having a little issue...

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Put the piston at tdc with both valves closed.

when you hook the gauge up to the compressor, you zero it then after that.. hook to the cylinder and see what percentage of leak you have.

you mention 20...I assume you mean 20% leak down, not good.
at the same time...g force smoking=leaky pan onto header/exhaust maybe.

tan plugs?
what part is tan?
you could be running too rich like that and not know it, black would be an eventual catastrophy.

you haven't had any exhaust leaks on the no.6 with those headers have you?
enough of a leak and burnt valve city...

btw...the only way you would end up with the ring gaps staying lined up is from an out of round cylinder, like 2+ thou or so.
 
just now seen the leak down post [was looking this page I loaded earlier and forgot to refresh]

you either washed the rings out of it, somehow all the valves are out of round 'been there before' or the machinist who honed it sucks

you should do the test with the pistons tdc/valves closed.
 
805moparkid said:
im sure it wasn't at 6K miles tho...
Click to expand...

This is true. More like 126000. But it is a good illustration of what can happen with bad rings. Rings can go bad quickly for a number of reasons. My Roadrunner broke one during break-in. Probably my fault, but I don't really know why.
I had oil dripping on my exhaust pipe a little too close to the header and it resulted in a fire, so be careful there.
 
1wild&crazyguy said:
Put the piston at tdc with both valves closed.

when you hook the gauge up to the compressor, you zero it then after that.. hook to the cylinder and see what percentage of leak you have.

you mention 20...I assume you mean 20% leak down, not good.
at the same time...g force smoking=leaky pan onto header/exhaust maybe.

tan plugs?
what part is tan?
you could be running too rich like that and not know it, black would be an eventual catastrophy.

you haven't had any exhaust leaks on the no.6 with those headers have you?
enough of a leak and burnt valve city...

btw...the only way you would end up with the ring gaps staying lined up is from an out of round cylinder, like 2+ thou or so.
Click to expand...

ok when i did the test the piston was at tdc compression stroke. both of the valves were fully closed and the rocker are were still at lash (.015/.021).

as for the plugs. the porclin around the electrode was a light tan with a red tinge, think we mtbe in our gas. the strap was mostly unchanged in color.

i do have a new gasket leak causing oil to hit the header but when i was doing the leak down test the first test i had that same "smoke" come out of the bottom end.

im gonna pull the head tomarrow and se whats up
 
magnumdart said:
This is true. More like 126000. But it is a good illustration of what can happen with bad rings. Rings can go bad quickly for a number of reasons. My Roadrunner broke one during break-in. Probably my fault, but I don't really know why.
I had oil dripping on my exhaust pipe a little too close to the header and it resulted in a fire, so be careful there.
Click to expand...

when im doing the leak down test i can hear the steady whoosh of air and the tone changes when i put my finger over the dip stick hole.
 
this is not a good pick, but what you want to see from a pump gas motor, it's out of my 340.
btw...black oxide plugs suck for reading the base ring, thats why I use the ngk/champion etc..
you want to see tan but only down inside the plug near the inner base-hard to see.
 

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805moparkid said:
mine looks the same except that mine is slighlty more tan than ur white, everything else is the same
Click to expand...

then you are on the rich side.
the base ring reflects chamber color-mixture.
if you have any soot/build up, you need to tune it leaner or fix the oil burning problem/stuck choke/fat idle.
the base ring, when tuned right, will reflect the the inner ceramic color, except it'll be a lil tan ring right where it meets the metal body.
the tang should show color change at the bend.
 
1wild&crazyguy said:
then you are on the rich side.
the base ring reflects chamber color-mixture.
if you have any soot/build up, you need to tune it leaner or fix the oil burning problem/stuck choke/fat idle.
the base ring, when tuned right, will reflect the the inner ceramic color, except it'll be a lil tan ring right where it meets the metal body.
the tang should show color change at the bend.
Click to expand...

there is no soot on the plug. and im running champion 404's
 
Just out of curiosity, what does the oil look like? Normally I try like hell not to take an engine down, but if the numbers you are posting are correct, you aren't going to be able to fix it without dismantling it. IMO. Some of the things posted here make a lot of sense, like bad hone job, screwed up guides, etc. I'm not thinking head gasket, but it could be. Nice if it was, 'cause it's an easy fix. As an after thought, it could even have a cracked head.
 
