[High On Octane]

This question is directed at ACE and BW:

I think I am going to order a set of head gaskets and lap all my valves, remove the base gaskets and set the spigot height correctly.  My question is, should I order the 1mm head gaskets or the .5mm gaskets?  I want to see how much compression I can make now before the new heads without doing any machine work to cylinders.

Scottie J

[Bullet Whisperer]

I think I sort of went over this as an aside recently in another post, but as the result of a lucky mistake, I once received a set of 1mm thick solid copper head gaskets for a 700 twin. Except, that in real life they were for a Meteor Minor Sports 500 twin and the holes for the bores were not big enough to pass over the spigots of the 700 barrels. Careful work with a flap wheel in the drill soon sorted this and a bit of filing at the pushrod holes got me a perfect fit.
 I think this gave a good advantage, as, usually, the 700 twins have a 'sandwhich' type of copper head gasket which can be prone to blowing - the inside edges of the head joints, where they are right next to each other seem to generate hot spots and the gasket faces of the heads can warp, so look out for this, too.
 I would try to get and modify these solid gaskets and anneal them before fitting to make them more compliant to any surface undulations and irregularities, although, ideally, your gasket faces need to be flat, especially if the machine is to be ridden hard.
 B.W.

[High On Octane]

That is exactly where mine blew the first time with the solid copper gasket, and then a second time on the other cylinder with composite gaskets.  The studs have been replaced with 3/8 studs with SAE threads, maybe I should pull one out and get replacements for those too.  The 2nd time I replaced the gaskets with solid cooper again, I hand torqued them because I didn't trust the threads I want to torque them by "feel".  I torqued the heads, went for a 20 minute ride and then torqued them again while hot.  Other than not setting the spigot height and leaking a bit of oil, I haven't had any other head gasket problems since.  Also, when I did the gaskets the first time I used my hard sanding block and used 180 grit paper over the top surface of the barrels and had a local respectable head shop inspect the heads and trued the mating surfaces for me.  And I noticed when I did the gaskets that they didn't fit the cylinder bore very well with my +.040 bore or the studs.  Do you think maybe I should just order the Interceptor gaskets instead?

Actually, I just looked at Hitchcocks and it doesn't look like the Interceptor even used a head gasket?   

[High On Octane]

I called Cometic Gaskets in Ohio today, they are the makers of the composite gaskets I had ordered from Hitchcocks before, but shortly failed.  After speaking with the guy in the tech department, he said that their composite gaskets are actually really good and use the same style gaskets on high performance V8s with great success.  We came to the conclusion that my gasket failed because the flame ring was likely damaged due to having a +.040 bore and the gaskets being made for a standard bore, thus the piston making contact and breaking the seal.  Bad news is that they no longer have a listing for the 700 twins.      BUT  They DO have a listing for pretty much every other type Enfield made from the 500 twins up to the new G5/C5 line up, including a composite gasket for the Interceptor.  But they do not stock them and will take 3-4 days to produce on top of shipping and is going to be about $50 after shipping.  So it doesn't look like I will have the bike fixed in time for the Distinguished Gentleman's Ride. 

[Bullet Whisperer]

The Interceptors used things called 'Cross rings', they were a bit like a chamfered piston ring which were crushed between the heads and barrels. You needed different sizes if the cylinders were rebored, just like piston rings.
 B.W.

[High On Octane]

Cometic sells actual gaskets for the interceptor instead of the cross ring or whatever.

[ace.cafe]

I recommend settling on some form of head gasketing that works for you, and getting the spigot set right, and then leaving it.
Compression tuning is best done by adjusting the barrel base gasket thickness, or even shaving the bottom of the barrel if necessary to get the piston height where you want it, in relation to the combustion chamber.
On a hemi chamber like these vintage engines have, it is easy to move the piston height around for compression tuning, because we don't have any matters of squish gap to be concerned with. You can move that piston height around with relative impunity, as long as it doesn't hit a valve near TDC, or actually hit the head.
This way, once you have set all the sealing factors at the head gasket joint, you don't have to mess around with that anymore. Get it right, and leave it be, and tune compression under the barrel joint.

[High On Octane]

What are the chances of pulling the head to lap the valve and reuse the head gasket that is there?

[ace.cafe]

What are the chances of pulling the head to lap the valve and reuse the head gasket that is there?

