Triumph Repair: spitfire commpression, dish soap, radiator cap

Question
QUESTION: Howard:

As you recommened adjusted valves. Applied compressor air to #2 when at tdc, in 4th gear etc. Would not hold any pressure. Was able to hear and see air escaping between the exhaust valve stem and its valve guide. I actually pit a few drops of dish soap around it and it blew bubbles when compressed air was applied. What do you think.

Pat

ANSWER: Hi Pat,

I have no clue what you are doing. Why are you checking for air leaking around a valve stem? No compression in the combustion chamber has any access to the valve stem unless it gets past the head of the valve and into the exhaust port. Once in the exhaust it would have to have a stopped up exhaust to force air up the valve guide past the stem.

If you did not hear any hissing at the tail pipe and you see leakage of air at the valve guide, then you have two problems. One- you have to have a burnt exhaust valve (for air to get past) and for air to be forced up a guide you have to have # Two problem at the same time and that is a stopped up exhaust system.

Howard

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QUESTION: Howard, sorry if my last correspondence was misleading or confusing. Let me try and clarify. I hooked up a compressed air line to the # 2 cylinder where the spark plug screws in. Trans in 4th gear, brake set, wheels chocked, air cleaner off, radiator cap off. The leak was so fast and loud that it drained a 20 gallon air tank at 110 psi in about 30 seconds. The tail pipe not only had a "hiss", but had a nice breeze that would blow out the candles on a birthday cake. In addition, there is a very strong hiss around the exhaust valve.(I have the valve cover off of course). That is why I dripped dish soap on and around the exhaust valve and head. There's nothing better then finding an air leak than the bubbles that form with dish soap. Anyway as I mentioned before there is also air escaping around the valve stem. I think it is inevitable that I remove the head but I would sure like your expert advise. Thank you for your passion and patience.

Pat

ANSWER: Ok, you had just left out the minor detail that air was coming out of the tail pipe. This is a burnt or bent valve. Most likely a burned valve because that is why you were to check the valve adjustment. A bent valve would have had a excess valve clearance on that exhaust valve.

Some air can come up the valve guide when an excess of air in entering the exhaust, so it is not necessarily something to be concerned with. If you have a auto machine shop do the head work, they will check stem to guide clearance to see if guides are necessary. If you decide to do it yourself you should get a manual and look at the specs for stem to guide clearance or get someone who does head work to just feel the side play to tell if guides are necessary. There are no stem seals used on Triumphs.

Be careful about the head gasket as there is an early and a late Spitfire head gasket which look alike but can not be switched and some aftermarket companies get them mixed and give you the wrong one. They are easy to ID by just looking at the top edge of your block for a grove around each cylinder. If your block does have the grove (called fly cut) the gasket MUST have a thick ring on the gasket around the cylinder to match the grove in the block. If you have the fly cut and the gasket is flat, don't accept it even though it seems to fit the block. Also be sure to put the correct side down on the block. (they are usually marked "Top" or "UP").

Howard

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QUESTION: Howard:

Finally got the time to take the head off.  Sure enough, no. 2 exhaust valve had a worn guide and bad valve.  Got he head back from the machine shop and am in the process of reassembling.  Question.  The torque settings that I have found on line say both the head studs into the block and the head   nuts on to the studs should both be torqued to 40 ft/lbs. Since all the studs came out when I removed the head I will be reinstalling them first. As I put the first stud in and started to tighten, it just felt that 40 ft/lbs is too much.  I get the feeling that if I try and tighten the stud to 40 fl/lbs it will strip.  Can you shed some light on this. Also if you have a tightening sequence that would help. And do I need to treat the head gasket with anything before assembling.

Regards, Pat

Answer
Hi Pat,

40 ft lbs is the head nut torque not the torque of the studs in the block. I usually just double nut the stud and just hand tighten the studs into the block first. If you want a torque figure use about 20 to 25 ft lbs.

Be sure you have the correct head gasket to match the block. There are two different ones that look alike. The flat top of the block must get the gasket that has a flat surface at the ring around each cylinder bore. The block with the "fly-cut" around the top of each bore must get the gasket with the thick ring around the bore and the added thickness must go down to match the "Fly-cut" in the block.

You can't depend on the year of the car because many of these cars after years of driving have had engines replaced.

Be sure to use the correct torque sequence and be sure to re-torque in about 500 mi. even if they say this is a no re-torque gasket.

Be sure to remove the (+) wire from the coil and remove the valve cover then spin the engine over until you see oil pressure on the gauge and you see oil at the rockers before starting after you change the oil and filter.

Howard