Curses! Foiled again!
I'll get one of those adpater plates someday....Ditto. If all you are looking for is better performance and fuel economy, there are much cheaper and easier ways of doing it than fitting a new transmission.
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| 727 to a 904 Issues? https://slantsix.org/forum/viewtopic.php?t=33633 |
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| Author: | 64'4$peed [ Wed Feb 04, 2009 5:13 pm ] |
| Post subject: | 727 to a 904 Issues? |
Trying to make my 67 A100 less of a slug off the line. I figure loosing some weight and freeing up HP with a 904 might be worth looking into. Engine is stock with a 1bbl. I'm not gonna super six it or add exhaust. it runs to good to mess with it. right now its got the smallblock 727 with that biga$$ adapter plate. It's also mounted from the top of the trans. no crossmember. any 904's have the same mounting provisions? what about the cable shifter? is all that gonna line up to the 904? I have very little automatic experience. all my cars up to this point have been manual trans. |
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| Author: | Reed [ Wed Feb 04, 2009 6:36 pm ] |
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I recommend fidning a mid 80s truck or van in the boneyard and grabbing the 904T tranny, It will have the wide ratio gears and a lock-up torque converter. The wide gears help with acceleration, the 904 is much lighter than the 727, and the lock-up converter is good for gas mileage. You will need to have a driveshaft fabricated since the 904 will be much shorter than the 727 and adapter plate. As far as the rear tranny mount goes, you *should* be able to bolt the 904 right up to the 727 mount. Can you post pictures of the mount? Does the mount actually bolt into the top of the tranny? However, the mount will need to be moved for or you might have to fabricate a new mount since the 904 tranny is shorter than the 727/adapter combo. If you do remove the adapter plate, I would be interested in purchasing the plate and all the moutning hardware that goes with it. This is definitely a doable swap, but it will require at least a little fabrication. I think it would be worth it though. |
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| Author: | Joshie225 [ Wed Feb 04, 2009 7:12 pm ] |
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By excluding induction and exhaust upgrades you're making performance increases much more difficult and expensive to achieve. The very first thing I would do, assuming you have electronic ignition with an appropriate advance curve, is 2 1/4" exhaust which will help power and economy. A transmission swap in an A van is going to be expensive and time consuming. All the B vans and D pickups use a transmission crossmember and have no provision for the top mount so the transmission mount is going to take serious fabrication. If your cable shifter goes directly into the transmission case rather than operating a lever on the outside of the trans you'll need a cable shifted 904. I don't think I would perform this swap if my 727 grenaded and the 904 were free. I'd rebuild the 727 instead. The only automatic trans swap I would consider worthwhile is an overdrive automatic paired with a rear axle ratio change. That way you could get more pep off the line and maintain or lower the cruising RPM. If you have a couple grand, plenty of wrenching experience and a lot of time on your hands you could pull it off. And why, if the van runs too good to mess with, are you proposing messing with the van? |
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| Author: | SlantSixDan [ Wed Feb 04, 2009 8:48 pm ] |
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Quote: By excluding induction and exhaust upgrades you're making performance increases much more difficult and expensive to achieve.
Yup, exactly. This what you propose to do is a backwards, not-very-effective, costly, difficult plan that will wind up disappointing you; you won't gain anywhere near the performance you seem to have in mind.Yes, the 904 weighs less than the 727. But not enough less to make the kind of substantial acceleration difference you sound like you want. If the transmission works well, leave it alone and concentrate your efforts and your money in the many other more effective and cost-effective areas for performance improvement. "It runs too well to mess with, but I'm not happy with how it runs" is the distillation of what you're saying, and your conclusion that the transmission's weight is restricting your performance is baseless. |
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| Author: | Reed [ Wed Feb 04, 2009 11:06 pm ] |
| Post subject: | |
Curses! Foiled again! I'll get one of those adpater plates someday....Ditto. If all you are looking for is better performance and fuel economy, there are much cheaper and easier ways of doing it than fitting a new transmission. |
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| Author: | 64'4$peed [ Thu Feb 05, 2009 9:29 am ] |
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elec ignition properly tuned advance curve check and check. This is bottom of my priority list I'm just throwing ideas around. Reed I've got an extra adapter plate, crank hub spacer and some other peices if you want em. name your price. |
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