Life in the fast lane

[skep419]

Went out with some biker friends last night. Needless to say 3.91 gears absolutely sucked. I have a 360 ede heads,rpm air gap, xe284 cam, sp 405cp pistons, stock rods/crank, 273 adj rockers, 727, holley 750 street hp mechanical.

I am thinking about putting the 275deh cam back in and the 3.23 742 3rd member.

It burned a quart of oil. I'm guessing from the 4500rpm average.

On a side note I raced the fastest Harley in the group and smoked him.

 

[jbc426]

I hear that! Good job on beating the bike. I love the acceleration out of the hole, but I've driven down the freeway for a mile or two with my automatic in 3rd gear just to get a feeling for what the 3.91's would be like if I wouldn't have gone to the trouble and expense of fitting a 200R4 in the car. Even with tall 275/60-15's in the rear, it's pretty wound up.

I know I would be hating it on the freeway for any length of cruise if I wasn't able to click the car into it's .67 overdrive and then lock up the 3000 rpm stall torque converter with the flip of a switch.

Whether you go with a cam & gear change with a good converter and a 904/727, or a 500/518 or 200R4 swap; it's nice to be able to cruise comfortably down the freeway. Although, overdrive automatics with or without lock-up converters can give you the best of both worlds. They do come with a weight and cost penalty though.

 

[Abodybomber]

Went out with some biker friends last night. Needless to say 3.91 gears absolutely sucked. I have a 360 ede heads,rpm air gap, xe284 cam, sp 405cp pistons, stock rods/crank, 273 adj rockers, 727, holley 750 street hp mechanical.

I am thinking about putting the 275deh cam back in and the 3.23 742 3rd member.

It burned a quart of oil. I'm guessing from the 4500rpm average.

On a side note I raced the fastest Harley in the group and smoked him.

Why did this combination, fail? Seriousness, what are the problems?....

 

[skep419]

The problem is solely too much rpm at cruise speed. I've tried just swapping gears and its a dog out of the hole. I think the 275deh with the 3.23's would be a better match. I have all the parts to do the swap. (it would just be gaskets) overdrive swap is out of the question.

 

[sledger46]

I know your pain as I have 3.91s in my Dart. My rear tires are 27" tall and I turn 3700+ running 65mph+ down the highway. Getting an OD trans into the car will give you the best of both worlds with less of a performance hit compared to swapping cams and gears. With a "flip of the switch" I go from 3700 RPM down to 2700 RPM and I am running a non lockup converter. I am actually running the same Edge Racing 9.5" converter(3500 stall) I ran in front of my 904. Getting an A500 to fit is harder then swapping a cam and changing out a center section, but the results are worth it.

 

[skep419]

I guess I'm thinking it wouldn't be that big of a hit. More or less moving the power band lower.

Anybody with a similar combo feel free to chime in.

 

[DusTed74]

In my Dart I'm running 3.55's with a 28" tire. 65 M.P.H. is 2900 rpm.
It has a 904 with a 2500 converter.
I'm getting over 15 miles to the gallon with my mild 408 and I really cant complain about how it accelerates. I haven't gotten to the track yet so I cant tell you really how fast/slow it is.

Ted

 

[95teetee]

with my 4.10s I used to cruise at 85 with my 340 (yeah, about 4500 rpm).
Now that I have an old stock 360 in it, I don't even like to take it to 60 that often (I know it's nowhere near redline, but still lol)

 

[skep419]

In my Dart I'm running 3.55's with a 28" tire. 65 M.P.H. is 2900 rpm.
It has a 904 with a 2500 converter.
I'm getting over 15 miles to the gallon with my mild 408 and I really cant complain about how it accelerates. I haven't gotten to the track yet so I cant tell you really how fast/slow it is.

Ted

maybe 3.55 gears would be the happy medium.
I guess I will find out soon enough. On the way from Dr Diff
The 3.23's that I take out will be up for sale.

 

[DusTed74]

What diameter tire are you running?

