New motor knock

[V4F]

just tried to start a rebuilt motor . pretty good knock near the distributor . have not pulled it apart yet . being a high knock , not bottom end , not the distributor , but maybe valve area . any ideas appreciated ..... thanks
.. steve

[H. L. Chauvin]

1. Was engine stored & not running for a length of time?

2. If so, for how long?

3. Was engine rebuilt by a reputable person?

4. Anything making it a non-stock Model A?

5. Tried to start -- did it start?

6. Is knock while cranking or while engine running?

[lindy williams]

Did you install the big spring in the valve chamber that holds down the oil pump drive gear?

[V4F]

1. Was engine stored & not running for a length of time? .... yes

2. If so, for how long? ... a few months

3. Was engine rebuilt by a reputable person? .... NO

4. Anything making it a non-stock Model A? ... no

5. Tried to start -- did it start? .. yes it started

6. Is knock while cranking or while engine running? ... running

[V4F]

Did you install the big spring in the valve chamber that holds down the oil pump drive gear? ..... i did not do the work . so im not sure .

[Logan]

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If its coming from the distributor area, and it has the short shaft distributor, with the mid shaft connecting to the drive gear I would check to make sure the fitting isn't sloppy. Sometimes those can cause a noise, also a chipped or bad drive gear could make some noise. Valves make more a clicking/ticking sound than a knock. There's a number of things it could be, like a block that's been surfaced to much and the piston comes above the deck and hits the head in either 2-3 cylinder, loose wrist pin. The list goes on and on. You could try shorting out the spark plugs one cylinder at a time, and if the noise gets quieter, it's most likely in that cylinder. That'll give you a starting point.

[H. L. Chauvin]

Not funny, but if your engine builder was not too swift, remember rare cases where some absent minded doctors have left their surgical tools in patients.

In reply no. (4) above, with the answer to question (3), past diagnostic experiences with the norm may not be so normal in this case.

Good tips above. Time to start carefully investigating & observing and quit running the engine.

[Tom Wesenberg]

Does the camshaft have a good spring and plunger in the front cover. Also, it MUST be greased on the wear surface or you'll have an off and on squeel for some time.

A worn center camshaft bushing can cause a knock.

[V4F]

thank you all . good info as always . waiting to see what the owner wants to do . i will update as i find out ............ thank you .. steve

[H. L. Chauvin]

Hi steve,

Also, not a bad idea to obtain a sturdy mechanic's stethescope that is similar to a physician's stethescope to place on different parts of the engine to try to pinpoint from where the knock is originating.

Amazon.com has them anywhere from $1.95 up to $20.00 or so -- local Auto-Zones, Pep's, etc. may also have them -- not very expensive.

Can saves lots of time & energy & reduce guess work.

Some prefer to be more frugal and vintage oriented like Fred Flintstone & use other engine listening devices such as dinosaur bones, broom stick handles. early Egyptian screw drivers, (2) beer cans & a string, tree branches, pipes, solid steel rods, etc., etc. -- each to his own -- nothing really surprising in the Model A world!

Please keep in touch.

[V4F]

i did use a dowel & it is in the distributor area but not the distributor . more checking to do ...... thanks all

[Brentwood Bob]

The driver could be one with an oversized gear. The fit of the two shafts is also important, there must be some give in the joints. The distributor can not be binding the shafts. There is a spring in the valve chamber holding the drive gear in position, it should be there to do its job. Front plunger and spring for the timing gear need to be correct. The replacement spring may be too short. Bob

[Tom Wesenberg]

I've sometimes had to use a thin file and take a couple strokes through the distributor shaft notches to get a snug slip fit. This is when I buy a new repro shaft.

[Fred K-OR]

Like Logan mentioned above, I had a consistent "click" in my engine. It was not the dull sound of a knock. So I did a lot of the things mentioned above but found the valve lifters needed adjusting. I adjusted them and now the engine sounds great.

[V4F]

still waiting on owner . just idling ! ........... thanks all ..........

[Chuck Sea/Tac]

See if you can find out the actual center cam bearing and block hole size, from the rebuilder. You could have a center cam bearing knock. Chuck

[BILL WILLIAMSON]

A stethescope, with the probe removed, just with the open hose, can help in localizing noises that transmit everywhere. Example, 1 loose ticking valve can be isolated by going along side cover, about 1/2" from touching the cover. Like, "That's it! the third one from the back"! Bill W.