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Old 18-01-2009, 03:16 PM   #1
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XR2 throttle/timing arm question and some fuel-stuff.

New to the Merc XR2...

Got some question about the throttle/timing arm on my XR2-I have just swapped this powerhead for a 2.5EFi i had laying in parts so it have not been fitted on the boat yet.

The other day, when having a coffee in the workshop, I pulled the throttle arm right back to WOT/full throttle and when doing so I noticed that the timing arm stopped about 3mm from the block. (Meaning the screw on the timing-arm stopped 3mm from the block, where it`s supposed to hit/stop.)

Tried again and same happended-the arm would go all the way when pushing it...

This function is supposed to run smothly right? Full throttle=full timing advance?
Or is there a difference when the Whole Throttle-system with linkage/Wire and all fitted and engine is running?

This powerhead is bone stock and has been kept as a reserve or something-because it has little running time from new and is in overall great shape.
Probably just a minor problem, just thought I should take it up with the wise men...


As for the fuel question, how do you set up this engine fuel-wise? I`m planning on using the stock block pump and not any red Holley (K.I.S.S)
Do you just run a single 10mm from the tank and that`s it? The pump on the engine does all the works or do you need to fit a manual pump on the line?(Bulb)

I`m also having a new tank welded, will the pump have any issues with pumping the fuel up from the tank through the top of the tank(pipe down from the top of the tank-the EFi pump surged with this solution) or should I make a sump i n the bottom of the tank and go out through there? (thinking about leaks here)...I`m kinda a novice with these engines, so have mercy!

Greetings from up north!
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Old 18-01-2009, 03:36 PM   #2
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sometimes the timing arms stick slightly, you can get over this by fitting a small spring on the timing arm and then onto the top of the head this helps gain full advance.
As for the fuel if you are using the stock mechanical pump then a priming bulb will be needed in the supply line, with your fuel tank make sure its baffled, and get the pick up pipe as close to the bottom of the tank as possible
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Old 18-01-2009, 03:51 PM   #3
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Okay Burty-Thanks!

I`ll look into it when I get back to the shop tomorrow, you wouldn`t have any pic`s of the spring-solution would you? As the spring would need to have enough tension to pull the Timing all the way to "full advance" and then go all the way back when letting of the throttle again...

The tank will be buffled of course, so the top of the tank is the way to go right? the pump will provide enough suction to provide a good fuel delivery to the engine?
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Old 18-01-2009, 05:13 PM   #4
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There can be a number of reasons for it not obtaining full advance. I would check the timing and sync if I was you, you shouldn't need to fit an additional spring to obtain full advance. It can be as simple as poorly routed trigger wires or overtight or incorrectly fitted throttle arm. If you don't know the history of the engine check everything before running it IT'S FAR CHEAPER.
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Old 18-01-2009, 05:57 PM   #5
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Quote:
Originally Posted by HT20 View Post
Okay Burty-Thanks!

I`ll look into it when I get back to the shop tomorrow, you wouldn`t have any pic`s of the spring-solution would you? As the spring would need to have enough tension to pull the Timing all the way to "full advance" and then go all the way back when letting of the throttle again...

The tank will be buffled of course, so the top of the tank is the way to go right? the pump will provide enough suction to provide a good fuel delivery to the engine?
here you go, you will never have problems with it returning as it is forced back by the throttle arm
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Old 19-01-2009, 03:31 PM   #6
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..........

Thanks Techteam and Burty...


I`ll look into the engine about the cable routing and clean/lube the arm up again, but I think I will install the spring to, just to make sure it goes all the way.
As for the rest of the engine I`m pretty sure it is all the former owner say it is, pluss it has 125-130si on all holes when cold. And it looks the part to.(Have seen a few...some bad some good.)

It wasn`t like it was hard to push all the way to full advance, it just needed a little help the last 3mm.

Thanks for the help and the picture!
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Old 19-01-2009, 03:37 PM   #7
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No problem, If you do fit the spring make sure the timing is spot on you don't want the spring to pull in too much advance especially on a manual fuel pump.
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Old 19-01-2009, 03:44 PM   #8
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Thanks for the advice! I`ll look into it a little later in the season when the boat is ready for testing (check the timing etc.)
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Old 23-01-2009, 05:43 PM   #9
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Sticky throttle arm.

In my experience the poblem with the the throttle arm is often the trigger wire routing is too tight where it runs past the top cowl support bracket, limiting movement, or the armour on the cable in the same place has gone hard and simply needs replacing. Hope this helps.
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Old 23-01-2009, 06:58 PM   #10
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........

I was back at the shop the other day, and after looking at it-it seems the wires is the case here too...

Thanks for the tips!
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