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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.
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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