1wild&crazyguy said:
have you tried jetting down till it surges and then back 2 jets?

and if so...did you also jet the secondaries down too?

how old was this motor?
Click to expand...

when i first broke in the motor @ wyotech we did some light pulls on the dyno and it was @ 16:1 with 66's on the primaries so i rasied the primaries to a 67 not long after and just recently went up to a 68. i think the pv is to big tho @ 6.5.

the motor was built middle of 09... has like 6300 miles on it. none at the track
 
magnumdart said:
Just out of curiosity, what does the oil look like? Normally I try like hell not to take an engine down, but if the numbers you are posting are correct, you aren't going to be able to fix it without dismantling it. IMO. Some of the things posted here make a lot of sense, like bad hone job, screwed up guides, etc. I'm not thinking head gasket, but it could be. Nice if it was, 'cause it's an easy fix. As an after thought, it could even have a cracked head.
Click to expand...

the oil is a little dirty, dark, but its just about due for an oil change, and i use brad penn 10/30. and will see today im pulling the head and posting pics. also will post pics of the plugs
 
so after pulling the head off i saw that the headers were leaking, see pics
after getting the head off and chking the head i saw no issues with it.
spun the motor over by hand with no issues and the cyl walls look fine, nice cross hatch
but the pistons rock in the bores... i found the info from when i built it and after the hone (block was already .080) the taper was only .001 on two cyl and taper was only .001 across the board.
ok here are the pics
 

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no.3/5/6/ exhaust valves should be checked as well as all the valve faces, look to see if the seated portion is dark/burnt, also spin the valves 90*-180* and look for light between the face/seat.

1 thou is big when it comes to cylinders, half a thou is ehhh..but might explain ring gaps all lining up.
if they rock in the bores, what pistons...forged? they will do that a lil, like 4-8 thou skirt clearance.

Most of the plugs look a lil rich to me, if the power valve was blown you would have bowl pressure making it though the pv channel and into the mains at cruise, if it was just rated to high for the actual manifold vac at idle in gear and had the combo of too much throttle blade opening at idle it would also give an over rich condition at idle.
People will argue about wether the pv will actually come into play at idle saying it's into the mains yet to initiate it, but thats where the bowl pressure comes in to play..
 
1wild&crazyguy said:
no.3/5/6/ exhaust valves should be checked as well as all the valve faces, look to see if the seated portion is dark/burnt, also spin the valves 90*-180* and look for light between the face/seat.

1 thou is big when it comes to cylinders, half a thou is ehhh..but might explain ring gaps all lining up.
if they rock in the bores, what pistons...forged? they will do that a lil, like 4-8 thou skirt clearance.

Most of the plugs look a lil rich to me, if the power valve was blown you would have bowl pressure making it though the pv channel and into the mains at cruise, if it was just rated to high for the actual manifold vac at idle in gear and had the combo of too much throttle blade opening at idle it would also give an over rich condition at idle.
People will argue about wether the pv will actually come into play at idle saying it's into the mains yet to initiate it, but thats where the bowl pressure comes in to play..
Click to expand...

the pistons are cast aluminum.
 
It is a very old hot rod trick. Pistons are not 100% round (at least in the skirt area) and the wrist pin is not dead center. Has to do with keeping the engine quiet when cold. Down side is a little faster wear and some more noise but it does reduce engine friction and makes more HP.
 
slant6/4speed said:
It is a very old hot rod trick. Pistons are not 100% round (at least in the skirt area) and the wrist pin is not dead center. Has to do with keeping the engine quiet when cold. Down side is a little faster wear and some more noise but it does reduce engine friction and makes more HP.
Click to expand...

well i already have an engine that wore out in 6K miles, i dont need anymore wear...
 
805moparkid said:
what??? why???? they are round and are flat tops? how would that help?
Click to expand...

Stock/ish pistons generally come with some offset in the pin in order to load the piston against the cylinder wall=keeps them quite, grandma didn't like noise in her new car, get it so far?

so that is friction/drag which decreases power a tinzy bit.

reversing them unloads them and wahlah! more power, as for wear? not really of any significance.

It's a good thing, trust me.

And...do you see any offset pins in performance pistons like KB/ROSS/WEISCO?, answer is no.

So what are you building, a stock engine or a performance engine?
 
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