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Just got around to starting my re-built engine (PI), good news is it started, bad news is that the revs went up quite quickly to beyond 3,000 so I turned ignition off.

First assumption was the idle screw was too far in, but I re-started and no amount of winding (in or out) the idle screw made any difference...

My next assumption was the butterflies had somehow opened, but lifting off the air box showed they were definitely closed...

Vacuum pipe to the servo, PI Meter, and to the idle screw are in place (as is the (new) air filter).

Manifold gasket all looks secure as do the pipes interconnecting the manifolds...

My possibly dumb question is can the PI meter deliver too much fuel (I've replaced 2 of the injectors but the other 4 looked fine), and can just pushing fuel in make it rev faster ? I thought you need air as well to make it rev....

Any thoughts most welcome especially any diagnostic hints ?

Many thanks.

Mac.

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Have you tried rearing the ignition, turn dizzy to get to slower idle ?

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Have you tried retarding the ignition, turn dizzy to get to slower idle ?

Edited by RobinTR6
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Yeah Mac, the Air Screw winds in to reduce revs! Or sounds like an air leak?

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as above this sounds like an air leak.

 

the idle control is just an air bleed, ie it lets more air in to increase the idle.

 

so if ther's n air leak elsewhere it will cause a fast idle.

 

steve

 

PS, i see you are in Woking, nearby if you need a hand at the weekend?

Edited by SDerbyshire
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Almost certainly an air leak on the throttle body to manifold. better to use a good quality gasket rather than the paper one in most kits. also you really do have to swing on the bolts to make this joint air tight. And finally you could use the Churchill tool to align the throttle bodies, this will make sure that they are flush with the head and perfectly in line for the throttle linkage to work perfectly.

 

Dave B

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Many thanks for all your prompt replies, consensus is that air is getting in somehow...

The Air bleed screw is fully wound in, throttle cable isn't connected yet (but the return spring on the mechanism at the manifold is; so it's holding the butterflies closed).

I don;t think this is anything subtle like ignition retard as 3,000 rpm is an underestimate.

I think I'll try blocking every orifice into the manifold and see what happens !

Thanks.

Mac.

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as above this sounds like an air leak.

 

the idle control is just an air bleed, ie it lets more air in to increase the idle.

 

so if ther's n air leak elsewhere it will cause a fast idle.

 

steve

 

PS, i see you are in Woking, nearby if you need a hand at the weekend?

Thanks for the offer Steve, I'll see what I find today, but if I'm still scratching my head I'll get back to you as it would be great to at least kick around a few thoughts on it. Mac.

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Thanks for the offer Steve, I'll see what I find today, but if I'm still scratching my head I'll get back to you as it would be great to at least kick around a few thoughts on it. Mac.

 

You are welcome, i'll blast over in my 6 so we can compare stuff if you like :-)

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Thanks for the offer Steve, I'll see what I find today, but if I'm still scratching my head I'll get back to you as it would be great to at least kick around a few thoughts on it. Mac.

I'm also in Woking, so if another head needed (3 better than 2!) happy to help... Edited by Ade_TR6
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Thanks again all, I think I've cracked it.

Giving an extra turn on the manifold nuts helped, but was still pulling a lot of air through the air box.

Although the butterflies looked closed they were in fact a few thou open (probably 5 or so), so a bit of fiddling with the adjustment screws seems to have fixed it; surprising how little opening it needs to get the revs going !

however, injectors 1&2 have decided to stop working now, so that will be tomorrows investigation !

 

Thanks to Steve and Ade for their local offer of help, but looks like I'm sorted (for the moment !) perhaps will be in touch again when I'm on the road... :-)

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It's worth making sure that the butterfly connecting rods are as long as they can be. That way you'll get maximum chance of them closing and also guarantee maximum throttle opening when you need it.

 

Actually thinking on a bit if the rods are set too long the butterflies might not close properly. However for full throttle they need to be set long.

Edited by peejay4A
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Good news !

 

Still happy to come have a look, prod, cup of tea if you're working on it over the weekend.

 

Steve

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Good news !

 

Still happy to come have a look, prod, cup of tea if you're working on it over the weekend.

 

Steve

Thanks Steve, got a bit side tracked today whilst working on the idle (which is now fine) I noticed a small pool of oil under the engine which I traced to the lower part of the timing cover (wasn't the seal), but tightening an extra turn on the screws slowed it but not stopped so have spent the day removing everything to get the timing cover off... One step forward 2 steps back, sound familiar ! I'm taking tomorrow off :-)

all the best. Mac.

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There's a Ali sealing block across front of engine which meets the bottom of the timing chain cover, it may be that leaking. They have little wooden sealing strips which can weep. If its that probably worth checking the steel replacements, sure there's some threads on this.

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Is just like to complain that there are far too many willing helpers living near Woking & I demand that some of you relocate to Edinburgh immediately!

 

:-)

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There's a Ali sealing block across front of engine which meets the bottom of the timing chain cover, it may be that leaking. They have little wooden sealing strips which can weep. If its that probably worth checking the steel replacements, sure there's some threads on this.

Thanks Robin, good point, I did replace the wooden strips but will certainly double check as I agree it's a weak area.

Mac.

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Mac

I hope you have not wasted your time but before you carry on was the leak around the screws?

As far as I could see there was no leakage around the screw heads, but I notice that one of the screw holes in the cover is not completely flat, which I'll need to sort.

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