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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Sun Feb 20, 2005 8:29 pm Post subject: motor not firing on all cylinders |
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i just put in a 80k lo3 from an 89 iroc
with my fully rebuilt and exhaust ported 416's
port matched performer intake
rebuilt quadrajet
accel super coil
accel pro stock wires
ac delco rapid fire plugs
summit double roller timing chain
high volume oil pump
160 stat
comp cams xe 256
summit headers
when i started it to run in the cam I had a quarter tank of gas, and it ran on only 5 cylinders and used the whole quarter tank in only 20 min when i had to shut it off before running out of gas completely. i put in more gas, but now it won't start at all.
anyone got any ideas?
btw the engine did have a little bit of water sitting in some of the cylinders for a while but they only had minor surface rust which wiped away with a shop towel, the cylinders still have cross hatch and no ridges at all. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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90droptoproc Member
Joined: 25 Jan 2005 Posts: 490
1989 Chevrolet Camaro RS
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Posted: Sun Feb 20, 2005 10:40 pm Post subject: |
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check compresion
new distributor cap?
did you set the valves yourself or atleast have someone you trust do it
oh and the fuel usage reminds me of a quadrajet I had that stuck the float, it ran on 7 then 6, then5 etc untill I shut it off, and used 1/8 of a tank in less then a block, got anouther carb to test with?
Rich |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Sun Feb 20, 2005 11:11 pm Post subject: |
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no other carb to test with, cap and rotor are not new, haven't checked compression I don't have a compression tester
i set the valves myself, and double checked it, I do everything myself. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Sun Feb 20, 2005 11:48 pm Post subject: |
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i hope it's not compression, I really don't want to pull the motor and spend another couple hundred after just putting it back in. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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Wolffy Member
Joined: 22 Jan 2004 Posts: 375 Location: Spokane
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Posted: Mon Feb 21, 2005 10:16 am Post subject: |
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well eliminate the basics first just in case its something simple, occasionally we get luck
check for spark on all 8 cylinders, check the wires with a plug in them against a ground & wear gloves or insulated pliars
that will confirm all 8 are getting spark, either bad wires, cap or rotor would be the likely cause on that
buy a compression tester, they are $20 at harbor tools
i will admit using one is a magor PITA with my headers, but it tells you a lot of good info,
testing another carb would be a good step, if one was available
if all the above checks out ok then id look at the internals on the engine
but there are more Knowledgeable individuals on here |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Mon Feb 21, 2005 1:04 pm Post subject: |
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How do you know it's only running on 5? Without having checked spark? |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Mon Feb 21, 2005 1:10 pm Post subject: |
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brand new headers and three tubes are still black, all the others have the paint burned. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Mon Feb 21, 2005 1:13 pm Post subject: |
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laegion wrote: | brand new headers and three tubes are still black, all the others have the paint burned. |
Check the spark on each. Just put the plug out or have a spare plug, hook it to the plug wire, lay it on the header, and have someone give the car a few cranks. If you have spark on those 3, and it's a carbed intake I don't know what to tell you other than lash or firing order is wrong(assuming the ignition module is good and it's timed right with the light.
18436572
EDIT: Remember you can't adjust the valves with an aftermarket cam like the book says because the durations are different. The ONLY way is the EOIC method.... Exhaust open(adjust intake) Intake closing(adjust exhaust)
Adjust all exhaust in firing order then intake and you only have to turn the engine over a handfull of times. |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Mon Feb 21, 2005 1:37 pm Post subject: |
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why can't you adjust the valves the way the book says? the valves will be closed on compression stroke or the motor won't run. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Mon Feb 21, 2005 8:02 pm Post subject: |
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If you use the method most books have, that says to adjust half the valves at one crankshaft position, then turn it over and adjust the other half, you may not get the correct lash with an aftermarket cam. That method assumes a fairly short duration. With a longer duration not all the lifters will be sitting on the base circle of the cam at that time. You are correct that you can adjust each cylinder while each is on its tdc point. Problem is it's hard to tell when its exactly at tdc except for 1 and 6. There are points in the combustion cycle which have both valves slightly open even. The method Paul mentioned always works. |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Mon Feb 21, 2005 9:15 pm Post subject: |
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i just always make sure that the cylinder i'm adjusting is well into the upstroke on the compression stroke but not quite at top dead center because in order for the engine to work I would assume that the valves have to be closed or the compressed mixture would escape. but I adjust them all in the firing order one by one. rotating the crank. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Mon Feb 21, 2005 9:23 pm Post subject: |
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here are the things I know are right
cam timing is on
distributor is in right
firing order is right
timing is off
idle mixture and idle speed are not set
unfortunately I can't get much done since the battery is dead. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Mon Feb 21, 2005 11:09 pm Post subject: |
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Start simple. Pull those 3 plugs and look at them. See if they're wet. From your gas consumption i'm bettin they'll be soaked. To see if its a plug or wire simply swap them to a cylinder you know works. If that cylinder dies you know its the plug or the wire, whichever you swapped.
