Running but not much power?
05-19-16, 03:25 PM
#1
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Running but not much power?
My 1982 RX7 with a street ported 12a starts and idles fine but hesitates and bogs when I jump on the throttle. It can still move but barely. Wondering where I should start? Not sure if it could be a carb issue. Guess I should do a compression test first.. Thanks for any help!
Last edited by 82rx7heaven; 05-19-16 at 04:40 PM.
05-19-16, 09:00 PM
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Ya, idles good and over 3000 rpm it is smooth with good response. Acceleration pump?
Last edited by 82rx7heaven; 05-19-16 at 10:02 PM.
05-20-16, 08:13 AM
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Should mention I have a 465 cfm Holley carb and a fuel pressure regulator which is set to 6psi. When I hit the throttle with car off I get a real good spray of fuel in the carb. Does that rule out acceleration pump? I don't know much about it. Could it just be the fuel pressure?
Last edited by 82rx7heaven; 05-20-16 at 08:55 AM.
05-20-16, 11:16 AM
#5
carb whisperer
Should mention I have a 465 cfm Holley carb and a fuel pressure regulator which is set to 6psi. When I hit the throttle with car off I get a real good spray of fuel in the carb. Does that rule out acceleration pump? I don't know much about it. Could it just be the fuel pressure?
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05-20-16, 01:11 PM
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I just took it out of storage after 2-3 years. It was tuned perfectly before though. Guess it needs a cleaning. Any advice on doing this. Do I need to remove the carb and take it apart or can it be done still attached?
Also, it kind of sounds like the engine is knocking or something. It seems to randomly get a bit louder and then go away.. Worries me a bit
Also, it kind of sounds like the engine is knocking or something. It seems to randomly get a bit louder and then go away.. Worries me a bit
Last edited by 82rx7heaven; 05-20-16 at 01:20 PM.
05-20-16, 02:35 PM
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Took a little video. Hopefully it helps a bit. Thanks for everyone's help. I really want to get this beauty back on the road. (Around 1:30 you can hear the knocking sound pretty good)
Last edited by 82rx7heaven; 05-20-16 at 03:33 PM.
05-20-16, 07:38 PM
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Ok so I pulled the T1 spark plug wire while it was running and nothing happened. Pulled L1 and again nothing. Running on one rotor, the rear. Checked for spark, lots. Pulled L1 plug and turned it over, I hear constant swooshes indicating there is even compression but without the compression tester obviously I don't know whether there is enough compression. Any tips!??
05-20-16, 08:16 PM
#11
carb whisperer
Ok so I pulled the T1 spark plug wire while it was running and nothing happened. Pulled L1 and again nothing. Running on one rotor, the rear. Checked for spark, lots. Pulled L1 plug and turned it over, I hear constant swooshes indicating there is even compression but without the compression tester obviously I don't know whether there is enough compression. Any tips!??
After that you may want a different carb, too. Those things are garbage. Especially "Holley" branded crap.
Someone will jump in here and defend them and say that it's perfectly reasonable to conduct seasonal rebuilds on holley carbs, and how "great" they are on rotaries, I don't know what I'm talking about, etc.
But your problem is 100% a junk carburetor. The separated intake they are on and uneven float levels they have (rotor 1 to rotor 2, rotor 1 has a lower level than 2) causes one rotor to run at a different AFR than the other. Tends to run r1 a bit lean, actually. It can actually shorten the life of that rotor, and I've seen it many times on engines with long term holley installs.
I think most likely your case is that the front side of the carb fuel circuit on the primary isn't flowing fuel. So it needs rebuilt, blown through with air after a good soaking in lacquer thinner.
You'll be doing it again this fall, and again in the spring. Enjoy.
05-20-16, 08:25 PM
#12
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Change your plugs.
After that you may want a different carb, too. Those things are garbage. Especially "Holley" branded crap.
Someone will jump in here and defend them and say that it's perfectly reasonable to conduct seasonal rebuilds on holley carbs, and how "great" they are on rotaries, I don't know what I'm talking about, etc.
But your problem is 100% a junk carburetor. The separated intake they are on and uneven float levels they have (rotor 1 to rotor 2, rotor 1 has a lower level than 2) causes one rotor to run at a different AFR than the other. Tends to run r1 a bit lean, actually. It can actually shorten the life of that rotor, and I've seen it many times on engines with long term holley installs.
I think most likely your case is that the front side of the carb fuel circuit on the primary isn't flowing fuel. So it needs rebuilt, blown through with air after a good soaking in lacquer thinner.
You'll be doing it again this fall, and again in the spring. Enjoy.
After that you may want a different carb, too. Those things are garbage. Especially "Holley" branded crap.
Someone will jump in here and defend them and say that it's perfectly reasonable to conduct seasonal rebuilds on holley carbs, and how "great" they are on rotaries, I don't know what I'm talking about, etc.
But your problem is 100% a junk carburetor. The separated intake they are on and uneven float levels they have (rotor 1 to rotor 2, rotor 1 has a lower level than 2) causes one rotor to run at a different AFR than the other. Tends to run r1 a bit lean, actually. It can actually shorten the life of that rotor, and I've seen it many times on engines with long term holley installs.
I think most likely your case is that the front side of the carb fuel circuit on the primary isn't flowing fuel. So it needs rebuilt, blown through with air after a good soaking in lacquer thinner.
You'll be doing it again this fall, and again in the spring. Enjoy.
Last edited by 82rx7heaven; 05-20-16 at 08:31 PM.
