Rear gear question.

A performer intake and 8k Rpm just dont go together. My engine set up is currently a mexican 302 block with 289 internals.....and ya with the flatest stretch of land in the world and Nitrous I doubt my motor would ever see 8k safely........How are you sure that your reving up to 8k....do you have a tach?

Mike

Working with the T5's .68 overdrive vs. a 1:1 4 speed in top gear:

3.55 gears at 5th gear will equal a 4 speed using a 2.41 rear end ratio.

4.11 gears at 5th gear will equal a 4 speed using a 2.79 rear end ratio.

Given that, when was the last time you drove a car on the freeway with ~2.41 gears? I have 3.40 gears now and it was nice with the 4 speed, but after going to the T5 I hardly use 5th gear anymore. It's way too high and lugs my engine at highway speeds unless I want to drive 80mph all the time. My 67's peaky, carbed 289 does not like 1800rpm at 65mph. My '86 GT with its roller cam and EFI does fine in 5th gear with 3.08s. It all depends on what you have and/or what you want.

Ghxst said:

I guess we'll never know unless I build another one, I just traded that engine for a 10k truck.

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is that 10K the cost or redline?

Ghxst said:

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.

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Im running 4.11's with a 347 Stroker Motor that redlines at 8000RPM (450hp) and 4 Speed Transmission.. If you do not plan on going over 60 to much you'll be fine.. If your going to take it on the highway I would go with 3.73's.. Now if you have a 5 Speed, Definitely 4.11's or possible the next up..

washMO66 said:

is that 10K the cost or redline?

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LOL...I was thinking it meant mileage.

I must admit that I've heard a very similar story, which, at this point, I have to consider an urban legend. A local guy in my hometown had a boneyard of old Mustangs when I was around 15 and getting into the hobby, and I bought several parts from him. This was 17 years ago. The word on the street (not only from him but from several other sources) was that he had built an absolute haint of a 289/302 hybrid in the late 70's/early 80's. At the time, I bought the story hook, line, and sinker being 15 years old.

Time brings some fuzziness as to his claimed part list, but here goes (I'm not even sure if these parts would work together without introducing pistons to valves):

289 block

302 crank (which should only make it slightly bigger than 302 cubic inches, right, and would cause valve clearance problems if I'm not mistaken)

289 hi-po rods ??? (see above)

289 hi-po heads w/ port work

a 3/4 cam (what in Hades is a 3/4 cam?)

other bastardized parts I simply can't recall at the moment

The legend as I heard it was as follows:

He welded the spider gears in the differential and lost the car shifting from third to fourth gear at 120 MPH, which caused him to wrap the car around a tree in a field. He told this graphic story of how he came to, thrown from the car, and tried to stand up, in the process realizing, when he fell down, that his tibia (leg bone)? (I'm no doctor, I only play one on T.V.) was buried into the ground and prevented him from walking.

The strange part about a good urban legend is that there is always support for these types of tales. My brother's ex wife's sister's ex-husband, current husbands at that time (wow that's confusing; yes the trailer porch fell and killed 7 dogs), claimed he had driven the car back in the day. He claimed that he gassed it at a stop sign at an intersection and lofted the front wheels across the street into the ditch accidentally. I'm callind bullshart on that one, but these sorts of stories apparently exist out there in Mustangland.

I'm not trying to be a d*** to the guy that posted this, but he should realize after all these posts that something is preposterous here.

P.S. I really apologize for the long post, but I am being held hostage by a guy who caught me drunk, let me pass out, and removed my kidney in an iced down bathtub. He is holding me hostage and made me write this post by threatening to flush my kidney down the commode if I make any sudden moves and don't post a long reply .

65up2d8 said:

289 block

302 crank (which should only make it slightly bigger than 302 cubic inches, right, and would cause valve clearance problems if I'm not mistaken)

289 hi-po rods ??? (see above)

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You can put a 302 crank into a 289 block, but not with 289 rods.

65up2d8 said:

a 3/4 cam (what in Hades is a 3/4 cam?)

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Back in 'the day' cams were sold as 1/2, 3/4 or full. Meaning "full race". A 1/2 cam was a strong RV grind, a 3/4 cam was pretty lumpy, and a full was a serious racing part.

thanks grandpa


jest kidding

Edbert said:

You can put a 302 crank into a 289 block, but not with 289 rods.

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Yes, you can but you can't use stock 289 or 302 pistons. The pistons require a modified pin height to compensate for the slightly longer rods.

Boss 302s used the longer 289 rods with larger rod bolts and a forged 302 crank. This is the same geometry I'm using in my 5.0 roller block.

6Stang7 said:

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.

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Block Twisting??

Ghxst said:

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.

Click to expand...

I'd stay away from a Locker for a street car.. You DO plan on turning corners, don't you?

e2mustang said:

Im running 4.11's with a 347 Stroker Motor that redlines at 8000RPM (450hp)

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Not trying to start another redline debate, but why would you have to / want to spin a 347 to 8K to get 450HP?

Since you are a new guy around these parts we like to know what ya got and how it performs.

Give details please, heads, camshaft, intake, carb, slugs etc......