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1967806

Roosa Master pump differences?

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Is there any difference in the roosa masters on 806 856 1206 1256 other than calibration? I was thinking the 1456's used a 4 plunger head and the other smaller models used a 2 plunger head?

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2 hours ago, 1967806 said:

Is there any difference in the roosa masters on 806 856 1206 1256 other than calibration? I was thinking the 1456's used a 4 plunger head and the other smaller models used a 2 plunger head?

Don’t know the answer but we do have a 806 pump from wrecking yard rebuilt on our 1256. We bought 1256 wrecked with bad motor. They had sold pump off so gave us what they had. Works good set for 1256  even had a 806 cam shaft

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The 1456 used the 4 plunger pump, all the others used the two plunger pump.  Only difference in 806 and 856 is the total degrees of injection advance.  Same with the 1206 and 1256 but IH supplied pump for 856 when you needed new one for 856 and also supplied 1256 pump for  1206.  You were supposed to use a couple less degrees static timing when using the pumps with more advance. 

The four plunger pump gives you a different rate of actual fuel delivery in relation to crankshaft degrees and is a lot touchier if timing if off just a few degrees.   First one we sold was sputtering at high idle in just a few hours as the timing slipped a few degrees due to bolts not being tight on drive.  Customers brother calls, says head gasket is out and I can see bubbles in radiator.  Checked and set timing, ran for years.  

 

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Thanks Pete. I could find a pump off any of the 4 models then and be ok. Phenolic ring is going out on ours and I dont want to pull it off and have to be without it for a week. Thinking Id like to find another pump and have it gone through ahead of time.  

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the earlier pumps had a different style advance than later ones. They will work interchangeably. Best to get an 8 pump for an 8, and a 1026/1206/1256 pump for those. As Pete said, the advance amount is greater on the 8, than it is on the 10/12. Many shops have cores on hand to rebuild for you if you give them your pump number.

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Virtually everything put into that pump can be different.

Different cut on the metering valve, different delivery valve or spring, different advance pistons, etc. etc. etc..

I would put the spare pump on while the original is being overhauled.

A little more work but an hour it should be running.

You then have the original pump back on the old girl.

 

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1 hour ago, Injpumped said:

the earlier pumps had a different style advance than later ones. They will work interchangeably. Best to get an 8 pump for an 8, and a 1026/1206/1256 pump for those. As Pete said, the advance amount is greater on the 8, than it is on the 10/12. Many shops have cores on hand to rebuild for you if you give them your pump number.

Do you have any cores to rebuild?

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I have quite a few, best to know what yours is, and the problem.

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1 hour ago, Injpumped said:

I have quite a few, best to know what yours is, and the problem.

I will look for some numbers on it when I get back to the shop. It starts and runs fine but the phenolic ring must be going out. It died the other day because the return line to the tank plugged up. I blew it out and it runs for now. Dont really want to run it like it is this fall on the augers and stuff.

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is it an 806? Many 806's have 856 pumps.

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Yep. 806 with M&W. Got a picture of the tag. 20190909_135216.thumb.jpg.45c8cff7b14bfe984eecb271eadfc3dc.jpg

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ok, that is a later style pump for an 856. I'll look, and see when I can get it rebuilt. 

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1 hour ago, Injpumped said:

ok, that is a later style pump for an 856. I'll look, and see when I can get it rebuilt. 

Thanks. Just let me know how far out you are booked up.

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