The Stovebolt Site Forums The Shop Area Engine Shop I know, again

I will start off by saying that I know this topic has been brought up here about a million times. I am doing a ground up restoration on a 1951 five window cab, which is by the way my first project. I have studied the archives and I am still not clear on this question. Most of the time on here I have seen that the patrick's ring and pinion set will give me about ten more MPH. The problem is I have never driven an advance design truck so I don't know what that means. I have seen here and elsewhere that a stock geared AD will go 40 but the pistons are swapping holes. I have also seen that they will run about 50 on top and even 55. Finally Patrick's claims that the with their kit the truck will go 65 without engine strain, which is what I am looking for exactly. So I guess the question in a nut shell is Patrick telling the truth? If the kit only gives you ten more MPH then the truck must run 55 stock? Is this factual? I am going to be running a 235 with fenton headers, dual carbs, dual exhast, and a mallory distributor. I will also be using the tall stock size tires. So I know this is lengthy and has probably already been addressed so I appologize if I missed it. Thank you for any comments!

If this information is already available on this website please let me know where because I was unable to find it in the archives.

Hi Ingo,
Since nobody else has chimed in, I will throw in my 2 cents. I daily drive a 48 - 3/4 ton with 4.57 gears and a 235 w/ 4 speed. I have 225 radials on back and I can run 40 without too much strain. I have run 50 or a little higher but its wound up pretty good. Your half ton will have 4.10's and should run a little faster. I would think that the Patricks gears would get 65 but I dont know at what rpm's you would be at. This subject has been discussed here in the engine and driveline shop many times. I know at least one of the sponsers or advertisers here has a rpm/speed calculator. You just enter your tire height and gearing, and it will give you rpm's or speed. Just do a search and see what you come up with. Maybe one of the wise bolters will chime in.
Ralph

What ratio is the patrick's setup? 3.55? I run a 3.55 rearend from a PG sedan in my Bel-Air. 65 is about 3,000 RPM with 205/70R15 radials.

Ingo,

Yachtcare posted this link a while ago. Go to the the bottom of that page and there is an RPM calculator(at the bottom of that page is "For Specific Transmission Ratio"):

Plu in values for the variables:
- 4.11 (stock '51 1/2 ton) vs 3.55 (Patrick's) rear end ratio (R & P ratio)
- 28" to 31" Tire Height (loaded diameter)
- 50 to 65 MPH
- 1.00 Trans Ratio

http://www.ring-pinion.com/calculators/calculatorsind.html

2,500-2,700 RPM seems a reasonable range (cruising at 3,000 or higher for long periods might be a strain).

Several people who frequent this forum have installed Patrick's conversion. Maybe they will give testimonials.

Tim

I run my stock 4.11 3100 at 55-60 mph a lot and it is just fine, although I do have a 261 in it. The valve train gets pretty loud but the tachometer indicates that I am in the safe zone. It is getting 3.07 gears soon though.

Some of the best money I have spent was going from 3.90 gears to 3.38 gears. My 56 runs quieter with better mileage. It cruises just fine at 70 mph with 29-inch tires along with a very healthy 235. I have no noticeable loss in acceleration. It still tows my boat and it drives up to Tahoe just fine. My experience with gearing up is very positive. It was worth the money. 4.11 to 3.55 should be similar, if the rest of your truck is up to the extra speed.

Thanks for the replys. No I am not planning on racing, I just want to build a dependable daily driver and I think that is very possible. I am going to discs on the front and dual master cylinder. I may go power brakes but I am not sure yet. Ralphy if I am following you correctly you seem to be saying that with my slightly hopped up engine I will have enough power to not need to change my rear gears? Is this what you are trying to say? I wouldn't think that the horsepower increase would make that much of a difference. Remember guys, building old trucks is about having fun. I have wanted build a old truck since I was ten years old and a AD since I was fifteen. Originally I wanted to butcher it by clipping it with a nova subframe. I am long past that and just want to build a truck that is safe as POSSIBLE, and as operable as POSSIBLE for todays driving conditions. I am not a fast driver now and I won't be in this truck, I do want to keep up with traffic however. I just want 65 on top without the pistons swapping holes. With as much torque as these long stroke inline motors make I think this can be done without total bottom end loss. I am just trying to determine how to do it with some insight from people who know much more that I do. Thank you!

I have 3.08 gears behind a GMC 270 with the stock 4-speed.

The truck will easily run past 70, and setup that way. However, pulling an empty trailer I feel the load starting out and trying to accelerate. It does make a big difference.

I put a lot of miles on a box-stock 58 Chevy Delray sedan, with a 235, a 3-speed standard shift and a 3.70:1 rear axle. Keeping up with 75 MPH traffic was not a problem, with the standard 14" tires. Now, I know it wasn't a pickup, but the same setup in a truck with somewhat taller tires should work OK, as long as you don't try to haul a bed full of gravel, or something similar.
Jerry

O.K. , my .02 , I have a 1949 3100 series work truck , poorly rebuilt 235 and SN420 gearbox , Patric's 3.55 gears in the Torque Tube and 29" tall LT205/85R16 tires on it , Rochester " B " series carby with no mods , used to have split manifold & twice pipes , no muffler but the manifold cracked so now it's a single exhaust again , I have plenty of power off the line unless fully loaded (it's a auto shop work truck) , cruises easily at 60 ~ 65 and I still tow cars with it haul scrap etc. .

It's fine for long distances , 300 mile trips out into the desert are routine for this truck .

I really noticed the loss of power between the split manifold and the single one and plan to replace the exhaust manifold withone split by Kansas Kustoms , plus the Offy dual carby intake with two Rochester " B " series carbies as I like them .

Go with this setup as you've planned , it'll go fine on freeway or in the hills plus reliability
will be good , don't use bias ply tires though , you'll be sorry if you do on a daily driver .