Bi-directional pistons??

Well gents,

after doing some investigating on this 268 block in the shop. It turns out that its not out of a 7710 like i was told, the numbers cross to a 9030 versatile. Its still a 268 NH block tho.. As I mentioned before it has only 2 compression rings per piston. So after much scrounging I came up with a part number for replacement rings. I called my supplier and had sticker shock on the cost, so while i had them on the line i asked about replacement pistons. I was informed that they could get rings but pistons are not available thru them, they are a special "Bi directional piston" that wasn't used much. Can anyone explain this to me. IN simple English Please.. I did notice that the 9030 has a higher compression ratio. Is that it? Now im wondering do i just get a tractor inframe kit and proceed??

Beginning to think maybe this block needs to be a boat anchor..

Thanks
 
How about what was used in the GM Jimmy 671 2 stroker (6 cylinder 71 cu in per cylinder), very popular at the time...I think city busses used them en-mass. Lots of "rock buckets running them on bobtails with 10 on the floor. An experienced driver could make those suckers play some sweet music.......had oil leaking problems as I recall.

Recollecting the fuel-air inlets and exhaust ports were in the center of the block and the pistons were on either end (opposed) attached to the same lobe on the crank (I think) so you got suck and blow simultaneously with one rev of the crankshaft. Don't quote me on any of this except the music part.
 
thats what im wondering. NH wants $94 per hole for the proper rings. I can get an 7710 overhaul kit with standard tractor pistons for around $500. Does anyone see or know of a reason why it wouldn't work?
 

When rebuilding a motor I always source the parts through the automotive machine shop. The one that I did last spring was out of a somewhat rare 50 year old car. The website that carries the most parts for this car wanted about $100.00 apiece for them. My machine shop got them for half that. Those guys shop for this stuff everyday and have good sources.
 
Did that. thru my machinist the aftermarket price for those Bi-directional rings is $65.58 per hole plus S&H etc etc.

65.58x4= 262.32 so say $275 for just rings..
and still need gaskets, The upper set with head gasket is anywhere from 80-150, lower set about the same.
Adds up to the cost of a kit quick.


Time to throw the old green canvas army tarp over it again for a while and work on a different job for a bit..
 

What is it that your working on?
I've seen post about stuck rings but no info on what it is, tractor, ind power unit?
A photo of the pistons and rods would help.
Never heard of bi directional pistons, some of those engines used a headland top ring that was only used a few years, if you have those pistons I'd replace them with a set of normal style pistons. Most of the turbo engines had Keystone style tapered top rings.
They changed the rods on the later engines which require a different piston.
What are you working on?
What are you wanting to build?
 
Its a 268 NH web block, the plan is/was to build it and put in in a 5000 basket case.


The original block had porosity, they had been adding water to it for some time, then water and freezing temps made it null and void. The rear exh port was completely plugged with carbon, cyl 3 was partial plugged..It had been run that way for some time..

The story I got with this used replacement block (short block configuration: crank,balancer,rods,pistons,cam,timing cover) was it was from a 7710 that had a cab fire. I decided while it was that far down to pull it apart and measure everything. Bores look like a simple hone and they will run, all bearings are std.

I got the pistons out and they had 2 compression and 1 oil ring, but not old headland style, and they are gunked up bad, piston #4 had the second compression ring stuck so bad I had to heat it to get it out of the ring land. I started trying to locate rings, every time I find 7710 rings they have 3 compression rings and 1 oil ring.
So I start chasing numbers, Bern confirms that the right pan rail numbers are NH numbers. 87840243 Part number 3m14 date code dec 14 93. 87840243 is the engine code for a 9030 versatile. So I look up 9030 and find 2 options for pistons and rings.. one of which is the same as the ones i have been looking for. NH is $95 per set, Reliance does them for 65.58 a set.
I was told these pistons are bi-directional pistons and have a higher compression ratio.

I hope someone can tell me if I can put standard 7710 pistons in it..

not looking for 100+ hp 75 would be plenty

Keep in mind, I wrench for the local Government 40+hrs a week and still help dad with the family farm. I do these oddball, weird, basketcase jobs on the side. Sometimes they are fun... Sometimes they make me want tear out what little hair I have left..
 
I don't want to wade in too deep over my head on this discussion but I think you are working on a BSD444HT engine. H for Headland and T for turbo. The tractor is Bi Directional, not the pistons. I have replaced the Headland pistons in the 3 cyl engines that were naturally aspirated and have never had a problem. The turbo piston may be different due to the size of the combustion chamber. The bore is 4.4 and the wristpin is 1.625 on both. The distance from the top of the wristpin to the top of the piston would need to be verified. I can get the rings for a good bit less than you were quoted but I have never personally seen a set of Headland pistons that were reusable. Pistons are still available but expensive.
 
yes the tractor is bi-directional.. the explanation Is the bi directional 9030 had over 17/1 compression ratio, the 7710 has a compression ratio of 15.6/1.. also the 9030 engine was rated at 2500 rpm a 7710 was rated at 2100.
 
