I'm using the 1.6 Comp Cams roller tip rockers on my new engine and it sounds like I have a vacuum leak. I've been unable to find any leaks (I've disconnected and plugged all vacuum lines) and I'm wondering if the sound could be the rockers.

Thanks for any input!

AD

 

I don't hear my 396 rockers/lifters, but I do hear a light ticking on the 305 (will be making one more attempt at adjusting soon). Both have stock ratio, roller-tip rockers.

I can see confusing a header leak with a rocker tick, but not vacuum.

 

I noticed that my 1.6RRs were a bit louder than my stock ones. They sounded like a bunch of angry bees under the valve covers. The noise went down a little when I installed the stud girdle and the CompCams polymer valve covers, but still noisey.

 

Well that sound is kind of funny. A little tapping is one thing, but a vac leak sound is probably something else, at least I would think so.

But my roller tip rockers and cam are noisier than the stock set up was. They are adjusted properly, several times. They still make a little more noise, but it's not much.

 

Thanks guys, I was pretty sure of this myself but couldn't figure out where the hiss is coming from.

I disconnected every vacuum hose and plugged the ports, replaced every gasket in my carb and base (which wasn't needed), and I can still hear the hiss. The only possible leak left would be the intake/head but this engine was professionally built and every gasket I can see is expertly sealed.

I've had a couple other people look at it and the consensus is that the hiss is coming from the airflow through the carb and is normal. The engine is running fine and shows no signs of a major leak, no hot cylinders (checked by drops of water on the headers) and the running temp is a lot cooler than my old engine.

What bugs me is this was never an issue on my old engine which was good for about 260hp. My new engine is easily making over 400hp so could that explain the additional noise at part throttle/high vacuum situations?

If you guys agree then I'll sleep better tonight

AD

 

five7kid ive got a 305 tbi engine and i replaced all the valve seals and im getting a slight ticking or tapping noise from the passanger side of the motor it sounds to be coming from the rockers closetst to the firewall like the 2 closest.Im going to trying re adjusting them again by losening them untill i hear them clatter then tighten till they stop clattering then turn another 1/2 turn i did a 1/4 turn would that make a difference.

 

1/2 turn would be less likely to tick than 1/4 turn.

Mine still tick, especially when warm. Adjusting didn't change anything, so I'm assuming it's the Crane lifters.

 

Yep, those Q jets do make a LOUD sucking noise, especially when the air cleaner lid is off. Its the small primaries, they tend to speed up the air velocity much more than other carbs and that causes the "sucking sound".