Head gasket failure, hole sizes

[512BB]

Re your location Pete, I see you have moved next door to a certain Mr Enfield.

LMS

[groucho]

Well, I've gone ahead and ordered the necessary gaskets as well as new set of ARP head bolts... they seem awfully pricey for what they are so hopefully they'll help keep things nice and tight! Hopefully I will begin cleaning and reassembly this weekend if the parts arrive in time. That means doing more research on the best way to clean these things... since what I did last time apparently wasn't enough.

In the short term you need to squirt some WD40 into the cylinders to prevent the rings getting rusty and sticking in their grooves. If you do decide to put it back together, you will change the oil before firing it up I hope

Oh yes, if not twice! The old oil was quite appalling... It looked more or less OK earlier in the summer and when I checked it the last time it was running, it was a terrible gray foam. Ugh!

[JJDraper]

I would endorse not disturbing the bottom end after a gasket failure, unless you really want to.. I had a major head gasket failure on a holiday trip, but drove home, topping up the water every 50 miles or so. Refurbed the head and refitted. The sump was drained, and the engine refilled with cheap oil. Run the engine for a few miles until the engine is up to temp, then drain and refill with good oil. My engine is still OK 50k miles later. As to why the gasket failed, the picture of the mating faces of the head seem very clean, and show no real sign of being pulled down tight. A leak past the fire band would have then eroded away the gasket until it reached a water way - my guess. I used an Ajusa (?) headgasket supplied by QED which seems to be solid. Worth checking that the gasket is the right size for the bore (mine is +60...) so the fire band sits nicely on the block and doesn't intrude into the bore.

New head bolts are a good idea, some people say you should have a new set every rebuild, but at 100GBP a set, I think they are OK for a few more uses. That said, the old bolts on my engine were showing signs of 'waisting' and were probably original and so were replaced. The old ones did provide a set of nice guide bolts for replacing the head though!

Jeremy

[bill308]

Groucho,

Your latest picture appears to show the block ok in the area of the failure. The distance between the coolant hole and bore appears marginal but probably adaquate. Assuming there is no depression at this point, and you should do a cursory check with a straight edge, I think you should be ok with a new gasket and new head bolts.

Bill

[groucho]

Thanks Jeremy and Bill! I will definitely check for any depressions in the block, just in case. I don't think there are any... if there are, the block won't be the only thing depressed!

Having some guide bolts to position the head will definitely ease my mind when refitting the head. I'm feeling reasonably good about everything. The new parts arrive tomorrow so I will hopefully get the car running again this weekend or maybe next. (There are no shortage of projects and distractions competing for my time!) I'll let everyone know how it goes.

[Mr.Gale]

You should join the Yahoo group "vintagetechnologygarage", Keith Franck has posted a lot of good info on twin cam head gaskets.

Gale

[JJDraper]

Quick pic of my old head bolts in use...

Jeremy

[groucho]

Jeremy, that's exactly what I'm planning. Of course, my engine is a lot dirtier!

I received the new parts today. I was very interested to see that the new head gasket is quite a bit different that the last one. The last one is copper-colored on one side, black on the other, and has what appears to be a paper gasket inbetween. The new one is copper-colored on both sides and has reinforcing around the center and a thicker material sandwiched inside. The reinforcing is in the area where mine failed, so perhaps this was a known issue... either way, I definitely feel better about the new gasket!

Looking at the head bolts, it's amazing that they cost about $25 each. There must be some magic in the metal or something!

[groucho]

Just to wrap this up - although it took a while (so little time to work on the car!), I got the engine back together and the car is running again. Things went pretty smoothly apart from a distributor issue (apparently it had been put in 90 degrees wrong last time, so all the wires were off by one), and the car seems to be running pretty well. I ran it for 5-10 minutes, changed the oil and filter again to get rid of as much of the awful old gray/brown oil as possible, and drove it to my winter storage location. Come spring, I'll drive it a few times then re-torque the head bolts and keep a close eye on things.

Thanks for everyone's help!