218 vs 251

[MarkAubuchon]

I have had this project started for many years,  pushed it in the corner while doing other things.  I have a 1950 5 window Dodge 1/2 ton, 8 3/4 with 3.55, Disc brake conversion with dual MC, all new brake lines, Frame blasted and painted new springs and shocks, Cab and front end painted, new glass, seals, wiring harness, gauges reworked, all chrome and stainless reworked, fresh 218 with dual carbs, exhaust, and E Ignition, T5 transmission, Recored radiator, 12 volt.  My Question is I have a complete 251 which would need rebuilding, set it up with tri power carb set up or something else.   Would I be better off putting that motor in vs the 218. Ideally Id like to pull my 18 foot Resto Camper.   While I have all the parts, most are still sitting in the cab of the truck, Drive line is in.  So switching out the motor wouldn't be too complicated.  Your opinions are welcome. 

[Plymouthy Adams]

your money your time your call..only you can truly decide the fate of the truck and what engine is going to be best for pulling the huge rig behind you.  Your fuel modifications as explained is only a valid option for a cam/exhaust mod that would make use of the added induction...that same carburation could be a bad choice for torque and pulling if  your cam is wrong profile on the other end of the spectrum.....study your cam profile and characteristics and approach for balance...torque when needed...bit of pep when sporting about and of course overall most important to many builders..the look of the engine bay and the awe factor

Edited December 11, 2016 by Plymouthy Adams

[wayfarer]

Yeah, I'd be looking at the curb weight of the trailer and the truck before attempting to use the truck as a tow rig. The 25" engine does provide more torque than the 218 but still not much in terms of the potential weight.

If you make the swap be sure to use a 230-250 flywheel.

[MarkAubuchon]

Thanks, Trailer weighs 3500#  light tongue weight of 200#   I know they had hauled a lot of stuff in their day.

[NiftyFifty]

You can never go wrong with a little more horsepower and torque, and side by side, 25" blocks are identical, so you don't lose any originality or any major changes....Id go for it...it's what I did, dumped the 218 and ran a 251

[Charlie Stephenson]

I'd do in in a heart beat AFTER I had the Dyno results on the engine the third member ratio tire size ( Drive on Dyno) call Earl Edgeington for a Cam regrind.   Tune it for the highway so the torque and RPM and HP are in perfect harmony then a good guess would be 80,000 miles, use engine oil with ZDDP and synthetics in the transmission and 3rd member. Charlie Stephenson 515-276-7877  Pilot House Charlie Stephenson .  I'm using a Vertex and 3 carbs with manual high speed adjustable jets and a serpentine radiator.

[55 Fargo]

13 hours ago, MarkAubuchon said:

I have had this project started for many years,  pushed it in the corner while doing other things.  I have a 1950 5 window Dodge 1/2 ton, 8 3/4 with 3.55, Disc brake conversion with dual MC, all new brake lines, Frame blasted and painted new springs and shocks, Cab and front end painted, new glass, seals, wiring harness, gauges reworked, all chrome and stainless reworked, fresh 218 with dual carbs, exhaust, and E Ignition, T5 transmission, Recored radiator, 12 volt.  My Question is I have a complete 251 which would need rebuilding, set it up with tri power carb set up or something else.   Would I be better off putting that motor in vs the 218. Ideally Id like to pull my 18 foot Resto Camper.   While I have all the parts, most are still sitting in the cab of the truck, Drive line is in.  So switching out the motor wouldn't be too complicated.  Your opinions are welcome. 

George Asche should really be mentioned on this now,

tri carb intakes, split exhaust, cam grinds, edgy is not the only cam grinder. I am not overly partial to the EDGY Heads, although they are not priced bad as compared to any vintage stuff. Infact get a head from a big truck 56-58, and mill appropriately  would be a super head for your use.

The T5,you already have  you better know the gear spread and ratio for the trans, as the NWC T5 had very low gearing in 1 series, with a first gear of around 4.03:1, so know what you are getting into and use the appropriate diff gearing, for future use with a more powerful 250, that can spin up a lot better than the 218.This is of course, will be accomplished with the desired cam profile for your needs and wants.

 

[MarkAubuchon]

Just wondering,  do you think I would need a different cam.  On my cars I have one with a stock cam, cut head dual carbs and exhaust, the other with a cam from George.  ?

[Plymouthy Adams]

what grind is the cam from George...basically what duration and lift...centerline etc..as stated..the cam grind will dictate your performance level and needs be balanced for the intended use of the vehicle...am sure George sent a timing card with the camshaft.

