vac advance

[mac123yre]

my car is running as if the vac advance is not working however if I suck the pipe all the parts move, but the hole in the inlet manifold seems to small any one have an idea for a fix? As wondered if the hole not big enough?

[tempus]

Does the hole suck ? small is good but they can clog up.

[GreenV8S]

Do you have a small plastic component in the vac line between the throttle and the dizzy? If so, remove it so you have a simple direct connection. How are you checking that the bits move when you apply suction, and what symptoms make you think it isn't working?

[mac123yre]

Symptoms are when I set timing up correct the car ticks over perfect, but wont pull as it should.
If I then advance the timing the car pulls ok, it’s as if the dizzy advance is not doing its job

[tempus]

If you take the pipe off the vac advance can you feel the engine sucking ?

[Wedg1e]

Throttle pot wiring OK?

[GreenV8S]

mac123yre said:

Symptoms are when I set timing up correct the car ticks over perfect, but wont pull as it should.
If I then advance the timing the car pulls ok, it’s as if the dizzy advance is not doing its job

How are you setting the timing up?

ETA: And, by "wont pull as it should" exactly what do you mean?

Not trying to be awkward, just that it is extremely difficult to guess what symptoms you have or what you've done so far, without a lot more detail than you're giving.

Edited by GreenV8S on Saturday 22 August 12:52

[mac123yre]

With the timing where it should be it revs up to 2k ok but struggles to go beyond, advance the timing on the distributor and it will take of at about 4k

[GreenV8S]

mac123yre said:

With the timing where it should be it revs up to 2k ok but struggles to go beyond, advance the timing on the distributor and it will take of at about 4k

:sigh:

What process did you use to set the timing (I mean in detail - did you set it at idle, at high speed, with or without vacuum advance connected, how did you measure the timing - passive strobe, active strobe, true timing or electronically corrected, have you verified the timing marks are accurate). What value did you set the timing to? Have you tested the effects on timing of the vac and mechanical advance? If so exactly how did you test them and what results did you get?

When you say it won't rev, exactly what are you doing? Are you revving it off load, or in gear? Do you get the symptoms under light, moderate or full load? Does "struggles" mean it's down on torque or is it misfiring or what? Is this a transient effect or does it happen in a steady state too?

It feels like I'm pulling teeth here. Without details it's impossible to know what the car is doing, or what evidence you've already collected.

Edited by GreenV8S on Saturday 22 August 13:57

[mac123yre]

sorry you find it frustrating, we would be better having this conversation over the phone, anyway was going of to the BNG today only to find another problem the heads gone, blowing back in to the water, so am gona sort it some time in the next few weeks, also the cam was a bit tappy so will replace that and the lifters, while doing this work will check that the distributor is in correctly as setting it up as per the timing marks it would not work.

Thanks for the help so far chaps

[adam quantrill]

When I bought my car the idle timing was well advanced but the engine was the same as yours when I put it back to 6deg BTDC. I found that the mechanical advance on the dizzy was locked up, and when I put in a working one all the problems went away, so you might look at that next.

[GreenV8S]

It's quite easy to test the vacuum and mechanical advance mechanisms, but before you get into that you really need to know that your timing reference point is accurate.

[mac123yre]

Yes I agree and that going to be the first thing to do on the rebuild.