If the motor wont start at all, pull all the plugs and check them. Also check for spark on at least 1 wire. If ignition seems to all check out you really need to do the compression test next. If theres no compression or low compression in a hole, squirt some oil in and try it again. Too much gas can wash the cylinders down and you wont have any compression. Or maybe its just from sitting. If you still dont get compression even with the oil then you have a valve problem, hopefully just adjustment.
If you do find that the plugs are wet, pull your dipstick and make sure the crankcase didnt fill up with fuel. If it did change oil. If the carb's flooding over, try clamping off the fuel line and starting the motor. Car will run until the fuel runs out of the carb. This drops the float down. Now unclamp the fuel line and start it again. Since the float is fully dropped down this will usually let any dirt stuck under the seat blow out. Then check if its flooding, you shouldnt see fuel runnin into the carb, it should just be vapor. If its still flooding you'll have to fix the carb.
Is the choke opening?
Anyway, thats a few things to check. |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Mon Feb 21, 2005 11:12 pm Post subject: |
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Oh BTW, I saw your mileage post on tgo. I run the XE256 in my 327. I'm runnin not so good, modified 450casting 305 heads. I dont have overdrive and have 3.23 gears.Went to Clackamas and back this weekend turning 3400 most of the way. Pulled down 19.1mpg and a couple years ago on the dyno put 227hp to the wheels. Its a fairly mild cam but should be prety nice in your 305. |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Tue Feb 22, 2005 9:36 am Post subject: |
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i have a feeling that it might be the carb, I didn't rebuild it, a friend of mine did. he's nearly an ase certified mechanic, (minus the field experience) but he does sloppy work sometimes especially when it's on my car, and also when I checked the oil after running it was way too high, and I know I didn't over fill it. it only got that high after running the engine. hopefully it's just a bad cap and rotor, or pickup coil or something, and the carb, the last thing I want to do it pull the engine again and spend more money on gaskets and coolant and all that other crap.
thanks for all of your help. and if none of this works I'll try adjusting the valves again. _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Tue Feb 22, 2005 1:20 pm Post subject: |
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The carb wouldn't make 3 cyl not fire, just lean out or too much fuel to 4 cyl at a time, unless it's a single plane. Pull the guilty plugs to see if they are wet, if they are wet, carb is doing it's job enough to get fuel there. |
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90droptoproc Member
Joined: 25 Jan 2005 Posts: 490
1989 Chevrolet Camaro RS
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Posted: Tue Feb 22, 2005 7:00 pm Post subject: |
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I can't explain why, bnut I have had a faulty carb shut down afew cylinders at a time, I swapped carbs and the whole problem disapeared never to be seen again |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Tue Feb 22, 2005 7:22 pm Post subject: |
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Paul it will flood out certain cylinders before others. Especially if theyre the back ones. With the high oil level now too, I'll bet its flooding. Since the carb was just rebuilt, he's probably got the needle keeper jammed. I'll bet all the plugs are wet now, thats why it doesnt run at all.
If the oil smells like gas change it!! You dont want to wash out your bearings. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Wed Feb 23, 2005 1:15 pm Post subject: |
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chevymad wrote: | Paul it will flood out certain cylinders before others. Especially if theyre the back ones. With the high oil level now too, I'll bet its flooding. Since the carb was just rebuilt, he's probably got the needle keeper jammed. I'll bet all the plugs are wet now, thats why it doesnt run at all.
If the oil smells like gas change it!! You dont want to wash out your bearings. |
Is it just because the primary bores are farther forward? it doesn't make sense that i'd flood/lean out others over all... say the given side a bore is on.... is it manifold design that does it? |
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laegion Member
Joined: 08 May 2004 Posts: 96
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Posted: Wed Feb 23, 2005 6:05 pm Post subject: |
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i would say it's manifold design _________________ 95 vw jetta gl
currently looking for a cheap ninja 250 or 500 or comperable 2cyl sportbike. |
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