05-21-16, 09:54 AM
#13
It looks like you have a lot of blowby. I've seen steam come out of those on a cold morning, but I've never seen that much smoke come out of one, especially on an NA, before.
It looks like you have more problems than just a Holley or a bad ignition system, to deal with.
It looks like you have more problems than just a Holley or a bad ignition system, to deal with.
05-21-16, 10:19 AM
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So what am I dealing with here?
05-21-16, 11:56 AM
#15
It appears you have some blowby, probably caused by sticky side seals due to too much carbon buildup from a holley that runs rich all the time. A quick solution is to try a little bit of marvel mystery oil down the carb, so it trickles into the engine and is allowed to sit with some hand turning of the engine on the 19mm bolt on the main drive pulley every now and then.
There is a procedure to follow, which I'm trying to remember but drawing a blank at the moment. I'm sure others will be along shortly to describe a sticky seal un-stick procedure. They may even prescribe other magic potions as well. I've seen references to sea-foam or was it power foam? on this forum but never used it before.
Stay away from ATF. That stuff can kill your engine.
There is a procedure to follow, which I'm trying to remember but drawing a blank at the moment. I'm sure others will be along shortly to describe a sticky seal un-stick procedure. They may even prescribe other magic potions as well. I've seen references to sea-foam or was it power foam? on this forum but never used it before.
Stay away from ATF. That stuff can kill your engine.
05-21-16, 09:37 PM
#18
84SE-EGI helpy-helperton
MMO will work, but does take time, up to several weeks. In this case you're just trying to free up seals so they will unstick and seal a little better, loosening up some carbon and ejecting it with the exhaust, so douse it good, find a mosquito infested area away from neighbors and cops, and run that sucker out. It's going to smoke like a chimney.
The longer you let the MMO sit, the better it will work. Stay far away from ATF down the intake. It will remove the "good" carbon as well as the bad, and some of that carbon helps to seal the old, tired oil control rings. The ATF will result in smoking long after the treatment and increase oil consumption over the long term. On the flipside, it won't matter if your OMP is working or not!
The longer you let the MMO sit, the better it will work. Stay far away from ATF down the intake. It will remove the "good" carbon as well as the bad, and some of that carbon helps to seal the old, tired oil control rings. The ATF will result in smoking long after the treatment and increase oil consumption over the long term. On the flipside, it won't matter if your OMP is working or not!
05-22-16, 01:25 PM
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MMO will work, but does take time, up to several weeks. In this case you're just trying to free up seals so they will unstick and seal a little better, loosening up some carbon and ejecting it with the exhaust, so douse it good, find a mosquito infested area away from neighbors and cops, and run that sucker out. It's going to smoke like a chimney.
The longer you let the MMO sit, the better it will work. Stay far away from ATF down the intake. It will remove the "good" carbon as well as the bad, and some of that carbon helps to seal the old, tired oil control rings. The ATF will result in smoking long after the treatment and increase oil consumption over the long term. On the flipside, it won't matter if your OMP is working or not!
The longer you let the MMO sit, the better it will work. Stay far away from ATF down the intake. It will remove the "good" carbon as well as the bad, and some of that carbon helps to seal the old, tired oil control rings. The ATF will result in smoking long after the treatment and increase oil consumption over the long term. On the flipside, it won't matter if your OMP is working or not!
05-22-16, 03:09 PM
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Well I can't find MMO anywhere in my area (Canada). When I get some do I just disconnect the distributor and pour a few ounces down the carb while cranking the car over? Then leave it sit for a day and turn the engine over with a wrench every once in a while? Not sure what the best method is.
Last edited by 82rx7heaven; 05-23-16 at 02:06 PM.
05-23-16, 08:40 PM
#21
84SE-EGI helpy-helperton
My preferred method with MMO is to remove the upper intake manifold and put about an ounce into each intake runner. This lets it run straight down into the intake ports and spread evenly as you hand turn the engine from the front pulley. Turn the engine one revolution every day or so, and it will move the rotors 1/3 of a revolution each time. Youre trying to give it time to soak in, so don't rush this process.
Know that when ypu get it all together, it's going to smoke like crazy on your startup, so get it out of your neighborhood if they would mind. Change plugs after that, and you'll get about as much benefit as you can.
Know that when ypu get it all together, it's going to smoke like crazy on your startup, so get it out of your neighborhood if they would mind. Change plugs after that, and you'll get about as much benefit as you can.
05-23-16, 08:44 PM
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My preferred method with MMO is to remove the upper intake manifold and put about an ounce into each intake runner. This lets it run straight down into the intake ports and spread evenly as you hand turn the engine from the front pulley. Turn the engine one revolution every day or so, and it will move the rotors 1/3 of a revolution each time. Youre trying to give it time to soak in, so don't rush this process.
Know that when ypu get it all together, it's going to smoke like crazy on your startup, so get it out of your neighborhood if they would mind. Change plugs after that, and you'll get about as much benefit as you can.
Know that when ypu get it all together, it's going to smoke like crazy on your startup, so get it out of your neighborhood if they would mind. Change plugs after that, and you'll get about as much benefit as you can.
05-24-16, 10:01 AM
#23
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Well I can't find MMO anywhere in my area (Canada). When I get some do I just disconnect the distributor and pour a few ounces down the carb while cranking the car over? Then leave it sit for a day and turn the engine over with a wrench every once in a while? Not sure what the best method is.
05-24-16, 11:48 AM
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