Adult swim

[mayhem]

Alright folks, it's time to move from the kiddie pool to the deep end (lol). All my life I've had automatic cars except for a Jeep CJ 4-speed in the mid-80s. I now have a '68 Dart GT that was originally a 3-speed which was converted to a Tremec 5-speed. The car retains its original 3rd pedal and Tremec trans tunnel alterations but is otherwise a blank canvas - no engine or trans in the car currently. Rather than change the pedals, reinstall a stock trans tunnel (even for a A833), etc., I'm dipping my toe into the big boy world of a Tremec - probably a TKX-5 with a hyd throwout bearing. I'll do this as a 'one stop shopping' kit.

More on the car: Full QA1 front end w/retained torsion bars, fiberglass front end (hood, fenders, bumper), frames tied w/Hotchkiss connectors welded in, Moser 8 3/4 w/their limited slip center section, 4.11 gears & Moser axles. Caltracs. Car is mini-tubbed and riding on 295/50x15 M/T tires. No rollbar or cage, yet. Engine is a 10.5:1 Indy aluminum block 528 Hemi. The cam is a small SFT (275/277 @ 020; 244/247 @ 050; 557/548; 108 LSA)

Car will be used for weekend ice cream runs and 'spirited' street driving, maybe a trip to the local track from time to time.

The question is, which ratio is 'best' for this car:

TKX Gear Ratios​

Wide Ratio - 3.27, 1.98, 1.34, 1.00, 0.72
Close Ratio - 2.87, 1.89, 1.28, 1.00, 0.81 or 0.68

Open to any and all responses. Thanks.

 

[Newbomb Turk]

Alright folks, it's time to move from the kiddie pool to the deep end (lol). All my life I've had automatic cars except for a Jeep CJ 4-speed in the mid-80s. I now have a '68 Dart GT that was originally a 3-speed which was converted to a Tremec 5-speed. The car retains its original 3rd pedal and Tremec trans tunnel alterations but is otherwise a blank canvas - no engine or trans in the car currently. Rather than change the pedals, reinstall a stock trans tunnel (even for a A833), etc., I'm dipping my toe into the big boy world of a Tremec - probably a TKX-5 with a hyd throwout bearing. I'll do this as a 'one stop shopping' kit.

More on the car: Full QA1 front end w/retained torsion bars, fiberglass front end (hood, fenders, bumper), frames tied w/Hotchkiss connectors welded in, Moser 8 3/4 w/their limited slip center section, 4.11 gears & Moser axles. Caltracs. Car is mini-tubbed and riding on 295/50x15 M/T tires. No rollbar or cage, yet. Engine is a 10.5:1 Indy aluminum block 528 Hemi. The cam is a small SFT (275/277 @ 020; 244/247 @ 050; 557/548; 108 LSA)

Car will be used for weekend ice cream runs and 'spirited' street driving, maybe a trip to the local track from time to time.

The question is, which ratio is 'best' for this car:

TKX Gear Ratios​

Wide Ratio - 3.27, 1.98, 1.34, 1.00, 0.72
Close Ratio - 2.87, 1.89, 1.28, 1.00, 0.81 or 0.68

Open to any and all responses. Thanks.

Wide ratio hands down.

 

[mayhem]

Wide ratio hands down.

Thank you, sir!

Other than the cam (really don't want to open that can of worms!), what else would you change (if anything). Specifically, I have 3.91s for the 8 3/4 but have an A-body D60 w/Powr Lok and 3.54, 3.73 and 4.10 ring & pinion sets if any of these would add to the performance.

Also, how far out are you scheduled for dyno work?

 

[Newbomb Turk]

Thank you, sir!

Other than the cam (really don't want to open that can of worms!), what else would you change (if anything). Specifically, I have 3.91s for the 8 3/4 but have an A-body D60 w/Powr Lok and 3.54, 3.73 and 4.10 ring & pinion sets if any of these would add to the performance.

Also, how far out are you scheduled for dyno work?

For me, I wouldn’t change anything. That .072 OD on that box with your tire size will give you about 2800 rpm at 75 MPH. If 2800 rpm is too high for you, you can drop down to a 3.91 and at 75 MPH you’ll be at a bit over 2600 so you’d gain a couple hundred rpm.

Im usually no more than a couple of weeks out. The exception is going to be when my engine goes on the pump. It will stay on there as long as it takes for me to flog its guts out.

I can’t imagine it would take me more than three days to break in the cam, install the inner springs, retorque the heads and finish the break in and then break in the pistons.

After that it will be sorting out the timing curve, tuning the carbs, adjusting the headers and lash loops. If all that goes well it will be about three days.

I try not to get myself buried because physically I can’t do it.

 

[mayhem]

For me, I wouldn’t change anything. That .072 OD on that box with your tire size will give you about 2800 rpm at 75 MPH. If 2800 rpm is too high for you, you can drop down to a 3.91 and at 75 MPH you’ll be at a bit over 2600 so you’d gain a couple hundred rpm.

Im usually no more than a couple of weeks out. The exception is going to be when my engine goes on the pump. It will stay on there as long as it takes for me to flog its guts out.

I can’t imagine it would take me more than three days to break in the cam, install the inner springs, retorque the heads and finish the break in and then break in the pistons.

After that it will be sorting out the timing curve, tuning the carbs, adjusting the headers and lash loops. If all that goes well it will be about three days.

I try not to get myself buried because physically I can’t do it.

