hello everyone!..need some pointers if possible..my Camaro has a small block 350, electronic ig--- mallory comp 9000, the problem seems like the car runs fine for about the first 45 mint. then after a while..even though it doesn't even reach temp, of 190 .. it starts missing after 2-3 gear of shifting..giving it a lot of gas...i was thinking it may be in the dist. maybe a module or something? if anyone could help..Thanks!

Try adjusting your mixture screws at idle when engine is warm.
When you turn them clockwis a few turns the rpm will change.
If there is no change in rpm your power valve is shot. That is if you have a Holley carb.
It is a cheap fix, I just did one myself and now the car runs great.

thanks Jim, im going to the pismo show in a couple of weeks.. so im not sure if i will pull it apart before the show..but i will let you know on the out come..:thumbsup:

Chris, can you be more specific? Like, is it missing only when returning to an idle? Or is it missing under full load at high RPM? Or both? Does it sound like it's dropping one cylinder or more? Any noises, like maybe a lifter is pumped up?

Chris, can you be more specific? Like, is it missing only when returning to an idle? Or is it missing under full load at high RPM? Or both? Does it sound like it's dropping one cylinder or more? Any noises, like maybe a lifter is pumped up?
hi Fred, it seems to be missing under full load/high rpm after its warmed up..idle seems fine even after its warmed up..its hard to hear any noises in motor, i have a sm 350 low compression, 6-71, two holley 650's..i just installed 3" exh. and it seems like when im really getting in a full load from 2 to 3rd gear is when it feels like its missing, then comes back alive again for a few seconds. Thanks for any input.

Whoa, not your everyday driver! Bet it's FUN! I'll pull to the curb and let the blower experts help you.

Hey Fred, well thanks for chiming in,..i have changed the plugs,fuel filters, i havent adjusted the timming or adjusted the carbs yet, im going to maybe see if my jeting is right sence i opened up my exhaust..not sure..it runs like a wild cat, but under extreme high rpm's it flunders a little

I'm not a blower man either, but I've been called a blowhard! Does that qualify me a little? hehe

It almost was like you were describing a surge "then comes back alive a few seconds". Which would head me looking at fuel delivery... pressure, bowl level, line size.

I'll let the blower guys get serious with this, but first thought is the 3" exhaust has got you a lil lean.

thanks Tim,Jim..sounds like it could be fuel..i will check the levels/lean

You might want to check some plugs, too, Chris. If she's gone lean on you, that would be bad at the pressure involved on a blown motor.

little update, i checked my timming it was good..i went ahead and adjusted my carbs-650 Holley double pumpers..to 1 1/4 turns out..im running rich at start up and at idle ..it seemed to help alot... but i think im still starving for fuel at high rpms..so maybe i need bigger jets? and could it have anything to do with ign.? im still thinking its fuel..as i lost some back presure by going with 3" exh. Thanks Chris

prolly runnin outta fuel at the top...when it breaks up, get outta the throttle for 3 sec`s and then stab it again...does it pull like hell through the spotty rpm range???if so, get a bigger pump, or turn up the fpr pressure when under boost...it is refrenced under boost, right???some regs are set at the low end for lets say 5-7 lbs, and 20 or so under boost...the blower is just working far more efficiently because of ther bigger exh...think of it like this, a motor under 14 lbs of boost feels like it`s twice the size of a normally aspirated car, because it is taking in aprox 1 full atmosphere of air more at 14 lbs of boost...therefore a 14 lb boosted 350 motor going from 2.5 to 3 inch exh is like going from 5 to 6 inch exhaust on a 700 cubic inch motor...lol...the blower is just a big air pump, and the more air you can get out of the motor, the more efficient the blower is at putting air in...more air obviously needs more fuel, so at this time, i`d address the supply problem, and then go up with the jets...maybe jody and others will suggest some jets for you...most of my experience is with centrifugal blowers and blowthru carbs, which are different than your pull thru setup, so i`ll refrain from suggestions on jet sizing...

prolly runnin outta fuel at the top...when it breaks up, get outta the throttle for 3 sec`s and then stab it again...does it pull like hell through the spotty rpm range???if so, get a bigger pump, or turn up the fpr pressure when under boost...it is refrenced under boost, right???some regs are set at the low end for lets say 5-7 lbs, and 20 or so under boost...the blower is just working far more efficiently because of ther bigger exh...think of it like this, a motor under 14 lbs of boost feels like it`s twice the size of a normally aspirated car, because it is taking in aprox 1 full atmosphere of air more at 14 lbs of boost...therefore a 14 lb boosted 350 motor going from 2.5 to 3 inch exh is like going from 5 to 6 inch exhaust on a 700 cubic inch motor...lol...the blower is just a big air pump, and the more air you can get out of the motor, the more efficient the blower is at putting air in...more air obviously needs more fuel, so at this time, i`d address the supply problem, and then go up with the jets...maybe jody and others will suggest some jets for you...most of my experience is with centrifugal blowers and blowthru carbs, which are different than your pull thru setup, so i`ll refrain from suggestions on jet sizing...
Hey Mike thanks! i have a better understanding on the system now..to address some of the stuff asked. i have a gas pressure gage where i can see it from the windshield, so when im on it, at high rpms..the pressure gage stays at its 6-9 lbs. which is normal..so your right when im on high rpms it stumbles but it also doesn't stop climbing.:) .i ordered a holley jet kit from summit so i should have it in a couple of days..im not sure how much to go up on the jets? and can i only go up on the secondaries? or should i go up evenly? and not the primeries? thanks

