can anyone help?
I have installed a rebuilt H30 31 PICT carby in my 1500 beetle, new plugs, new valves all set, new leads, new 009 dizzy, clean oil bath in air cleaner... timing is set to around 7 degrees BTDC, but my engine still pings every now and then and I have flat spots in accelleration. Would this problem be caused by an air leak somewhere in the manifold, or the main jet too small in the carby? I cant seem to figure out the problem and have tried everything...
cheers people
BizarreModeratorThe artist formerly known as blue74l
I read somewhere that the 009 dizzy causes poor acceleration under certain conditions (ie - flat spots), since it has no vacuum advance (low rpm?). Designed for early split busses, which usually ran open throttle and high rpm, vac advance wouldn't help. I don't remember where this was, but here's one site...
Try using LRP rather than unleaded, it's 98 octane and cheaper than PULP with additive.
The 009's are notorious for causing flat spots or hesitation in 1500-1600 engines. I cann't remember exactly why this is, I thought 009's didn't have enough total advance or something like that??
The other factor that causes pinging is overheating, is all your tinware in place, fan running etc? Any other signs of overheating?
Are the cylinders, pistons and heads all standard? If not you could be running higher than normal compression.
yeah, all tinwear is in place, new heads, pistons > all stock... she only seems to ping when in idle, other than that its the old hesitation/flat spot scenario
would adding a larger main jet in the carby help?
BizarreModeratorThe artist formerly known as blue74l
hmmmmm, well it sounds like pinging > not the same pinging you get when going up steep hills but the sort of mis-timing ping when idle...brrmm brrmm ping brrmm brrmm brmmm ping ping brmmm brmmm, I also get slight fluctuations in idle speed, only slight though...
As Craig implied the fuel ratio has one of the biggest effects on pinging. A bigger main jet, and/or idle jet will reduce pinging.
Also, LRP is not 98 octane, but it is crap.
You might also want to check for vacuum leaks. Spray WD40 around the manifold joints while the engine is idling. If the idle speed changes you have a leak.
Check your total advance (@ 3000 RPM), not the static - no more than 32 BTDC total, I would start at 30 BTDC.
If the carb is new it may be leaning out, check the main jet, and cicuit for a block, if it still happens then ( as long as you have good fuel pressure ) open up the jet .05 mm untill it stops.
Plugs too hot can cause detonation too...
BizarreModeratorThe artist formerly known as blue74l
Adrian is on the right track, you cant properly static time a 009 distrubutor. Too much variation in the total advance in these pretty cheaply built units.
Only way to do it properly is to set total advance 30 degrees at 3000rpm.
You normally need to up the main jet size on a standard 1600 solex to accomadate the 009 advance curve and remove some of the 009 flat spot.
The hesitation at idle and the pinging you hear could be due to a sticky or leaking valve too. Maybe run some upper cylinder lube thru the next tank full and see if that changes anything.
Opps just noticed that its had new valves so it kind rules that out.
crumbs, there are so many things to check! and so many variables!!
Thanks all of you for your help: will do some checking over the weekend for air leaks > actually can anyone tell me why the volume control screw on the NEW carby doesnt do anything to the engine when turned > would it just need cleaning out?
if the volume screw doesn't do anything, or more importantly if the mixture screw doesn't do anything, then that means the idle jet / idle circuit has a blockage.
