Rocker arm issue

[1967JMG]

I just installed a rebuilt log head on my mustang. I got everything back together but now starting around 2500rpm I get this ticking sound. I went back in a made sure my rockers were torqued to spec and they were. I am thinking that possibly, since this is a rebuilt head and I'm not sure how much it has been milled, the push rods may be too long and putting too much preload on the lifters causing my valves to stay open, or at least not close all the way. Could this be possible? I put some paper behind my mufflers and when I give it the gas and let off, it looks like it tries to suck the paper back in... Can I use V8 shims for the rocker pedestals to lift them a bit and fix this problem(if that's indeed what it is).

I hope this makes sence and doesnt sound completely stupid.
Thanks for the help guys
JMG

 

[rbohm]

8) a ticking sound usually indicates excessive clearance. you might have a slight exhaust leak that crops up when exhaust pressure hits a certain level. another issue might be a dirty lifter, or a bad valve spring. usually if the valves are set too tight and the valves are hanging open, the engine loses power due to a loss of compression pressure.

 

[1967JMG]

how would i be able to detect exactly were the exhaust leak is coming from? if that indeed is the problem.... I didn't have this problem before. I only had to replace the old head because of a crack. So the only things that have changed are the head, valve spring, and a new thicker head gasket, so not many things have changed... Im not sure if this head has been milled or not since its rebuild tho

 

[mustang6]

You probably also r & r'd the header didn't you?

 

[1967JMG]

r&r'd...? forgive me, I'm not quite familiar with that one...

 

[fordconvert]

removed and re-installed

 

[Ronbo]

I just did a head swap and low and behold, same sort of problem. Its getting worse each time I start it. My case is a bad weld that becomes more evident with each time the thing got coated (X3) (Clifford Header, NOT CI product). It appears the coating folks got it right this time but...that weld, I forgot about it :roll: Its very distinct, not like valve clatter but a clicking noise. In your case it''l be harder to find because it takes higher RPMs. Give it time though, you'll hear it coming off idle soon.

Ron

 

[1967JMG]

well. i guess that's good to know that it's probably not something that is going to cause the mass destruction of my motor or something. i think for starters i'll replace the header gasket and see what happens. next on a day when the motor is cold i'll spray so soapy water around the exhaust manifold and see if i see any bubbles or anything like that and then just keep moving from there. i had some welding done on my header also. if thats what the problem is then oh well. i plan on taking the old exhaust manifold and making a j-pipe and startings for a turbo. so i'll be ditching the header eventually anyway...

 

[Ronbo]

Problem is, I believe, depending on the size of the leak you can end up doing damage. Burning a valve ect. I'm going to try some "therm-steel" around that particular tube and see what happens. With the AUS head its really hard to get in there You try and think of everything and then......Mr. Murph shows up!

 

[1967JMG]

True. Well, I plan on getting in there this weekend and trying to see what I can find. I definitley don't want to go burning up any valves or anything. Thanks for the help and ideas.
I'll post whatever I find... If I find anything at all....

 

[Ronbo]

Ditto

 

['68falconohio]

How does an exhaust leak burn a valve(intake or exhaust?). Does the engine run lean due to the lack of restriction?

 

[mugsy]

There area couple of ways to find a header leak.

Frist is to block the air flow from the fan with a small piece of cardboard in front of that side of the engine. Then move your hand very slowly and as close as you dare to the different seams and joints around the header. You'll feel the nice pop of hot exhaust on your hand. Also look for any tailtale signs of black carbon building up at a potential leak point.

A more visual approach is to buy some combustion chamber cleaner. Slowly pour it down the carb throat. This stuff typically makes HUGE volumes of white smoke. You'll notice it out the tailpipe. Anyway, look for the white smoke coming out around the header. The combustion chamber cleaner should be safe for the engine and its a great leak detector too!!

 

[1967JMG]

One other thing i forgot to mention was that my gas mileage has dropped from close to 27mpg's all the way down to about 17... could an exhaust leak really do that?

 

[Ronbo]

How does an exhaust leak burn a valve(intake or exhaust?). Does the engine run lean due to the lack of restriction?

I'm guessing the extra O2 causes it to heat up to the point of damage. I'm not taking any chances with it because this leak is pretty bad. On the log head the ports are small so I guess it was partially obstructed and I didn't notice. With the AUS head the ports are huge so..... :roll:

Ron

 

[1967JMG]

what tools are needed to remove and replace valve springs?

 

[rbohm]

what tools are needed to remove and replace valve springs?

8) that depends, are you going to do the job with the head on or off? if on you need a way to keep the valves from dropping into the cylinders, usually shop air will do fine, or you could pack the cylinders with rope through the plug hole and use the piston and the rope to keep the valves in place. then you need a spring compressor like this one;

http://www.summitracing.com/parts/OTC-4573/

if you pull the head you can use this valve spring compressor if you choose;

http://www.summitracing.com/parts/WMR-W89409/

 

[1967JMG]

Well. good news is I think the problem is just the header gasket is blown. That's an easy enough fix. Bad news is my head gasket is blown and seeping from the driver's side. I had the dame problem with my previous head. I thought that by switching to head studs with this new head and changing the head gasket the problem with that would be solved but I guess not.
So, new question- could this head be warped or could it be the block? What do I have to do to see if it's the block?
btw- already checked the torque. Everything is to spec...