Need some carb help...
04-17-04, 04:02 PM
#1
Need some carb help...
OK I have a Weber 48 IDA following specs
Venturies 37 mm
Main Jet 180
Air Jet 160
needle seet 3.5 glass ball
Float turbo prepped filled with foam and sealed
0 bypass plug
Fuel pressure is at 4 on my summit (god only knows how accurate) guage
Enigne porting is stock
Heres what is happening. She idles good, runs up through the rpms great no problem. but when you stop to coast say 3000 rpm she buck and grumbles doesnt matter what rpm you stop and coast at, she complains.
Venturies 37 mm
Main Jet 180
Air Jet 160
needle seet 3.5 glass ball
Float turbo prepped filled with foam and sealed
0 bypass plug
Fuel pressure is at 4 on my summit (god only knows how accurate) guage
Enigne porting is stock
Heres what is happening. She idles good, runs up through the rpms great no problem. but when you stop to coast say 3000 rpm she buck and grumbles doesnt matter what rpm you stop and coast at, she complains.
04-17-04, 07:37 PM
#2
I reset the float level to the stock settings per the haynes manual, but I think the float is heavier now with the foam, so the fuel level in the carb maybe too high. Could this be the problem? Does anyone have a reference point on were the fuel level should be in the carb itself?
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09-22-04, 08:45 PM
#10
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Perhaps your valves are not closing all the way, allowing the idle circuit too much signal.
How does it idle? Is it consistantly the same RPM when you let off the throttle to idle? (IE, Is the valve set sticking?)
How does it idle? Is it consistantly the same RPM when you let off the throttle to idle? (IE, Is the valve set sticking?)
09-22-04, 10:04 PM
#12
CarlRx7
you havent told us the set up on your carb. Have you taken it off and cleaned it? tried blowing compressed air in the places you cant get too. bucking and nasty is usually a sign of going lean. mine was a combination of dirt and incorrect timing. little twig or some type of stuff in the idle circuit.
Whats your timing set at?
Whats the set up on the carb?
Baseline fuel pressure--this could be a biggy. I kicked mine up to 6 and that made a world of difference too.
Also the only vid I have on my car right now is in this http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMESE%3AIT ebay auction. its just 10 seconds of looking at the dizzy on a running engine. not so much what your looking for.
you havent told us the set up on your carb. Have you taken it off and cleaned it? tried blowing compressed air in the places you cant get too. bucking and nasty is usually a sign of going lean. mine was a combination of dirt and incorrect timing. little twig or some type of stuff in the idle circuit.
Whats your timing set at?
Whats the set up on the carb?
Baseline fuel pressure--this could be a biggy. I kicked mine up to 6 and that made a world of difference too.
Also the only vid I have on my car right now is in this http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMESE%3AIT ebay auction. its just 10 seconds of looking at the dizzy on a running engine. not so much what your looking for.
Last edited by Rx7carl; 09-23-04 at 08:07 AM.
09-23-04, 11:07 AM
#13
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in that movie,, thats how my car USE to run. now its lub lub lub.
but since then, i taken it apart and cleaned everywhere i could get that carb cleaner straw in. i agree in the lean part, basically, because my a/f gauge bounce like no other.
i just ripped the header off and checked the gaskets, no signs of blowout. and i sanded and painted it with some 1500 ceramic paint. better than watching it rust away.. also it may help me if i have an exhaust leak somewhere around there.
if that doesn't work. then i will give the idle circuits a blast. if that dont work i will rip the bitch off and throw it across the parking lot, then put a new base gasket on.
my setup is a mikuni w/ wrap around intake mani. my idle jet is a 62.5 main 190, air bleed 240. and thats all i remember off the top of my head. alls i know, is that it use to purr like a kitten at idle with these same jets, so im not gonna changed them.
i can adjust my fuel pressure from 0, 3-20 psi. my manual recommbed 2.84 - 4.98 psi. so far nothing has changed.
carl.
but since then, i taken it apart and cleaned everywhere i could get that carb cleaner straw in. i agree in the lean part, basically, because my a/f gauge bounce like no other.
i just ripped the header off and checked the gaskets, no signs of blowout. and i sanded and painted it with some 1500 ceramic paint. better than watching it rust away.. also it may help me if i have an exhaust leak somewhere around there.
if that doesn't work. then i will give the idle circuits a blast. if that dont work i will rip the bitch off and throw it across the parking lot, then put a new base gasket on.
my setup is a mikuni w/ wrap around intake mani. my idle jet is a 62.5 main 190, air bleed 240. and thats all i remember off the top of my head. alls i know, is that it use to purr like a kitten at idle with these same jets, so im not gonna changed them.
i can adjust my fuel pressure from 0, 3-20 psi. my manual recommbed 2.84 - 4.98 psi. so far nothing has changed.
carl.
