2 cylinder diesels fact vs fiction

REDEYE

Member
I am starting to look at building a JD 2 cylinders diesel, don't know much about them and have found that there is not much info out there and a lot of is is conflicting. I was hoping to get some help to straighten some of it out. I would really like to be somewhat competitive at 6500# 3 mph. There are some big cube olivers and molines that run well, but I think 3 MPH will even it out some. I know that an NA diesel will not make as much power as gas and they are heavier, but my 20 month old daughter loves to watch youtube videos of tractor pulling and how can you argue with a baby that wants to "watch smokes" with daddy when I get home from work. She takes a special interest in the Full Strut and Super Strut videos. I have probably watched them 100 times with her. No complaints.

Anyhow here is what I know is fact:
730D Nebraska test 594 56.66 HP 7899# with 15.5-38 and operator
830 Nebraska test 632 72.8 HP 8729# with 15-34 and operator

Now comes the claims I found and need some help with:

R/80/820/830
There are big bore blocks (8") for 820/30. 8" bore X 8" stock stoke 830 would be 804ci. (where do you get them?)
With a little work they can be lightened to 6500lbs or less. (hard to believe)
R missing center main and breaks cranks at 100 hp (believable)
Easy to get an 830 under 7500 and over 100 hp (believable)

70/720/730
70 does not have creeper, to fast to pull (believable)
730 10% over rpm and full rack will make 97 hp (hard to believe)
Can't stroke them due to hollow journals, if you do they break (believable)
Run a Cummins piston offset ground crank with welded G rod ends on the crank @ 3.300" journal; bushings in the piston (maybe)

I think some of these claims are hard to swallow am I on the mark with my comments? Who are the better shops to work with for the JD diesels?
 
A 730 with STOCK pumps set up the whole way will make ~65-68hp at 540 pto rpm. As long as the rest of the engine and fuel system is up to snuff. That's what I saw on the dyno anyways.

That's the only one I can answer for you.
 
fact#1 820 block will bolt on an R 820 head would then go on but fuel filers and mounts will need to be fabbed

fact#2 820 crank will fit into R. 720 center support could be added

fact#3 11 inch stroke possible billet crank probably

Fact#4 stock block could be sleeved and welded to 7 or 7.5". yes new 8" blocks were made, expensive. not that difficult to make new solid block but expensive. pistons rings $$$

fact #5 a new from scratch 4 valve head would be best for any thing over 800 cubes

fact #6 new custom fuel system will be in order 15mm pumps minimum.I have always dreamt of common rail or common rail + stock type fuel system

fact #7 stock rebuild can run $5000 and up. you could add the price of a new pickup or more to do all of the above

Paul
 
I think Garry Power built the fuel system in the strut tractors. I would contact him, he's the best at 2 cyl diesels. Not sure of his contact info, do a search on this site you'll find it.
 

Beyond the usual "Build', improve the INLET air flow from one end to the other.
An NA 2 cylinder Diesel (especially) NEEDS all the air it can draw...
The bigger you make it, the better the Inlet air-flow has to be also..
Those "Full Strut" videos are really something to watch..!!

Ron.
 

No need to set the pumps "all the way up"..it only makes smoke..
What DOES do the job is a Performance Cam, larger pumps with higher cracking pressure and a very high Flow air entry to the Intake valve.
One at Plain City, Ohio is a JD 70..
It Pulls like a locomotive and shows NO smoke at all..
Has throttle response like a nice healthy Gas 720..
 
You will be able to get a 720D in 6500 but its going to take lots of parts removal and custom flat back.
I pull a 720D electric start and it just makes 7500 with a narrow front and 18.4-38's on pressed steel wheels. No weight to move around. Still has rockshaft and hyds.
Also if your pulling 3mph a stock 720 will be competitive. Mine is a creeper and run 2nd gear up to 10,500, and never blows the 3mph horn.
It is possible to make .22hp/ci with a good fuel system (not stock size injectors or pumps) in a 720. Yes it will make more smoke along with power. I got mine from Garry Power, he checks in here, if not I can get a hold of him.
 
You can get creepers for both the 700 and 800 series 2 cylinders.
This is my 820...
It's got a few extra hp. :)

16508.jpg


Maybe you'd like to just buy mine and save yourself all the work? :)
- Creepers
- XXXL rubber (combine tires something like 31 x 32's? I forget) on brandy new rims with tubes.
- roughly 200 hp (big bore not stroked)
- Industrial front end and pan
- Filled skidder front tires
- Power steering
- Rigitized rear. Rear is reinforced to main case
- Head is ported and polished etc. and fitted with 3-1/16" diameter intakes and the old intakes are now the exhaust
- All topped off with pretty double wall stainless stacks and a bunch of other new parts.

As it is you won't be pulling in any light classes and just exhibition pulling at any standard pull.

16509.jpg
 
Long time since we've chatted... Hope all is well with you...!

Not really planning on selling but if I could get a good part of what I have in it back I'd sell and maybe build something else. Been so busy at work last year+ that I didn't even fire it up last summer. I was told they were changing the rules in the King of the mountain pull so I didn't go this last year. Won a couple years and lost one year when it was super muddy. Couldn't get down to any dirt with the floaters on it so skinny tires whooped me. Hind sight I should've put it in third and thrown some mud... :)
Dry track it's hard to beat in a dead sled pull.

I'm going to make a point to light it up this year and take it for a stretch. Want to drain all the fuel and change the filters and put fresh in it. The fuel in it has been in there for about three years and I'm afraid to run it through it. Might be infested with gunk.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top