I have a problem I have never encountered in all my years. All responses welcome. My Deuce Hiboy Roadster has a maxed out flathead and has run excellent for years. My new problem stumps me. I have 3 x 2 original Strombergs and were rebuilt a couple years ago and it ran fine. Now i have to run with no air cleaners or open scoops otherwise the engine flattens out at 2700 rpm. As soon as I remove the air cleaners it pulls good up to my redline of 4500 rpm. I makes no differance which air cleaners I use, I have several sets Stellings, Edmonds, Chrome louvers. I'm running a hidden electric fuel pump with a fuel regulator set a 3 lbs.My problem is I can't figure out why it dies at 2700 rpm with any air cleaners and pulls great with out any. Can any help with an idea or if you've had a similar problem. All responses welcomed....
Did the motor do that before the carb overhaul? If so, look at jet changes and power valves. Did the spark plugs get changed at the same time? If the motor has champion spark plugs, replace them. My flatty ran to 5000 with NGK's. Did removing the carbs change the vacuum signal to the advance? Does it pop and backfire, or just flatten out?
You also might check the torttle linkage and make sure the carbs are comming all the way open. Sometimes they loose adjustment or they stretch a bit. If you are not getting enough air that could change when you pull the air cleaners. Just another thought and it won't cost you a dime to find out. You will have to have someone inside to push the peddle while you look down the carb throat.
My flathead has ran great the past six or seven years, until this past spring. Ran WAY rich, crappy mileage. I farted around with new plugs, idle adjustment, etc. It always seemed to run good when I was adjusting everything, with the air cleaners removed, but ran like crap when I put everything back together. Then it dawned on me to leave the air cleaners off. It runs GREAT without those damn air cleaners. I had heard that they didn't let enough air in, and I guess with a 10K miles on them, they just block too much air flow. They look new.... but they're in the trash now. Rich
I thank all who have responded so far, great advice. The carbs are opening full vertical when floored. All carbs were rebuily fully using correct rebuild kits from 'speedway' and ran great right after, the problem started some time later (2-3 months). Can anyone think of a problem directly related to air flow? It runs strong with out air cleaners or the open scoops i'm running now, i'm at a total loss...stromberg '97's flow about 175 cfm's each even though it's bored and stroked to 284 and an isky max 1 cam, does not have a vacuum advance, 12* initial timing and 25* at 3000 rpm. I've gone thru the mallory duel point and even had a hot rod shop check and set the distriubtor on a sun machine. Again any advice welcome and thanks guys...
I have found that some of those small airfilters (specifically Spectra brand) will not flow well after they get wet. Even after they dry out they seem to lose their porousity. Get them wet in the rain or washing the car, and they never flow right again. They look fine, but the fibers are swelled closed. Have you tried new filters? Tomcat
I'm thinking that the Speedway accelerator pump is wore out an your getting to much fuel that is why you need the extra air..Just a thought.. I think the Speedway pumps are "crap".. Duane.
I had the same problem and mine would idle like shit and i would keep adjusting it then the air cleaners, they only lasted like 300 miles. So i made some useing only screens, now it works good. You can look at my thread "flathead 2x2 air cleaners what works".
Benno, I dont know about the torttle linkage, but the wife sure makes a killer torttle lini, sorry bud couldn't resist {FUGETABOUTIT}
sqhd, CARL I'M INTERESTED IN KNOWING MORE ABOUT YOUR SUGGESTION ABOUT ADJUSTING THE VALVES. I DID 'EM 1200 MILES AGO AND THEY SOUND FINE, NO UNDO CLICKING OR CLATTER. I DO HAVE NOS JOHNSON ADJUSTIBLE LIFTERS WHEN I PUT IT TOGETHER SO THE ACTUAL ADJUSTING IS NOT SO BAD, IT'S GETTING TO THEM, INTAKE AND SUCH. MAYBE YOU COULD GIVE ME SOME TELL TAIL SIGHS I COULD USE TO DETERMIN IF IT WAS IN FACT THE VALVES BEFORE I TAKE IT APART ONLY TO FIND THE VALVES ARE OK. THERE IS NO BACK FIREING AND IT STARTS AND IDLES GREAT AND THE VACCUM AT IDLE IS 13 INCHES EVEN WITH THE BIG CAM. ANY HELP IS MUCH APPRECIATED.....
and the EXPERT has spoken.....As soon as you mentioned "speedway" that's were my thoughts about your problem drifted.
Ran into this filter issue also. I drilled holes into my expensive filter element and installed my wifes hose over them. Now I just change her hose whenever I get the itch. I'm serious here.
Going back fifty years. Had the same problem with my 59AB in a 32 pick up. It turned out to be the gaskets under the 3 97's. I found it by spraying starter fluid at the carburetors and the engine would race up. I changed the intake to carburetor gaskets and the problem went away.
The Jalopy Journal
