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Trans options for flat crank 72 304 Matador |
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j2sax
AMC Apprentice Joined: Sep/29/2010 Location: SW MO Status: Offline Points: 104 |
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Posted: Nov/23/2014 at 11:53pm |
So, I am going to get the 72 Matador that has the trashed BW trans in the trunk. A friend noted that if it had the BW trans, it likely has the flat crank tail.
My original plan was to use the 74 Ambo 727 and driveshaft, however, if this has the flat tail, that would require some sort of adapter on the crank tail for the flexplate? IF that is the case, maybe I should just go ahead and go with an AW4 (have a RWD sitting in the garage). In reality I would love to have a T5 manual trans in this eventually, however, I need to get this moving under it's own power asap. If all this becomes too complex, I have several 401's sitting around I could drop in, as one would bolt right up to the 727 I have.. but I really was not wanting to make a radical machine out of this, just a nice cruiser to maybe do the next Power Tour with, so the extra MPG of the 304 might be nice (though I know it's not a lot) Your experienced opinion is appreciated! Jesse
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j2sax@yahoo.com
Plenty of FSJ's Eagles and other AMC's near Springfield, MO |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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There is a bolt-on crank adapter (comes with a spacer to go between engine and bell) and a permanent mount adapter (requires machining of the crank). Both end up costing about the same once the machining costs are considered. If the engine is apart I'd go the machined route, with engine assembled (and not needing a rebuild) I'd use the bolt-on.
The AW4 will easily stand up to a 304. That might be the best way to go. Note that to use the AW4 OD effectively you need a lower geared rear axle. I initially ran a 3.08 in my 63 Classic wagon (hopped up 4.0L EFI) but couldn't use OD unless cruising at least 70 mph. I switched to a 3.55 gear (stock in the XJ w/4.0L) and gained 2 mpg over all! The AW4 has a high efficiency torque converter that only multiplies torque about 1.2:1 (may be 1.4:1.... going from memory) instead of the usual 2.0-2.5:1. That means it needs more rear gear for take-off as well. 72 Mat w/304 had 2.87 gears stock, 3.15 optional -- neither will be good with an AW4, and not real good with any other OD trans either. The 200-4R would be better as the converter multiplies torque more until locked (don't need it at highway speeds, just take-off), but would still be better with a bit more gear than the 3.15. I wouldn't run it with the 2.87 at all. You probably have a 71 engine/car - 72 was the first year Chrysler trannys were used. A 72 should have a 998 behind a 304. The 727 will bolt up and work, but it takes a good bit more power to turn than the 998. Would do until you got that five speed though... |
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Frank Swygert
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j2sax
AMC Apprentice Joined: Sep/29/2010 Location: SW MO Status: Offline Points: 104 |
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From what I have seen, it looks like AMC had some BW's left over and threw them on early 72's as I have talked to others who have a similar mid-year issue. The VIN and title both indicate 72 and since this is a essentially a 2 owner car and was a DD for the old feller, I don't think they went to all the trouble to install the early 304 with the Power Steering Setup, 3 hole crank and BW trans! My eventual plan is to keep the AMC20 rear and I have a 3.54 set with factory posi... might just switch it all and go with a 3.54 and TruTrack (with the requisite diff). Does the AW4 require the same adapter as the 727? Since this is a running 304 I don't want to yank it apart if I don't have to. If it comes to that, I will just drop in a 401 with the 727 or use my GM adapter for a 700R4. I am hoping I can get it on the road a lot simply than all that, though the engine swap may be the easiest route! Since I also already have a T5 with modified bearing retainer, what vehicle can I scavenge the clutch/brake pedal setup from.. will one from a Javelin or Spirit work? I have several of the former, but have never had a "Big Car" with a manual trans. Will the flywheel for a manual work with the flat tail? I think I actually have a 70 model 360 flywheel somewhere, but if not i have several 360's, which I believe are interchangeable with the 304's (not the other V8's due to balance). Thanks! Jesse
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j2sax@yahoo.com
Plenty of FSJ's Eagles and other AMC's near Springfield, MO |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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I'm not sure about the adapter being required for the AW4. There is a thread on putting an AW4 in an AMC in the trans section -- you may want to read that.
I think you need the pedal setup from a big car -- 67-78. The earlier ones are more likely to have a manual trans than 72 up. The later flywheel should work with the flat crank. Might require some machining on the flywheel -- it has to center on the crank somehow, not just by the bolts. A six cylinder flywheel is neutral balanced and will bolt up. You just have to have it match balanced to a V-8 flexplate or flywheel (balance weight should be the same) for your engine. |
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Frank Swygert
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carnuck
AMC Addicted Joined: Mar/31/2010 Location: Seattle Status: Offline Points: 3942 |
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I'm putting the nailhead TH400 (that was stock in my '73 J4000 with 360, which was dead when I got the jeep, so I swapped in my '77 AMX 304) behind a 290 with the 304 flexplate (rebalanced) They used the same factory crank adapter to work with both styles of crank but the flexplate is a customized Buick one, as is the torque converter pilot hole.
I took an AW4 plate in with the 304 one to have it match balanced for $100. The flat crank and stepped crank are the same balance weight. Adapter ring for nailhead TH400 Here's the crank adapter (reason I bought a second kit) Edited by carnuck - Nov/25/2014 at 1:21am |
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