usually you stay within 10 jet sizes of eachother with primary and secondary, but usually closer to 6-8 sizes...the blower tuning thing is a long drawn out process, so dont go too big at once...the breaking up thing but still climbs is still saying out of fuel to me, but i could be wrong...just cuz the guage says 6-9 doesnt mean you are getting the volume you need, ya know...could be wrong though...do like my earlier post...back outta the throttle for a second...this will allow fuel to return to the fuel bowl...then stab the pedal again...i realize this is hard in a blower motor, but its the only test i can think of...you could run it up in the rpms slowly to high rpm in 3rd gear on the hiway, and once you hit 4000 stab it...if there is no fuel in the bowls, you will go lean...keep in mind that going lean on a blower motor is VERY bad...detonation and such...its always better to be fat in forced induction...you can only go up on the 2ndaries by the way...as long as you stay within 10 sizes of eachother...what kind of fp???regulator???we run an aeromotive moving 180 gph...believe it or not, too much more power out of our 383, and we need a bigger pump...lmao...and thats thru a single 650 dp...

i ran it last night late..when the air was cool and it seemed to run fine..it was hard to back off then stick it again cause the blower runs for just a sec. when you let off so it seemed impossible to stab it again..but my jet kit came in so ill check my plugs the go up a few sizes on my secondaries..ill keep you guys posted Thanks Chris

Chris, I think you should either edit the title on this post (if you can) or start a new one, making it clear in the title that a blower is involved. We have some very good "blower guys" here, but they are not involved yet. Mike and I are good, but input from Jody or Royce or a few others would be better.

Messing with your idle setup is not gonna help a problem at high rpm / load in third gear.

You do need to look at some plugs. I'd put new plugs in it, do a hard pull, shut it down immediately, and pull some plugs.

If around town driveability is good, I'd work only with the secondary jets. I'd go "too rich" first, clear the symtoms, then start coming back down, checking plugs / AFR the whole time. If you go up 6 on the sec mains and the problem doesn't clear, you'll have a fuel delivery issue, punp, reg, or lines, but I think it will clear.

Be careful with this... a high speed leanout on a blower motor is an easy way to turn your investment into scrap.

jim`s right...jody has way more experience with force feeding than i...thats why i refrained from spouting jet sizes...blowers are a big learning curve, and can get expensive quick if you lean it out on the top...i dont wanna feel responsible for lunchin your motor...lmao...maybe you could pm jody and get his thoughts...search out camcojb...

haha, ya, I know what you mean Mike. I tried to stay out too, but kept reading. Would hate for chris's engine to melt tho.

Royce is real good with GM blowers, but he's not around much and seems to only read posts with blower in the title!

rotflmao...

haha, ya, I know what you mean Mike. I tried to stay out too, but kept reading. Would hate for chris's engine to melt tho.

Royce is real good with GM blowers, but he's not around much and seems to only read posts with blower in the title!
Update: Royce is helping me via e-mail, my stock jets on my two 600 Holleys are 73 all the way around..well i changed my primary jets to 79 on one and 78 on the other, then on my secondaries i went 84 on one and 85 on the other..now it stumbles at take of and at high RPM's ..i have new plugs,wires,fuel filters, so im wondering noe since i didn't have the problem with take off i should go back to 73?..to top it off i only have a few days to fix this if im going to make the pismo show Thanks for any input

..i am running an electric Summit fuel pump, my jets are all 73 front and back, i changed the primaries at first and it didn't clear the problem so then i did the secondaries and it made it worst..so im not sure if maybe my fuel pump isnt big enough now? whats wierd is that it seems to run ok when its cold still misses a little but runs good when i take off and run through the gears..then after the engine warms up it starts spluttering and stumbles more after the engine is warm, but im still at the right temperture..so i almost thought about laser cutting some spacers with a 2 1/2" hole and mounting it beteewn my collectors, to see if back pressure is the problem? im not sure what else i can do? i was thinking maybe my power valves were blown or exceleration pumps were messed up? the carbs are only 1 year old, but before i tear down the carbs..i was thinking back pressure? but then again does that mean blower motors can't run straieght headers? cause they would stumble also?

These carbs don't have any chokes, right?

If so, then you are rich.

Have you thought about putting her on a chassis dyno wide a wideband hooked up?

These carbs don't have any chokes, right?

If so, then you are rich.

Have you thought about putting her on a chassis dyno wide a wideband hooked up?
Hello Jim, yes no choke..it seems to run rich at idle, then leans out like it should, the only thing i havent done was change the jets to a smaller size,..i was also thinking maybe escaping exh. faster by the 3" would not run my headers so hot, in turn its not burning as hot and making it rich.. but i have gotten so many differant opinions im just trying to tackle the easy stuff first then i may have to send it to a dyno shop

forced induction cars really resdpond to larger exhaust well, so dont worry about going the wrong way with the exhaust...the lazer cut spacers are a genious idea for the test, and i`d be interested in the results...sounds like you should go back to the original jet sizes and start over...if you now have a stumble with the original jets that wasnt there 2 weeks ago when this mess all started, then you know to move on to fuel delivery to the carb, or ignition...

forced induction cars really resdpond to larger exhaust well, so dont worry about going the wrong way with the exhaust...the lazer cut spacers are a genious idea for the test, and i`d be interested in the results...sounds like you should go back to the original jet sizes and start over...if you now have a stumble with the original jets that wasnt there 2 weeks ago when this mess all started, then you know to move on to fuel delivery to the carb, or ignition...
Mike, update, i laser cut some spacers to go inbetween the collectors, and ran it..it runs better, i have a lot better bottom end, and lauches pretty good i still have a surge at high rpms, so i may look at the excelerator pumps or power valves..i know engines like to run rich when cold, so im thinking maybe differant power valve..not sure yet. but i seem to be going in the right direction.