Spitfire My Spitfire Mistake - Advice Needed Re. Head Gaskets

[dklawson]

Let's start by saying I made a serious mistake and now I'm looking for things to check.

I needed to get the the front pulley off our 1500. We couldn't break it loose with the car in gear and holding the brakes. So... I pulled the plug for #4 put a foot of rope in the bore and brought the piston up to TDC on the firing stroke (valves closed). We put a huge breaker bar and socket on the pulley with a cheater bar. Still nothing. Then my son and I pulled on the breaker bar together. Still no luck. We stopped when I saw nothing was loosening but the 3/4" breaker was bending. I was concerned I had damaged something when the rope came out with cuts.

To confirm my fears we did a leak down test. First we tested #1 as a control. It was acceptable. Moving the tester to #4 we couldn't get any reading on the gauge and air was pouring into/out of the block. There was no audible leak in the cooling jacket, intake, or exhaust. Yetch.

Tonight we took the head off and I was expecting to see a rope-knot sized hole in the top of the piston. We found nothing. No holes or cracks in the piston, no broken head studs, nothing. My plan at this point is to take the head to the machine shop and have it tested for cracks, leaks, and flatness. If it is OK I may have the seats recut anyway for a future application. Once I know the head is good I am planning on temporarily fitting it to the block with an o-ring at the top of the bore for #4 and repeat the leak down test as all I can figure is that somehow I lifted the head enough to unseat the gasket sealing ring for #4.

If you can think of other things for me to check or test please let me know. I don't want to pull the engine and tear it down if I don't have to.

Thanks in advance for your suggestions.

 

[dklawson]

After work today I believe I found the problem. It appears that my rope pinched in just the right place to collapse the top of the piston crown adjacent to the intake/exhaust side of the block. The piston crown does not appear to come all the way up to the deck on that side but does for the rest of the perimeter. I suspect that I have pinched the compression rings and they can no longer follow the bore.

Anyone have a used +30 1500 piston? This is a driver and while I'm not opposed to new pistons and rebuilding the engine I really don't want to get into that this summer. I seem to have a lot of car projects at the moment.

 

[trrdster2000]

WOW, Doug that is turning out to be one tough nut to crack. Sorry I don't have a piston for you, hope some one will come up with one.

Wayne

PS Found a new set of Rotoflex universal joints for the rear of your GT6, make me an offer if you need them.

 

[Deleted member 8987]

Just for next time.
Breaker bar and socket.
Wedge the bar on the frame top rail in direction of rotation.
Pull the plugs to be safe.
Neutral, brakes on.
Crank it.
Trust me.
I could find the thread on these very forums where everybody pooh-poohed it.....until DNK and I went over to the guy's house and I did it.
Safe.
No holes in pistons.
And yes, it was a Spit.
Dave

 

[Deleted member 8987]

I guess I cannot. 31JAN12 was the date of the interchange with Cufley, an 80 Sprite. Maybe it's in the archives.
Dave

 

[Guest]

Bent valve?

 

[Geo Hahn]

Wow, that is the first time I have heard of 'the rope trick' doing damage, but I can see how it could happen. I suppose I've only used it for fairly modest holding (e.g. flywheel bolts) -- for the crank nut I also usually resort to the 'bump the starter' techinique.

 

[dklawson]

Dave, the wrench on the pulley and starter motor method is also used in the A-series world. I have never tried it and was afraid to try it on the Spitfire but really wish I had!

Until now I had only used the rope trick for modest tightening also. I didn't give thought to how hard we were pulling on the cheater bar for the pulley nut until it was too late. I am absolutely furious at myself about this. I should never have pulled that hard on the breaker bar.

Not worried about the valves yet with the piston being messed up. I really don't expect valve problems though since you use the rope on the firing stroke when the valves are closed.

Wayne, thanks for the offer on the Rotoflex. However, our GT6 is a Mk1 which has the u-joint rear end much like our Spitfire has.

 

[Andrew Mace]

...Breaker bar and socket.
Wedge the bar on the frame top rail in direction of rotation.
Pull the plugs to be safe.
Neutral, brakes on.
Crank it....

Funny, but I thought I'd invented that procedure in the early 1970s. I'd splurged on the 3/4" drive breaker bar and socket, but no other technique was working. I figured I had nothing to lose except a bit of paint on the chassis, so I set the breaker bar with socket at about 12 o'clock and hit the starter. Darned if it didn't work, and I've been telling people about it ever since. I suspect quite a few of us "old-timers" somehow happened on that back then....

And same here: I've never heard of the rope trick doing that sort of damage. It must have been a fluke!?

 

[dklawson]

Andy, I have a quick question that I bet you can answer without even thinking. Do you know the wrist pin height for 1300 and 1500 pistons? I understand that while the bore is the same the pin height is different on the two engines. I don't think that information is in the few books I have at home.

 

[Andrew Mace]

Sigh...unfortunately, Doug, I can't answer that question.

 

[Don_R]

doug, in my notes i have listed a 5.7 and 6.0 center to center on the rods but nothing on the pistons themselves

 

[CJD]

An impact driver seems to be to safest thing to use on crank bolts. The hammering slowly breaks the bolt free while using the mass of the crank assembly.

 

[dklawson]

The impact gun is what did finally work for us. However I had to run it "forwards" and then in reverse multiple times to finally work it loose. It literally took 5 minutes of going between forward and reverse before the nut spun off.

I will post an update to this thread when I get the engine torn down. I don't own my own hoist or stand so I borrowed one today and will try to get the engine out and block torn down over the next two days so I can get the block to the machine shop.

 

[dklawson]

I got the engine torn down tonight with the exception of scraping off some seal residue and removing a couple of core plugs. There is no point in my trying to post a picture of what I found wrong as it would not be possible to see. You have to feel it.


I did indeed squish the piston on the side towards the intake/exhaust. Both compression ring glands were collapsed just enough to make it difficult for the rings to float and find their center in the bore. If I were on a super, super tight budget I would probably just fit new rings and turn the pistons in the lathe at work to restore the gland width.


However, the rest of what I found says that would be a wasted effort. There was a substantial ridge at the top of the bores and my relatively new (4 years and maybe 10k miles) big end bearings were scuffed badly... some through the top layer into the copper. There was some modest scoring on the rod journals on the crank also. The main bearings looked fine.


My crank end float measured 0.008" which is what I measured 4 years ago. It's right on the high end of the spec in the factory manual so I will buy new thrusts when I order the rest of the parts.


My plan at this time is to take the block, crank and pistons (with rods) to the shop (hopefully tomorrow). I'll obviously have them tell me what to do about the bores/pistons. I'll have them check the crank and advise me on whether to polish the journals or grind them. I also want them to check that the big ends of the rods are still round and sized correctly.


I wasn't planning a rebuild but after peeking inside this engine I think it was probably coming due soon.


Doug L.