gear change ?

I've recently bought a 70 challenger 440 auto, ported 906 heads hyd cam not sure what, maybe a .509, victor int, 850 holley dp, 3800 conv reverse pattern VB, quicksilver shifter 8-3/4 with 4.10 gears a spare set of wheels with 28" slicks. Car has full interior, chassis connectors, has run a best 11.99 at 112mph.
I'm looking to change the VB to a stock one with a shift kit, fit the kickdown back on and change the gears for maybe a 3.23 or 3.55. I've seen some 3.23's for sale so may plump for them.
What sort of et loss do you think i will see? also i would think the gears would raise the stall a few hundred.
Mick

I don't think it will slow down much at all if it has the "right" converter in it. Maybe a tenth or two.

I don't think the taller gear will raise the stall but it might increase the flash some

Somebody here, I think Cab has some back to back track data that confirms if the converter is spec'd correctly for the combo, there isn't much change ET wise from 4.10 to 2.76, again maybe a tenth or two.

Does the RMVB have rear band apply? If it does I would just leave it in and see if I got tired of it. No band apply? Bye bye.

Kevin

My street driver Chevelle ran 12.20 @ 112 with a mild 502 with a 3.70 gear. ..Changed to a 3.08 and 12.42 and big gas mileage improvement. Good 3800 converter

If you go from 4.10 to a 3.23 your convertor WILL stall more. I changed from 3.50 to 4.56 and mine changed a lot.

Thanks, i'll be happy if it runs high 12's, i just want a fairly healthy street, strip car i can use, i've already got a race car i dont need two.
Mick

What RPM do you shift at? If it is 6,000 or above, it is hard to get the WOT automatic shift points where you want them. 1-2 and 2-3 splits, 2-3 overlap, delayed 1-2 when manual shifted, etc.

Will the car see more street time with the changes?

I just recently switched to a forward manual after many years with a full auto. I really like the total control. The tranny does what I want, when I want. That isn't always true with an auto, even with governor changes.

I used a shift kit with manual option in a stock valve body so that I have external control over the line pressure. I wire the throttle pressure lever back just enough to give firm shifts without banging when driving around town.

But if you shift below 6,000 then you might be happy with an A&A governor. But it will take some experimenting.

Taller gears will raise your converter flash. But you may still be able to drove it comfortably. Just put a tranny temp guage in and keep an eye on it.

The bigger the cam, then the less fun the car may be with taller gears on the street. After some adjustments, there shouldn't be a huge impact on E.T. MPH should stay about the same.

The double pumpers are way rich on the cruise circuit on the street.

My experience w/ gear switch: 3.55 = 12.4 at 112; 4.10 = 12.2 at 112... a solid .2 difference in ET, but no change to MPH.

I see a cam with a lot of duration for a street car coupled with a high rpm single plane intake and a big race-type carb.

My prediction is that you won't be happy with the combination and 3.23 gears, at all.

R.

Assuming it has that cam of which i'm not sure, unfortunately the previous owner died of cancer, 55 yrs young so no easy way to find out. I will use it for longer runs on the street with a change of gear, as far as shifting i'll let you know next weekend because i'm taking to the track for the first time.

Should I add that this 440 used a small 239 at .050" x .540" solid flat-tappet cam and a Six Pack? Nice and torquey, but all done by 5800 RPM.

As you say, big heavy cars need to get moving, it isn't always about the size of the parts. If i can engage drive, cruise at 70 mph on the motorway without it revving it's nuts off and runs high 12's i'll be happy.
Was that a dwayne porter cam or off the shelf ?

can you share more specs on your combo? Converter Stall and car weight? I'm pondering a gear change myself....

It will depend on if the converter is spec'd close for that combo. At low speed or around town it's going to be on the converter more but if it's a 3800 converter the engine will make more than enough torque to get you across an intersection in a sporting manner. It won't care to be cruised much under 2500.

I have a similar combo as far as cam is concerned (if it's an MP509) with less compression (9:1) but RPM heads. M1 single plane with a 950 cfm TBI. It does have 53 more cubes but it's also in a 4800lb New Yorker.

I know apples to cucumbers but it drives around just fine. I had 2.76's in it and it didn't sound happy cruising much under 65 mph on the highway and around town you left it in 2. With a 2800 Turbo Action converter it's 60' was a spinning 2.23.

It has 3.23's now and it sounds and feels happy cruising at anything over 2K.

Once I put in the 3.23's the only other annoyance if you will was the borderline vacuum for the power brakes. I have an electric pump to solve that.

It all depends on your expectations and what you are willing to live with if a couple come up a little short.

Kevin

3700# E-body
Stock '70 440 bottom end
Home-ported '452' iron heads
Aluminum Six Pack intake w/ OEM-replacement vac. sec. carbs
Cheap 1.75" heads w/ 2.5" exhaust & h-pipe
2800-stall converter


Cam was an Engle KV-series (.904" sft) that I spec'd myself: 239 at .050", .540" lift (1.5 Crane gold rockers), 110 LSA.

My testing was from 3:73, 3:91,4:10 to 4:30 in my old Duster, I found out later after swapping gears my fuel system had problems with to small of a fuel filter between the tank and the fuel pump so maybe the 1/4 mle ET and MPH results may have ended up a little differenently with all the problems solved I have swapped from 3.55 to 4.89 ratio in a SB 4 speed Duster, that ratio swap made the car feel awesome, it did make that car faster between 2 to 3 tenths faster in the 1/4 mile,(14:60 to 14:30) not near as fast as it felt though