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Valve Adjustment On E9 500

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I've pulled the heads for a valve job and new head gaskets. Everything is nearing completion and I am ready to set the valve lash on the E9. It has the mack engine brake.

I have a Mack service manual for the motor and it says to set the valve lash at TDC which corresponds to the timing marks aligning with the P mark. My understanding is that this P references the Pump timing and the V mark references the valve timing. Somewhere, I've read where other Mack motors set their valves when the timing is set at the V mark.

Which is the correct procedure? Should TDC be aligned with the P mark or the V mark? I'm thinking that maybe someone set the gear timing wrong if the V mark should be TDC.

Now is the time to get this resolved while the motor is still out of the truck. I would appreciate any available expert advice on this motor.

Thanks

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I've pulled the heads for a valve job and new head gaskets. Everything is nearing completion and I am ready to set the valve lash on the E9. It has the mack engine brake.

I have a Mack service manual for the motor and it says to set the valve lash at TDC which corresponds to the timing marks aligning with the P mark. My understanding is that this P references the Pump timing and the V mark references the valve timing. Somewhere, I've read where other Mack motors set their valves when the timing is set at the V mark.

Which is the correct procedure? Should TDC be aligned with the P mark or the V mark? I'm thinking that maybe someone set the gear timing wrong if the V mark should be TDC.

Now is the time to get this resolved while the motor is still out of the truck. I would appreciate any available expert advice on this motor.

Thanks

You can't set the cam timing wrong its doweled! V is valve set p, is pump timing ! Set at V in firing order! They changed the pump timing some when they moved to the robert bosch pump for some reason.the other stuff your reading is likly for an engine equiped with the ambac fuel system they use the same pointer for timing and valve set on those!

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Thanks for the reply.

The Mack museum sent me a copy of the original owners manual and maintenance manual. The maintenance manual corresponds with the service book that I already had. "valves must be adjusted in firing order sequence with the piston at the top of its compression stroke." TDC corresponds to the P pointer. I've already determined that with a dial indicator when I had the heads removed. The V pointer corresponds to ATDC.

If these adjustments are to be made at TDC then why does the pointer not line up at the V mark if that is where TDC is supposed to be?

If the timing is located via dowel pins, there should be no way to get this wrong. I've not finished the re-assembly and insertion process yet. I just want to make sure things are set correctly.

I guess I will need to put the dial indicator on the rockers to see how much of a difference the 2 marks have between them in order to satisfy my curiosity and confusion on this matter.

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Thanks for the reply.

The Mack museum sent me a copy of the original owners manual and maintenance manual. The maintenance manual corresponds with the service book that I already had. "valves must be adjusted in firing order sequence with the piston at the top of its compression stroke." TDC corresponds to the P pointer. I've already determined that with a dial indicator when I had the heads removed. The V pointer corresponds to ATDC.

If these adjustments are to be made at TDC then why does the pointer not line up at the V mark if that is where TDC is supposed to be?

If the timing is located via dowel pins, there should be no way to get this wrong. I've not finished the re-assembly and insertion process yet. I just want to make sure things are set correctly.

I guess I will need to put the dial indicator on the rockers to see how much of a difference the 2 marks have between them in order to satisfy my curiosity and confusion on this matter.

The manual is telling you to set valves at tdc and that is telling you not to set on the exhast stocke and when it said tdc that is when the piston is at tdc but not at a perfect tdc because that cam is probley has the dynotard ground ramp in the exhaust close to the tdc and if you try to set exhaust valve at tdc you can be in the dynotard ramp and then when you get out of that the your valve will be too tight so they make another mark away from tdc then tell you to set the valves ther .I dont work on that engine but the 6 cylinders are like that and when you set the valves like you should then you can turn the engine over and check the clearance on the exhaust valve as you turn it and you will feel the engine brack ramp as it will have excess clearance at one point. hope you can under stand what i am try to tell you if not call me. glenn