If the spigot seals the compression properly, then the oil should be abe to be sealed with a used gasket and some joint sealing compound. If the compression is not properly sealed at the spigot, then no kind of gasket is going to remain intact.

[ERC]

There isn't any spigot on the cylinders I have for the 700s and there isn't any recess cut into the heads to accept one.The Bullet cylinders have them not the 700 twins that I have. The 500 twins I have do have a spigot on them.  ERC

[High On Octane]

ERC, my motor does have the spigots.  I had to remove them when I resurfaced the cylinders last year.

[ace.cafe]

ERC, my motor does have the spigots.  I had to remove them when I resurfaced the cylinders last year.

Well, if your engine has no spigots, you need a fresh head gasket.

[ERC]

The motor must be a 736 cc. I think on those they had a piece called a cross gasket ring. I've never had one of those apart. Have you ever had the serial # checked to see exactly what motor it is.  ERC

[High On Octane]

The motor must be a 736 cc. I think on those they had a piece called a cross gasket ring. I've never had one of those apart. Have you ever had the serial # checked to see exactly what motor it is.  ERC

When you ran my numbers thru Graham the motor came back as a '57 Trailblazer.

[ERC]

That's interesting the cylinders if stock should be flat with no spigot. All the  ones I have are flat. Maybe someone else can shed some light on this.  ERC

[Bullet Whisperer]

That's interesting the cylinders if stock should be flat with no spigot. All the  ones I have are flat. Maybe someone else can shed some light on this.  ERC

Hi ERC,
 If you look at the pictures near the top of page 1, you can see an early 700cc Meteor I worked on a couple of years ago. It has been in the same family from new and, as far as we know, I was the first to lift the heads at 20,000 miles from new [it was laid up in 1968]. You can see in one of the pics that it has spigots at the top of the liners.
 Scottie - if you have ground your spigots away, some solid copper gaskets for a Meteor Minor sports should go straight on for you, with maybe just a bit of filing at the pushrod holes required 
 Here is the machine I overhauled completely after all the work was done, only the paint work was left alone.
 B.W.

[ERC]

Thanks for the info on that B.W. That's very interesting, then the heads must have had a cutout to accept the spigot?  ERC

[Bullet Whisperer]

then the heads must have had a cutout to accept the spigot?  ERC

Hi ERC, correct - you can see it clearly on the underside of the head in the last of my three pics on page 1
 B.W.

[ERC]

Figured it out B. W. Scottie has pre 1955 cylinders on a 1957 engine case. Went through all my old parts manuals the # for those cylinders is 36500, they have detailed pictures showing the spigot on the early ones. Glad you could throw knowledge in on this B.W.    ERC 

[High On Octane]

Every damn time I work on this bike it becomes more of a mystery.  So let me ask this then.  Are the spigots good or bad to have in there?

On the Hitchcocks diagram, the '63 Series 1 Interceptor shows no head gaskets, spigots or any head gasket of any kind. 

http://hitchcocksmotorcycles.com/partsbooks/pages/687/Cylinder_and_Head_Assembly


The '64 Series 1 shows the spigots and the cylinder cross ring.

http://hitchcocksmotorcycles.com/partsbooks/pages/2474/Cylinder_and_Head_Assembly


I'm really starting to think that the Interceptor composite gaskets from Cometic might be my best choice with this.  I had the gentleman there describe the pic of the gasket to me and it is definitely what I need.

Figured it out B. W. Scottie has pre 1955 cylinders on a 1957 engine case. Went through all my old parts manuals the # for those cylinders is 36500, they have detailed pictures showing the spigot on the early ones. Glad you could throw knowledge in on this B.W.    ERC 

What is even more bizarre than that is the fact that it is sitting in a '63 Interceptor frame and has the Interceptor head stays.  How can it have a a '63 frame and be titled as a '58?

[ace.cafe]

Maybe it was originally titled as a 58, and later the frame was switched, and the engine number still matched the title, so they didn't worry about it.

[ERC]

That happens, I've got a couple that the title year is different than the actual year of the bike.  ERC

[High On Octane]

Tom - I think I'm going to pull my heads in a little bit here while I'm listening to the Broncos game.  I'll take the heads to work in the morning and lap the valves and try and get the one to seat and lap the rest of then while I'm at it.  I'll be extra careful removing the heads so I can reuse the gaskets.  Just a few quick questions:

I want .25 on the spigot height correct?

