Rear gear question.

Ghxst · Apr 10, 2005

I am getting ready to install my refreshed 289/302 hybrid motor and I will be using a refreshed c4 for now. I am going to stay with the stock 8" rear since I am staying the small block route with this car and I was wondering what gears I should run. The motor will have a redline of about 8k so keep that in mind. Also, I live out in the middle of boofoo land and have to travel a good distance to get anywhere. I have the opportunity to get a locker with 3:55 gears for next to nothing and I was wondering if this would be an o.k. choice of gears for the c4 tranny. I will be swapping in a 5 speed manual in the future but at the moment that is not on the immediate to do list. Gimme some ideas here. Thanks.

gjz30075 · Apr 10, 2005

Great for a T5 but pretty revvy at highway speeds for a C4. I bought my 3.55 locker from a fella with a C4 who swapped in 3.25's instead. Sounds like the price will be right. Get it anyway, for the future.

ForceFed70 · Apr 11, 2005

8000RPM? Must be one heck of a motor.

3.55's with the C4 is doeable, but will still kinda suck on the freeway.

12sec67 · Apr 11, 2005

how in the heck is it going to redline at 8000roms? what did you do?

6Stang7 · Apr 11, 2005

given the proper internals, a ladder, and a solid valve train ( might be doable with a rapid bleed hydro), i'd say 8grand is possible. still, must have been a $$ motor.

anyways, if you are going to get a t-5, then my vote is for 4.11's. here is why.
1. you have a rev happy motor. high gears like 4.11's and rev happy motors love each other.
2. when you do get the 5 speed in, depending on rear tire size and what OD ratio your t-5 has, you'll spin about 3K at freeway speeds.
3. well, 4.11's kick arse! they are by far 1 on the best parts i have installed on the 67.

Max Power · Apr 11, 2005

If your motor actually makes power at 8k, you will need 3.55s or more.

It's very rare that a motor designed to make power at 8k will be happy at 2-3k.

HuKares · Apr 11, 2005

If it seriously does 8K. You need 4.11's or more.
-Brian

Ghxst · Apr 11, 2005

O.k., here's the cat out of the bag. My godfather used to race a street stock cougar at the local track back in the 70's and 80's. He would take a stock 302 block and install ALL 289 stock internals. With all stock parts and a 2b carb he would turn the motor up to 8k all summer long and usually got at least one full summer out of the motors. My motor came from the factory this way, it was a 68 289 but they ran out of 289 blocks so ford used a 302 block in it's place. I decoded the engine code and discoved that this motor came from the factory this way, and to think that I bought the whole 68 coupe as a parts car for $300. When I started dismantling this motor I discovered that the top of the block had 302 on it so I looked the code up figuring someone had swapped the motor at some time in the cars life. Not so, the engine vin matched the cars. Anyway, I refreshed the internals and then put on a set of ported and polished 65 289 heads that have had the 2.02 valves with 3 angle valve seats installed. Then I put an edelbrock performer intake with a 750 holley to top it off. No, I haven't put it on the dyno yet but knowing from seeing this motor combo work so well myself, I have no doubt what so ever that I can push it to 8k. So, now the little secret that I have been holding in the ol bag of tricks is out of the bag. Any more questions??

redhotcomet · Apr 11, 2005

8K from a stock 289?

6Stang7 · Apr 11, 2005

289's and old 302 have a problem with the block twisting at around 6K and up. i just dont see how the bottom end holds up.

65ShelbyClone · Apr 12, 2005

Ghxst said:
With all stock parts and a 2b carb he would turn the motor up to 8k all summer long and usually got at least one full summer out of the motors.

Therein lies the cause and effect. Not balanced, not blueprinted, and definitely not designed for that kind of abuse.

Even with your big valve 289 heads, you wont make power past 6500. It will rev to 8000 or until a rod bolt lets go, but you wont need to. A Holley 750 is going to be too much also. A 600-650 wont hold you back and will keep a smidge of economy and torque on the table.

IMO, 3.00-3.25 w/C4, 3.50 w/ T5 if you want some economy(since an 8000rpm engine will offer none of that).

Ghxst · Apr 12, 2005

O.k, lets see. I hate to get upset but have any of your actually tried this setup yourselves?? Probably not. I did balance the bottom end and as far as the carb goes, riddle me this. What carb did ford put on the boss 302? Just remember that my heads are about 10x better than the heads that were used on the boss stock from the factory.

latamud · Apr 12, 2005

Ghxst said:
O.k, lets see. I hate to get upset but have any of your actually tried this setup yourselves?? Probably not. I did balance the bottom end and as far as the carb goes, riddle me this. What carb did ford put on the boss 302? Just remember that my heads are about 10x better than the heads that were used on the boss stock from the factory.

The Boss used Cleveland heads, and untouched, will outflow machined 302 heads. They have 1.73 rocker arms, 2.19 intake valve, and 1.71 exhaust. You can't fit a 2.19 intake valve in a 289/302 head. A 302 block with 289 internals is a 289. A 289 block with 302 internals is a 302. The blocks are interchangeable. Although the Boss 302 did use the same rods as a HiPo 289. I guess you can rev any engine to 8000. That's a lot of gas. Have fun.

redhotcomet · Apr 12, 2005

Heads are ten times better than a stock boss? As far as stock heads go, you can't get much better than the Boss ones.

Your valves are gonna float way before 8K. Unless you are using solid lifters.
Which arent stock.

Balanced bottom end? I don't think Ford balanced then from the factory.

Have I ever tried this? I had a stock 289 transplanted in my 80 T-Bird. It wouldnt rev passed 5200.

Ok, I will admit that a 289 can be built to rev to 8k. But you're trying to say a stock one will? Come on, tell me another one

HuKares · Apr 13, 2005

redhotcomet said:
Have I ever tried this? I had a stock 289 transplanted in my 80 T-Bird. It wouldnt rev passed 5200.

That's do to I/H/E (intake/heads/exhaust) and cam and carb too. That doesn't mean the bottom end wouldn't take it.
I doubt the stock 289 bottom end will survive long at 8K. With hi-po rods, balanced, arp bolts, and a good oiling system, I think it's possible.

65ShelbyClone · Apr 13, 2005

Ghxst said:
O.k, lets see. I hate to get upset but have any of your actually tried this setup yourselves?? Probably not.

I'm not trying to derail your plans. I'm just saying you have clashing goals in regards to building a car. You want an 8000rpm engine with big induction, but mileage too. Even EFI cant give you all that. You'll have to make tradeoffs, and I think the best one for the long run will be lower your expectations of the engine.

classic boost · Apr 13, 2005

Ghxst said:
Then I put an edelbrock performer intake ...

performer intake and 8,000rpms? nobody is going to take you seriously, please edit your 1st post and start over.

Edbert · Apr 13, 2005

The problem is that any gear we recommend for you to use with your C4 is going to be the wrong gear for the T5, and vice versa. For cars without OD I usually say 3.25 to 3.55 is a good place to stay, for OD equiped cars a 3.89 or 4.11, depending on power curve of the engine, tire size, etc.

I'm not going to even get involved with the 8K redline discussion

brianj5600 · Apr 13, 2005

I hope you have at least a 4500 stall speed. If you do it will suck on the highway with any gear! I know, I've done it. Driving around town is fun, but any distance requires a trailer. *k plus distance = no good.

LMan · Apr 13, 2005

Edbert said:
I'm not going to even get involved with the 8K redline discussion

Rear gear question.

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