Hey guys,
Thought Id through a vacuum gauge on my 327, never used one before. She's got an incredibly rough idle, sitting there not in gear at about 750rpm she just about wants to die. Now its gotta cam and pro top line sports heads so this may explain but well see. The cam is a compcam 212-12-2 and the manufacturer says the following it has a duration of 280/280 and a lift of .480 and .480. Now doing a vacuum test full manifold vacuum not in gear in park at 700rpm I have 2 on the vac gauge and the engine lopes really bad its a reasonable 2 maybe up and down by a half, at a 1000rpm she smooths out quite a bit and has a good 9 on the vac gauge at 1400rpm shes a solid steady 14. Now the car doesnt run on petrol its pure LPG my initial timing is currently set at 8 btdc at 12BTDC she runs a little bit hot and backfires under hard accel. Is the above readings simply the type of cam I have or is there something else. The book "generic" for vacuum setup talks about at idle approx 20 for the vac. Anyone got any ideas,
Thanks Steve