Ted

 

[skep419]

28"

 

[rigger3006]

i went from 3.9s to 3.55s, i only found about a 300 rpm diff at highway speeds, wasnt really worth 1400$ IMO

 

[skep419]

I have two 742 sure grip center sections. 3.91/3.23. The plan is to swap out the 3.23 with 3.55.

 

[diymirage]

I have two 742 sure grip center sections. 3.91/3.23. The plan is to swap out the 3.23 with 3.55.

wait wait wait

you have TWO suregrip unit and I have NONE?

I think we all know what our socialist president would want you to do

 

[R4Sedan]

Man I've been through all this with gear swap's 3.91's to 3.55's. If you wanna cruise your better off to keep the higher gear and just save for the OD. That's what I'm gonna do.I've read what people have done and I'm gonna try the 200r4, JUST my opinion. Best bang for the buck.

 

[DusTed74]

Sam, you should see (as said above) approximately a 300 rpm drop. That could put the engine right where it wants to be.
I agree with your first post. I would take that chevy grind cam out.

Ted

 

[66340SEDAN]

My combo, 340 4-speed, Isky .505 cam, 650 Holley DP, 255/60 15 rear tires, 4.10 gears....I love it! It hauls the mail at any speed...loves the street, track and interstate driving....I run it at 70 mph all the time and engines runs about. 3,700-3,900 at that speed....good on gas, infact, my car gets better mileage than my friends 65 Cuda with a rebuilt stock 273 4bbl and his car has highway granny gears lol

Wish you lived closer Sam, I would let you drive my car...but then you will want a 4-speed :burnout:

 

[cosgig]

There's a reason the chrysler called the 3:23 their "maximum performance" rear! I went from a 3:23 to a 3:91 in my stock GTX and didn't pick up not even a tenth!! Spending more $$ in gas now up in the zone!! Someday I'll swap that back out, when I get the time!!

 

[thesiren74]

3.23s are perfect !

 

[Infecteddog]

Were you in 2nd gear or were you at the speeds I think you were? That'd be pretty hard to maintain good performance at low speed and not turn hard if I'm not wrong in guessing the speed. In OD my Jeep turns 2800 up there. (3.73s and I forget the final OD ratio- wanna say .65s, it's great out of the hole for being stock)

Regardless it looks like 3.55s should knock out 400RPMs. 'course a 500/518 swap would knock 1400 revs off cruise speed with the same rear gear. Especially with a 500 and 3.91s it wouldn't be a dog out of the hole.

 

[skep419]

wait wait wait

you have TWO suregrip unit and I have NONE?

I think we all know what our socialist president would want you to do

If the 3.55's don't work out I could sell you the chunk!

Man I've been through all this with gear swap's 3.91's to 3.55's. If you wanna cruise your better off to keep the higher gear and just save for the OD. That's what I'm gonna do.I've read what people have done and I'm gonna try the 200r4, JUST my opinion. Best bang for the buck.

If I go overdrive there's going to be a third pedal.

Sam, you should see (as said above) approximately a 300 rpm drop. That could put the engine right where it wants to be.
I agree with your first post. I would take that chevy grind cam out.

Ted

If it doesn't work out I will either live with the 3.91's or swap cams and rock the 3.23's

My combo, 340 4-speed, Isky .505 cam, 650 Holley DP, 255/60 15 rear tires, 4.10 gears....I love it! It hauls the mail at any speed...loves the street, track and interstate driving....I run it at 70 mph all the time and engines runs about. 3,700-3,900 at that speed....good on gas, infact, my car gets better mileage than my friends 65 Cuda with a rebuilt stock 273 4bbl and his car has highway granny gears lol

Wish you lived closer Sam, I would let you drive my car...but then you will want a 4-speed :burnout:

couple thins you've got going that I dont. First your motor is internally balanced. second your rings seal hahahaha.
I agree with wanting the 4 speed.

