chattering sound

[rob63mess]

Hey Guys,
The 30 roadster is running great. Its been 90 degrees or better here in central Ohio and I've been putting plenty of miles on the car with no overheating or problems of any kind. However, when accelerating, the motor is a little chattery. Doesn't do it at Idle. Not a knock and as soon as I get to cruising speed and back off the accelerator its as quiet as a kitten. I replaced the pistons last summer and checked all of the babbit and clearances on the mains and the rods. I was thinking maybe a small exhaust leak or something along those lines. I've tried to think of the obvious like making sure the distributor shaft it well lubed. Again, I cant tell you how well the car is running, but I would like to here any suggestions you guys have. As always, i'm indebted to all of you for the help you provide.
Rob

[Safewiz]

I also have the exact thing you are mentioning. I can rev it at a standstill, nothing, only on acceleration on a pull. Let off nothing. Checked for exhaust leaks, nothing. Mine runs great as well. Stand beside the car and rev it up again no noise.

[Safewiz]

Mine is more of a tick, sounds like a lifter noise, but if that's the case I would think it would be all the time and not just on a pull.

[rob63mess]

Sounds like mine

[Tom Wesenberg]

What happens if you retard the spark some?

[rob63mess]

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I tried that Tom....and although it may help a little, it doesn't cure the problem completely.

[Patrick L.]

My first thought was spark knock too.

[rob63mess]

Tom and Patrick, you guys know way more than I do for sure, but I don't think its a timing knock. I'll take it for a spin and retard the spark considerably and see what happens....if she starts to get hot i'll know I went to far.

[Patrick L.]

I suppose it could be an internal issue such as a piston or wrist pin problem, but, they should be able to be replicated while sitting still.

I'd also recommend looking closely at the exhaust for any sign of a crack or leak at the manifold or flange if it sounds more like a 'tick' or 'psst' than a 'ping'. There may be a carbon track to lead you to the problem.

Do you know for sure where the timing is set at ?

[katy]

Check your spark plugs.

[rob63mess]

Patrick...not sure exactly where I'm at on the timing, however I recently bought the nurex timing wrench and set the timing according to the instructions.

[George Miller]

Sounds like a exhaust manifold leak to me. Check at the back of manifold and see if it is black around there. Also put a straight edge on it and see if the back of the manifold drupes down.

[rob63mess]

I will check.....it is a new manifold....just put on last summer.....but I'll check it out. Thanks.

[DJ S]

Originally Posted by George Miller

Sounds like a exhaust manifold leak to me. Check at the back of manifold and see if it is black around there. Also put a straight edge on it and see if the back of the manifold drupes down.

I agree, it sounds like an exhaust leak. My grandfather's fordor displayed the same symptoms you are describing and it was an exhaust leak.

[Patrick L.]

Originally Posted by rob63mess

Patrick...not sure exactly where I'm at on the timing, however I recently bought the nurex timing wrench and set the timing according to the instructions.

I'd recommend looking at Marco's site for timing instructions. Fast and simple, as it should be.

[RUNNERBUN]

Originally Posted by George Miller

Sounds like a exhaust manifold leak to me. Check at the back of manifold and see if it is black around there. Also put a straight edge on it and see if the back of the manifold drupes down.

I agree also that it sounds like an exhaust leak, however quite often the leak is in an area that is out of sight. I have found that an excellent way for checking for exhaust leaks is by the use of a short length of garden hose or plastic tubing. Place one end to your ear and work the other end all around the manifold and flange joint. If there is a leak, you will definitely hear it.
Good luck and enjoy your Model A

[Patrick L.]

Well, in any event it'll be interesting to see what you find.

[rob63mess]

OK....may have found some of the problem. Using a dental type mirror I discovered a small carbon mark on the gasket at the rear exhaust port where the manifold meets the motor. I also discovered that I was able to get almost a full turn on that manifold nut. I was a little sheepish when I put that manifold on last year because I didn't want to break it. I snugged every thing down and it seems to be much better. I will order a new gasket set well. Thanks to all who have helped.

[Patrick L.]

Originally Posted by rob63mess

OK....may have found some of the problem. Using a dental type mirror I discovered a small carbon mark on the gasket at the rear exhaust port where the manifold meets the motor. I also discovered that I was able to get almost a full turn on that manifold nut. I was a little sheepish when I put that manifold on last year because I didn't want to break it. I snugged every thing down and it seems to be much better. I will order a new gasket set well. Thanks to all who have helped.

Well, OK, we go way back to reply #9.
Noises can be tricky. Those darn carbon tracks will betray the leak every time.

[Jacksonlll]

Always a good idea to keep those plugs cleaned. They do foul a lot.
Get the new exhaust gasket and put 45 FT# on those nuts.