Hello needing some help on a P40

[FG45]

Hello, I have a Komatsu FG45-4 forklift with a P40 Nissan motor and it has a Hitachi DAF342-70 Carb.
Weeks of research has led me to here. I can not find that carb anywhere, so I have finally started looking for an alternative. I thought maybe some other model of the DAF342 would work, and then started seeing some Webers and alternatives that may work.

So I am here hoping someone can give me some help or advice.

Really appreciate it!

Thanks

[Esteban]

Hello, I have a Komatsu FG45-4 forklift with a P40 Nissan motor and it has a Hitachi DAF342-70 Carb.
Weeks of research has led me to here. I can not find that carb anywhere, so I have finally started looking for an alternative. I thought maybe some other model of the DAF342 would work, and then started seeing some Webers and alternatives that may work.

So I am here hoping someone can give me some help or advice.

Really appreciate it!

Thanks

Sorry bout the carb problems. Unfortunately, our Patrols use the P engine with a single barrel carburetor, so most of us won't have an idea. There were a few years with Patrols being equipped with the P40 engine, between 1980 to 1984.

I hope member Johnnyroadkill chimes in. He knows how much CFM the carb should be rated. Probably between 240 to 300 CFM. Look for a Weber in that range.

Please come back with your findings if you go the route of the Weber.

[FG45]

CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456

241.40 cu/in x 4400 max rpm = 1,062,160
1,062,160 x .85 = 902,836
902,836 / 3456 = 261 CFM

241.40 cu/in x 5400 max rpm = 1,303,560
1,303,560 x .85 = 1,108,026
1,108,026 / 3456 = 320 CFM

Looks like you are about right on, its just a forklift so not really taking it to redline. I am thinking a 300CFM would probably be good.
How do I know what webers will bolt up to the P40 manifold with that CFM range?

Thanks

[Esteban]

There is an online service manual for the 160 & 61 Patrol (the 160 is also known as the MQ). The 160 model was fitted with the P40 engine as well as the L28. The following is the link to the Fuel section that has all the specs for the carburetor. Might come handy eventually.

https://www.mq-patrol.com/service-manua ... hapter-05/

And this one is for the main page of the manual:

https://www.mq-patrol.com/service-manua ... nual-1980/

[Johnny Roadkill]

A Weber 32/36DGV or DGAV would be about the right CFM rating and was a common swap for 4-cyl Datsuns running a Hitachi 2BBL from the factory using an adapter plate...companies like Redline in Australia used to make those but I don't know if they're still available.

Holley 350 2BBL will flow more but be thirstier, again an adapter will be needed and the one I have is a hack job, not something off the shelf.

I suspect you might need another Hitachi for a bolt-up swap...

Cheers,
D

[Esteban]

...again an adapter will be needed and the one I have is a hack job, not something off the shelf.
Cheers,
D

Johnny, member FG45 has the P40 engine, so no adapter will be needed if he goes to a two barrel Weber.

[FG45]

A Weber 32/36DGV or DGAV would be about the right CFM rating and was a common swap for 4-cyl Datsuns running a Hitachi 2BBL from the factory using an adapter plate...companies like Redline in Australia used to make those but I don't know if they're still available.

Holley 350 2BBL will flow more but be thirstier, again an adapter will be needed and the one I have is a hack job, not something off the shelf.

I suspect you might need another Hitachi for a bolt-up swap...

Cheers,
D

This link is saying a 32/36 is for 1200cc-2300cc, the P40 is a 4000cc motor:
https://motofaction.org/mechanical-101/ ... fferences/

[Johnny Roadkill]

I hope you're right about the adapter not being needed Esteban, I can't say whether or not that's true in this case - I did pop down and measure the stud pattern on my G61 manifold (originally a P40 motor with Hitachi 2BBL) and it's as close as I can measure without removing the carb to 1.75 x 3.125 inches if that helps.

As for CFM requirements, the Ford 2 litre in Escorts and Cortinas came with that Weber carb...CFM is somewhat proportional to horsepower - all else being equal - and also to capacity x revs x efficiency, and I would expect a more modern OHC engine (compared to a P/P40) to be more efficient, spin to over 6000rpm and make nearly as much HP. Additionally, smaller revvier motors seem from my understanding to be over-carburettored compared to larger motors of the same advertised power output. Esteban and others may remember me prattling on 8 years ago about hot Datsun L4 motors running twin 2BBL sidedraughts with 900CFM capacity, but they sure don't use all of that. It seems to me a higher inertia engine can squeeze more power out of a CFM rating, or perhaps peak power isn't at max rpm like it tends to be in a smaller motor ?

Having said all that - I've never done this carb swap on a P40 so this is all one person's opinion only, even if a rather verbose one !

Cheers,
D

[Esteban]

Great input Johnny! Thanks for your insight about this topic.

We have some homework to do tonight!

[FG45]

Thanks for all the information. I'm placing an order on a 32/36DGV. Once it gets here I'll post back if it bolts directly on and how it turns out.