Knowing I only have 125psi in my good cylinder, and being that I can physically see thru the spark plug hole that the intake valve is no where close to hitting the piston, I should beable to safely remove the base gaskets, correct?

And lastly, what brand/type of compound do you recommend using for this job?

Thanks.

[ace.cafe]

Tom - I think I'm going to pull my heads in a little bit here while I'm listening to the Broncos game.  I'll take the heads to work in the morning and lap the valves and try and get the one to seat and lap the rest of then while I'm at it.  I'll be extra careful removing the heads so I can reuse the gaskets.  Just a few quick questions:

I want .25 on the spigot height correct?

Knowing I only have 125psi in my good cylinder, and being that I can physically see thru the spark plug hole that the intake valve is no where close to hitting the piston, I should beable to safely remove the base gaskets, correct?

And lastly, what brand/type of compound do you recommend using for this job?

Thanks.

I don't know what height you need on that spigot. I have no measurements or experience with those vertical twin head gaskets, so I can't say what they need to be. The OEM Bullet head gasket likes to have a .025" gap which will crush correctly for sealing both surfaces, but I have no idea whether that will be correct for your heads and gasket.

Yes, it is likely that you can remove the base gasket without worry, but it wouldn't hurt to do that clay measurement on it to be sure.

I use regular silicone RTV on the gaskets, but only a very thin smear of it applied around the pushrod tunnel holes. We don't want any excess squeezing out into places where we don't want it to go.

[High On Octane]

This is what I discovered last night.  I'm thinking that whoever put this motor together with the 3/8" head studs didn't bore out the holes in the heads big enough.  I had a hell of a time trying to get the heads off again, took about a half hour to get the 2 heads to release.  And when I finally did I noticed all kinds of metal shaving around some of the studs.  I had to put a large screwdriver thru the head steady bung on the frame, put a ratchet strap over the screwdriver and put the hooks in the intake and exhaust ports, tighten it until I couldn't get it any tighter, then go back with a pry bar and try to work it loose from the joint.  Needless to say I still ended breaking the tack weld where 1 fin was already broke on the left cylinder and broke a small piece off of the right cylinder.       Good news is once I got them off, the mating surfaces appear to be in excellent condition still.  Even that small area between the 2 cylinders wasn't damaged or burnt.  You can see in the pic of the cylinders tho where the gasket was to small for the bore and flared up a bit, other than that, the gaskets are still in one piece and didn't appear to have that much crush on them.








And A Video Of The Seats

https://www.youtube.com/watch?v=Ssd7i7y6m_Y&feature=youtu.be

[ace.cafe]

From the looks of the surfaces, it appears that there may be a flatness issue on the heads on the exhaust sides, where the gasket appears to have leaks. I would check those heads for flat surface, especially on those areas.

[High On Octane]

Am I better off just removing the spigots all together?  Seems like Roger doesn't have any spigots in any of his twins.......   

[ace.cafe]

I can't see from this angle how far the spigots protrude up, but they need to go all the way into the head recesses in order to work right. And that means they have to go all the way up in there with the gaskets in place. If that is not happening, then there will be problems until that is corrected.
You can cut the barrel gasket mating surfaces on a lathe, without cutting the spigots, until you have removed enough material to have taller spigots. Measure as you do it, and make it so there will be enough spigot to fit full-depth into the head recesses with the gasket in place and crushed.

Alternatively, you can cut off the spigots entirely, but then you will definitely need a new head gasket type that has a fire ring, or is a solid copper type gasket. Then there are no concerns about spigot height anymore, and the gasket thickness just needs to be taken into account as to how high it sets the heads off the barrels, because that gasket thickness will affect the compression ratio. Like a car.
And if the head recesses overhang past the edge of the head gasket, they should be welded-up or filled with something that can't burn out, because any overhang of the empty spigot recess over the edge of the head gasket can cause the head gasket to blow.

You can do it either way. But it needs to be done right, whichever way you pick.

[High On Octane]

Thank you so much Tom.  I really appreciate all of your insight and help.  I think I will just remove the spigots for now, they came right out with a pair of vice grips last time I removed them.  I will also check to make sure the heads are still flat, but I have a feeling that the spigots were actually holding the heads up as they protrude out of the cylinders about a full inch.

[ace.cafe]

Thank you so much Tom.  I really appreciate all of your insight and help.  I think I will just remove the spigots for now, they came right out with a pair of vice grips last time I removed them.  I will also check to make sure the heads are still flat, but I have a feeling that the spigots were actually holding the heads up as they protrude out of the cylinders about a full inch.

