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[tdskip]

MGC up-date

(warning - cross-post)

After some coaching on how to wire the starter and solenoid got her starter to spin her over.

Compression results;

#6 – 90-100 +/- (but battery was almost dead)
#5 – 130 +/- (so-so battery, not really spinning it)
#4 – 105 (but battery was almost dead)
#3 – 145 ( freshest charge of the battery)
#2 – 120 (so-so battery)
#1 – 120 (so-so battery)

I'm not going to put too much weight into the numbers since the throttle wasn't wide open, the carb pistons are stuck closed, and the battery wasn't fully charged.

Good news is that there wasn't any knocking or rattling or other expensive sounding noises.

Hard to tell on oil pressure but but I definenatly have some. Better than none, right! Turns out the MGC has an electrical oil gauge and since the rest of the electrical sytem isn't working I don't know what sort of pressure. Oil is definatley flowing pretty well however, since when I pulled the filter as a sanity after the last round of compression checks there was enough oil in the housing to spill all over the driverway.

 

[Deleted member 8987]

Re: MGC up-date

How many "hits" on each reading?

Everyone has their 'druthers in shops, I settled on 5 hits decades ago.
If you get 140 on one hit, 10 hits to get 105 is not any kind of comparison.

Just asking.

Also, I'd be screwing a mechanical gauge into the outlet where the electric sender goes, so I knew what the oil pressure was while cranking.

Dave

 

[tdskip]

Re: MGC up-date

Hi Dave, I did a 10 second count on all of these. Very low rpm.

 

[tdskip]

Re: MGC up-date

Just did #6 again with the battery better charged and got 120 this time....

 

[DrEntropy]

Re: MGC up-date

I too use the five stroke maxim. And with a battery that'll keep consistent cranking.

At least ya know there IS compression.

A "hard" gauge on the OP would be better, no tellin' with a 'lectrical gizmo wot ain't seen load in all those years. :wink:

 

[tdskip]

Re: MGC up-date

At least ya know there IS compression.

That is really what I was looking for Doc, rings will need some heat cycles to fully seat again and all of that stuff. I am fairly encouraged by those results actually.

 

[DrEntropy]

Re: MGC up-date

As am I, Tom. Just go at it with the thought in mind that at any time you may encounter "ugliness" and be pleasantly surprised if none shows up. And have one hand on a "kill switch" if you decide to light it off without havin' gone thru it first. Twisted internals on an MG six-banger is a baaad thing.

 

[tdskip]

Re: MGC up-date

Yeah, not too excited yet, lot that could be wrong in there still.

Looks like the mechanical oil pressure gauges are not available new, time to hunt down a used one or should I just run a "modern" oil pressure gauge you think?

 

[DrEntropy]

Re: MGC up-date

For what you're doin' I'd be for any old gauge you can plumb up. It just needs to read what you have there temporarily.

 

[tomgt6]

Re: MGC up-date

I would do a leak down test as well. I did a compression test on my spitfire and found 115 to 130. The funny thing is once I started the car I would get smoke every where. When I took the engine apart the mechanic friend of mine couldn't believe we got that type of compression. The top 2 rings were broken, the pistons fell right out of top of the block and the groves around the top of the piston rings were bent 3 times bigger then the ring.

We did get some leakage in the number 3 piston with the leak down test. I also found if you take the head off and pour some Marvels on top of each piston and see how fast it leaks down that will tell you something as well. The number 3 leaked down in a couple seconds were the rest took hours and 1 was overnight.

I do a 5 count compression as well. But the long and short is you can't always trust the compression and leak down test.

Best of luck.

 

[Deleted member 8987]

Re: MGC up-date

Like everyone is confirming, a 10-second count is not gonna do it.
Count the hits.
You'll hear 'em.

I have two old aftermarket oil gauges, taken from junkyard dogs.
One has a 14" or so hose on it (hydraulic.....like the old Chevy 235 oil lines).

I have a box of adaptors gleaned from years of doing this.
Thread an appropriate adaptor into the block, thread the gauge into the adaptor, and you can read it while cranking.

Dave

 

[tdskip]

Re: MGC up-date

Got it guys - I'll redo it.

 

[DrEntropy]

Re: MGC up-date

What Dave said! :wink:

You ~could~ even use the comp gauge but adapting it would be a bigger PITA and reading it dicey, in that it's made to read higher pressures. Low scale readings may be erroneous.

