Amskeptic wrote:renobdarb wrote:
seems to run just fine in 1-3 gears,
fourth it seems to flatten out and bog down,
even with the gas mashed down.
The only thing left are my carbs (dual Weber 44's). Could out-of-sync carbs cause a loss in power?
That and possible fuel delivery issues or clogged main/power jets.
Double-check timing at 3,200-3,400 rpm for 28-30*. Also bring the engine up to 4,000 rpm briefly to make sure the timing is not advancing still further. You want the top of the centrifugal curve to be 28-30*.
How does it pull in 3rd gear between 40-55 mph?
Colin
Hi, Colin... thanks so much for the reply! This has been really frustrating... I just can't seem to track down what's causing this power loss.
Anyways, I took the 'ol bus for a test drive this morning. I checked and rechecked the timing... It's at 8.5* BTDC at idle (I live at 6,500 feet), and at 28* at about 3,400 rpm. I just installed a new SVDA distributor a couple days ago (I was having this power loss issue before that), and here's a note that came with the distributor:
A) 28-30 Total Advance (hose disconnected)@ 3500 RPM.
B) 38-45 Total Advance (hose connected)@ 3500 RPM.
Let it idle and re-check the timing, you can now use this timing setting to set
the timing at idle, though we do recommend you check the full advance settings
to make sure the SVDA is working properly at both idle and full advance.
Do NOT be alarmed if you do not get the full amount of vacuum advance coming in
right away; the vacuum advance diaphragm is new and is VERY STIFF, it make take
up to a month or two of driving (A month sitting in your driveway or garage is
not the same) to loosen up as it's used.
...so I'm assuming I'll get more advance once this thing gets "broken in"...
Anyways, back to the test drive. It seems to run pretty well in 1-3 gears, but seems to flatten out on the upper end of 3rd, say around 45 mph, and seems to hold the speed there. In fourth gear, it holds steady at, say, 60 mph on FLAT roads with no headwind, but if there's even a slight rise in the road or headwind it'll decelerate.
I also took it up a
real hill, and I had to downshift and downshift and downshift again. Basically, I used to be able to climb this hill steady in 3rd gear and now I struggle in second. It just doesn't seem to be getting the power it should.
Thanks again, Colin, for your help. If I sound desperate and pathetic, it's because I
am desperate and
feel pathetic, because I feel like I've tried everything and just can't figure this out. The carbs are the only thing I haven't tried, so do you think my problem may be there?
Also, do you think this might be a fuel delivery issue, like with my fuel pump? It sounds like it's working fine... Also, I changed out all my fuel hose last summer, so I can't imagine they'd be clogged...
Any way I can talk you into swinging through the beautiful Teton Mountain Range on your next circut?
Cheers,
Brad