Engine compression vs leak down test expert needed

[Rage]

Originally Posted by I'CE

Smitty, maybe maybe not some NASCAR guys used to try and cheat by line honing a block and effectively raise the compression in an engine just a few points SOOOOOOOO yea tech.possible. ie: raising the center line of the crank in the block.

FYI, I checked the deck height on each piston, rod, bearing assembly during build (which I did) and nothing unusual there.

Thanks,

Bill

[Rage]

Originally Posted by stevesxm

he's right. but just google it. a million people make them and ill bet there are some on e bay cheap.

I did not know that. I will give Ebay a try.

Thanks,

Bill

[BUIZILLA]

bent rods shorten the compression distance, and you'll get lower readings, and it won't affect the leakdowns...

[rssteiny]

Originally Posted by rssteiny

running a leak down test on engines that have not run since september and its in a garage but no heat and cold here. will it be acurate or do they need to be run first (that i cant do do to being winterized) or can i just crank them over a few times then do it.

anyone

[stevesxm]

it depends how you stored it. if you pulled the plugs and oiled it down and put them back and backed the rockers off so the valves were all closed and oiled behind them and sealed the exhaust and intakes and are well certain that the valve seats didnt rust up, then you could probably pull the plugs back out, re oil it hand crank it a few revolutions and leak it down and get representitive numbers. the lack of temp will leave the cleances a bit wide in the bores but, again, it will be a judgement call. if its 5 % then that tells you everything. if its 30 % that tells you everything... but you start getting to 10 or 15 % and the numbers are all the same, then whats that mean on a cold motor that you may or may not know anything about... or if its got 6 holes at 10 and 2 at 15.... ?

there is just no hard and fast answer to this question... it all has to do with how and where the motor was stored.

[stevesxm]

Originally Posted by BUIZILLA

bent rods shorten the compression distance, and you'll get lower readings, and it won't affect the leakdowns...

if this motor had rods bent bad enough to affect cranking compression, he wouldn't have to be wondering whether he had to take it apart. his post would have read " gee, does anyone know how to fix my back seat ? i started the boat this morning and a connecting rod went through it"

[Rage]

Originally Posted by MDGperformance

Really need to run the engine to get accurate compression results,I have checked cold engines(a couple cylinders a little low)then have ran engine and copmpression came up,with the leakdown ok this might be whats going on,snap-on makes a nice camera-scope that you can look down the cylinders,check for scoring

Do you know anything about the Visual Optics Video Bore Scope (picture attached) unit ie if it gives a sufficiently good visual image to diagnose cylinder wall condition?

[BUIZILLA]

Originally Posted by stevesxm

if this motor had rods bent bad enough to affect cranking compression, he wouldn't have to be wondering whether he had to take it apart. his post would have read " gee, does anyone know how to fix my back seat ? i started the boat this morning and a connecting rod went through it"

you don't have to be a smart a$$,,,, i've seen this happen once or twice before, and many a guru missed it...

[stevesxm]

Originally Posted by Rage

Do you know anything about the Visual Optics Video Bore Scope (picture attached) unit ie if it gives a sufficiently good visual image to diagnose cylinder wall condition?

i have a milwaukee that uses the same camera technology and it can see anything. also, any of the basic non camera types on ebay ( i looked and there are a 200 of them...) will do the job as well. the only thing you have to make certain of is if it has its own light source. for a couple hundred bucks its a tool that you almost can't be without .

[KNOT-RIGHT]

Originally Posted by stevesxm

i have a milwaukee that uses the same camera technology and it can see anything. also, any of the basic non camera types on ebay ( i looked and there are a 200 of them...) will do the job as well. the only thing you have to make certain of is if it has its own light source. for a couple hundred bucks its a tool that you almost can't be without .

Snap on just came out with one. It is amazing on the clarity
it is 400. My Snappy guy sold 200 of them the first month.
It also has right angle attatchments and a longer probe I ordered to do Gp inspections on my Turbines.

When you put the probe in ur pocket it reads the dates
off quaters cristal clear.