As for leak-down, I'd be for doing that after/if it has gone thru a couple heat cycles. Anything before that will likely be bad data. If compression is in the 110~120 range it'll light off (all the OTHER stuff like carbs working and O/P checked, oil changed, coolant up to proper level etc.) and run.

<span style="font-style: italic">psst!... this is exciting.</span> :wink:

 

[tdskip]

Re: MGC up-date

Oh man - when was the last time you guys went to remove the brake and clutch MC on one of these? What a pain to get to compared to a TR. I lover her and all, but want a pain.

(pulled the radiator today too Doc. Moving right along)

 

[DrEntropy]

Re: MGC up-date

A set of 1/4" swivel sockets goes a long way to doin' the "tight" jobs you'll be needin' to do on that thing.

MORE TOOLS!!!! :laugh:

 

[cheseroo]

Re: MGC up-date

Hi Tom,
I am my mother's son so I must interject my opinion -

Keep your eyes on the ball - do the least amount to get it running/driving and then go from there. When I say the least I don't mean the primary braking system is the hand brake. Get it running and sort the hydraulics so you can drive it around the block. If at that point something is obviously wrong, then tear into it.

The car has enough compression to run and it appears to me that it will end up being even enough across the cylinders to run fairly smoothly. I wouldn't bother with any more compression checks until after you get it running. Once it's been run for a week or so would I run the compression tests again. Once you get it running and if it won't stop smoking, runs rough or has some other ailment you can't figure out then at that point would I do a leakdown test so you can diagnose if the problem is in the head or the block. A car that has been sitting that long isn't going to give reliable numbers until after it's been run. At this point in the project, what exactly are you going to do if one cylinder is 15lbs off another?

I do agree with the opinion that you should look into the oiling system first. You'll do far more harm with a bad oiling system than bad compression. I have a mechanical gauge setup that's currently on the TR8 you are more than welcome to borrow. Rough rule of thumb at this point should be 10/lbs per 1000rpm. If you've got that then you won't see any bottom end damage from lack of oiling. If you can get 10lbs from just the starter motor then it will probably do more once running.

 

[tdskip]

Re: MGC up-date

Hi Tom,
I am my mother's son so I must interject my opinion

So that is where it comes from, eh? LOL.

When I say the least I don't mean the primary braking system is the hand brake. Get it running and sort the hydraulics so you can drive it around the block.

Believe it or not Rich, I was actually paying attention out at the hanger. I did in fact put down the compression gauge and started pulling off the brake and clutch MCs to figure out if they could be rebuilt or need to be replaced. Should finish pulling them tonight after work.

At this point in the project, what exactly are you going to do if one cylinder is 15lbs off another?

Lean on you to coaching me through a rebuild maybe? Plenty of good drink and an extra pair of hands on your race car build would be forthcoming....


Plan from here;

1) grab that mechanical gauge from you tomorrow at Cars & Coffee?
2) radiator fixed - discovered a hole in the core yesterday when I pulled it, and no, I didn't do it
3) get distributor back from Jeff, already sent off
4) brake and clutch hydraulics sorted out
5) ordering new rear brake cylinders & shoes today since they are past it, need to pull the front calipers and see if they can be saved
6) swap the carbs out for rebuild ones I have on the shelf (rebuilt for the 122s which is now in deep storage)
7) need to sort of why I'm not getting power from the battery, but that will wait until I have the alternator, distributor and starter wiring properly connected back up

Sound right?


Thanks, as always, for telling it to me straight guys!

 

[cheseroo]

Re: MGC up-date

Originally Posted By: cheseroo
At this point in the project, what exactly are you going to do if one cylinder is 15lbs off another?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Lean on you to coaching me through a rebuild maybe? Plenty of good drink and an extra pair of hands on your race car build would be forthcoming....[/QUOTE]

Answer: Wrong. If 1 cylinder is 15lbs down and nothing else seems amiss you are going to drive it for a least a year before you do anything. Enjoy driving this one stinking car for a while before you take it apart.


<div class="ubbcode-block"><div class="ubbcode-header">Quote:]1) grab that mechanical gauge from you tomorrow at Cars & Coffee?[/QUOTE]

Not sure about CnC tomorrow. I've got a sailboat race. I can pull it off the car and leave it on my porch and text you my new address if you are planning on needing it tomorrow.

2-6) Isn't it a lot more fun than owning hondas?

 

[tdskip]

Re: MGC up-date

Some more progress today;

 

[rick_ingram]

Re: MGC up-date

Be careful with that brake m/c assembly.

The reservoir is made of "unobtainium".