Apologies for the essay, but it may help with diagnosis

Thought I was going to make another milestone on the Midget restoration today, but it was not to be. Got everything ready to start and discovered a water leak from the weep hole in the water pump. Bought a new one, fitted it and after around 30 mins was ready to go again. Car started within about 15 seconds which aint bad for a car that's not run for 5 years! It ran for around 10-15 secs then died, but I think I flooded it. Anyhow, turns out the settings on the SUs were waaaay too rich. Leaned out and tried again. Car started straight away but was lumpy as hell! Removing plug leads one-at-a-time proved 3 & 4 were not firing. I thought it might be a carb issue as each one feeds a pair of cylinders. But I did a compression test on them and 3 & 4 have zilch! So I'm guessing the head gasket has gone between 3 & 4.

Anyone had that happen on a newly rebuilt engine before?

I'm just hoping it ain't something more sinister

Might just be a sticking valve on each cylinder, lift the rocker cover and check the valve clearances, if the valve clearances on cylinders 3 and 4 are very loose it may be possible to free off the offending valve

Don't, discount spark plugs. I chased my tail for a while with my pinto and twin 40s. Turned out the brand new Bosch plugs were no good, fixed with correct NGKs

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Originally posted by JeffHs
Don't, discount spark plugs. I chased my tail for a while with my pinto and twin 40s. Turned out the brand new Bosch plugs were no good, fixed with correct NGKs

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Yep, as Chris said, there is no compression on 3 or 4. I did take the rocker cover off and checked 'off-rock' for gaps on the rockers. i didn't measure them, so they could be a tiny bit high and I guess a valve doesn't have to stick by much to lose compression? But they do seem about right so I will have to check with a feeler gauge.

I did not check the head for warpage though which I am regretting. So going to have to whip the head off anyhow if the valve gaps are OK. Hey Ho, gotta love cars!

If you can beg, borrow or steal a cylinder leakage tester it will identify the problem straight away. IIRC British Trident may have posted about a D.I.Y tester. My money would still be on a valve stuck open , if , when the engine was running it was spitting back through the carbs then suspect the inlet valves. Have also had similar problems with badly worn cams and tight valve clearances but on a rebuilt engine that shouldn't be the case

Oops! Must read the post properly.

Comp test remove all plugs turn engine over with ful throttle this ensures you get air so it can be compreesed.

Well, loosened the valves to 3 & 4 to make sure they were not sticking down, still zero compression, also noticed No.2 had dropped from 120 to 90psi!! So, off with her head as they say, and what did I find? Looks like it was only a matter of minutes bofore 1-2 went as well


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Anyhow, I'm a tight a**e and begrudge parting with her majesty's coinage when I can do it mysel

So....I have a decent sized engineer's plate, and being a Locoster I thought I'd have a go at trueing the head myself

I stuck aluminium oxide to the plate with grease, used light oil on it and spent 1 1/2 hrs pushing the head backwards-and-forwards on an ever decreasing pile of paper utnil I got the results below. I reckon another hour should see it about right, I measured the gap in the middle of the head against a straight edge and reckon I've got about 3-thou to remove

Still, gives one a great sense of well being

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After:

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[Edited on 10/11/13 by Daddylonglegs]