So, no solution found as yet to the low manifold vacuum, but with tinkering with the air flow meter (spring preload, contact arm position and the co screw) and deleting the vacuum supply to the fuel pressure regulator I have got to the stage where the car drives very well and performs as good as I think it should with the setup it has. Now getting afr readings (measured with the aem uego wideband sensor in the exhaust just after the downpipe flange ) of high 13s to low 14s on light to moderate throttle, mid 12s on full throttle with the cam on song, and 14.7 at warm idle. No odd spikes, no flat spots, smells right and will pull in 5th gear from 15mph to goodbye licence speed cleanly. I think the low vacuum is also responsible for making the brakes feel a bit meh, but have some parts to fit and that's a different story. Thanks to all who contributed.
Looks good there (14's on cruise and 12's under acceleration). Cams can ruin the manifold vacuum so it makes sense originally it was rich at idle because the FPR will have thought it was under load (low vacuum reference). For a NA car running fixed fuel pressure should be fine, a lot of motorcycles run fixed fuel pressure.
its good that you have found a way to make it work? have you asked the question what causes the vacuum signal to be low in your engine? the GS2H is a fairly tame cam which shouldn't really make too much difference, my 2042 engine ran a schrick 288 and had plenty of vacuum until it got up near 5000 rpm, where I started to see a wobbly signal, which was attributed to the big cam. does the engine have decent compression? I assume its heathy? could cam timing be an issue? have you looked at the vacuum pipework for the servo,? checked the servo itself? there is a lot of things that could be leaking.
Bit late in response to KeithMac and drunkenallen, sorry, been busy tinkering still. All vacuum pipework is good and the servo holds vacuum. Used a smoke Pro and a manifold pressurisation tester to check thoroughly for any leaks. Pleased to report that I now have it running very nicely indeed after quite a bit of minor tweaking. Having adjusted every aspect possible of the air flow meter including loosening the screws that hold the circuit board and moving it so that the arm runs on fresh track, moving the arm on the spindle and setting the preload got the air fuel ratios consistently good across the board. Now back to having the fuel pressure regulator connected also. Re timed the camshaft as I was using the old pulley with the tiny dot which people say to line up with the top of the cylinder head with the rocker cover removed. The head has been skimmed which may be why it does not line up exactly but had set it so it was very slightly below the top of the head, as moving it one tooth made it above the top of the head by a greater margin so opted for below as it was closer. Now running the agg pulley with the 0T mark on the outside which is much easier to see, set to the position that puts the dot above the head but the 0T mark is better lined up with the cambelt cover mark. Reset the ignition timing following the exact procedure and adjusted the idle and co. Haven't done any other tests but it now sounds, smells and drives exactly as I hoped it would with a crisp pick up and a nice little extra shove on cam. It's interesting what differences all the little adjustments make but I'm very glad to have now got it dialled in!. Thanks all!
