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stock engine replacement or repower with something else

colelkhunter

New member
I recently bought a m35A2C that has a rod through the side of the block. Rest of the truck is in great shape with a full cargo cover, dropside bed,troop seats and bows.

Money is tight these days and I have a little to spend on this project right now. Question is why go back with the stock engine? Besides the fact that I can't seem to find one within a days drive, and will have to pay more for it than a big block gas engine? I know that this has been discussed here before but from what I have searched and read (over 20 threads) covering this, no one has listed what it actually entails to install a big block into a deuce. All just say they have done it and leave it there. Also what would the expected fuel mileage of a gas engine be in a deuce? With the stock diesel getting around 10-12 mpg in my other trucks, I am looking to improve on this. I also know the Cummins engine swaps are popular and am familiar with them. I will not be using one in this truck and the simple reason is cost. So lets leave that out of this equation. I want a Gas Big block to stock diesel comparison.

Also In my opinion the other advantage to gas would be the ability of adding an OD transmission very easily. I just wonder how it would hold up in the 13k lbs vehicle. It would be kinda nice to cruise on the interstate in a deuce and keep up with traffic.
 

197thhhc

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This is my opinion. You can run a big block and a 4l80e auto trans or a HD 5 speed manual and they will both hold up fine. You will increase top end speed with the OD and higher rpm capability of the engine. Also it will have more HP and Torque than the stock multifuel. The enine will need custom mounts and you will have to do a custom saft between the trans and transfercase. Besides some wiring , and there isnt that much if you use a carburator and HEI distributor. Its not that tough of a swap.

However you probably wont improve on gas mileage that much. If any. The advantage of a deuce engine is they can be safely turned up if you use a pyrometer in the exhaust With 46" singles you can run 65-70 mph and most important you can run on waste oil. Which makes mileage a non issue. If you calculate gas at $3.00 per gallon and going up and was oil processing at $1.00 or less per gallon The deuce engine starts to look better.2cents
 

Wildchild467

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It seems like replacing the Multifuel would be the most cost effective. no fabrication involved, a direct swap. plus you have a parts engine if you ever needed it like having a spare IP and what not. agree with 197THHHC that it wouldnt be a bad swap, but things would nickel time you on some stuff to do the swap if you didnt have it. I never worry about top speed with the deuce.... thats half the fun of owning it. haha! I respect anybodys modifications to their deuce, thats what makes it fun. i am not sure the going rates for engines, but i wouldnt think they are that expensive. If you take care of a multi, it should last a long time..... but who knows how they were treated befroe we got them. I put 5000 miles on mine this summer and haven't had a single problem other than the starter drive which wasnt a bad fix.
 

colelkhunter

New member
yep it's in tennessee Gimp. It will get it's new engine here as well.

Ok heres the math. This is what I have been able to find. Recon multifuel is running about 1,000.00. Add to that the cost of a new clutch and pressure plate ( personal opinion but not doing it is stupid) say 300.00. Now figuring miscellaneous, 1500 would be a good round estimate. I have a friend locally that has a 429 that has a fresh build that he will donate to the cause for 800.00 complete with carb. and dist. Now the trans will be a challenge for this as an OD is the only way I see this conversion being a plus and not a minus. Called a local transmission guy that has done work for me in the past and he seems to think he can get me a ford BB OD trans rebuilt and ready to bolt up for around 600.00 with a warranty. I have no idea which it is, but I trust him. Now I am not saying that going gas is going to save any money, but adding these up it seems to be a wash price wise. Now the more HP and torque are the advantages of going gas. The multi has the advantage of using any fuel. But to me it's not that huge of a deal to me. I am more interested in using the truck for hauling some sort of camping rig I.E a s250 shelter or something similar. So it needs to go down the road well.
 

colelkhunter

New member
I also heard a rumor that a stock deuce trans. would bolt up to a big block something. I have not been able to find any direct information on this, such as which bellhousing will work or mods that have to be done to the trans. Not that I would consider this unless it was almost direct bolt in with the overdrive gearing which is pricey and would eat up most of the budget and delay things longer.
 

