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Old 09-18-2017, 11:13 PM
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Tigger4X Tigger4X is offline
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Arrow NEED HELP - wisdom and discernment getting my 401 set up right

As of now I have a '74 J-10 with stock 401/th400/Dana 20. It will be for mostly street use, going to the river, lake, but also some light trails, it probably won't see much towing or much weight if it does, but most often will have a slide in pop-up camper in the bed. ( I have an EB Performer non-EGR manifold and had planned to install a new cam/lifter kit. The exhaust will need some attention so I'm putting the $ aside for it too. I have contemplated a number of times to convert it to LPG like the 360 I had in my '76 Cherokee as I have all of the components, but lack the funds for the head work & compression bump. I would like to keep it in mind with this new thread, but fully understand it may not be an A to B to C path and that it may be Option A or Option B. )

Finally on to my inquiry . . . While researching for info on ideal cruising RPMs and power band I came across a thread about Emissions, Mileage, and Power, here ~~> http://ifsja.org/forums/vb/showthrea...ight=Powerband There was a good bunch of tech info, most over my head, and it got me to thinking about how to get my 401 running more efficiently. Not having to worry about smog regs I wont have any issues yanking any of the emissions stuff off. With it gone I can use the non-egr Performer 2131 I already have. My base question is what all can I do to bring up the efficiency of my 401? With a good amount of the tech specifics being over my head, and being geared mostly to the 360 I could really use your help with getting it running at peak.

In that thread it was said that according to the '75-'78 TSMs the 401 cam has 61* of overlap which is supposed to be great for racing at higher rpms but not in the range typical for a J truck. I checked Tom Collins website & the '74 TSM says it's has over 68* of overlap. The suggestion was to pull that cam and replace it with a 360 model or one a little overlap that's more truck friendly; having the EB Performer 2131 I checked the EB website & they have a combo pack with 2132 cam/lifter set. The overlap didn't stand out in the specs. I'm assuming this cam is in their package as its better than the stock 401 cam, maybe it isn't offered any more? Would this resolve the issue about the cam overlap & it now being more efficient?

A bump in compression ratio was suggested as well. I could have the heads milled, but having read about sealing issues with aftermarket intakes my mind goes to an increased issue of sealing; at the usual points as well as flow and/or sealing between intake and heads. I'm wondering if the intake could be milled to better align them all for a better seal? I have heard of higher compression stock heads, but several attempts to chase down the info in the past left me no further ahead than when I first started. If/when I convert to propane I would need to bump the compression to get the most out of it. LPG has a 110 octane rating with an ideal compression ratio of 10 - 10.5-1. I know there are pistons out there that can increase compression, but for now going that "deep" in the engine is not wallet friendly. Does anyone have solid info on those higher compression heads?

Of course the timing/dizzy will need to be adjusted. Aside the the typical advance/retard there is so much more to it that I don't know about. I'm pretty sure I have a Jacobs brand points-less conversion. It would be nice to not have to deal with points any more. They drove me nuts on my old VW bug and Mustang. Springs, weights, dwell and such are sure to cause me fits. I'm not opposed to learning new stuff, but learn far better in person hands on. Any help here is big.

Exhaust - stock, shorties, long tube : age old argument there. I've port matched stock before so that's an option, and I have a pair of Hedman long tubes I got in a package deal some time back. The OO put a new muffler and pipe on that looks like it was done on the cheap. I'm not thrilled with the routing and it suffers from back pressure issues being undersized begind the Y-pipe so it's on the Must Do list. My biggest thought on this is whether to run it single or go duals. Cross pipe or true duals would no doubt be another scrimmage match. True worked much better on my newer Mustang and Capri, but thats with all the newer tech. But maybe that doesnt amount to much difference?

