4 replies to this topic

[Junaid]

Hi

Can someone please advise if late or retarted cam timing will cause a lean mixture at wide open throttle, I don't have a wideband just reading of the plugs (super white, almost like porcelain), which is also leading to pre ignition and heating

Getting a steady 10 inHg on a vacuum gauge (it's not a vacuum leak)

No matter how much richer I make the mixture, still runs lean at wide open throttle, tried various needle, BDL, BDP, BBC

Another thing is I have no idea why I have late or retarted cam timing as I've triple checked and the cam/crank gears/sprockets are lined dot to dot, even used a dial indicator to double checked ended up at 106, even tried another cam, (both are standard)

1275 (fairly standard)
HIF44 on alloy intake with MED stub stack & filter
Ignition timing 10 degrees at 1000 rpms

Edited by Junaid, 15 November 2022 - 03:40 PM.

[sonscar]

I would say weak at full throttle is not enough fuel.Low pump performance?low float level?restricted lines or filter?tank vent?Random thoughts.I take it the vacuum is at idle.Steve..

[cal844]

Needs an AC Dodd check 😉

[Junaid]

@ sonscar, all that has been checked over

[sonscar]

Is the piston rising to the top?the jet is practically fully open at full throttle and at 90 thou should be plenty big enough.The manifold pressure at full throttle should be atmospheric,I am sure you know this.No criticism intended but I would pretend you have never seen the car before and start again assuming nothing.Check ignition timing whilst running at over 3.5k.Just trying to help.Steve..
Hif44 100 thou jet,even bigger.

Edited by sonscar, 15 November 2022 - 10:46 PM.