I'm good with 2600-2800 rpms at 75 mph and since the 4.11s are in there already, I'll leave them - one less thing to check off the list. On the engine side, the block & rotating assembly are back from the machine shop, cleaned up and ready to go together. I'm waiting on a rear main seal block and a distributor. Both are coming from a private source and shold be here by Thanksgiving. I spoke with A&A Trans this past week and they are shipping the cross ram hardware and fuel lines so that should be the absolute last parts needed to complete the engine. Next on the list is to fabricate some air bells ($600 is too dear for 2 of those! Holy highway robbery Batman!) and screens for the carbs.

 

[Super-Cuda]

Alright folks, it's time to move from the kiddie pool to the deep end (lol). All my life I've had automatic cars except for a Jeep CJ 4-speed in the mid-80s. I now have a '68 Dart GT that was originally a 3-speed which was converted to a Tremec 5-speed. The car retains its original 3rd pedal and Tremec trans tunnel alterations but is otherwise a blank canvas - no engine or trans in the car currently. Rather than change the pedals, reinstall a stock trans tunnel (even for a A833), etc., I'm dipping my toe into the big boy world of a Tremec - probably a TKX-5 with a hyd throwout bearing. I'll do this as a 'one stop shopping' kit.

More on the car: Full QA1 front end w/retained torsion bars, fiberglass front end (hood, fenders, bumper), frames tied w/Hotchkiss connectors welded in, Moser 8 3/4 w/their limited slip center section, 4.11 gears & Moser axles. Caltracs. Car is mini-tubbed and riding on 295/50x15 M/T tires. No rollbar or cage, yet. Engine is a 10.5:1 Indy aluminum block 528 Hemi. The cam is a small SFT (275/277 @ 020; 244/247 @ 050; 557/548; 108 LSA)

Car will be used for weekend ice cream runs and 'spirited' street driving, maybe a trip to the local track from time to time.

The question is, which ratio is 'best' for this car:

TKX Gear Ratios​

Wide Ratio - 3.27, 1.98, 1.34, 1.00, 0.72
Close Ratio - 2.87, 1.89, 1.28, 1.00, 0.81 or 0.68

Open to any and all responses. Thanks.

Wide ratio for sure!

With that 3.27 first gear , rear end ratio and a 528 Hemi??

That's an 11 second car all day with a set of slicks.

Plus, its still very streetable.

 

[66Valiant528]

Im going to say close ratio. With that rear gear and first in the wide ratio first gear will be too steep. I've got 4.10s and a 309 commando first gear. At the track you have to shift almost immediately after you dump the clutch. That said if you change the rear gear to the 3.54s I think you will be OK with the wide ratio.

 

[AJ/FormS]

Open to any and all responses. Thanks.

How slow do you expect to drive?
Do you want to Parade?
>Assuming;
4.11s. and 27"tires,
900rpm would be;
6.1 mph, with the 2.87 low, versus
5.4, with the 3.27.
Uh-hunh.

FYI;
I ran a FTH 292/292/108(248@050) in my 367DD for one summer, with 25.6" tires, 3.55s and a 2.66low ............ 550rpm was ~4.4 mph, which wouldn't smooth out until retarded to 5* advance.
Then I tried it with a 3.09 low/overdrive box, and 3.55s, for 600= 4.1mph
But I broke the od, twice. So then, I reinstalled the 2.66box, and ran 4.30s for a bit; 600= 4.0mph, but the hiway rpm was outta sight.
>> If you're gunna try to run it at 550, you might as well put a HV oil-pump on it, cuz the oil pressure gets real low down there.

One summer of that cam, was enough for me. It was darn near impossible to parade it.
HappyHotRodding

 

[mayhem]

How slow do you expect to drive?
Do you want to Parade?
>Assuming;
4.11s. and 27"tires,
900rpm would be;
6.1 mph, with the 2.87 low, versus
5.4, with the 3.27.
Uh-hunh.

FYI;
I ran a FTH 292/292/108(248@050) in my 367DD for one summer, with 25.6" tires, 3.55s and a 2.66low ............ 550rpm was ~4.4 mph, which wouldn't smooth out until retarded to 5* advance.
Then I tried it with a 3.09 low/overdrive box, and 3.55s, for 600= 4.1mph
But I broke the od, twice. So then, I reinstalled the 2.66box, and ran 4.30s for a bit; 600= 4.0mph, but the hiway rpm was outta sight.
>> If you're gunna try to run it at 550, you might as well put a HV oil-pump on it, cuz the oil pressure gets real low down there.

One summer of that cam, was enough for me. It was darn near impossible to parade it.
HappyHotRodding

Thanks for the real world examples/question. No parades; my cruising the local 'loop' from one end of town to the other trying to attract members of the opposite sex are long past (besides wifey wouldn't tolerate it) and I don't have the patience to putt-putt in a 4th of July type stop-n-go parade. The only parading I'll be doing might be on the return road at the track - and 6.1 or 5.4 mph is fine.

 

[mayhem]

Im going to say close ratio. With that rear gear and first in the wide ratio first gear will be too steep. I've got 4.10s and a 309 commando first gear. At the track you have to shift almost immediately after you dump the clutch. That said if you change the rear gear to the 3.54s I think you will be OK with the wide ratio.

I hear you but I was thinking of treating the TKX as a 'Glide - leaving in 2nd with a 2-3 shift and a 3-4 shift out the back end. I'm not chasing ETs; not entering a Quick 16, not competing for points, or anything like that. Cutting a good light on a consistent dial is where I'd win any race on the 2-3 times a season I might enter. If this were a dedicated race car, the cam and TKX would get tossed but this is primarily a street car with the look of a SS Dart.