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The manual is telling you to set valves at tdc and that is telling you not to set on the exhast stocke and when it said tdc that is when the piston is at tdc but not at a perfect tdc because that cam is probley has the dynotard ground ramp in the exhaust close to the tdc and if you try to set exhaust valve at tdc you can be in the dynotard ramp and then when you get out of that the your valve will be too tight so they make another mark away from tdc then tell you to set the valves ther .I dont work on that engine but the 6 cylinders are like that and when you set the valves like you should then you can turn the engine over and check the clearance on the exhaust valve as you turn it and you will feel the engine brack ramp as it will have excess clearance at one point. hope you can under stand what i am try to tell you if not call me. glenn

Would you please clarifi if you have a V pump ( AMBAC) Or Robert Bosch! If you have robert bosch use the v pointer to set the valves . The p pointer is for instalation of the fuel pump! If your using the v pump then the tdc pump pointer valve set pointer are all the same one mounted right hand lower of the timing cover directly behind the AC pump if equiped!If the directions you have are not for the robert bosch style pump engine which was intoduced in the late 80s early 90s there will be no mention of the second pointer.the manul u are useing may not be for that engine! Rule of thumb ! If that engine has a STRAIGHT fuel pump ( ROB Bosch)

USE THE V Pointer to set valves If it has an ambac pump that looks like a mini v8 in the valley then use the tdc pointer to set valves.

By the way if it has the rob bosch pump the fuel lines can be a real bear to get sealed to the injectors ,be prepared to buy several injection lines before your done!

Edited by fjh

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Would you please clarifi if you have a V pump ( AMBAC) Or Robert Bosch! If you have robert bosch use the v pointer to set the valves . The p pointer is for instalation of the fuel pump! If your using the v pump then the tdc pump pointer valve set pointer are all the same one mounted right hand lower of the timing cover directly behind the AC pump if equiped!If the directions you have are not for the robert bosch style pump engine which was intoduced in the late 80s early 90s there will be no mention of the second pointer.the manul u are useing may not be for that engine! Rule of thumb ! If that engine has a STRAIGHT fuel pump ( ROB Bosch)

USE THE V Pointer to set valves If it has an ambac pump that looks like a mini v8 in the valley then use the tdc pointer to set valves.

By the way if it has the rob bosch pump the fuel lines can be a real bear to get sealed to the injectors ,be prepared to buy several injection lines before your done!

My engine has the Robt. Bosch pump. I've reset the valves as of today and the difference between using the P and the V mark is minimal. About 0.002" difference was noted on a couple of the valves when I checked them before resetting them to the proper timing mark. I don't see how the engine could be damaged if the wrong mark is used, although I do prefer to have the timing set correctly.

The engine is now back together, running and awaiting a road test. It should be noted that on the retorque of my heads after the initial run in period that there was a significant amount of take up on the re-torque. While none of the bolts were loose, every one of them seemed to take up considerably more slack when re-torqued. I don't remember if I ever re-torqued my E6 a couple years back, but I will always check after todays demonstration. It is time consuming to perform but it should be well worth the invested time to do the job right!

Thanks to all who posted their helpful opinions on this matter of correct valve timing.

post-1547-1193981207_thumb.jpg

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My engine has the Robt. Bosch pump. I've reset the valves as of today and the difference between using the P and the V mark is minimal. About 0.002" difference was noted on a couple of the valves when I checked them before resetting them to the proper timing mark. I don't see how the engine could be damaged if the wrong mark is used, although I do prefer to have the timing set correctly.

The engine is now back together, running and awaiting a road test. It should be noted that on the retorque of my heads after the initial run in period that there was a significant amount of take up on the re-torque. While none of the bolts were loose, every one of them seemed to take up considerably more slack when re-torqued. I don't remember if I ever re-torqued my E6 a couple years back, but I will always check after todays demonstration. It is time consuming to perform but it should be well worth the invested time to do the job right!

Thanks to all who posted their helpful opinions on this matter of correct valve timing.

post-1547-1193981207_thumb.jpg

GOOD JOB BUD

Apears to be an rd 800 or dmm your working on???

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