37 Ford Main bearing noise?

[Mark's 37]

I can hear the main bearings knock on a cold start-up, deep knock, that gets better after it warms up a bit. The valve train is noisy too, but clears up after warming up also. It "clucks" on acceleration, best way I can describe it, in any gear but not at cruise or idle, just under a load. This seems like plain old main bearing noise to me, but this is my first flathead. Oil pressure at idle on cold start is 20 psi and 30 psi at 1500 RPM, drops to about 15 psi hot idle and doesn't go over 20 psi at higher RPM hot. Using Valvoline 20-50 VRI. I am going to have the motor out in a couple months to do a new clutch and mounts so I plan on looking at the bearings then, any thoughts about the current knock/clucking? Thanks.

[my4dv8]

You say you can hear the mains knock on a cold start which is possible. But have you double checked the timing advance , the ol flathead can make a cluck noise on power if it is advanced too far . Do the simple checks first.
20psi is survivable low but, it's about flow not pressure.

[flatheadmurre]

Take the pan and a head off.
Not my favourite guessing...so check piston clearance and rod/mains.
That gives you a hint if a new sets of bearings and a rering job will give you some more years or it needs a major rebuild.

[Mark's 37]

Myfdv8,
I have been thinking about the timing being too far advanced also. I need some education on how to determine and, if necessary, adjust the timing advance. The screw adjustment on the drivers side of the distributor? Can I back off the timing in small increments with it?

[flatheadmurre]

Timing has to be set with dizzy out of the car.
The vacuum brake you can tighten up a bit until it stops pinging if thats the problem.

[Mark's 37]

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I looked just now at the distributor. The "plate" adjustment the passenger side is set at the middle mark on the plate. Is the other adjustment on the drivers side the vacuum brake?

[flatheadmurre]

Bolt with a locking nut is vacuumbrake.

http://www.vanpeltsales.com/FH_web/F...tor_timing.jpg

Wrong dizzy but you find it on his page.

[Mark's 37]

Got it. So tightening the pressure on the vacuum brake will reduce the advance but no effect on the initial timing? Since the engine knock is only under a load, with little vacuum signal from the intake to the distributor, it would seem the initial timing is too advanced. But...it is worth a try. The distributor was set up by Bubba's in 2014 but the previous owner spoke about having set the timing "perfectly" and not to fool with it. Has me a little skeptical.

[flatheadmurre]

You need a fixture to set the dizzy...if Bubba did it...dont tinker with it.
My advice is when you have the engine out take of the pan and a head so you can do a real checkup then you dont need to guess.

[Mark's 37]

Being that Bubba's rebuilt the distributor and set it up I tend to agree to not fool with the timing. I think possibly the previous owner may have fiddled with the timing after Bubba's work. I met a local guy who has a Sun distributor machine and does some flathead work so if it comes to it, I will look him up.

[Lawrie]

What about a piston noise,that would be quiter as it warms up and expands,mains you would think would be the other way round,quite when cold (thicker oil)
Lawrie

[Mark's 37]

Could be piston noise but doesn't have the typical tone of piston slap, more of a heavier deep thud knock of a main bearing. Pistons tend to expand as they gain temperature and take up some clearance and it isn't the double rap of rod knock. This noise is at cold start idle and after warming to full temp it is better at idle but very noticeable under part to 3/4 throttle load. Light acceleration or cruise is fairly quiet. I might pull the distributor and use the "2 ruler" method to see what the point gap is, if it looks out of whack I'll get it on a distributor machine to have it checked.

[Mark's 37]

Took the distributor out today. Found the vacuum brake lock nut loose and backed off so it is hard to tell what it was set at previously. The advance adjustment plate is set a the 3rd increment from the bottom of the scale. Using the "2 ruler" measurement led the left points just coming up on the lobe starting to open. The gaps are to about .012 on the right side and a and barely open (.010 or less) on the left.. I rotated the shaft and checked the gap on all the lobes and they are consistent. Found one adjustment step by step saying both point gaps should be between .014 and .016 on the cam lobe. Haven't changed anything and it sits on the bench. Any thoughts about the point gaps, etc.?

[flatheadmurre]

Point gap is set by dwell.
Make yourself a degree scale and you can check it.
A buzzer or testlight and a degree scale and youre good to go.
Then final adjusting of timing by ruler.

[Mark's 37]

Well, after some investigation and advice from the local flathead guru in Santa Cruz, turns out the distributor has an eight lobe cam instead of a four lobe and only runs one set of points, with the second set non-functional. Also the points won't adjust out far enough to get to .016, with one set only getting to .012. Not sure why, possibly the points rub block is too worn down, but he will sort it out and set up on his Allen dist. machine. Doubtful this is the source of the main bearing-like noise but learning a lot as I go. He talked to me about crankshaft run-out and main bearing wear, also worn cam bearings causing low oil pressure. Vern Tardels, Frank Oddo's and Ron Bishop's books were delivered yesterday so the library is full.

[deuce_roadster]

What you describe doesn't sound like a professional rebuild on the distributor, more like a backyard Band-Aid because they didn't understand that the 2 sets of points act as one. The previous owner may have not told the truth. Get the distributor to someone who knows how to set it up, on a machine if possible.

[flatjack9]

All Ford V-8 distributors have an 8 lobe cam. Also sounds like you have some aftermarket junk points.

[scooder]

First the "guru", he doesn't know (as stated previously) how a dual point ignition works. I would not let him at your ignition, little knowledge can be a dangerous thing.
Second, your library is only just started in the flathead world.
The only stock Ford flathead ignition with a four lobe cam is the Lucas industrial distributor. Quite rare over there I'd think, the plastic parts have been made from unobtainium for years.
Martin.

[Mark's 37]

Ok, now I am confused. Maybe I misunderstood what he was trying to tell me, not the first time that has happened. I will know more on Monday when I pick it up. Things don't add up at this point, the guy is well known around here. He and his son have been in the hot rod/race car community for years. His son builds flatheads and just finished a 42 Mercury coupe with a beautifully done flatty, does all the work himself. He parked next to me last weekend at the weekly Saturday morning deal and the workmanship is great. I dug out an old Mallory dual point for an FE motor I have and it has a four lobe cam, maybe there was some confusion with that kind of set up. Hope I haven't stepped too deeply into a turd pile.

[flatheadmurre]

That dizzy aint rocket science and was designed when your local greasemonkey did the repairs.
If the points dont adjust to open enough the contact to the lobe is just worn out get a new set of points.
Assuming bearings arent totally shot in it.