09-23-04, 11:16 AM
#14
CHANGE THAT AIR BLEED!!!!! the higher the number on the air jet the leaner it is. and that should start kicking in around 3000 to 3500 rpm. at least thats where it is on the IDA. From the pictures im guessing yours is sidedraft.
HMMMM this thread got shorter all of a sudden.
HMMMM this thread got shorter all of a sudden.
Last edited by seanrot; 09-23-04 at 11:21 AM.
09-23-04, 10:53 PM
#16
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ok here is my thursda update.
today i started the car up. and now i know for sure that it is not an exhuast leak. i watched my nicely painted header go from red to purple.
so i took out the idle jets. gave them a blast of carb cleaner,
no differance.
the only thing that i found out today, is that the richer the mixture the more LUMPY the idle and off idle was. i first started @ 3 turns out., puffing smoke and burning my eyes. i eventually turned them all the way in. unfortunatley i hadn't reconnected my a/f gauge so i couldn't tell wut the mixture was at. but it sounded lean. and the header got even hotter (big sign) but the idle was almost (ALMOST) perfect, a nice purr with a lil blip occaisionly. but would still shake at cruise.
after that i decided to call it a day, so i pulled the plug on the fuel pump to let the carb run out of gas, and it seemed like it was running better!
wut i am thinking is that my floats are going bad or my needle is stuck. causing it to overflow into the main circuit.
my rx7 is no longer my main car, i drive the wifes old car, so if any1 would like to take a look at the carb i can send it to you for you to take a look at it for me. some1 that knows about mikuni's and could put it on there car to see if they've fixed it. just give me an email @ carl.bradley@comcast.net
tommarow i am going to dissasemble the carb again. and check the needle and floats. and reapply gasket sealent to the base of the carb.
carl.
p.s. if any1 has a SPARE stock carb and stock intake manifold that runs good. i will pay for the shipping. and even better if they have another mikuni or webber. i promise i will return it.
today i started the car up. and now i know for sure that it is not an exhuast leak. i watched my nicely painted header go from red to purple.
so i took out the idle jets. gave them a blast of carb cleaner,
no differance.
the only thing that i found out today, is that the richer the mixture the more LUMPY the idle and off idle was. i first started @ 3 turns out., puffing smoke and burning my eyes. i eventually turned them all the way in. unfortunatley i hadn't reconnected my a/f gauge so i couldn't tell wut the mixture was at. but it sounded lean. and the header got even hotter (big sign) but the idle was almost (ALMOST) perfect, a nice purr with a lil blip occaisionly. but would still shake at cruise.
after that i decided to call it a day, so i pulled the plug on the fuel pump to let the carb run out of gas, and it seemed like it was running better!
wut i am thinking is that my floats are going bad or my needle is stuck. causing it to overflow into the main circuit.
my rx7 is no longer my main car, i drive the wifes old car, so if any1 would like to take a look at the carb i can send it to you for you to take a look at it for me. some1 that knows about mikuni's and could put it on there car to see if they've fixed it. just give me an email @ carl.bradley@comcast.net
tommarow i am going to dissasemble the carb again. and check the needle and floats. and reapply gasket sealent to the base of the carb.
carl.
p.s. if any1 has a SPARE stock carb and stock intake manifold that runs good. i will pay for the shipping. and even better if they have another mikuni or webber. i promise i will return it.
09-26-04, 03:34 PM
#17
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BAD NEWS AGAIN.
i would of responded sooner but this damn hurricane has my flight in a cluster ***.
anyways,
i took the carb off and opened up the float chamber, there was a lil poo inside so i cleaned it out. and then started to clean out the jets. the main and air bleed looked good. when i got to the idle jets, i could of sworn one of them was all clogged up. i was so happy. so i cleaned then both out with some cleaner and blew threw them to make sure they werk clear. i even checked the needle, and that was good.
i put a super thin layer of holimar(?) blue stuff. awesome stuff. on the carb's base o'rings to help them get a good seal. i threw it all on and still the same shyt!!
well, i am going back down to FL and im gonna bring the carb to let my dad take a look at it.
i am starting to think that i have an apex sealing problem.
carl.
i would of responded sooner but this damn hurricane has my flight in a cluster ***.
anyways,
i took the carb off and opened up the float chamber, there was a lil poo inside so i cleaned it out. and then started to clean out the jets. the main and air bleed looked good. when i got to the idle jets, i could of sworn one of them was all clogged up. i was so happy. so i cleaned then both out with some cleaner and blew threw them to make sure they werk clear. i even checked the needle, and that was good.
i put a super thin layer of holimar(?) blue stuff. awesome stuff. on the carb's base o'rings to help them get a good seal. i threw it all on and still the same shyt!!
well, i am going back down to FL and im gonna bring the carb to let my dad take a look at it.
i am starting to think that i have an apex sealing problem.
carl.
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