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+--- Thread: What are these parts trying to tell me? (/showthread.php?tid=4359)
What are these parts trying to tell me? - Torkey - 02-17-2013
Had trouble starting the car today. Seemed like the starter was having a harder time turning the engine around. Finally got is started by using the hair dryer to pump in hot air into the intake.
It was running.. but idled like crap with lots of unburned fuel coming out of the exhaust and just didn't have any power. While idling we noticed that it sounded like one of the exhaust valves was out of adjustment. The classic chuff chuffa sound.
Took off the valve cover and found two of the cam towers broken.
I've got replacement parts from the 'donor' car but want to understand what caused this failure so I can fix it.
What story are these parts trying to tell me?
RE: What are these parts trying to tell me? - Simpler=Better - 02-17-2013
Excessive vibration?
Chain slop making it torque hard?
No solid diagnosis, just throwing some ideas out there
RE: What are these parts trying to tell me? - MFSuper90 - 02-17-2013
Judging from the break marks on it, it looks like they have been broken for awhile.
Thats wild! never expect cam towers to break...
RE: What are these parts trying to tell me? - Torkey - 02-18-2013
(02-17-2013, 10:16 PM)MFSuper90 Judging from the break marks on it, it looks like they have been broken for awhile.
Thats wild! never expect cam towers to break...
Good eye MFSuper90!!! The second cam tower breaks are shiny and worn where the breaks on the first tower are rough and new.
This engine was rebuilt over the winter. When the engine failed it was cylinder three that took the brunt of the punishment. Thinking maybe the cam tower had started to fracture then. We have maybe 300 miles on the car after the rebuild. It might have completely failed and the other towers were not able to handle the force so the second one failed.
RE: What are these parts trying to tell me? - dieselmeken - 02-18-2013
did you grind the cylinder head? How much if yes?
RE: What are these parts trying to tell me? - Torkey - 02-18-2013
(02-18-2013, 12:34 AM)dieselmeken did you grind the cylinder head? How much if yes?
We had the cylinder head tested and mag fluxed. We also installed new valve guides and had the seats ground but nothing more than that.
RE: What are these parts trying to tell me? - willbhere4u - 02-18-2013
if the #3 piston had smacked the valve it could have fractured the cam tower before the rebuild? and the cold weather finished it off?
RE: What are these parts trying to tell me? - Mark_M - 02-18-2013
Can you replace the cam towers with parts from another engine? These are usually line bored so typically no 2 engines will be identical. You could replace all of them right enough but just a couple wouldn't seem right to me.
RE: What are these parts trying to tell me? - Druk - 02-18-2013
Were the cam towers replaced in their original positions? Even wrongly by accident? If they are line bored then having them out of sinc might impart undue stress once they are torqued down.
Just a thought......
.
RE: What are these parts trying to tell me? - Mark_M - 02-18-2013
(02-18-2013, 12:45 PM)Druk Were the cam towers replaced in their original positions? Even wrongly by accident? If they are line bored then having them out of sinc might impart undue stress once they are torqued down.
Just a thought......
.
It's a good thought. I didn't think about that being the cause of the original failure but if they were put back in the wrong order you could be spot on.
RE: What are these parts trying to tell me? - Torkey - 02-18-2013
They went back on in the right order. The towers were never taken off the tube that ties them all together. But that is a interesting piece of information and one I didn't know.
We are using the complete cam assembly from the donor car. Also using the rockers from the donor.
On another note... the prechambers were removed and I got a good look at the piston crowns. It looks like #3 exhaust valve hit the piston. Not sure how badly the valve was damaged. The plan is to put it back together and do a compression check. Hoping we don't have to pull the engine out. There is a race this weekend and pulling the engine would be a show stopper for us.
Here is a shot of the piston crown using the digital scope.
RE: What are these parts trying to tell me? - Simpler=Better - 02-18-2013
Ah shit! Oh well, make sure there's no loose crap in there and run it hard. Worst case you're pulling it apart again, best case it's fine.
RE: What are these parts trying to tell me? - fordheaded - 02-18-2013
Hopefully the valve didn't bend from getting whacked. A compression test should verify that though.
RE: What are these parts trying to tell me? - Torkey - 02-18-2013
Feel like I dodged a bullet here. Compression tests say that cylinder is 10 percent weaker than the average of the other cylinders. Must have only grazed the piston.
I think I should go buy a lottery ticket.
RE: What are these parts trying to tell me? - willbhere4u - 02-18-2013
luckily the valves in these engine go straight up and down lessening the chance of bending a valve. maybe the adjuster loosened up and lengthened until the piston and valve hit causing the cam tower to break
RE: What are these parts trying to tell me? - Simpler=Better - 02-18-2013
Well then, that's grrrrreat!
Ajust em, run it for a while, check em', and run on along
RE: What are these parts trying to tell me? - Torkey - 02-18-2013
Another example of how bulletproof these engines are. Not sure another engine would have faired so well. I consider this a major failure with minor repercussions
.
RE: What are these parts trying to tell me? - lpumb3 - 02-24-2013
(02-18-2013, 08:50 PM)willbhere4u luckily the valves in these engine go straight up and down lessening the chance of bending a valve. maybe the adjuster loosened up and lengthened until the piston and valve hit causing the cam tower to break
do you adjust your valves after every race ?
RE: What are these parts trying to tell me? - Torkey - 02-25-2013
Quote: do you adjust your valves after every race ?
We adjust the valves before and after each race.
UPDATE - Torkey - 02-25-2013
Wanted to post an update on this. The car was in an race this weekend and performed flawlessly. It was run hard approximately 6 hours on Sat and 8 hours on Sunday. Abolsolutely flawless. We did run out of fuel 4 turns before the checkered but we finished by using the starter to limp the car across the line. It was epic!
RE: What are these parts trying to tell me? - Simpler=Better - 02-25-2013
That's awesome! Sounds like it's time to inflate the tank to 80psi and stretch it out for a few more gallons.
RE: What are these parts trying to tell me? - willbhere4u - 02-25-2013
We need some pics of the car!
You can install an extra tank and double the range! might be a little tail happy with an extra 20 gal of diesel in the back lol
RE: What are these parts trying to tell me? - sassparilla_kid - 02-25-2013
I just say add another 5-10 gallon reserve tank
RE: What are these parts trying to tell me? - Torkey - 02-25-2013
(02-25-2013, 03:22 PM)willbhere4u We need some pics of the car!
You can install an extra tank and double the range! might be a little tail happy with an extra 20 gal of diesel in the back lol
Lots of pics on our Facebook page (click link below). We will be posting pictures from this weekend tonight.
Dirty Little Freaks Racing