VT 49 & VT 61

HP engines (Hirtenberger, AG Austria) tech support. Owned by RJL Industries since 1990

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VT 49 & VT 61

Postby Zelio » Sun May 13, 2007 4:38 pm

I have recently been given both a 49 & a 61 to overhaul and set up. Both engines are Austrian built and have bearing heads.

I have now dis-assembled the engines and have found in both cases that the pinion shaft has moved forward and 'machined' away about 25% of the thickness of the connecting rods! In both engines the strap (saddle) screws were VERY tight but the shafts had still moved.

Question 1 - Is this a known problem and if so is there a mod or fix for this?


In the 49 the front bearing is plastic shielded both sides while the rear bearing is open. In the 61 both bearings are plastic shielded both sides.

Question 2 - Which is correct?


I notice in your parts list for these engines you list a 'Bearing head update kit'

Question 3 - Can you give a brief description of this please.


Your parts list also details a çon rod shim'. There are no shims in either of these engines.

Question 4 - Where does this shim go (in front or behind the rod)? Do all engines have it?


The owner of the engines has had trouble with fuel draw - both engines have the main needle wound so far out they are almost off their threads! The engines were run with 20% oil but only 5% castor. Both also had muffler pressure to the tanks.
I have now read your comments about the importance of correct oil % and type and will try this when I set them up.

Question 5 - do you think this is likely to solve the WOT needle setting issue? I would have thought that valve sealing would have been critical a low speed rather than WOT. If not can you suggest anything else?

Many thanks,
Zelio
 
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Joined: Sun May 13, 2007 4:05 pm

Postby MECOA » Mon May 14, 2007 11:02 am

lots of questions so I will copy and paste your post with my answers

----

I have now dis-assembled the engines and have found in both cases that the pinion shaft has moved forward and 'machined' away about 25% of the thickness of the connecting rods! In both engines the strap (saddle) screws were VERY tight but the shafts had still moved.

Question 1 - Is this a known problem and if so is there a mod or fix for this?


This will usually happen if there is excessive drag on the valve from the use of the incorrect glow plug or improper shimming of the valve. The gear is twisted trying to turn the valve and the pin will work its way out.

the only fix I can give is to silver solder the strap to the pin. You must use silver solder, not lead.

-------

In the 49 the front bearing is plastic shielded both sides while the rear bearing is open. In the 61 both bearings are plastic shielded both sides.

Question 2 - Which is correct?


The open rear bearing is preferred so it can receive oil from the fuel. I have no clue why you have a sealed one.

I notice in your parts list for these engines you list a 'Bearing head update kit'

Question 3 - Can you give a brief description of this please.


Valve cover, roller bearing, bearing race, and gasket.

-----

Your parts list also details a çon rod shim'. There are no shims in either of these engines.

Question 4 - Where does this shim go (in front or behind the rod)? Do all engines have it?


The shim goes between the rod and the gear to keep the rod from contacting the drive slot on the gear. (another reason the pin may have worked its way out)

-----

The owner of the engines has had trouble with fuel draw - both engines have the main needle wound so far out they are almost off their threads! The engines were run with 20% oil but only 5% castor. Both also had muffler pressure to the tanks.
I have now read your comments about the importance of correct oil % and type and will try this when I set them up.

Question 5 - do you think this is likely to solve the WOT needle setting issue? I would have thought that valve sealing would have been critical a low speed rather than WOT. If not can you suggest anything else?


(WOT means Wide Open Throttle) Usually at WOT it is a timing issue or an extreamly worn valve. Be dure the idle nedle isn't in too far as it will restrice the high speed needle. I suggest backing out the idle needle very far and start by tuning the high speed mixture first.
MECOA
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