I'm planning to buy a '66 slant from a guy in Seattle when I get back to the states, and before I install it into the car I'll be getting a rebuilding a late model, lockup 904. I'm told that the crank inset on early slants is smaller than on later models. Will this be easy to find an appropriate lockup converter for, given that early 904 were non lockup? I had been under the impression that it would be a simple job to mate a later 904 to an early engine. Perhaps not?

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

It's easy to mate a '68-up engine to a '67-down transmission, but harder to go the other direction. There is no appropriate lockup converter for this what you want to do. Non-lockup custom converters to do this job have been specially built, but I'm not even sure if a custom lockup converter can be made to fit the pre-'68 small-counterbore crank. It may be easiest just to machine the counterbore on the early crank so that it is 1/4" larger (I.D.) and go ahead and use an off-the-shelf lockup torque converter.

I take it you're going with a late-model trans to get the wide-ratio gearset? I did that...once. Didn't like it, not gonna do it again.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

So I take it machining the counterbore on the crank is the only way to achieve this? I suppose I could have that done easily enough. I've honestly never pulled a crank before, but I suppose I have to start somewhere (and it'll be on an engine stand until I have a tranny ready to go anyway).

The wider ratio gearset isn't really a concern to me (though I would rather have closer ratio gears). I want the later model tranny so I can have the lockup function for long stretches of highway driving and for the economy aspect of it (it'll be mated to a Gear Vendors OD at some point in the future).

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

My setup involved the installation of an input shaft and some front pump parts from a '66-'67 trans into a '68-'77 non-lockup trans equipped with the '80+ wide-ratio gears. I didn't like the wide-ratio gears. I can understand wanting lockup — it can save you 5% or so on fuel — but just think through how you're going to go about it beforehand, and do the math to figure out your payback period on that and the (very costly) GV unit.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

So seeing as how I'll be rebuilding a lockup 904 anyway, would my better option be to install an input shaft from an early 904 (if they're even interchangeable)?

Were there any lockup 904s with the close ratio gearset?

Man I'm starting to winder if I'd be better off trying to mate a four speed auto to my slant...

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

The answer to your question hinges on whether a small-nose, lockup torque converter can be built, or if you can machine the counterbore in your crankshaft, or swap in a '68-'76 crank. If the answer to any of these is "yes", then installing a lockup trans will be simple, though cost may vary depending on parts availability.

The 4-speed autos aren't as sturdy as the 3-speed units, but a properly-built one ought to hold up OK behind a slant-6. Floor, crossmember, and driveshaft mods will be needed. The (discontinued) AREngineering adaptor plate could be used to mount one of these to the slant, but you will still run into the very same torque converter/crank fitment problem.

It seems to me you could probably do a 5-speed manual swap for less than a GV over/underdrive...

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Not too long back I think Charrlie S had posted that because of how the lockup is set up you can only get the lockup torque convertor in the large hub/snout... so you will be in for a late crank, turning the crank pocket on the 66 crank, or a crank kit for a 1968-1975 225...

-D.Idiot

I didn't post that, but I would believe it. The best thing to do would be to call a converter builder, and ask. I have seen several people post, about machining the early crank to the late model hole size. I have to question if this can be done. There is a pilot to locate the flexplate. I don't know it this will be a problem or not. I will measure this tomorrow, and see what I think. Has anyone actually machined the hole in the early crank, and verify, that it works?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Charrlie back in March 10, 2006... when another member had the same problem and I didn't have access to a lockup rebuild book...
here

You 'da man!

-D.idiot

The four speed comment was just in jest. It'd be even less work to install a kit from classic5speedmopars.com (who I'm still waiting to hear back from on an A body, slant kit as I heard one of our members is letting them use his car as the guinea pig). If that ever comes to fruition, I'll go that route instead of the GV unit on a lockup 904. My next deployment will pay for either a GV unit or a 5-spd kit, depending on what's available at that point

At this point I'll plan on pulling the crank and having it machined to accept the later model torque converter.

Now, here's another question: is there any difference in strength between early and late model crank shafts? I'm wondering if it would be better for me to get a late model crank, have it balanced and use that instead. Then while everytihng's apart I could balance the whole bottom end...

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Hell that was 2 years ago. At my age I can't remember 2 days ago.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I hear ya Charlie....its not what you know...its what you can remember at the time....


CRS

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Yeah....Im the one who destroyed this rare, vintage automobile.....

double post

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

That is certainly an option, perhaps the best option. I'm pretty sure the cranks are interchangable other than the tranny hookup as long as you don't try to use the cast crank from the late engines.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

Yeah I'd much prefer to use a forged crank. What years started getting the cast crank, and what'd be a good course for me to find one (forged)?

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me