ole flipped around manifold trick.The late 60's jeepsters used this idea to clear the steering box.
If you did use the 258,it'll bolt rite in the motor mounts are the same on the 4.0L.
As far as the trans the AMC TH400 will bolt to it,but all the transfer cases are pass side drop.Also the flexplate for the 360 will bolt to the 258 but I think it would have to be rebalanced.
OlyWa

OlyWaXJ said:

Ahh yes the ole flipped around manifold trick.The late 60's jeepsters used this idea to clear the steering box.
If you did use the 258,it'll bolt rite in the motor mounts are the same on the 4.0L.
As far as the trans the AMC TH400 will bolt to it,but all the transfer cases are pass side drop.Also the flexplate for the 360 will bolt to the 258 but I think it would have to be rebalanced.
OlyWa

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Yes, I knew I've seen a similar setup before. But it looks like eagle is right the ports are not symetrical - though the bolt holes are on the centerline. I may have to pull a manifold to check. Yes, I have the rest of the J10 drivetrain to match up to the BW 1339 Quadratrac driveline. I found a flexplate balanced for the 258 that will match up to the TH400 TC. And its cheaper than a 21spline AW4 -> Dana 300 conversion which would be my only other option to running the 258.

This way I can tackle the axles and transmission first, and down the road worry about the engine mounts and exhaust clearances and cooling issues that the 360 will bring up.

Eagle said:

Up side down? Definitely not with the newer heads and manifolds with the "dogleg" ports, maybe with the older ones that had rectangular ports. Don't recall if the bolt holes were located on the vertical centerline of the ports. My friend didn't flip them upside down, he just ran two passenger side manifolds.

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I kinda thought that may be the case, but my brain is a jumble sometimes. It seemed to me it would be easier to route exhaust up and down the trans tunnel rather than all the way to the front of the engine and back underneath. In any case it doesn't look like I will have to worry about that just yet. Having the rest of the drivetrain mounted will make the 360 transition easier down the road and give me time to tear down the 360 a little bit.

Thanks