68 400, drivers side tick

[Birdflu]

Hello everyone, new member here. I have 68 firebird with a 71 400 block and #96 heads, lunati mild roller 220/227 @.50, holley street dominator aluminum intake, just rebuilt with fresh hone, rings, and bearings all around. The break in is complete and oil is squeaky clean with no signs of wear. I'm running 10-30 with a 80psi oil pump, 30psi hot idle and 60-80 cruising
I have an audible tick coming from the drivers side valve cover, only thing is it was there in the same place with the previous 2 motors as well. I can't really pinpoint the noise it sounds like the #1 or #3 cylinder or possibly the exhaust crossover. I only did the rebuild because of this tick and it's driving me crazy, it has brand new lunati roller lifters that came with the entire cam kit. Pushrod length was checked and rechecked, I tried cold lashing, hot lashing, different preload etc and tick never goes away, the high pressure pump was installed thinking the lifters didn't have enough pressure to stay pumped.
I just got rid of the old iron exhaust manifolds and put on hooker long tubes as well, the old exhaust had leaks, and I did the welds on the new exhaust with a cheap gas lass mig and they still have some leaks through the welds, would an exhaust leak mimic a lifter tick? Also I noticed so witness marks on the intake pushrods where they come through the pushrod holes in the heads, but rockers are dead center on the valve. Anybody have any ideas on what else to check?

 

[melsg5]

The fact that it has been there on previous motors and that you are using a hydraulic roller seems to point to the problem not being valve related. I had an issue with the exhaust crossover and if your heads have been milled in any of the rebuilds you have done the intake may no longer be properly sealing. Try a stethoscope to pinpoint the sound. If you know how much has been taken off the heads there is a formula for figuring out how much to take off the intake. See the link below.

Head Milling 101: The Basics of Head Milling to Gain Compression

Compression equals horsepower. The reason is simple: The more you squeeze the air and fuel mixture in the combustion chamber, the more power you can create. In theory, forcing air and …

www.onallcylinders.com

 

[Birdflu]

Thanks for the quick reply, I figured the valve train was fine being a new roller set up. I'm going to order an actual stethoscope today, I tried the vacuum line thing but my hearing isn't the best in the first place

 

[melsg5]

What about the head/manifold?
Have the heads been milled?

______________________________

 

[Birdflu]

I don't know if they've been milled or not, they came with a 70 gto block that came with the car, I only used them because they already had screw in studs. I have #99 & #15 heads the tick is in the same place

 

[Birdflu]

I finally fixed the problem. I took my aluminum intake off yesterday and found a leak at the exhaust crossover from the wrong gasket, passenger head has the small hole and the drivers side had the larger hole. Not only was that leaking but there was a 1-2" crack underneath the manifold on the driver's side crossover big enough to fit my fingernail in, which was also creating a vacuum leak. I grabbed one of my spare iron intakes and it runs like a dream now. Thanks for the help guys, I prob wouldn't have taken the intake off without the suggestions

 

[melsg5]

Glad to hear you found the cause. Nice looking car and good luck with it.

 

[Birdflu]

Source of the leaks

______________________________

 

[melsg5]

So that Dominator was a single plain intake? Is it running better with the dual plane you have now?

 

[Birdflu]

So that Dominator was a single plain intake? Is it running better with the dual plane you have now?

It's running alot better now, noticably smoother going down the road. Though I can't really compare because the single plane had the vacuum leak, but it did spin though 1st at the stop lights

 

[cammerjeff]

That crack would cause alot of issues, glad you found it. If you mostly street drive the car you will be much happier with the duel plane intake, more low end & midrange Torque. But you do give up some HP above 4500 RPM. But how much time to you spend at that RPM on the Street?

Either way Glad it is running better & it is a Looker!

 

[Birdflu]

That crack would cause alot of issues, glad you found it. If you mostly street drive the car you will be much happier with the duel plane intake, more low end & midrange Torque. But you do give up some HP above 4500 RPM. But how much time to you spend at that RPM on the Street?

Either way Glad it is running better & it is a Looker!

Thanks, it is just a street car and I don't like spinning it past 4-5k even though it's got a nice roller setup. I mainly did it to avoid wiping another flat tappet and get some reliability. It's only 220/227 @.50 so it's a pretty mild cam

______________________________