That's very interesting.
The Bullet spigots are integrally cast with the barrel liner, and cannot be removed without machining. If they are pressed into the barrel, then removing them will leave an open area where they used to be, and that could affect some things. Might be good to post up a photo of the cylinder with the spigot pulled out, so we can see what is going on with that thing.

[High On Octane]

OK, I was thinking of doing that anyhow.  Still trying to get motivated for the day.  I have a couple of errands to run and then I will start working on the bike again.  I'm going to call Drew and see if I can come down to his shop to use his spring compressor quick.  His shop is only a few miles away, and my work is 30 miles away, so that would be nice if that works out.

[ERC]

The spigot we're talking about goes around the cylinder not the 2 locators that are sticking out of the cylinder. If I'm understanding what you are saying. The pictures don't show any cylinder spigots that I can see.  ERC

[ace.cafe]

The spigot we're talking about goes around the cylinder not the 2 locators that are sticking out of the cylinder. If I'm understanding what you are saying. The pictures don't show any cylinder spigots that I can see.  ERC

Yes, it is important that we are all talking about the same thing.
I don't see any tall spigots on those cylinders, so he may be talking about the locators.
In any event, we can get it figured out, once we are all on the same page.

[High On Octane]

What a long freaking day.  Had to run to HF and picked up a ring compressor, 3/8" torque wrench, some wire wheels and I figured I'd give their high temp red RTV because it was only $4 and said it was made in the USA.  Then stopped at my Co worker Eric's dad's house to try some home brewed beer.  Then to Ace Hardware for some new bolts.  Then to advance to borrow a valve spring compressor and buy some grinding compound.

Spring compressor was beat up and the damn thing didn't want to release after compressing the spring, but got it to work anyhow.  Found a 3/16" chunk of carbon on the exhaust valve seat.  The suction cup lapping tool didn't work worth a shit so I removed the rocker arms and carefully attached my cordless drill to the top of the valve stem and ground it both directions twice.  Did all 4 valves put them back together and the right exhaust valve was still leaking a bit but not as bad.  Pulled that valve and lapped it again and then I noticed that the drill had the slightest bit of a wobble.  Looked at it again and rolled it on a flat surface.  The stem wasn't bent but the seat of the valve had a tiny tweak from where it must have been hitting the carbon deposit.  Put it back together and used a 13/16" socket and rubber mallet and tapped the valve a bit, spun it and tapped it some more.  Did the water test again and got just a tiny dribble.  I think after running it a bit it will seat again now that I got it all cleaned up.  Took me 5 hours to do it.  At least Eric came over to hang out and drink beer with me.   

[Arizoni]

I sure am glad I'm not doing this.

I don't see no stinkin' spigots on the picture of the cylinder/head gasket and I don't see no stinkin' relief in the heads for them to fit into.

'Course my definition of a spigot is a circular area that protrudes from the top of the cylinder.  It is precision machined on its diameter and on its end surface.
The diameter is a slip fit into counterbored areas in the head and its end surface forms a sealing surface with the flat surface that is at the bottom of the counterbored holes.

What I do see is a pair of flat cylinder heads that rest on a flat gasket mounted on top of the cylinders.

I suspect Octane is talking about "spigots" that fit into those two (per cylinder) holes that look like they are about 9/16 or 5/8 inch in diameter?  Those two (per cylinder) holes are the only place I can imagine something 1 inch long sticking out.

[ace.cafe]

I sure am glad I'm not doing this.

I don't see no stinkin' spigots on the picture of the cylinder/head gasket and I don't see no stinkin' relief in the heads for them to fit into.

'Course my definition of a spigot is a circular area that protrudes from the top of the cylinder.  It is precision machined on its diameter and on its end surface.
The diameter is a slip fit into counterbored areas in the head and its end surface forms a sealing surface with the flat surface that is at the bottom of the counterbored holes.

What I do see is a pair of flat cylinder heads that rest on a flat gasket mounted on top of the cylinders.

I suspect Octane is talking about "spigots" that fit into those two (per cylinder) holes that look like they are about 9/16 or 5/8 inch in diameter?  Those two (per cylinder) holes are the only place I can imagine something 1 inch long sticking out.

I agree, that's what it looks like.

