Struggling to lower engine revs (after top end rebuild)

[jmiemiec]

Gents, can someone shed some light on this one, please…

2.7s, RS pistons, SC cams (timed at 1.62s), had to do some wiring jobs on the WUR and CST (still not too sure if correct), probably also turned the fuel mixture out of curiosity once or twice during the rebuild. Other than that, only a top-end refresh was done to the car with some typical refresh parts.

The effect appears to be:

• engine revs at ca 1200 at start up and when warmish (have not yet tried hot)
• idling screw is set to lowest (can't turn it any lower)
• ‘Forcing lower revs’ through ignition timing retarding (to about 1000 rpm) indicates 25º ATDC (it should be 5º as per spec)
• I can set the ignition timing to 5º ATDC but then the revs go up
• Tried decreasing the mixture but don’t know if this is working out properly; can’t really see any drastic effects
• Dwell angle at about 32º
• Points set to 0.35mm


What could cause this? I haven’t yet examined any vacuum leaks or similar but presume this would a different effect.

Input highly appreciated. Many thanks.

[Steve@Rennsport]

Jacob,

Is the vacuum advance hose connected properly??

Is the advance mechanism inside the distributor sticking?

Is the sensor plate positioned correctly at rest?

Are the control pressures (cold to hot) within spec?

I'd kindly suggest that the WUR connections are correct before proceding further,.....

[jmiemiec]

Thank you, Steve.

Is the vacuum advance hose connected properly??
From distributor to Deceleration Valve (I think this is what it is but mine has two horizontally connected vacuum hoses into it) I can observe that when removing the hose the revs go up.

Is the advance mechanism inside the distributor sticking?
I am unclear how to confirm this. The one change which was made to the distributor is new points installation.

Is the sensor plate positioned correctly at rest?
It appears to be at rest but when inserting an allen key into the mixture adjustment hole and pressing down gently, I can observe the revs coming down (I just can’t keep them there since turning the screw appears ineffective) Pressing the allen key down, I can easily reach 950rpm on the tach

Are the control pressures (cold to hot) within spec?
Control pressures?

I'd kindly suggest that the WUR connections are correct before proceding further
I remain confused on this point and feel that this might be a critical part to solving this issue. My WUR (intake manifold 2) has only one connector going out – this is connected directly to the coil+ outlet. Voltage is present on the connection but I have not gone further in evaluating the WUR. The WUR, btw, on the right hand side of the pic had a little plastic plate glued on which fell out during the disassembly; I glued it back on.