Torching cylinder head

Torching cylinder head - pictures of the damage

We just burned a hole through the front of the number one cylinder. This is the second time this has happened in a row. We haven't pulled the head off from the latest incident but the last time the spark plug looked brand new and the piston was fine. The only indication of heat was the hole in the block and head.

We chucked the number five rod, had the block repaired, made a couple dozen good runs and then burned it up in the lights. Had it repaired again, made one half track pass to make sure everything was good and then hauled it out of town. This time it burned up at 1000' and about 2" higher up. The plug looked like it got some heat in it but nothing outrageous. We are running the fuel system plenty fat and there doesn't seem to be any obstructions in the line or nozzle.

What is causing this and how do I make sure it is fixed before I burn it up again?

TFX 96
BAE 5 heads
Littlefield 14-71 hi-helix delta case, 42% over
Pro mag
Lencodrive
125" funny car




Thanks

Tony

 

How old are the lines? are they Dyco Rubber lines? Aluminum Nozzle body or brass? What does the bearing look like n the hole you keep torching?

Jonathan
978.423.5881

 

I just did the same thing in a BBC on cylander number 2. Shot it out about 1000ft pushed the head gasket out. The copper gasket sliced the strap on the engine diaper even. Suppose to be getting the head back tomorrow so we will try it again this weeknd.

 

Ck to make sure the sleeve is not sitting too low in the block register

 

i would replace the line for sure. also, what have you changed? different nozzle body by chance? also, you haven't happened to have stripped the spark plug threads and installed a steel insert in that hole lately ? those steel thread serts will throw the cylinder off in a bad way. ..

 

If the sleeve isn't making contact with the register in the block at that spot you will get a hot spot as the sleeve can't get rid of the heat fast enough ----- use a telescope gauge to check the size of the register in that area --- it's probably bigger than the OD of the sleeve ------you may need to rebore all the registers and go to a thicker wall sleeve to restore the proper fit ---

 

I got a gasket a time or 2 and it was always a fuel issue. I got a head and block, piston was perfect plug wasn't burnt but bearing had a little smash.

I thought I had a bad nozzle so I replaced it and tried again did the same thing, fattened it up and never happened again.

 

I've had this happen when the timing got a few extra degrees somehow (crew guy can't see the marks). It torched number one and everything else looked fine plug, bearing were good.

Doesn't hurt to check it just in case.

 

What's a "hoop"?

I've torched heads, spit gaskets out, etc because the o-ring on the inlet of the pump was sucking air. It didn't leak fuel out but when I took it apart the o-ring was cut and after I changed it the problem went away.

 

Hoops

My AJ Fuel Heads have alcohol valves and has what AJ calls "junior" hoops. One piece stainless steel ring, about .100 tall,
in the head instead of a wire oring. I would suppose a full out "Fuel" head would have even larger hoops than my junior hoops. I think they are great. They seal well and don't fall out.
If someone has oring groove damage, I think the hoops are the best way to go and solve the oring problem for good.

 

4th picture down :

http://www.darkside.ca/node/26

pictures above show why you need thicker head to install hoops around intake seats

 

Check the O rings where the head and intake mate together some guys add a little silicone to make sure they dont suck air.

 

How is it going to suck air on a supercharged engine?

 

The lines are the Enderle brand sold by Dragparts. I haven't looked at the manufacturer of the hose. They are probably 5 or 6 years old. Aluminum nozzles. The first time we did it everything, including the bearing, looked perfect (except the hole, obviously). I haven't yet pulled it apart after the most recent incident.

Our current plan is to have the whole fuel system flowed, have the block and head repaired and examined closely. I don't want to make another run until I've identified the problem.

Any suggestions on who to use for flowing the fuel system?

 

Nothing changed

Nothing changed from one run to the next. We made a dozen good runs last season including one the same day as the first incident. The only thing out of the ordinary on that run was a small backfire when warming the car due to a faulty kill wire. It took me a year to get everything put back together. We made a half track pass at Bandimere to make sure everything worked. A week later we loaded the car up and towed to Great Bend. Our first run out it nuked at 1000'.

No stripped spark plug threads. The heads were almost pristine. It had just come back from repairs as BAE.

 

I am with Mike's question on the torque pattern. If everything is OK on the fuel and ignition and on the other comments re sleeve projection out of the deck...check the projection on the 4 corners and if they are the same then look at the torque pattern. I have found that it is best.....not essential....but best to go from the outside in rather than the inside out. The ends are unsupported as compared to the centre studs so it is better(among equals) to torque toward the centre to avoid bending the ends up and having less torque there.
Jeff Johnsen

 

I'M guessing the shear velocity of the air being forced in, sucks air usually accompanied by oil from the lifter valley. just as gasoline is sucked into the motor on a carbureted motor from the air rushing through the ventury.

Two times in the past that I've torched cyl heads I've found a portion of the intake gasket on a chevy missing on the port going to the torched cyl.so I'm guessing in that case it pushed the gasket out and then went lean, but I could be wrong. and on my BAE with Veney heads the intake o rings failed to seal when I went from a .050 head gasket to a .080 must have changed the angle between the heads and intake mating surface . on that one, it was sucking oil up from the lifter valley and the inside of the headers and runners in the heads were coated with oil and it lightly torched one of the heads.

 

I have always circled from the inside to the outside. Never having heard otherwise I never thought to do it differently. I will do it that way from now on.

 

When i did head work on a well known TF car here in Europe we always did the heads from the outside ends to the center alternating back and forth starting with the inner studs in the vally, then the long studs on the rockersstands, then the short studs by the exhaust flange and then the long studs on the rockersstands last because they take more torque than the short ones. This way works and is the way i do my alcohol hemi too. Never had a problem, related to head torque. I know they still do it like that on the TF car. This is TFX stuff tho. i don't know about the BAE stuff.