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Re: What Ford 9" rear-end ratio should I go with?
ColbyG #1420371 Thu Aug 12 2021 03:04 PM
Joined: Dec 2008
Posts: 1,655
P
'Bolter
3.XX numbers work well @ high cruising speed, but you'll be reaching down frequently between 50 and 70.

Re: What Ford 9" rear-end ratio should I go with?
ColbyG #1420836 Mon Aug 16 2021 07:52 PM
Joined: Dec 2020
Posts: 37
C
ColbyG Offline OP
'Bolter
Man, you guys are so helpful with all of this info! Sorry I have been MIA the past few weeks.

I can give you guys the cam info. I have almost no idea what this stuff means, but this is what the card says (photo of it also attached):

Part #: 12-600-4
SN#: 308997-19

Engine: Camshaft, CS 279T H-107 T Thumper

Valve Adjustment: INTAKE HYD EXHAUST HYD
Gross Valve Lift: .479 .465
Duration @ 279 297
.006 Tappet Lift

Valve Timing OPEN CLOSED
@.006 INT: 36.0 BTDC 63.0 ABDC
EXH: 76.0 BBDC 41.0 ATDC

These specs are for CAM Installed at 102.0 INTAKE CENTER LINE

INTAKE EXHAUST
Duration @ .050 227 241
Lobe Lift: .3190 .3100
Lobe Separation: 107.0


Now that you have the cam info, is there any more info that y'all can offer? Also, I have decided that I'm going with an EFI system instead of the 4 barrel carburetor.

Thank y'all!

Attached Files
Comp CAM SHAFT Info.jpg (229.42 KB, 110 downloads)
Last edited by ColbyG; Mon Aug 16 2021 07:55 PM.

colby

1951 Chevrolet 3100: Photos [photos.app.goo.gl]
–Engine: 219 to 250 to 350 (waiting to be dropped in)
–Currently: Readying a 1987 S10 frame for mounting the body.

1956 Chevrolet 6400
–Engine: moved the 250 from 3100 - newly installed
–Currently: Adjusting Brakes & Installing New Headlamp Switch

1963 Chevrolet C10 Fleetside
–Engine: EMPTY
–Currently: Sitting in Barn
Re: What Ford 9" rear-end ratio should I go with?
ColbyG #1420837 Mon Aug 16 2021 08:23 PM
Joined: Mar 2007
Posts: 1,397
T
Crusty Old Sarge
That's a NASTY cam, lots of thump. A cam with those numbers will need a higher RPM power band to work correctly. It will work great with a lower gear, not so much with a tall ratio.


Craig

Come, Bleed or Blister something has got to give!!!
59' Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
Re: What Ford 9" rear-end ratio should I go with?
TUTS 59 #1420849 Mon Aug 16 2021 09:30 PM
Joined: Dec 2020
Posts: 37
C
ColbyG Offline OP
'Bolter
TUTS_59, can you explain a bit more of what you mean?

The guy that built it just told me that idle is about 800 RPMs and I'd need to go to about 3000 to 3500 RPMs for shifting. That seems high, but I don't know anything about CAMs, so that's why I'm asking for more info/education.

Thank you!

Last edited by ColbyG; Mon Aug 16 2021 09:31 PM.

colby

1951 Chevrolet 3100: Photos [photos.app.goo.gl]
–Engine: 219 to 250 to 350 (waiting to be dropped in)
–Currently: Readying a 1987 S10 frame for mounting the body.

1956 Chevrolet 6400
–Engine: moved the 250 from 3100 - newly installed
–Currently: Adjusting Brakes & Installing New Headlamp Switch

1963 Chevrolet C10 Fleetside
–Engine: EMPTY
–Currently: Sitting in Barn
Re: What Ford 9" rear-end ratio should I go with?
ColbyG #1420868 Mon Aug 16 2021 11:58 PM
Joined: Mar 2007
Posts: 1,397
T
Crusty Old Sarge
Your cam is developed to run at a higher RPM to create more top end horse power. A lower geared rear end will get the vehicle to that RPM range quicker, with a higher geared rear end it takes longer to reach that RPM range.

Your cam is similar to my cam in my 327, it's meant to have more top end horse power with the sacrifice of low
end torque. It takes a higher engine RPM to move the truck.

A lower gear would give you the performance the cam will designed for and the higher geared overdrive would allow you to cruise at highway speeds.

Last edited by TUTS 59; Tue Aug 17 2021 12:06 AM.

