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| engine compression problems https://www.slantsix.org/forum/viewtopic.php?t=15978 |
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| Author: | brendanhall [ Tue Jan 31, 2006 1:43 am ] |
| Post subject: | engine compression problems |
hey there. i just purchased my very own valiant ve. i have been a holden and chev man until i saw this blue machine with a 225 slant 6 now i am hooked! need some help though. any response would be appreciated. the engine lacks power underload. have done a compression test and found all cylinders to be 130psi with only one of them 150psi. is 130 psi too low a compression. i put oil in the cylinder to check the rings and it didnt alter the compression. i am going to adjust the valve heights with a feeler guage. but at the end of the day i may have to take the head off and check the condition of the valves. although i dont really want to do this it seems like a mission. how easy is it to reco the head myself? how do you reseat the valves. what does that mean? how hard is it to re ring the pistons? i will overhail, distributer and spark plugs and capacitor and ignition leads and check the points gap. but i dont think the problem is there? anyone? |
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| Author: | SlantSixDan [ Tue Jan 31, 2006 7:59 am ] |
| Post subject: | Re: engine compression problems |
Quote: the engine lacks power underload.
OK...what's the state of tune? How sure are you that the carburettor is in proper repair and adjustment, and that it's internally clean? Ignition components including the function and adjustment of vacuum and centrifugal advance? Initial timing? Fuel and air filters?Quote: have done a compression test and found all cylinders to be 130psi with only one of them 150psi. is 130 psi too low a compression.
Not really, no. The 130psi figure doesn't raise my eyebrow so much as the difference between four cylinders at 130 and two at 150. I'd want to try to figure out why that difference exists.Quote: i put oil in the cylinder to check the rings and it didnt alter the compression.
OK, so you could need to free up some stuck valves and do a proper tappet adjustment.Quote: i am going to adjust the valve heights with a feeler guage
Good, see here for a detailed description of the procedure.Quote: but at the end of the day i may have to take the head off and check the condition of the valves.
With 130psi in even the "weak" cylinders...? I'm thinking probably not...Quote: how do you reseat the valves. what does that mean?
Good question. Not really sure what you mean by "reseat the valves".
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| Author: | brendanhall [ Fri Feb 03, 2006 4:17 am ] |
| Post subject: | update |
well i replaced (much to my wifes disgust) the dizzy cap, capacitor, rotor. got spark going on all leads in a timely fashion. big improvement! is there any way to check if the valves need reseating without removing the head? |
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| Author: | brendanhall [ Fri Feb 03, 2006 4:20 am ] |
| Post subject: | carb |
yeah the carb sounds a bit suspect. has quite a big sucking sound under load...hmmm |
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| Author: | Doctor Dodge [ Fri Feb 03, 2006 7:49 pm ] |
| Post subject: | |
Check timing advance, make sure the vacuum advance and machanical advance is working and give the engine as much advance as it will take without spark knock. (detonation) DD |
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| Author: | brendanhall [ Sat Feb 04, 2006 1:23 am ] |
| Post subject: | vacuum advance |
well i got the spark running fine and put the dizzy back in the right place (i hope) when i put the timing light on i encountered these problems. when i attached it and checked the dwell angle on the meter there was nothing on the needle. it was too the far right and shaking around a bit. this was ar 1000rpm. i checked the advance on the wheel and i am supposed to set to 7.5 BTDC that means that it was above the mark. but the distributer would only advance to 7 BTDC and that was as far as the distributer adjustment would allow. i would have thought that i could advance it more. could it be that the distributer is out a cog. what is the maximum i should be able to advance the distributer! when i floor it there is plenty of revs but cuts out underload. |
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| Author: | emsvitil [ Sat Feb 04, 2006 1:38 am ] |
| Post subject: | |
There's 2 distributor adjustments........... 1 on top, and one underneath (visible when distributor is out) |
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