red line for a 302
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red line for a 302
Thanks to the advice I got here I figured out that the 302 engine in the '67 F100 I just bought dates from 1976 (I also figured out that I got a '67 not a '69 in spite of what the registration and the former owner said).
Now I've got a question about the max rpms for this engine. The truck has a four speed in it (an old one but I haven't figured out how to date it yet), and when I'm in fourth doing about 55 mph the tach (someone mounted one on the steering column) reads just under 3000. How high can I safely take the rpms when I'm in 4th (and 3rd for that matter)?
While I'm at it, I've read lots in this forum and others about gear ratios for transmissions. The one I've got doesn't have a synchronized first gear (you have to be at a complete stop to shift into it) and 2nd and 3rd are both geared pretty low. How do I figure out what the actual gear ratios are?
Thanks
Now I've got a question about the max rpms for this engine. The truck has a four speed in it (an old one but I haven't figured out how to date it yet), and when I'm in fourth doing about 55 mph the tach (someone mounted one on the steering column) reads just under 3000. How high can I safely take the rpms when I'm in 4th (and 3rd for that matter)?
While I'm at it, I've read lots in this forum and others about gear ratios for transmissions. The one I've got doesn't have a synchronized first gear (you have to be at a complete stop to shift into it) and 2nd and 3rd are both geared pretty low. How do I figure out what the actual gear ratios are?
Thanks
Elder User
Joined: Apr 2003
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From: Tumwater, Wa
For a stock 302, i wouldn't want to rev it much past 5,000. Limiting factors are rod bolts and hydraulic cam.
you have to figure out what 4 speed it is to find the ratios. First is a granny gear, the rest are like a 3 speed manual
It is most likely a T-18 or a NP435 trans.
you have to figure out what 4 speed it is to find the ratios. First is a granny gear, the rest are like a 3 speed manual
It is most likely a T-18 or a NP435 trans.
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From: Thomson, GA
You hit max power at about 3800-4000 RPMs, and I would be afraid to take a stock carbed one past 4500 (although I have, and it didnt blow up). I usually shift at around 2500 with my 3.25 axle gears (20 mph into 2nd, 40 mph into 3rd-1:1)
If you drive alot of highway miles and dont do alot of towing, I would consider some taller gears. It sounds now like you have 3.73 or maybe even 4.10's. At 65, my truck is turning 2800 RPMs and is comfortable up to 85 and I have had it up to 110-115 (dont tell my mom).
If you drive alot of highway miles and dont do alot of towing, I would consider some taller gears. It sounds now like you have 3.73 or maybe even 4.10's. At 65, my truck is turning 2800 RPMs and is comfortable up to 85 and I have had it up to 110-115 (dont tell my mom).
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Muchtomydelifht: Ya, you're shifting a lot higher than I am. I'm mainly going to be on the highway (I bought it to haul my quad and other stuff, but not too much towing) so lower rpms at 60-65 mph would be nice (save on gas and all that). This is probably a dumb question (but I'm a newbie): can I change the axle gears without changing the entire transmission?
Pat67shorty: can I figure out the type of transmission by looking for casting codes somewhere? Or is there another/easier way?
Thanks
Pat67shorty: can I figure out the type of transmission by looking for casting codes somewhere? Or is there another/easier way?
Thanks
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From: Thomson, GA
You sure can change them. I would recommend the 3.50's for you. I have to shift a bit higher because of the gearing. Tire size also affects this, as a bigger tire acts like a lower(numericaly) set of gears. There are several calculators out there. www.4lo.com has some. For virtually all non-overdrive transmissions, top gear is 1:1. You can get your rear end ratio from the door tag or by jacking up the rear end and counting driveshaft revolutions/tire revolutions.
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That's a handy site, thanks for that and the info. Is it a big deal to change the axle gears? I'm not that experienced working on cars/trucks myself, but I figure this is a good chance to learn. It won't be till next summer anyway, as it's *cold* up here already.
Pat67shorty: I found an earlier thread that had a link to Novak Conversions that explains how to id a T18, so that should get me started at least.
Pat67shorty: I found an earlier thread that had a link to Novak Conversions that explains how to id a T18, so that should get me started at least.
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From: Thomson, GA
Ive never done it, but I hear that ford 9 inchers are the best thing to cut your teeth on as far as gear changes.
Expect to pay about $200 for the gears and another $100 for the installation kit (bearings, crush sleeves, gasket, clips, etc)
Expect to pay about $200 for the gears and another $100 for the installation kit (bearings, crush sleeves, gasket, clips, etc)
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From: Ohio
Most of the early 302 "truck" motors did not make much power up in the band. I'd say anything under 5000 will keep it alive for many more years.
I used to run my 302 at 3500 rpm on the highway all day long with 4.10 gears. It got 10-11 mpg no matter what.
The old Boss 302 motors had different heads on them that made them high rpm motors(like tennis ball size ports). Plus they had steel cranks and good rods with 4 bolt mains.
As for changing rear gears, if you have a 9"(like you should), I would suggest finding a used set and spend an afternoon swapping them out. Pull axles, pull center, put new center in, put back axles. (this is the abbreviated description, but that is pretty much it). Most swap meets have vendors selling this stuff for pretty cheap($150 should get you a 3.50 open rearend).
Larry
I used to run my 302 at 3500 rpm on the highway all day long with 4.10 gears. It got 10-11 mpg no matter what.
The old Boss 302 motors had different heads on them that made them high rpm motors(like tennis ball size ports). Plus they had steel cranks and good rods with 4 bolt mains.
As for changing rear gears, if you have a 9"(like you should), I would suggest finding a used set and spend an afternoon swapping them out. Pull axles, pull center, put new center in, put back axles. (this is the abbreviated description, but that is pretty much it). Most swap meets have vendors selling this stuff for pretty cheap($150 should get you a 3.50 open rearend).
Larry
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From: Brea CA
I used to take my warmed-over 260 over 6k regularly but it was still making power up there. I remember a long time ago somebody had a Mustang in the parking lot and when they started it the throttle must have been stuck wide open 'cause it revved into the stratosphere for about 30 seconds and made all sorts of wierd harmonic noises. Didn't seem to hurt, it was back there the next day.
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Just thought I'd mention I figured out it's an NP-435 transmission and the rear end is a Ford 9", 3.70 gear ratio. Thanks for the advice. There's an amazing amount on this site - you guys are great.