Phil C Posted May 5, 2023 Report Share Posted May 5, 2023 Hi All, I have been trying to get my rebuilt engine running sweetly for a while now. Progress was being made as the rich running was down to a repro fuel pump delivering 15psi fuel pressure. Thanks to another post on here for directing me to look at that one. Regulator fitted and all was well. On a recent test run I was doing about 40 mph with the engine running well, I slowed to turn right and then the engine spluttered and became difficult to keep running with little or no power. Luckily I was very close to home and it was downhill all the way. The engine would tick over but very lumpy. Delayed or little response to throttle. Engine note dull and flat I checked all the usual suspects. Fuel ok and spark ok. Carbs function ok, inspected the rocker operation ok, compression test ok. Although the dizzy hadn't moved I checked the timing with a strobe and found it to be around 30 BTDC !! Trying to adjust closer to a more realistic value simply caused the engine to stall. Obviously the problem but what caused it? I thought may be the timing chain had slipped but at TDC, No 1 cylinder remains on compression stroke and the rotor arm points to No1 ignition lead. To be sure I removed the timing cover to confirm marks on the two sprockets still lined up, they did. However I have fitted a Lumenition Magnetronic Electronic Ignition Kit. Not sure if this could cause such a problem? I always thought they either work or didn't work! Your thoughts please. Link to comment Share on other sites More sharing options...
johny Posted May 5, 2023 Report Share Posted May 5, 2023 57 minutes ago, Phil C said: Hi All, I have been trying to get my rebuilt engine running sweetly for a while now. Progress was being made as the rich running was down to a repro fuel pump delivering 15psi fuel pressure. Thanks to another post on here for directing me to look at that one. Regulator fitted and all was well. I take it the carbs were over flowing due to the high pressure overcoming the float valves? Link to comment Share on other sites More sharing options...
Phil C Posted May 5, 2023 Author Report Share Posted May 5, 2023 (edited) 24 minutes ago, johny said: I take it the carbs were over flowing due to the high pressure overcoming the float valves? Not visibly. The float valves withstood the pressure but once there was a fuel demand I think the high pressure within the fuel feed pipe caused too much fuel entered the chamber until the valve closed. The engine ran but started to choke up on tick-over/low revs. No fuel could be seen to overflow so it was a difficult problem to identify. Edited May 5, 2023 by Phil C Link to comment Share on other sites More sharing options...
johny Posted May 5, 2023 Report Share Posted May 5, 2023 very strange as the chamber should have a vent to atmosphere (the overflow) so impossible to pressurise it. Then the level in there is controlled by the setting of the float.... Link to comment Share on other sites More sharing options...
Phil C Posted May 5, 2023 Author Report Share Posted May 5, 2023 I agree the chamber can't be pressurised but I'm guessing fuel level within became erratic and often high due to the feed pressure .......all guesswork but the fuel regulator sorted it! Link to comment Share on other sites More sharing options...
Iain T Posted May 5, 2023 Report Share Posted May 5, 2023 (edited) When did you fit the Luminition? Is this the first time it's happened? I had a similar lack of power situation and it was two plug leads that weren't quite pushed on enough (new leads and the rubber cover very stiff). They looked fine but on a drive with bumps and jolts they must have loosened and created too big a gap. I have to say and I have my fingers crossed my Pertronix has been perfect in the 5 years since I fitted it. The Distributor Doctor only fits Pertronix, I wonder why. However that doesn't solve your problem. Iain Edited May 5, 2023 by Iain T Link to comment Share on other sites More sharing options...
johny Posted May 5, 2023 Report Share Posted May 5, 2023 With the dizzy suddenly showing so much advance without anything being touched I wonder if either its vac advance or centrifugal advance has got stuck or broken? You should be able to detach the vac pipe and suck on it (a lot) while checking that the EI sensor head is rotated clockwise around the rotor. Then you can check the rotor itself rotates by twisting it anti-clockwise (simulating that the internal weights fly out to do this) and then its springs should return it... Theres a need to lubricate the dizzy components that often doesnt get done so things seize up or the return springs can break - description of how it should work is very good in the free to download workshop manual👍 Link to comment Share on other sites More sharing options...
Phil C Posted May 6, 2023 Author Report Share Posted May 6, 2023 14 hours ago, johny said: I wonder if either its vac advance or centrifugal advance has got stuck or broken? I did check the the vacuum and all was working as it should. The Dizzy is new/rebuilt. Link to comment Share on other sites More sharing options...
johny Posted May 6, 2023 Report Share Posted May 6, 2023 Ah remember the bath tub curve! New stuff can have problems just as much as old.... Link to comment Share on other sites More sharing options...
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