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Title: Running poorly Post by: fe on November 15, 2011, 08:13:21 PM :(Hi
I have a grey engine 138 and its a little tired ,lately its had a bad miss and doesnt improve with acceleration.Ive put a new dizzy cap and cleaned all the sparkplugs and cleaned the points ,Ive checked the timing and all appears ok Im hoping someone can shed a little light on other ideas I can try Title: Re: Running poorly Post by: snuff69 on November 15, 2011, 08:26:12 PM Leads ??? ??? Dave
Title: Re: Running poorly Post by: ACE on November 15, 2011, 08:54:22 PM Compression Test ;)
ACE 8) Title: Re: Running poorly Post by: Harv on November 15, 2011, 09:08:51 PM Get the vehicle to miss whilst parked in the driveway. Pull the plug leads off one at a time while it's missing - if the miss gets worse, then that plug lead is not the culprit. if the miss gets no worse when you pull a lead, you've found the crook lead/plug.
Is the rotor button sitting down properly? New Bosch rotor buttons are pretty snug, and if "sitting up" can cause an intermittant miss. Slop in the dizzy main shaft can do the same (don't ask me how I know ::)). Has someone stuffed around with the carburettor at all? If it's lunning lean, it may surge or miss (particularly if someone has farted around with a variable main metering jet). If it's got a variable main, you can screw it out a bit and see if the miss goes away. Tried hunting down a miss on a 308 VK Calais at one stage... spent a small fortune replacing electricals... still couldn't find it. Ended up being a worn cam lobe leaving the exhaust valve shut (Ace's compression test should help pick that one). Cheers, Harv Title: Re: Running poorly Post by: Rod on November 15, 2011, 11:39:21 PM Support Compression test also. Sounds like it could be a burnt valve.
Rod Title: Re: Running poorly Post by: KFH on November 15, 2011, 11:42:41 PM As Harv said try shorting the plugs out one at a time and note if there is any difference to the miss. If it is a spark related issue try a new or different spark plug. I have, had on two different occasions, plugs causing this type of problem. One of them was almost new.
Keith Title: Re: Running poorly Post by: fe on November 16, 2011, 07:43:57 PM Hi Thanks guys ,I appreciate your help
I will try new leads and check the spark plugs I have no instument to measure the compression To give you more info on the engine , its missing constantly ,Ive cleaned the spark plugs and they appeared ok it farts when under heavy load and you have to back of the power ,I think its worsening I will give you the results soon Title: Re: Running poorly Post by: fe on November 30, 2011, 09:13:52 PM UPDATE
I changed all the leads today and there is no improvement at all My next guess is to change all the plugs Im very frustrated Does anyone know of a mechanic who enjoys fixing old Holdens on the Central Coast Title: Re: Running poorly Post by: mcl1959 on December 01, 2011, 06:00:31 PM Buy a compression tester - they're not very expensive. I support all the other people on this thread who suspect a burnt valve. Don't bother chnging the plugs unless you can see an obvious defect like broken electrode.
Ken Title: Re: Running poorly Post by: fe on December 01, 2011, 07:21:20 PM Hi Thanks Ken
If its a burnt valve ,what are my options Title: Re: Running poorly Post by: mcl1959 on December 01, 2011, 09:39:30 PM Pull the head off and replace the valve. Not a real difficult job as long as you follow all the steps correctly.
The compression test will tell you straight away clear as day if it is. You will get readings between 100 - 120 lbs/sq in on good cylinders and 0 on the cylinder with bad valve. Ken Title: Re: Running poorly Post by: fe on December 02, 2011, 09:01:13 AM ok I will do that
So Im in the market for a compression tester anyone have one for sale or I can borrow Title: Re: Running poorly Post by: 57effie on December 06, 2011, 03:11:18 PM Like Ken said, they are cheap new. Don't muck around with 2nd hand. Buy a new one. Then your mates can borrow it off you.
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