Hello to all, since this site has helped me so much in the process of restoring the cutty.
So here is what I've got. 72 cutlass supreme convertable. 350 sbo. Mondellos forged aluminum 455/ 4.068 bore (I think) Pistons. Cam and all other engine parts were purchased from and matched by mondellos. It runs good but I have a noise that sounds like alt. bearing or something. It only makes the noise when snapping throttle under load. I cannot here it when in park. I removed the drive belts one at a time and the problem still exists. The engine still has break in 20-50 oil in it. I don't know what it could be and desperately need help as nobody can seem to find the cause of the noise. PLEASE HELP IM OUT OF OPTOINS.

 

Is there a chance you or someone could post a video to Ytube?

It might help, to let more ears hear that sound. It could be a lot of things.

 

I hate to say it but that is usually a bad sign. I would remove each spark plug wire, one at a time, see if the noise goes away, and you will at least have identified the cylinder. Do you happen top know what the piston clearance is?

 

That same exact scenario happened to me when I snapped the throttle on a fresh motor. Sounds funny/stupid, but it turned out the fan blade was hitting the bottom of the old style double wire hose clamp I had in there

 

 

You removed the drive belts "one at a time" but have they all been off at the same time? You can run it for a quick minute without the water pump to see if maybe it is the water pump.
Also, there is an "oil shield" that goes on the crankshaft behind the steel plate that covers the timing chain, etc. I put mine in backward once and had a similar problem. Good luck.

 

[QUOTE=Briansteinke;856272]Hello to all, since this site has helped me so much in the process of restoring the cutty.
So here is what I've got. 72 cutlass supreme convertable. 350 sbo. Mondellos forged aluminum 455/ 4.068 bore (I think) Pistons. Cam and all other engine parts were purchased from and matched by mondellos. It runs good but I have a noise that sounds like alt. bearing or something. It only makes the noise when snapping throttle under load. I cannot here it when in park. I removed the drive belts one at a time and the problem still exists. The engine still has break in 20-50 oil in it. I don't know what it could be and desperately need help as nobody can seem to find the cause of the noise. PLEASE HELP IM OUT OF OPTOINS.[/QUOTE]

- What kind of noise?
- Cannot recreate it in park? Regardless of RPM?
- When you removed the drive belts- you tested it under a load with hard throttle?
-How many miles are on the motor?
-What kind of oil pressure and temperature are your recognizing when you hear the noise

 

 

- What kind of noise?
- Cannot recreate it in park? Regardless of RPM?
- When you removed the drive belts- you tested it under a load with hard throttle?
-How many miles are on the motor?
-What kind of oil pressure and temperature are your recognizing when you hear the noise[/QUOTE]
It is a rattle noise
Will not do it in park
Belts removed and hold brake down in gear and snap throttle to make noise.
15 miles on motor
Good oil pressure
Temp was from 130-170, seems to do it at any temp.

 

Could you tell us a little more about the build?

If it internal I find it very hard to believe that it won't do anything in park

Rattle possibilities:
-Broken exhaust hanger
- Ping? long shot I know.

 

Several times I have seen scuffed pistons do that, only made noise under a load, I could see a rod issue doing the same.

 

Trying video again. If it works then you can here the noise at first when throttle is snapped when in gear. Then I put in park and it goes away. What is this damn noise.

 

When you try to play it, it show this video is private. You may have to share it?

 

I think video works now. Please advise.

 

Kinda sounds like a leak at the header gasket?? I don't think it is an internal engine noise.

 

What about taking a look at the converter and the flex plate? As it only makes the noise in gear I would start looking in this area. It could be anything from cracked/loose flex plate to broken converter. At least these things are relatively easy to check and replace compared to a piston or a rod.

 

So I unplugged the plug wires one at a time, still does it after every cyl. Did the hose technique and found a small header leak, but it doesn't get louder when the noise happens. Flex plate and TC seem to be fine, and are fairly new. I turned the idle down a hair and now I can get it to make the noise in park, if the engine settles down for a min and throttle is snapped fast. Does not do it if throttle is leaned into slowly. This is driving me absolutely crazy I cannot figure this out.

 

Two ideas. Have you tried the long screwdriver or piece of wood as a "stethoscope". It actually works well and may pinpoint your problem area. On one build I put in a slightly larger cam that caused a rocker arm to tap tap tap the top of the valve cover, valve cover baffle plate. I installed a thicker valve cover gasket and solved it

 

hose makes a great "stethoscope" also
hold one end to your ear, pass the other end here and there. It will make pinpointing noise easier. Touch the rocker covers, see if you can feel a lifter hitting them.

 

If you have a Harbor Freight in your area, you can purchase an inexpensive Stethoscope for about $3.99.

 

my guess is vacuum advance/detonation rattle. move your timing a bit, looks to have some torque also

 

Sounds to me like a valve noise.
Adjust the rockers correctly?
Been a number of years since I've played with internals but it sounds like the lifters may have finally been 'broken in' and now one of the push rods are sloppy.