[Jeff Balazs]

Mark;

It is not the tongue weight that will cause you to pause. A well balanced large trailer should always have around 200# of tongue weight. It is the 3500# of trailer you need to be concerned with. That and the 3.55 rear axle will probably not go all that well together. I am pretty certain you will not be able to accelerate in traffic safely. At the very least you may have to go back to a 4.10 ratio axle.

Jeff

[Plymouthy Adams]

the 3.55 is an excellent ratio for all around use of a truck.   You just need the torque peak to be centered about the speed you wish to operate.  If  you are running OD...balance the RPM, today's drive trains are engineered to be 200 below peak torque so not to have to downshift for small things like a overpass rise etc...torque peak is usually early and often runs fairly flat for bit before dropping off and the need to build HP in the upper rpm when added load or desired increase of speed really presses the engine to work....I would love to see the torque curve of these  engines, I have looked high and low and yet to find it listed.  I do not mean just the torque at x rpm..but over the entire operating rpm..

[greg g]

Looking at the specs you are adding about 15 HP and 20 (around 200 @ 1200 rpm for the 251) or so pound feet of torque in stock form.  Doesn't sound like much but I'm sure it would be beneficial.  Might you consider an auto trans for the torque converter benefit for towing?  My small Studebaker engine is rated at 210 # ft and seems to have plenty of grunt.  My 3.0 Mitsubishi v6 is rated at 204 # ft, and it pulls our popup (2500 lbs) just fine.

 

I think if you plane the head to get a bit more compression and add intake and exhaust mods, you would be fine.  Talk to Tim Kingsbury regarding cam grinds suited to the job.

[wayfarer]

19 hours ago, MarkAubuchon said:

Thanks, Trailer weighs 3500#  light tongue weight of 200#   I know they had hauled a lot of stuff in their day.

You are correct...in their day. However, we are now in 'this' day and road speeds are much higher even on secondary two-lane jobs.

I have little doubt that a bone stock 251 would move truck and trailer at a guess of 6,000lbs and I am also quite sure that it won't happen quickly.

As Jeff mentioned, you may well need a 3.9-4.1 gear unless your t5 has the lower 1st gear.

Whatever you do just be confidant in the ability to stop as well as go.

[Jeff Balazs]

7 minutes ago, wayfarer said:

You are correct...in their day. However, we are now in 'this' day and road speeds are much higher even on secondary two-lane jobs.

I have little doubt that a bone stock 251 would move truck and trailer at a guess of 6,000lbs and I am also quite sure that it won't happen quickly.

As Jeff mentioned, you may well need a 3.9-4.1 gear unless your t5 has the lower 1st gear.

Whatever you do just be confidant in the ability to stop as well as go.

Where I think this rig will really fall short of being a safe tow rig is mid to higher speed acceleration. Safe towing requires the ability to merge into the traffic flow. I just don't think either engine mated to a 3.55 ratio axle is going to be able to do this........no matter how it is built up. I have a 3/4 ton with 230 and a 3.55 and I sure as heck wouldn't attempt it.

Jeff

[wayfarer]

7 minutes ago, Jeff Balazs said:

Where I think this rig will really fall short of being a safe tow rig is mid to higher speed acceleration. Safe towing requires the ability to merge into the traffic flow. I just don't think either engine mated to a 3.55 ratio axle is going to be able to do this........no matter how it is built up. I have a 3/4 ton with 230 and a 3.55 and I sure as heck wouldn't attempt it.

Jeff

...me thinks that a hi-compression 270 Poly would do a nice job.....and look great besides. Of course we already know that a 354 will fit in the hole......

[NiftyFifty]

You could likely get away with a common 3:73 rear axle from a Cherokee/Jeep, but 4:11 would be better with the T5...that or you won't get much use out of OD, as you won't have enough rpm for the engine to keep lugging.  I have 3:5? Gears and my truck lugs on really windy days and steep hills...but I'm not running a ground cam, and just a single carb...future plans are twin int/exh and Pertronix distb 

[MarkAubuchon]

Thanks for all your input.  Exactly what I was looking and hoping for.  Hauling the  trailer might be a problem, but I'm hoping hauling #$s  wont be.

[55 Fargo]

21 minutes ago, MarkAubuchon said:

Thanks for all your input.  Exactly what I was looking and hoping for.  Hauling the  trailer might be a problem, but I'm hoping hauling #$s  wont be.

