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I have a pair of 800 Holleys on a 454. Blower is a B&M 250. My problem is if I mash the gas it has a huge hesitation (sp)?
My carbs have 6.5 power valves. 31 shooters . 78 mains. 82 secondary jets. Plugs are a nice tan. I think my jetting good.
Im thinking bigger shooters. ????????
I have a pair of 800 Holleys on a 454. Blower is a B&M 250. My problem is if I mash the gas it has a huge hesitation (sp)?
My carbs have 6.5 power valves. 31 shooters . 78 mains. 82 secondary jets. Plugs are a nice tan. I think my jetting good.
Im thinking bigger shooters. ????????
do you have 50cc pumps....if so try bigger ramps and nozzels
Im pretty sure I have 30 cc
Im pretty sure I have 30 cc
might want to step them up....a bog is most of the time not enough fuel at the hit of the gas
from 30cc to 50cc will help with the same nozzles?
You may want to step up the nozzles to somewhere in the 32 to 35 range. You might even try this prior to using the 50 cc pumps. You can also richen the idle mixtures screws a little to see if it will get the hesitation out. The blower requires more fuel during the transition due to all the area of the case and rotors versus a normally aspirated single four deal.
Hey Dan,
what drive ratio are you running on the blower?
Get your boost gauge fixed.
Been thinking that you are leaving a lot of HP on the table. You should be able to stomp my little 396 worse than you do.
Better get your ducks in a row. Changing my gears this week.LOL
Be good, Jim
larger squirters with a more agressive pump cam will solve the hesitation.
Jim why do you think im asking??????:)
Them squirters are pretty darn small. Start there. Change only one thing at a time. Make at least a lerge enough chsnge to tell the difference, like a 36 ++ then go backwards if you have to. IMHO your acc pump diaphrams will most likely be enough just change squirters.
First and cheapest is to replace the pink 3 hole accelerator pump cams with the white #218 cams and install them in the #2 position. The pink cams have a soft ramp rate and don't provide enough initial pump shot. The white ones will. Don't forget to readjust the arm setting either. TIMINATOR
First and cheapest is to replace the pink 3 hole accelerator pump cams with the white #218 cams and install them in the #2 position. The pink cams have a soft ramp rate and don't provide enough initial pump shot. The white ones will. Don't forget to readjust the arm setting either. TIMINATOR
Dan,
after making the changes, you can't just sit in the boat and make pretend engine noises.....You have to actually put the boat in the water and run the engine.
Be good, Jim
P.S., leave the larger nozzles in, change the cams and I bet you will be there. You can always put the smaller nozzles back in it if too rich.
A good rule of thumb is to use the bigger cams, like the green ones for 4150's, and then rap the throttle hard and see if the accel spring colapses much. If it bogs with a lot of collapse use bigger squirters, maybe even 50's. See if the motor likes it or not. More squirter/cam usually fixes it.
Are your power valves "boost referenced"? If not...there is the beginning of your problems.
Wags
1) get em boost referenced, or plug em and square the jetting.
2) is the linkage 1:1? If not, under part throttle 1/2 of engine will run fine, other half will be lean.
Wags
Do it right the first time before you push out head gaskets and say blowers are junk for boats.
Nobody has addressed your curve in your mag or distributor. I have found that if the motor revs quick enough, the curve in an advance will not stay up with the rise in RPM. On all of my blower motors we have locked in the advance, and have had good luck doing that. I am currently running 41 degrees of advance and it hits hard, never coughs or bogs. If your ignition system is too retarded, it will bog/hesitate. I am on currently on alcohol but when we run racing gas we run no more than 37 degrees of advance-38 degrees seems to be border line on holeing a piston. Secondly, take out the power valves and jet up 10 sizes all the way around. Run the idle circut on the rich side for the low end hit. Good luck with all of the advice!!
Denis:D
I have a pair of 800 Holleys on a 454. Blower is a B&M 250. My problem is if I mash the gas it has a huge hesitation (sp)?
My carbs have 6.5 power valves. 31 shooters . 78 mains. 82 secondary jets. Plugs are a nice tan. I think my jetting good.
Im thinking bigger shooters. ????????
With my N/A motor with a pair of 830's, I need 37 primaries and 41 secondaries - I'd say the 31's are way too small.
If it hesitates, then goes, your squirters are too small. Bump the squirter size up. 35-37 would be a good place to start.
If it goes, hesitates, then goes again, the pump is too small for the shot. You either need to drop the squirter size down (which may get you back to #1), increase the shot size by changing the pump cam, or if you are on the largest cam already, upgrade to a 50 cc acc pump.
I spent Saturday at a friends. We discovered that the passage way from the pump to the shooter was plugged with some crap. We also found a few other problems.:idea:
I have had this motor for about 5 years. I think that passage was blocked from day one. I ran it yesturday for most of the day. IT HAULS ASS NOW!!!!!:jawdrop: :) ;) :D
good to hear it!
I spent Saturday at a friends. We discovered that the passage way from the pump to the shooter was plugged with some crap. We also found a few other problems.:idea:
I have had this motor for about 5 years. I think that passage was blocked from day one. I ran it yesturday for most of the day. IT HAULS ASS NOW!!!!!:jawdrop: :) ;) :D
Heaven forbid we verify our fuel delivery system is functioning before start changing parts! :idea: No, wait a second... Don't we always do this backwards? "it ran fine when I bought it in '97...":eek: