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DRR Trophy
posted
after running car 6 runs, pulled plugs, number 2 cylinder is still white looks new rest have good color, not as much heat building in that cyl with heat gun. its getting spark to that plug any ideas??
 
Posts: 7 | Location: carbondale | Registered: April 05, 2008Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
Check the valve lash on number 2 intake, look for broken rocker, bent push rod, or anything else associated with number 2 intake valve train.
 
Posts: 138 | Location: Midlothian, Texas | Registered: October 19, 2000Reply With QuoteReport This Post
DRR Pro
Picture of rusty
posted Hide Post
put a new plug in it


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

 
Posts: 1420 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Top Comp
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Had an engine on the dyno a few years back that the EGT was 1000* low on one cylinder....checked valves, compression, leak down, looked at the plug....nothing wrong...went to put plug back in and I hear a little "tink"... turn the plug over and examine it again....looks fine...just for the hell of it I shake the spark plug...rattles pretty good...turns out the porcelain was broken up in the plug and would drop down to the electrode when you turn it down in the installed position. Indexed another plug for that cylinder and ran the engine again...picked up 80hp and obviously the EGT came up to normal in that cylinder....


.
Dave



F J B

 
Posts: 4478 | Location: Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
Yep what they said, new plug first, then try different plug wire.


"Sugar Shane"
 
Posts: 119 | Location: No clue | Registered: March 01, 2009Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
have tried several plugs and wires . getting good fire to plug have adjusted valves still no difference
 
Posts: 7 | Location: carbondale | Registered: April 05, 2008Reply With QuoteReport This Post
DRR Pro
Picture of rusty
posted Hide Post
leak down and compression


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

 
Posts: 1420 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post



DRR Pro
Picture of Mike Beck
posted Hide Post
Like topfuel said, check everything with that intake valve! If it isn't opening, no gas will ever get to the chamber to do anything.

A bad plug/wire/reluctor on the distributor shaft, can leave that cylinder NOT firing, but if run enough, should at least get wet, unless that cylinder is also never getting any fuel.
 
Posts: 1444 | Location: South River, NJ | Registered: June 19, 2007Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
compression checked out good, while putting air preasure to spark plug hole, to do leak down
valves closes more than with just spring???
 
Posts: 7 | Location: carbondale | Registered: April 05, 2008Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
is this engine injected, it so check for plugged nozzle.
 
Posts: 138 | Location: Midlothian, Texas | Registered: October 19, 2000Reply With QuoteReport This Post
DRR Trophy
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not injected
 
Posts: 7 | Location: carbondale | Registered: April 05, 2008Reply With QuoteReport This Post
DRR Sportsman
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If valve moves closed when pressurised for leak down check something is deffanatly wrong with that spring. Most likely broken.
 
Posts: 501 | Location: Going to or returning from the chipmine. | Registered: July 01, 2011Reply With QuoteReport This Post
DRR Top Comp
posted Hide Post
Years ago we were dyno testing manifolds for a company near us.
One manifold was down 50hp and #3 cylinder was 1000* less EGT. Leaked down that cylinder and it was 95% leakage. Manifold company guy pulled the intake and cylinder head (his engine).
Cylinder wall was destroyed. Had a lip at the top that looked like even .030 over bore wouldn't clean up. Top of the piston had grit of some sort in the valve pockets.
Long story short, the intake runner for that cylinder had a plug of casting sand blocking the entire port off. It was in the turn of the port so you couldn't see it if you weren't looking....
Customer said it must have missed "clean up" before boxing...lol


.
Dave



F J B

 
Posts: 4478 | Location: Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR Sportsman
Picture of FootbrakeJim
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quote:
Originally posted by Wooley:
If valve moves closed when pressurised for leak down check something is deffanatly wrong with that spring. Most likely broken.

^^^ THIS. Possibly guide or valve stem issue, but sounds like broken or very weak spring. Did you look at the inners? They can be hard to see all the way around...


Dan "Jim" Moore
Much too young to feel this damn old!!
 
Posts: 1045 | Location: Farmersville, TX  | Registered: December 05, 2002Reply With QuoteReport This Post



DRR Pro
Picture of rusty
posted Hide Post
quote:
posted September 06, 2018 04:12 PM Hide Post
quote:
Originally posted by Wooley:
If valve moves closed when pressurised for leak down check something is deffanatly wrong with that spring. Most likely broken.

^^^ THIS. Possibly guide or valve stem issue, but sounds like broken or very weak spring. Did you look at the inners? They can be hard to see all the way around...

Dan "Jim" Moore
Much too young to feel this damn old!!

should still some sign of combustion i would think


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

 
Posts: 1420 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Sportsman
Picture of FootbrakeJim
posted Hide Post
quote:
Originally posted by rusty:
should still some sign of combustion i would think

Have seen it both ways, Rusty. Broke an outer spring on the intake side, header pipe was much cooler than the others, but plug did show light coloration. Compression gauge tests were all over the place, (some times valve would close, sometimes not). Had an exhaust guide/seal get tight and grab the valve stem and hold it open slightly, and that plug stayed looking just like new. Not sure if broken spring would show same result though.
Hopefully OP will share the findings.


Dan "Jim" Moore
Much too young to feel this damn old!!
 
Posts: 1045 | Location: Farmersville, TX  | Registered: December 05, 2002Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
springs look good loosing about 7 per cent on leak down test
 
Posts: 7 | Location: carbondale | Registered: April 05, 2008Reply With QuoteReport This Post
DRR Sportsman
Picture of Slick Vic
posted Hide Post
Cap/Rotor? Is it crank trigger or dist. pickup? Check the tabs under the rotor, i call it the reluctor, not sure if that's the correct name.


302-786-1078
slickvic@slickvicracing.com

slickvic@slickvicracing.com
www.slickvicracing.com
302-786-1078

Dealer for most major brands, including Simpson, Necksgen, Hans, Strange, Moser, Amsoil, Aerospace, Digital Delay, Hoosier, M/T, Goodyear, Redhorse, MSD, Racepak, Lucas, and more.

Complete racecar wiring and custom CNC parts available.
 
Posts: 131 | Location: Delaware | Registered: June 12, 2008Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
crank trigger, have changed cap and rotor
 
Posts: 7 | Location: carbondale | Registered: April 05, 2008Reply With QuoteReport This Post
DRR S/Pro
posted Hide Post
If your getting good spark when its needed and still no color or signs of heat, you could have a fuel distribution issue causing that hole to run cold. I have seen air scoops do weird things, so it may be worth trying to run an air cleaner. If the scoop is causing issues with air disturbance an air cleaner will smooth things out with the air entering the carb.
 
Posts: 2161 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
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