Listen, a Gent I know was hauling a camper trailer with his 32 Chrysler, stock 250 engine, T5 and 3.90 gears, all through the Rocky Mountains in Canada.

Now I have ridden in this car, and it will hit 70 mph real easy, so no reason you can't do the same..

[pflaming]

32 Chrysler, stock 250 engine, T5 and 3.90 gears,

Correct me if I am wrong which I have been. So then in 5th gear the ratio is 1:1 on the 3:90 and with a 250 that is an easy pull. So in 4th he must be close to a 4:10 ratio and in 3rd possibly a 4:30 +/-. All those are guesstimates, but I think you get my gist. That will be a lot less expensive and less work than a T5 et. al.  

I get 70 mph with a 218 on a 3:73 in a B3B, and it pulls hills with ease in 3rd gear. I truly believe we underestimate what the flat head is capable of doing. I've toyed with all this for some time and now I'm making plans to put a sync 4 speed behind a 218 with a 3:43 or less.  In third I would have close to a :3:73 ratio which I have now an would then have 4th for cruising.  The options are endless, do the math and build to taste.  

Never let the engine get hot, keep the oil fresh and full, be careful on the high RPMS and these engines run forever. JMHO 

[55 Fargo]

33 minutes ago, pflaming said:

32 Chrysler, stock 250 engine, T5 and 3.90 gears,

Correct me if I am wrong which I have been. So then in 5th gear the ratio is 1:1 on the 3:90 and with a 250 that is an easy pull. So in 4th he must be close to a 4:10 ratio and in 3rd possibly a 4:30 +/-. All those are guesstimates, but I think you get my gist. That will be a lot less expensive and less work than a T5 et. al.  

I get 70 mph with a 218 on a 3:73 in a B3B, and it pulls hills with ease in 3rd gear. I truly believe we underestimate what the flat head is capable of doing. I've toyed with all this for some time and now I'm making plans to put a sync 4 speed behind a 218 with a 3:43 or less.  In third I would have close to a :3:73 ratio which I have now an would then have 4th for cruising.  The options are endless, do the math and build to taste.  

Never let the engine get hot, keep the oil fresh and full, be careful on the high RPMS and these engines run forever. JMHO 

Like what, you had some Christmas Cheer, or what?

The engine is a 1956 250, the trans is from an 1988 s10, the rear end is stock.

1932 Chrysler 6 is nothing like the post 38 engines

Just for the record, this car takes off in 2nd gear, no problem, again the T5 with a 4.03 1st gear is nothing I would want...

[Merle Coggins]

12 hours ago, pflaming said:

Correct me if I am wrong which I have been. So then in 5th gear the ratio is 1:1 on the 3:90 and with a 250 that is an easy pull. So in 4th he must be close to a 4:10 ratio and in 3rd possibly a 4:30 +/-. All those are guesstimates, but I think you get my gist. That will be a lot less expensive and less work than a T5 et. al.  

Paul,

The T5 transmission, like many 5 speeds, is Overdrive in 5th gear. 4th would have the 1:1 ratio, much like 4th in my truck or 3rd in yours. 5th gear would be less than 1:1. I don't know the exact ratios, but it's likely in the 0.75:1 to 0.80:1 range.

[55 Fargo]

Here are the gear ratio and spread for NWC S10 T5s, the older lower not the best, unless you are running higher diff gears.

Edited December 13, 2016 by Rockwood

[pflaming]

Yes, I posted a poorly thought out message. Should have edited, but mind sometimes is cloudy at my age.

 

[55 Fargo]

2 minutes ago, pflaming said:

Yes, I posted a poorly thought out message. Should have edited, but mind sometimes is cloudy at my age.

 

Its okay Paul, you will forget this in a few minutes....LOL

[Jeff Balazs]

We should all stop and consider the added weight and wind resistance of a trailer the size the OP suggested. It might not be too big a deal on lightly trafficked level roads. You might even be able to take on some hills. But add in some wind gusts or a twisty section of off camber road and I am pretty certain it would be a white knuckler at the very least. And everyone who has done a fair amount of towing also knows how critical the ability to accelerate in any situation can be. Especially when merging into traffic. Personally I don't see one of these smaller trucks making a safe tow vehicle for anything much bigger than a small boat or a teardrop type travel trailer in today's world. Push this vintage envelope too much and something or somebody will most likely get hurt.

Jeff