830 valves in 730 Head

[Anonymous-0]

Is it possible to put 830 inlet valves in a 730D head. If so do I need to change valve guides. If anyone reading this has done this what were the benefits?

 

[buickanddeere]

More airflow if the ports and manifolds were not the flow limiters.
Even a set of 720/730 valves will flow much more with a good race engine five angle valve job. Vs a Bubba valve job.

 

[Mike Aylward]

Geoff, I assume you are trying to make your 730 breathe better. I believe the stem size is the same in both valves if memory serves me right. One thing to consider, however, is whether or not there is room all around for the larger valve in your head. You can actually use a larger valve and make the head breathe worse if the valve becomes shrouded by the chamber. A large valve gets closer to the edge of the chamber and you can actually hurt rather than help. Mike

 

[F-I-T]

Along with the rest of the comments, I'm not sure that a dry filter air cleaner would not help more.

 

[buickanddeere]

The bore size is identical on the 730 and 830. The face of the head is flat so the 830 valves maybe viable?
Measuring port volume between the two heads would be interesting.

 

[BushogPapa]

Advisable to look for a Performance Cam for that 730 too..
Injector work along with higher cracking pressure..

Ron..

 

[Mike Aylward]

Yes, Glen, I am aware of the same bore size. But if the head is designed for a smaller valve the valve spacing may not be the same. Sometimes bigger is not better. Mike

 

[F-I-T]

Curious, what does the higher cracking pressure do? Do you use to effectively change the timing?

 

[F-I-T]

FWIW, I only have valve specs for the 720D and the 80. Now the 80 shared valves with the 820 and 830, and without typing all of the dimensions here, it appears that at the same bore, IF the centerlines of the valves were located in the same spot, the valve skirts would sit .0985" outside of the 720D set. That might explain why the 80/820/830 head gasket has the scalloped reliefs. Is the top deck of the 80 block relieved as well?

Again not sure what other interference you would experience, if the seats would collide (which I doubt) or if the lodations are indeed the same. On the intake side, you would grow from 2.375" to 2.605". That would grow the area by 20%. On the exhaust side, by 18.5%, both pretty impressive numbers.

 

[jd2cylman]

Higher pressure generates finer mist=more complete burning.
Current Tier IV engines generate 10,000 to 20,000 psi. No more cracking lines to check for, well anything. Injectors are self bleeding and incorrectly firing cylinders are checked with a computer program.

Adrian

 

[F-I-T]

(quoted from post at 19:55:39 07/15/12)
Higher pressure generates finer mist=more complete burning.
Current Tier IV engines generate 10,000 to 20,000 psi. No more cracking lines to check for, well anything. Injectors are self bleeding and incorrectly firing cylinders are checked with a computer program.

Adrian

Ok, but it's a 60 year old engine, and the nozzles have not been EDM'd like those of today. None of what you said is applicable to the 730D. So again, what will you achieve with higher cracking pressure, since you can jimmy that today by changing the spring set and adjusting the timing setting. The compression is still the same since there ain't no turbo, and there is no computer to compensate the mechanical variables. On top of all this, it's still a close second for all time economy at Nebraska.

 

[jd2cylman]

It must be, as our 830 was. It's pretty odd to see the top part of the cylinder walls machined out to make room for the valves. When we were having it bored out, I was a little worried, but that part need not change. Just cleaned it up with emery cloth. So, I suppose 830 valves could work if the bores were properly machined, however, I don't know about the distance between the valves on the 730. That will be the problem I think.
Should be an interesting experiment. I might be able to lay hands on the old 830 valves if you would be interested. They're just hitch pins to us :lol:

Adrian

 

[buickanddeere]

I asked a highly respected expert at Renasance Tractor
about higher cracking pressure.
He assured me that the HP difference is zero. And that cam
and follower failure or pushrod or pump failure will occur.

 

[F-I-T]

(quoted from post at 07:22:05 07/16/12) I asked a highly respected expert at Renasance Tractor
about higher cracking pressure.
He assured me that the HP difference is zero. And that cam
and follower failure or pushrod or pump failure will occur.

That's sort of what I was thinking. For the 45 or so years that I have been around diesels, it seems the cracking pressure has always run around the 1900-2400 range.

 

[Tyler-MO]

I did it on my 720D without doing anything to the cylinder block. I measured everything back then and the valves cleared by over an 1/8" inch (if my memory serves me right. With a .045 oversize bore and intake & exhaust valves from an 820/830 I have a PTO dyno at 66 hp. The fuel rack is set to stock settings also. I'm glad I did the switch to the larger head valves.

 

[F-I-T]

(quoted from post at 08:52:22 07/16/12) I did it on my 720D without doing anything to the cylinder block. I measured everything back then and the valves cleared by over an 1/8" inch (if my memory serves me right. With a .045 oversize bore and intake & exhaust valves from an 820/830 I have a PTO dyno at 66 hp. The fuel rack is set to stock settings also. I'm glad I did the switch to the larger head valves.

Tyler, do you know what you had in hp before? I'd be interested in how much improvement you experienced in the valves alone.

 

[jd2cylman]

(quoted from post at 04:02:57 07/16/12)

Ok, but it's a 60 year old engine, and the nozzles have not been EDM'd like those of today. None of what you said is applicable to the 730D. So again, what will you achieve with higher cracking pressure, since you can jimmy that today by changing the spring set and adjusting the timing setting. The compression is still the same since there ain't no turbo, and there is no computer to compensate the mechanical variables. On top of all this, it's still a close second for all time economy at Nebraska.

I agree. The only thing I would do is set them to the top end of the spec. If the range was 2250 to 2450, I'd go to 2450. I would not set stock injectors above the recommended setting.

Adrian