No doubt there are factors that I'm missing, but I'm looking forward to learning some new stuff and putting it to good use. Thanks for your time to read through all of this and in lending your knowledge.
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Old 09-23-2017, 03:56 PM
Ristow Ristow is offline
 
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the stock 401 cam was an epa reg byproduct. a performer grind will out run it.

you won't make any real gains in compression milling heads. do it with pistons or leave it alone. early heads had a smaller chamber,which bumops compression but also can shroud valves. if upping compression with pistons go with the bigger chamber heads and dial the compression in with the piston.

ditch the points. go with a stock motorcraft setup or hei.

long tube headers and dual exhaust with big pipe.
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Old 09-24-2017, 12:51 PM
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Tigger4X Tigger4X is offline
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Thanks for the input Ristow

At the least I can install the 2131 Performer intake and get a 2132 cam/lifter kit for it. Maybe even freshen up the front end with the matching timing chain/gear kit when I install the new water pump and radiator. Might be prudent to get a new oil pump for good measure while I'm in it "that deep".



In order to run propane efficiently the compression has to go up so if I'm going to keep this 401/th400/Dana20 I'll have to save hard and bite the bullet on getting into the engine and not just bolt on kind of stuff. Being new to Oregon it's gonna take some hunting to find someone who knows AMC and will do the work right. It's a heckuva drive up to WA, but a call to Ryan @ BJ's would probably be a good start.

Perhaps I'm going down the wrong road to begin with. Maybe swapping in a newer powertrain with an OD trans is the wiser move. Of course thats a LOT more than I have wanted to think of putting into it. Is it worth putting more into this stock set up and not getting much more out of it? Maybe I'm holding on too hard to "staying true" AMC blue. I have heard that a newer 350 can be stripped of the EFI stuff and I could convert it to propane then. Maybe not, and I'd have to use a carbed engine.

It's quite possible that this would be better solved by finding the highest mountain and climbing it to reach the Jeep guru in the clouds for answers. LOL

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Old 09-24-2017, 04:40 PM
yossarian19 yossarian19 is offline
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I think Ristow said all there is to say, really, about dialing in a 401 - at least one with a carb.
If you have the time, patience & skills, you could do a Megasquirt fuel injection system. Anything from TBI to sequential MPFI is possible. Likewise, you can run it fuel only (OEM spark control), have it control advance on a dizzy, or run all the way up to LS1 style coil-near-plug.
Or you could run an EFI kit on the AMC. There are tons of these available, from Edelbrock's MPFI kit with manifold to Fitech's $800 four-barrel TBI unit.
However you get there, EFI of some variety is an improvement on carbs.
As for LS swap, to me, you have to be planning to put a lot of miles on it for this to be worth the effort. It's not technically that difficult but each and every component in the vehicle has to be accomodated. Shift linkage, fuel system, air intake, transmission, transfer case, driveshafts, exhaust, gauges, motor mounts, you name it. It all has to be done. If you are building your new daily driver, makes sense. For 6 camping trips a year and the occasional Cars & Coffee outing, maybe not.
4 speed trans swap makes sense if you are going to take it on the interstate a lot, otherwise, don't bother. 1:1 (third gear in a TH400) is fine for local roads, up to 60 or 65.
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Old 09-26-2017, 01:27 PM
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Tigger4X Tigger4X is offline
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I agree with what Ristow said as well about my 401 and will get at it once I have the components on hand.

I'm not a fan of electrical or electronic stuff to begin with and having more components to keep track of, maintain, and/or diagnose when they go wonky. Rather than an EFI set up I'd put the money into pistons and such to set the base to support my propane conversion. I get all of the benefits of EFI on the cheaper side and fuel will cost me a lot less as well as increase longevity on the engine itself and then some.

I wouldn't object to swapping another jeep powertrain into it if it was advantageous. I've had a propane 360 before and would be open to the Buick 327, Buick 350 or even the 258/4.0 if it could do the job. Although it may be easier to adapt an O/D trans/t-case combo. When I had the 360 I had looked at an NV4500/5600, but the cost was a good bit more especially trying to find a 4wd combo with the 5th gear upgrade to avoid issues down the road.

Let the fun continue . . .

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