[High On Octane]

OK, so I guess I am confused as to this whole spigot situation.  This pic shows what I am referring to.  Perhaps they are just locating pins?   



Also before lapping the valves, I soaked them in brake cleaner and then used a wire wheel to remove all of the deposits off of them too.  The intake valves were damn near spotless.


Also, here is a pic of the carbon deposit I found.





And what the heads looked like when I was done.  I guess I forgot to take pics of the actual seats when I was done grinding them, but they did look really good and uniform.

[Bullet Whisperer]

Early on in this thread, I posted pictures of an early Meteor engine with the heads off and showing the spigots on the barrels and recesses for them in the heads.
 However, here is a picture of a head removed from the 'Bob Mac' Super Meteor, with pre production Constellation engine fitted - the heads are flat faced, like Scottie's machine has, so no spigots at the top of the bores on this one either 
 B.W.

[Bullet Whisperer]

Just found this picture from another, late 700cc engine I rebuilt a few years ago, note the locating dowels sticking up through two stud holes and again, no spigots ...
 B.W.

[ace.cafe]

Okay, no spigots.
These locating dowels could possibly stand the heads off the gaskets when the head is tightened down, though, so we want to be sure that isn't happening.

[ERC]

Now we're on the same page. You just have locating spigots on the stud area. before you put it together make sure the head lays all the way down with those locators in place with no gasket as Ace says and you'll be ok.  ERC

[High On Octane]

I'm going to leave work a little early today so I can finish the top end and hopefully get the bike reassembled.  When I pull the cylinders I'll make sure to give those locators all a good whack and make sure they are seated all the way.  I'm curious as to what rods and pistons are actually in this bike.

[ace.cafe]

I'm going to leave work a little early today so I can finish the top end and hopefully get the bike reassembled.  When I pull the cylinders I'll make sure to give those locators all a good whack and make sure they are seated all the way.  I'm curious as to what rods and pistons are actually in this bike.

The pistons look like a low compression type. Hardly any valve reliefs in them, so the aren't gettin up very high. Dome looks low.

[High On Octane]

Yeah, I'm guessing only 7.5-8:1 compression.  That's why I want to get those base gaskets out of there.

[ace.cafe]

Yeah, I'm guessing only 7.5-8:1 compression.  That's why I want to get those base gaskets out of there.

According to the specs, they are probably only 7.25:1.

[Bullet Whisperer]

Yeah, I'm guessing only 7.5-8:1 compression.  That's why I want to get those base gaskets out of there.

According to the specs, they are probably only 7.25:1.

If you want to liven things up a bit, some Meteor Minor Sports pistons might do the trick - I have used a good number of these in my 'Asbo' 350 Bullets. I don't know if Hitchcocks have any, but Burton Bike Bits, also in the U.K. still had some standard size ones recently 
 B.W.

[High On Octane]

I got the top end together last night, and there are some goods and bads.  Bad news is that the torque wrench that I bought from Harbor Freight is a POS.  I had it set at 20 ft# and it seemed like I was really cranking on the bolts and the wrench wasn't clicking so I dropped it to 15 ft#.  Go back around the bolts again thinking the whole time "this has got to start clicking any second" when I stripped a head bolt.       I'm nut sure if the threads on the nut stripped or if the stud pulled out of the case, but something stripped.  Even at only 15 ft#, I only got the wrench to click on maybe half of the head bolts before my internal torque wrench told me not to tighten any further.  Other bad news, I took a peek under the piston and the conrods are stamped with the factory "W41720" stamp.  Which means I need to be very careful of how hard I rev the bike.

Good news is that the pistons only had light scuffing on the skirts and no actual scoring, bore still looks good too, looks like the rings seated nicely.  Also, the alignment dowels were not all the way into the cylinder, so I used a deep socket that fit just over the edge of the dowel and whacked them down further and saw all 4 of them move about a 1/4".  Also removed the base gaskets and fought like hell trying to get the cylinders back on without any extra hands to help, but I got it.  All said and done, once I had the heads torqued, when I went to adjust the valve lash again, I had to back off the rocker adjusters almost 3 full turns.  Then I put about a half ounce of oil in the cylinders and kick her over a bunch of times with the spark plugs out and checked for valve/piston interference, and there isn't any.  Wiped up all the oil that made a mess, put the plugs in and kicked her again, and there is a noticeable amount of compression increase.  I'll put the tank on and fire it up tonight.  Now I guess it's just a waiting game to see how long before the head gasket blows on the left cylinder.     