There's a reason the chrysler called the 3:23 their "maximum performance" rear! I went from a 3:23 to a 3:91 in my stock GTX and didn't pick up not even a tenth!! Spending more $$ in gas now up in the zone!! Someday I'll swap that back out, when I get the time!!

The GTX had big block torque. My 360 starts to make power above 3500.

3.23s are perfect !

With enough torque I agree.

 

[famous bob]

Were you in 2nd gear or were you at the speeds I think you were? That'd be pretty hard to maintain good performance at low speed and not turn hard if I'm not wrong in guessing the speed. In OD my Jeep turns 2800 up there. (3.73s and I forget the final OD ratio- wanna say .65s, it's great out of the hole for being stock)

Regardless it looks like 3.55s should knock out 400RPMs. 'course a 500/518 swap would knock 1400 revs off cruise speed with the same rear gear. Especially with a 500 and 3.91s it wouldn't be a dog out of the hole.

another alternative that works: taller tires. unless you are a (stock) restoration junkie, you can rework the fenders, "and", or, relocate the rear end a little, for taller tires and get the rpms down, and probably have better traction. I built a 600 horse sbc, w/ 3:73 gears, and 30 1/2" tall tires, that got 16.1 on the hiway if "I kept my foot out of it". it was a 92 gmc shortwide, that would run hi elevens w/ 10x28" slicks. 2900 on the hiway at 70mph.--just food for thot.-----bob

 

[sledger46]

If you are not going OD then look into getting a lower gear set 904. Your car will be faster with the 904 and the lower gears in the trans will get you out of the hole with the 3.23/3.55 gears. Also you may want to look into a smaller (8"-9.5"), more efficient converter with a higher stall.

 

[Infecteddog]

With enough torque I agree.

That's quite true. The more torque, the less gear you need. Been true for years with 360s vs 318s/340s, the V10s need far less gear than the 360s to be as strong, and the 4" SBs fall somewhere between all that.

If I go overdrive there's going to be a third pedal.

Dunno- low 1/2 with a good OD and have lockup too isn't too much of a downside and it sure seems like autos are a whole lot cheaper to deal with than the 3 pedal transmissions. I've been running 2.45s with the stroker and I do like them, but I'm sure there'll be a big jump with 4.10s and a 42RH/42RE- whichever I grab first cheapest to go back through.

 

[skep419]

I told the girlfriend that I ordered 3.55 gears and she did not approve. "quit being a sissy, they're not that bad"

here is the 2 cams
Part Type:Camshafts
Product Line:COMP Cams Dual Energy Camshafts
Summit Racing Part Number:CCA-20-418-3

UPC: 036584850144
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,000-6,000
Intake Duration at 050 inch Lift: 219
Exhaust Duration at 050 inch Lift: 235
Duration at 050 inch Lift: 219 int./235 exh.
Advertised Intake Duration: 275
Advertised Exhaust Duration: 284
Advertised Duration: 275 int./284 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.462 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.482 in.
Valve Lift with Factory Rocker Arm Ratio: 0.462 int./0.482 exh.
Lobe Separation (degrees): 110
Computer-Controlled Compatible: No
Grind Number: 275DEH
Valve Springs Required: Yes
Quantity: Sold individually.

vs

Part Type:Camshafts
Product Line:COMP Cams Xtreme Energy Camshafts
Summit Racing Part Number:CCA-20-225-4

UPC: 036584047001
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,300-6,500
Intake Duration at 050 inch Lift: 240
Exhaust Duration at 050 inch Lift: 246
Duration at 050 inch Lift: 240 int./246 exh.
Advertised Intake Duration: 284
Advertised Exhaust Duration: 296
Advertised Duration: 284 int./296 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.507 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.510 in.
Valve Lift with Factory Rocker Arm Ratio: 0.507 int./0.510 exh.
Lobe Separation (degrees): 110
Computer-Controlled Compatible: No
Grind Number: CRS XE284H-10
Valve Springs Required: Yes
Quantity: Sold individually.