Craig

Come, Bleed or Blister something has got to give!!!
59' Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
Re: What Ford 9" rear-end ratio should I go with?
ColbyG #1420921 Tue Aug 17 2021 02:17 PM
Joined: Feb 2004
Posts: 23,246
H
'Bolter
Start out with a 4.56 ratio rear end, and maybe you'll need to go a bit lower- - -possibly a 4.88. Get used to running the engine at or above 3K RPM all the time. If I were doing a dyno test on an engine with that cam, I wouldn't bother making a pull below 2500-2800 RPM, and I'd expect the peak HP to come in somewhere north of 7K. Below 3K or so, it won't make enough torque to get out of its own way. The name "Thumper" on the cam card should give you a clue what to expect. If you're planning to pair the engine up with an automatic transmission, use a torque converter with a stall speed around 2800-3000 RPM.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: What Ford 9" rear-end ratio should I go with?
Hotrod Lincoln #1420940 Tue Aug 17 2021 03:58 PM
Joined: Dec 2020
Posts: 37
C
ColbyG Offline OP
'Bolter
TUTS_59, what rear-end gears do you run in yours? And would you recommend I do the same for simple highway cruising? I won't be racing it.

Hotrod_Lincoln, I will be running at Borg Warner manual 6 speed in it (the T56 gears are 2.66, 1.78, 1.30, 1.00, 0.74, and 0.50). So with a Thumper and since I'm not racing it, would y'all recommend I get another cam or will it do? I'm wanting to cruise it and hopefully get decent gas mileage (say 15-18 MPG) with an EFI setup (probably a Holley Sniper).

Last edited by ColbyG; Tue Aug 17 2021 04:31 PM.

colby

1951 Chevrolet 3100: Photos [photos.app.goo.gl]
–Engine: 219 to 250 to 350 (waiting to be dropped in)
–Currently: Readying a 1987 S10 frame for mounting the body.

1956 Chevrolet 6400
–Engine: moved the 250 from 3100 - newly installed
–Currently: Adjusting Brakes & Installing New Headlamp Switch

1963 Chevrolet C10 Fleetside
–Engine: EMPTY
–Currently: Sitting in Barn
Re: What Ford 9" rear-end ratio should I go with?
ColbyG #1420949 Tue Aug 17 2021 06:24 PM
Joined: Mar 2007
Posts: 1,397
T
Crusty Old Sarge
Colby, I'm not running an overdrive, I have a Muncie M20 4 speed. I have an 8.2 10 bolt rear end with 3.08 gears. I may go deeper later on 3.42 or so. With a 255/60 15 (27 inch tall) I will be about 2400 RPM at 65 MPH.

I built my engine to run street or strip. I would like to run it on the local drag strip once in awhile.

Last edited by TUTS 59; Wed Aug 18 2021 01:14 PM.

Craig

Come, Bleed or Blister something has got to give!!!
59' Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
Re: What Ford 9" rear-end ratio should I go with?
TUTS 59 #1420954 Tue Aug 17 2021 06:55 PM
Joined: Dec 2020
Posts: 37
C
ColbyG Offline OP
'Bolter
TUTS_59, ahhhh, I understand. With my cam, would you also definitely recommend a 4.56 or so in mine? I do believe that I will learn more once I get it all together and running, but also, I would like to save as much time and money as possible and if I don't have to change the gears from my first choice, that would be ideal.


colby

1951 Chevrolet 3100: Photos [photos.app.goo.gl]
–Engine: 219 to 250 to 350 (waiting to be dropped in)
–Currently: Readying a 1987 S10 frame for mounting the body.

1956 Chevrolet 6400
–Engine: moved the 250 from 3100 - newly installed
–Currently: Adjusting Brakes & Installing New Headlamp Switch

1963 Chevrolet C10 Fleetside
–Engine: EMPTY
–Currently: Sitting in Barn
Re: What Ford 9" rear-end ratio should I go with?
ColbyG #1420956 Tue Aug 17 2021 07:20 PM
Joined: Feb 2004
Posts: 23,246
H
'Bolter
I'm a little crippled up from a motorcycle wreck a few years ago, but I think I could outrun anyone who tries to GIVE me that cam and make me run it in a street machine. It's totally unsuitable for anything short of a bracket racer, or maybe a round track car. The accessories that it needs such as double valve springs, lightweight spring retainers, hardened pushrods, guide plates, oversize valves, and ported and polished cylinder heads, are going to cost somewhere over $1K, after the cost of the cam is factored in. Then you'll have an engine that belongs on a race track, not in a street machine.

The biggest mistake most rookie engine builders make is "too much cam"- - - - followed by "too much carburetor". You're halfway there.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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