[High On Octane]

Well, the bike is running.  But after 3.5 hours on Sunday, 5 hours on Monday, 4 hours on Tuesday and another 2.5 hours tonight, not to mention 10 hour shifts at work yesterday and today, I am freaking whooped.

I remembered at work today that I had ordered 1 single head nut a while back and never used it because it was a 5/16" nut and I have 3/8" studs.  So I borrowed a tap from a co-worker and drilled out the new nut and retapped it, luckily it worked out good and I was able to torque the head properly.  Threw the tank on and fired up on the 3rd kick.  Let it idle for a while to get the oil flowing then went around the block to get the engine hot.  Once it warmed up it started to ping really bad.  I thought it was the valve at first as it is making a bit of noise too, but then it got kind of loud, so I very carefully and gingerly limped it back home a block.  Pulled the tank and did my hot torque on the head bolts and installed the head stays.  Put the tank back on and pulled the timing back quite a bit and went back out.  The exhaust valve is making a bit of a chirping noise, but I've been hearing that for a few months now.  At least now I know what the noise actually is.  Not sure if the rings need to reseat, if it's the valve is causing an oil leak, or just the oil burning off that I dumped in the cylinders, but I was getting a little bit of smoke out of the exhaust.

Clutch is still slipping when cold, but after she warmed up the bike was pulling pretty hard.  I think I need to put a little bit more timing back into the bike, it was running good, but felt sluggish at the top.  I'll figure that out tomorrow when I have my patience back and more day light, been getting dark at around 7:45p.  Either way, I think I have the bike ready for the DGR ride.  Which ultimately was the only goal for this particular repair.  So despite some head aches, set backs, and a handful of profanity, I was successful with what I wanted to accomplish.

[DanB]

Congrats and nice work Scottie!  Enjoy the DGR now.

[High On Octane]

Thanks Dan!  I also noticed when I was getting on it, the exhaust seems louder and snappier now with the higher compression.  I'll bring home the compression tester tomorrow and check it out.

[High On Octane]

I finally got a chance to take a good video.  You can hear the chirping out of the right exhaust valve and also hear the difference in the exhaust pipes.  Seems to be running pretty good tho.  Like I mentioned earlier, I had noticed that chirping noise about 6 or 7 months ago and knew it was coming from the head somewhere but I couldn't figure it out.  The timing isn't completely dialed in but it's not pinging and I don't plan on riding too terribly hard until I get that valve replaced.


https://www.youtube.com/watch?v=fxcktM23lro&list=UUOuxT3uDOINbn5OmZ0BwRVA

[ace.cafe]

Sounds stronger in the thumps. Probably the higher compression that you did.
But the chirping and difference in sound of the cylinders is not good.
It's not fixed, but it might limp okay for a while.

[High On Octane]

Sounds stronger in the thumps. Probably the higher compression that you did.
But the chirping and difference in sound of the cylinders is not good.
It's not fixed, but it might limp okay for a while.

I agree Tom.  The left exhaust pipe sounds much more aggressive than before.  I assume that "chirping" noise is the flame burning past the valve seat?  It does not do it when just idling after it warms up a little bit and does not do it when cruising at speed, only under load.  I do want to replace that valve ASAP, but being that I've heard that noise for a while now and there wasn't any noticeable damage to the head I think I'll be fine for a few more rides.  Yes?

[ace.cafe]

I agree Tom.  The left exhaust pipe sounds much more aggressive than before.  I assume that "chirping" noise is the flame burning past the valve seat?  It does not do it when just idling after it warms up a little bit and does not do it when cruising at speed, only under load.  I do want to replace that valve ASAP, but being that I've heard that noise for a while now and there wasn't any noticeable damage to the head I think I'll be fine for a few more rides.  Yes?

Probably okay for a while.
Can't say exactly how long.
It is leaking past the valve, and that does do some amount of burn every time it happens. How much damage is done each time is usually related to how much leak it has. The bigger the leak, the more the flame cutting each time. Small leak might last a while.

[ERC]

I think before you assume what it is, do a compression and leak down test on each cylinder. Could be the"chirp" isn't what you think it is.  ERC

[High On Octane]

I know it's the exhaust valve.  The noise only comes from the right exhaust valve cover, plus I did another water test before I put it back together and that valve is still leaking.  It's not as bad as it was but definitely still leaking.