If it would help you or someone else
I have a good pair of headland pistons here.
They are from a NA 201 that was on an irrigation pump. Judging by damage to the head and piston it sucked a 7/16" nut into #2 piston.
The bores look almost new.
I saved them just because.
Would let them go pretty cheaply to someone who could use them.
 

How much of the 268 do you have, complete engine with turbo, long block, short block?
You said you where working on a basket case 5000 with a bad block so you have a few choices.
You can use the 5000's crank and rods to build a 256 engine.
268 crank with the 5000's rods and a kit for a 6610 will get you a natural aspirated 268, my 6610 is 72 pto hp
Or if you have all of the parts you can build a complete 268 turbo engine which will get you 85-100hp
If you don't have the turbo or plan to use it I'd got with the cheaper naturally aspirated kit.
If your not to far away I'd be willing to trade you a good 5000 block for the 268 block, I'm building a 256 turbo engine and am not looking forward to drilling and taping the oil fittings in the block for the turbo.
 
I have the 268 block with crank, balancer, rods, cam and timing cover..

I have the complete 5000 engine (I hope, it showed up in buckets and boxes!!) but from what Ive seen everything seems to be there.. FYI the original is a 233, it has eaten enough water that the crank needs ground.

So the plan was to just re-ring and bearing the 268 block, change the front timing plate so we can use the 5000 inj pump.
I have the tools and can rework the head, I also have the tools to check and build the injectors.

sounds simple doesnt it.. til we go to put the block on the stand.. the head bolts are the wrong size, newer blocks are 9/16 bolts not 1/2. ok NH has a stud kit.(OUCH). My father is a machinist, and says he can build the studs. I get the pistons out and now we are here..

Thanks Destroked
it seems you understand basket cases too.

OH where are you located... Im in Idaho..
 

233 is the small bore block but has the same stroke as a 256.
Can you post a photo of the pistons.
I'd probably use the 268 crank, 5000 rods and get a rebuild kit for a late 6600 or early 6610, I'd also talk to you dad about boring the holes in the head for 9/16 bolts and forget the special studs.
After a bit of search I found the pistons used in the 9030 where also used in the 6.6/7.8 Brazilian truck engines.
But the rings where used in a verity of tractor engines including the 4630 turbo, 7740 and a number of the later Genesis engines.
Located the rings thru parts spring for $45 per hole.

Piston # 83993129 supersedes E9HZ6108A and E7HN6108LA
Ring #87802834 supersedes 87802834 these rings fit a large number of Ford/NH turbo diesel engines.
 
Yes that's the right number for the rings! Parts Spring?? never heard of that one before..

I'll see if I can get pics of the pistons in the next few days.

Ive wondered about boring out the head bolt holes with the mill or magnetic drill. Id also have to bore out the rocker arm shaft and supports that could be tricky..


Kentucky, well I don't see us swapping blocks then..

Thanks again
 
(quoted from post at 22:09:07 11/12/19)

Kentucky, well I don't see us swapping blocks then..

Darn it!
Guess I'm back to drilling on mine.
Good luck with yours.
If you in up going with a rebuild kit check out Ag Kits, they have reasonable prices with Reliance parts, good stuff.
Rebuilt a DT466 in a combine recently with Reliance parts, I was impressed with the quality.
This site also sales kits but I haven't used one yet.
Normally get my kits thru my local machine shop, they give me a good discount.
 
The 6-71 (in fact ALL -71 series engines) were not opposed piston design. There were ports in the side of the block that were pressurized by the Blower; and there were exhaust valves in the head.

There were 2-cycle engines made like you mention, but they were usually very large engines like for Ships and perhaps locomotives; and also German Junkers aircraft Diesel engines of WW2.
 
I have used kits from here on a customers 8n.. My last rebuild for myself was a 2000 3cyl gasser, I used a reliance kit for it... ive had good lock with both.. Ag Kits is the retail side of reliance.. ive been on the phone with both sides and they have great customer service.

Thanks again... ill keep posting as I proceed
 

Not sure about today but locomotives used to run EMD "Electromotive Diesels" similar to ones used on river barges.
Large V configuration in 12, 16 and 20 cylinder, basically a really big 2 cycle Detroit Diesel with a 18" bore and 24" stroke.
I worked in the engine room a river barges when I was a younger man but I was to dumb to stay there and make a career out of it.
I'd be setting on a nice retirement check now if I had. :cry:
 
Drilling the head shouldn t be a problem. A neighbor installed a 304 short block in a 7700 with the 256 head, couldn t find a 256/268 at the time. He drilled the head out himself with no issues. The rocker hold downs and shaft shouldn t be an issue with a mill or a good drill press.
 

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