Cylinder One occasion knock at 4800 RPM

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Model T Ford Forum: Forum 2016: Cylinder One occasion knock at 4800 RPM
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 12:12 pm:

Just kidding A more realistic guess is around 1800 RPM.

Yesterday I installed the aluminum Z head and am now hearing a sound louder and more often, of course. The sound was originally hidden by the lower pulley rattle that I have now fixed.

I did the high-idle "spark plug short" test and narrowed it down to cylinder number one. My engine has a very rough RPM point that makes me wonder if maybe one of those detachable crank counterbalance weights is coming loose.

I'm also worried that I might be over revving the engine in low. Today I attached a GPS speedometer to remind myself to switch to high gear no later than 15 mph, right?

Before I tear into this and get all dirty, I would love to hear any shortcuts or advice from wiser men than I.

Should I order parts in advance, and which ones?
I love using old-school tools as much as possible but are there any
Modern Tools needed like plastigauge, any others?
Rod and main bearing torque specs.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 12:14 pm:

I really enjoy using old-school tools whenever possible, like this speedwrench. Of course it's probably 50 years newer than my car.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rick Goelz-Knoxville,TN on Tuesday, July 19, 2016 - 12:17 pm:

Retard the spark a little at a time and see if the knock goes away.

Rick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 12:17 pm:

Speedwrench


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 12:18 pm:

Rick,

Yes, I can eliminate the not by retarding the timing. Does this mean that it is preignition?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 12:19 pm:

Knock


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, July 19, 2016 - 12:23 pm:

RE; Modern Tools needed like plastigauge*, any others?
If you use it,*, oil the crank and bearings and make sure it fresh. I have found using plastigauge just like to embed in the babbitt dry rather then spread. I have been using the aluminum foil method to check clearances.
About 35 on the rods, 80 on the mains and 45-50 on the head.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 12:26 pm:

Mark,

Thank You for the specs. I will Google the aluminum foil method you mentioned.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 12:39 pm:

That search revealed that my front main bearing might be the problem.

I hear the knock slightly high idle and under load st "high" RPM in Low

There are also several RPM points in which the engine feels totally out of balance from side to side. I don't know if that is related to the knock, or a cause, or a symptom.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Tuesday, July 19, 2016 - 12:48 pm:

Chris - Never had experience with a Z-head, but what I've learned from this forum is that sometimes, there is close clearance involved with installation of a Z-head. For this reason, common practice is to lay the head in place but not bolted, (and with no head gasket) then turn the engine over to be sure of no interference when pistons reach TDC. If there "IS" interference, I'm told that just a slight bit of grinding takes care of it with no problem. If you did not make this "interference check") I'm thinking you might have a piston just barely contacting the head, or possibly the edge of head gasket) just enough to cause the "knock". FWIW,......harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, July 19, 2016 - 12:55 pm:

It's easy, depending on the thickness of the the aluminum foil you have on hand fold a square about 1" X 1" two or three thickness thick (about .0015). Place in rod or main cap. Torque down. If it turns real easy, take a shim leaf from each side. If it still turns but with some resistance take one leaf off just one side. Repeat as needed swapping back and forth removing shim leaf's. I set to the point with the foil in place the crank just wants to turn. I use oil when doing it this way.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 01:26 pm:

Thank You all

By shifting at 12 mph I have not heard the knock on this drive yet. 10 miles at 93' F

So far; so good. I guess it was worsened by driver error and the knock is going into remission for awhile.

I did fit the head without gasket first, but only to check new head bolt lengths. Wish I had turned it over now.

I'll just slow down a bit...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Plank - Three Way, TN on Tuesday, July 19, 2016 - 01:43 pm:

I helped a friend install a Z head awhile back and we had to grind some out of 1 and 3 to get clearance above the pistons. Once we got it to where it didn't hit without the gasket, we added the gasket and torqued it down. I installed a Z head on a different car that was ok without any grinding. They need to be checked.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Tuesday, July 19, 2016 - 02:59 pm:

Here is a video that shows how to check for interference between the pistons and the combustion chamber of a Z head (before you install it for good!).

https://www.youtube.com/watch?v=EYyRaw63iWE&index=38&list=PLYG_lIhIwKyLG8WQm4tGm KK1nA0Yctp6G


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 06:55 pm:

Thank You, Mark!

That's a great tech video series and I'm learning.

I don't know where I saw it, but I thought I saw some removable crankshaft counterweights on a model T crank, but I don't remember where and the crank in the rebuild video does not appear to have such attachments.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, July 19, 2016 - 08:02 pm:

The removable type are the Dunn counter weights. I think the dealers carry them (or did). You have to make sure which type they are because they could be ether for the diamond (early) crank or straight for the later (approx 1926-27) crank. While people in the past have just bolted them on, it's best to have the crank balanced with them on if you went the route.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 08:13 pm:

Thank You, Mark. Detachable crank counterweights sound like a risky idea unless I already have them and find one to be loose.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Tuesday, July 19, 2016 - 08:19 pm:

As the song said; get out and get under! Drop your inspection plate and have a look see. Watch out for oil in the dips. :-)You don't even have to drain the oil.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 08:33 pm:

Whaattt??
I can leave the oil in??

No offense intended but that Sounds iffy given that "rod dipper" scoops are sold to help oil splash around.

Sincerely,

A gullible new guy


Top of pagePrevious messageNext messageBottom of page Link to this message  By Corey Walker, Brownsboro TX on Tuesday, July 19, 2016 - 10:26 pm:

Even if you drain the oil, there will still be oil in the 3 troughs for the rods. You can leave the oil in the pan, when you remove the inspection cover be careful and try to let it straight down or you will have a mess from oil spilling. When you replace it add oil to fill in the troughs, they fill up then let the excess out the top petcock.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Laughary on Tuesday, July 19, 2016 - 11:19 pm:

Thx Corey

I'm ordering the gasket now and will try to make a video without getting my camera wet.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, July 20, 2016 - 11:09 am:

The oil in the pan is below the bottom of the inspection plate as long as it's not over filled. Look at a line from the the top petcock to front. The oil dipper trays however will have a good amount of oil in them that does not come out when you do an oil change. One way to minimize oil in the tray is to raise the front of the car up as high as your jack will allow and let the oil drain over night back into the flywheel area. Put the car back down before you start working under it or on jack stand to give you more work room. Be sure to put card board under before you start, there will be oil loss no matter how careful you are.
Think of it this way; there is oil trapped in the dipper trays, the inspection plate is sitting below the bottom of the pan the thickness of the pan plus gasket and there is the ring around the inside that the inspection plate screws go into add into that if the floor slants down in front oil pool in the front.
A little oil goes a long ways when it comes to a mess or leak! :-)


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