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OS .21 VZB V-Spec compression?

Old 01-07-2008, 03:36 PM
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mrbonk
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Default OS .21 VZB V-Spec compression?

Hey all,
Just wondering how much compression/pinch my V-Spec should have. It's a second hand car/engine, so I don't know what a new engine should feel like. At present, I'm able to wind the engine all the way over by hand. With the plug in, it provides obvious compression over the top, but with the plug out, I can wind the engine over fully without feeling any 'pinch' at TDC. Is this normal, or is it starting to get worn out?
Old 01-07-2008, 03:47 PM
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Default RE: OS .21 VZB V-Spec compression?


ORIGINAL: mrbonk

With the plug in, it provides obvious compression over the top, but with the plug out, I can wind the engine over fully without feeling any 'pinch' at TDC.

Are you sure??? It happens to me on reverse. When i put my glow starter on, the engine becomes easier to spin, but it might be the fuel also. I never experienced sush situation. And what do you mean by "wind the engine over fully without feeling any pinch"? If you mean freewheel, without a bit compression, i think you might want to open your engine. To check it out easier, open the behind of the engine (the back cover plate, easy to access). Then, tell me again, except if someone post. Sorry to help you I hope is nothing. Did you run the engine?
Old 01-07-2008, 03:56 PM
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Default RE: OS .21 VZB V-Spec compression?

With the plug out, you shouldn't feel any pinch, because if you do feel pinch with the plug out that means its not broke -in all the way. if you turn the engine over slow and it has no compression or you hear the air blow by the piston then compression is fair, with a engine that has great compression you should be able to turn the engine over slow and no air blow by the piston. if any air blows by the piston if its just a little then it should be good-fair compression, and this is with the flywheel on, if you can turn the engine over with out the flywheel so you're just using your hands then compression is low.
Old 01-07-2008, 04:02 PM
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Default RE: OS .21 VZB V-Spec compression?

Now that you mentioned flywheel, i had a lot of problems with the flywheels and that stuff. If i understand now more clearly,...hey mrbonk, check turning the flywheel. You said no difficulty to turn, right? It might the flywheel nut unscrew and the flywheel is not attached to the engine at all. The flywheel spinning but the engine doesn't moving.
Old 01-07-2008, 04:53 PM
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Default RE: OS .21 VZB V-Spec compression?

Osiris - The engine is fine. I've been running it, but just wondered how much compression it's *supposed* to have. Having no real experience with performance car engines, I wasn't sure what it was supposed to feel like.

JB: Cheers for that. I didn't want to shell out for a new piston and liner if I didn't really need it yet
Old 01-07-2008, 08:02 PM
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Default RE: OS .21 VZB V-Spec compression?

They sall compression gauges but I dont have one, keep forgeting to order it. Mines got 4ish gallons on it and I can do the same thing, plug in you fell alittle tight up to, plug out it spin rather easy. You could always pinch it or just run it as is. Ive seen v specs go through many gallons before sleve set up was replace, 8-10 range. Bearings is another issue.
Old 01-07-2008, 08:30 PM
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Default RE: OS .21 VZB V-Spec compression?

Yeah, I've been warned about engine bearing life. I'll go ceramics when these ones die. I've already shredded 2 clutch bell front bearings! I'm trying some hybrid ceramics on that too, just to see how much longer they last.
Old 01-07-2008, 09:30 PM
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Default RE: OS .21 VZB V-Spec compression?

I have a compression gauge but there are not any standards for what compression should be on RC engines. The way you use them is after break in check compression and then check it from time to time to see if you have a big drop. I never use it and run an engine till I start having problems then take the piston and sleeve out and see how far I can push the piston through the sleeve. I have a V spec and have no problem turning it over with the plug in by hand. I take my engines apart about every 3 gallons and check them. My STS engines keep a tighter pinch then my V Spec.
Old 01-08-2008, 01:50 AM
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Default RE: OS .21 VZB V-Spec compression?

A nice hard thump is all you need or should worry about with the plug installed and turning the flywheel w/your finger. If there's zero resistance and the engine wont run right then it's time for a rebuild.


too many people worry about compression. run it and worry about compression once it won't run right anymore.
Old 01-08-2008, 07:22 AM
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Default RE: OS .21 VZB V-Spec compression?

Yes, i agree. First time i was trying to start that engine, it was MEGA HARD to rotate it with your fingers below of the chassis (if i take the engine of the car and trying to turn it with my whole hand, the compression was not so hard). Now, that my engine did a few gallons and after replaced piston, sleeve and con rod and performed the break-in procedure again, is just fine, easy to turn the engine
Old 01-16-2008, 12:28 AM
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Default RE: OS .21 VZB V-Spec compression?

has any1 tried one of those stupid looking sleeve pinchers? i think theyre pretty pointless and probably VERY inaccurate but has anyone tried one with a vspec sleeve yet????
Old 01-16-2008, 01:27 AM
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Default RE: OS .21 VZB V-Spec compression?


ORIGINAL: mrbonk

Osiris - The engine is fine. I've been running it, but just wondered how much compression it's *supposed* to have. Having no real experience with performance car engines, I wasn't sure what it was supposed to feel like.

JB: Cheers for that. I didn't want to shell out for a new piston and liner if I didn't really need it yet
Ignore Osi, he's clueless and never makes any sense.
Old 01-16-2008, 06:34 AM
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Default RE: OS .21 VZB V-Spec compression?


ORIGINAL: Da Smak


ORIGINAL: mrbonk

Osiris - The engine is fine. I've been running it, but just wondered how much compression it's *supposed* to have. Having no real experience with performance car engines, I wasn't sure what it was supposed to feel like.

JB: Cheers for that. I didn't want to shell out for a new piston and liner if I didn't really need it yet
Ignore Osi, he's clueless and never makes any sense.
No comment. I just PM what i have to say to you AGAIN Da Smack. You making my live AND THE LIVES OF OTHERS TOO, JUST TOO DIFFICULT.

As for the thread, i'm happy that the engine is fine. I have 2 V-specs and i think i have an opinion Da Smack. Please, do not continue this. More info in your inbox...[]
Old 01-16-2008, 11:46 AM
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Default RE: OS .21 VZB V-Spec compression?

How's your post count now then?
Old 01-16-2008, 05:19 PM
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Default RE: OS .21 VZB V-Spec compression?

If you are talking about the ring with a screw save your money, send it off and have it pinched or replace it. The proper tools to do the job properly are expensive.

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