broman78

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fuel is going to continue to go up. With a max of 5 mpg, it would be fun to drive but also expensive. Multi and transmission is proven big block and unknown tranny not proven.
 

colelkhunter

New member
The big block gas engine has been used in 2 tons and dumptrucks for decades. The only real guess would be the overdrive tranny. the 429 that I am looking at is not a hotrod it's a talldeck torque monster from a F600 or something like that dump truck. It weights more than the deuce and is capable of hauling way more. I know the truck that this came out of and it is a 70 something model I think that they bought new. It has been used ever since. With a 5 spd it got around 8 mpg empty, of course it was half that loaded down. They use it mainly to haul a dozer and backhoe around on a pintle trailer. Rode in it a couple times and it gets down the road pretty good even loaded. I would judt like some objective opinions, not just the standard origional is better. which we all know isn;t true or no one would ever Mod. one. Fact is deuces benefit from modification and I am simply looking to make another mod. Make no mistake if i could find a multi for a reasonable price that wouldn't cost me 500.00 in fuel to get home I would be interested. I have a couple months to play with, and am in no hurry to jump on this as my bobber still needs a little work to be finished. I have a hard time letting it sit as I would like to use it this spring and summer.
 
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mudguppy

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if it's an industrial block like you said, i wouldn't hesitate to drop that in place. that means it also has an SAE bolt pattern, yes? well for lowest cost, you could bolt it up to the deuce spicer (with adapter to get it to SAE#3?). i wouldn't - the torque from that gas motor will toast the spicer in short order.

i'd pick up a 5 or 6 speed OD from a truck yard and use that combo. maybe it uses the 385 series bolt pattern which is why your trans guy is offering a Ford auto OD? this would be strange - i didn't think the industrial motors used the 385 transmissions... but i dunno.

either way, i'm in favor of the gas motor going in!
 

AR MOG GEDDON

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This is a really interesting thread, as have always considered swapping out my gas engine for diesel or multi not the other way around. I have ran several 1 tons with BBC 454 engines, and when loaded around 16000lbs they get like 8mpg if you are nice and don’t push it. And if you do push it, you only get there a few min. sooner, and get 6mpg.

As for me, my Deuce has a gas OA331 engine. I am trying to decide between turbocharging the gas engine (I live at 6000ft, and can’t get more than 35MPH up a hill) or swapping it for a Cummins. But as far as the BBC goes, I bet you could count on 8MPG in an unladen Deuce.

Now if you want to put out the cash, and drop in a vortec 7.4 or 8.1, you could get a lot more power and better mileage also. But IMHO a carbureted 454 would get around 8mpg.
 

colelkhunter

New member
I have had a couple folks come forward with multi fuels at a decent price. Still the urge to put a firebreathing big block in it is strong. I know the capabilities and limitations of the stock engines. Still I have to wonder what it would be like to get a HEALTHY big block shoved in there. Something along the lines of a 440 mopar with a blower on it....LOL. Gas miliege would suffer for certain, but the end result would be quite unique. Still up in the air on this and I guess I will let fate decide my direction with the best value being the deciding factor.
 

M543A2

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Something to remember in changing is if you want a winch in the future, you could have problems getting the drive hooked up.
My son and I have done several conversions in other things than Deuces. I can say from them that it always looks like you have the details sorted out in the beginning, but one or more possibly serious complications hit you before you are done. Unless you have welding and machining capability, it soon turns into a money pit.
The thing is to not go so far cutting and modifying the parent vehicle that you cannot go back original if you find the conversion to be very impractical. With the good service we have from our multi fuels, I would never switch one out for a gas or a Cummins 5.9. A properly monitored, turned up well maintained 478 like these is hard to beat. As I have often testified on here, the White farm tractors use them and it is no sweat to get over 4,000 hours on them in harsh heavy load field conditions with power turned up. You will never put that kind of time or load on your truck.
Regards Marti
 

wreckerman893

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had another thought. If it was gas it could also be made to run as a dual fuel on propane. I have seen a couple 1 ton trucks locally that are running propane.
Just about any gas engine can be run on CNG.....but speaking as a person who has to use it for heating and cooking it is getting expensive too. If you get caught running untaxed propane you get the same fine as offroad diesel fuel.

