rear gear help!!
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Joined: Jan 2001
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From: Virginia
That doesn't look like the correct number, but if the 3 08 was spaced out by itself, it could be. If it was part of the that long number, I don't think so.
What year truck, what tranny/engine, what model do you have(f100, f150, etc.) and what number or letter do you have on the door jamb sticker for the rearend?
What year truck, what tranny/engine, what model do you have(f100, f150, etc.) and what number or letter do you have on the door jamb sticker for the rearend?
Thread Starter
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Tuned
Joined: Jun 2008
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From: sc
it an 84 f150 302 c4 trans and the axel# is 18 on the door jam. i'm just trying to figure it out so i know what engine parts(cams headers etc...) to buy for the rebuild. just trying to get 300 horses or more daily driver. for around $1200-$1600 budget! if you know a wining combo let me know!
Elder User
Joined: Jan 2009
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From: Blue Eye, mo. hwy 86 & JJ
hmmm... does that mean a 300 horse 351W would need a 3.73 also??? i'm droppin one in mine and i've got the 3.08 gears, and i was considering a swap for the 2.72 gears (better highway mileage, and it goes would go faster! 
)
so i guess that would be a no-no?
)so i guess that would be a no-no?
Postmaster
Joined: Jun 2007
Posts: 2,621
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From: Sweetwater Texas
The 351W has more low end grunt than the high revving 302, so you may not need as high as gears as the 302 would need. You might get by with the 3.08's, she'll be a little sluggish in the low end. I would drop in the motor and see how she does, but be on the lookout for a good set of 3.55's.
Methanoholic
Joined: Mar 2009
Posts: 6,442
Likes: 8
From: Maine (NorCal Native)
The 302 would need lower gears, not higher gears!
The Higher the number the Lower the gear! ie: 3.55 is Lower then 3.08!
-Enjoy
fh : )_~
The Higher the number the Lower the gear! ie: 3.55 is Lower then 3.08!
-Enjoy
fh : )_~
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Postmaster
Joined: Jun 2007
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From: Sweetwater Texas
Festus don't confuse us (well me anyway) again with your lower is slower but quicker, higher is faster but slower chinese riddle again.
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Joined: Jan 2001
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From: Virginia
To me 300 hp means a decent cam, head work or aftermarket heads, aftermarket intake one level above a performer type but still dual plane, 650-750 carb, headers with dual exhaust, and some distributor work. Depending on tire size, I would say 3.50 gears would be minimum to let this engine breath a little bit.
I may be wrong, but I think a 300 hp engine is going to be a little more radical than people think.
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
300hp from a 302 isn't hard, but it tends to move the meat of the powerband up the tach so more gearing(higher numerically) makes better use of it. If you don't have an OD tranny and the tires are close to stock then highway rpms can get excessive with ratios higher than 3.55, but ratios down into the 2.xx range are doggy at in town speeds or when towing. The 351 produces a broader powerband so it can better deal with a lower numerically gear, but these still hurt overall performance unless the truck is exceptionally light.. like under 4000lbs. The best results for both motors happen with 3.73+ gears and an OD tranny.
Elder User
Joined: May 2001
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From: washington
The problem is that you do not have an OD tranny. If gas mileage is a concern, then you want to keep the gears high (meaning lower number). I agree with the above poster and would not go above 3.55 unless you could care less about mileage.
3.08x31" tires @ 60 mph = 2057 RPMS
3.55x31" tires @ 60 mph = 2370 RPMS
3.73x31" tires @ 60 mph = 2491 RPMS
I have an AOD tranny so I will be going to a 3.9 gear ratio set for the rear.
3.9x31" tires @ 60 mph in OD = 1699 RPMS
3.9x31" tires @ 60 mph in D = 2604 RPMS
Obviously 2604 RPMs would be a little out of range if you had a 351w and were towing. If your towing or hauling, everything changes since you need to be concerned with the torque curve rather than higher RPM's
3.08x31" tires @ 60 mph = 2057 RPMS
3.55x31" tires @ 60 mph = 2370 RPMS
3.73x31" tires @ 60 mph = 2491 RPMS
I have an AOD tranny so I will be going to a 3.9 gear ratio set for the rear.
3.9x31" tires @ 60 mph in OD = 1699 RPMS
3.9x31" tires @ 60 mph in D = 2604 RPMS
Obviously 2604 RPMs would be a little out of range if you had a 351w and were towing. If your towing or hauling, everything changes since you need to be concerned with the torque curve rather than higher RPM's
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Tuned
Joined: Jun 2008
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From: sc
so if i keep my current set up, will i need to get a higher stall converter? i do want to keep the mileage decent i'll use the expedition for towing. which cam would be the best also cause what ever you guys come up with that's what i'll be buying. now i already have the edelbrock preformer intake & 1406 600cfm preformer carb, shorty headers off a 92 mustang gt & summit racing catback exaust kit!!
Moderator
Joined: Jan 2001
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From: Virginia
With the setup you have for the engine, install a mild rv cam and you will be able to keep your 3.08's and the rest of the driveline stock. You won't be making 300hp, but it will be a very nice running practical engine that you will get a lot of use out of.
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Tuned
Joined: Jun 2008
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From: sc
well even if doesn't make 300 it should be close right and that would be plenty as long as it moves good and get out it's way right!!!
if it is a solid stout running everyday driver i'm happy i'll just have to wait on dad's 64 impala for the 500hp it's putting out to the tires!!
if it is a solid stout running everyday driver i'm happy i'll just have to wait on dad's 64 impala for the 500hp it's putting out to the tires!!