When you add fuel tax to the cost of buying propane you will not see much cost savings. If I remember correctly they get less MPG on propane than gasoline.

I would stick to the multi fuel for ease of maint, fuel flexability and swapping out.
 

oldMan99

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Polk County, Florida
With the stock diesel getting around 10-12 mpg in my other trucks, I am looking to improve on this.
With all respect... I know you did not intend for this to be funny but when I read it I almost fell out of my chair laughing...

There is no way you are ever going to get a big gas engine to get even close to that kind of mileage in a Deuce, must less better.

Look at all the Suburbans and pick-up trucks out there with gas engines (big or small block) These trucks weigh less than half of what a Deuce does and are lucky if they can get 7 or 8 mpg. Using the most modern engineering available Ford was not able to find a way to get more than that in the Excursion. The mileage in the Excursion (even in the Diesel) was so bad that it was bringing the company average for all Ford vehicles MPG to low to meet federal guidelines and they had to drop it from production in 2005.

Assuming properly sized engine to load it is going to be the very rare exception that you will ever be able to get a gas engine to give better MPG than a diesel.

Also, when you make an engine work by hauling a load, heavy vehicle or both the diesel will always last many items over the mileage of what a gas engine will be able to provide before it expires.

Diesels are much more tolerant of extended idling and normally more resistant to overheating and require smaller radiators per given power output.

If your looking for more power and higher RPM than the stock engine then a gas engine will provide that... At the cost of MPG and lifetime of service.

If your looking for more power in a reliable package that will not kill you at the pump and will last many thousands of miles then a larger and/or more modern properly set up turbo charged diesel is realistically your only choice.

Unfortunately you eliminated what would have been my recommendation of installing a Cummings 5.9. This should give you everything your looking for except low initial cost. However, the higher initial cost will be offset by better MPG and engine life, and will give you the power and higher max speed your looking for.

One way to make it slightly more affordable is to buy a complete running truck take the engine and automatic with overdrive trans out and part out the rest of the truck. Take your time, shop for the right truck and when done getting what you want and selling the rest you can actually come out pretty well.

Don't forget that a decently well cared for 5.9 can easily go several hundred thousand miles with ease. If it starts easily, runs smoothly, no water or oil mixed in the radiator or crank case, (Check this before you start it) no big oil leaks no abnormal noises I would not hesitate to get one with even 200,000 miles on it. For a daily driver I would want less miles but for a weekend toy, that will likely see less than 10k miles a year.. No problem...

Lacking the ability/desire to do that, I would make the trip to go get a stock replacement (or have it shipped) and live with stock performance. Going back stock has it's advantages. You retain the "Historical value", no modifications, no backyard engineering, no guessing. You know it fits and works. When/if you go to sell it there are no questions about the quality of the modifications because there were no modifications, only repairs/replacement.

If the choice is stock or gas, my vote would without a question be stock. Of course there is actually more to it than that...

If your use for the truck is going to the mud hole and blasting about then there is not question I would go with a 454 or 460 gas with a decent cam, roller rockers, headers, big carburetter and a torquer II manifold and maybe some spray for extra fun. That is of course if you won't let me put in a built up 450-500hp 5.9 Cummins...lol.

If your use for the truck is more along the lines of what most people consider "Normal use" for such a truck then refer back to my statement of stock over gas without question.

By the way.... Back to the MPG question... I bet a properly set up 5.9 could beat your 10-12mpg by a decent margin if you drove it reasonably.

Just my 2cents ... but you did ask for it... lol.
 
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