Rod knockin like a mofo, motor hot, and other stories.

[TucsonHooligan]

1964 Falcon with a stock 170 motor (pertronix ignition). Starts right up, idles smooth, basically runs like a champ for the first 10 minutes. Once it warms up, i get a rod knock at higher rpms. When cruising at about 55 on the freeway, its audible when I maintain speed. If I accelerate or cecellerate, it goes away. I've tried heavier motor oil to no avail. Its fine as an around town cruiser, but makes a helluva racket on the freeway. Also, at those speeds, it heats up and runs toward the "H" on my temp gauge. Regular driving it stays semi-cool, in the middle of the gauge, but jumps up as soon as I get on it. It stands to reason, I suppose, but what can I do, for both the rod knock and the overheating? It has been 107 degrees average here over the last few days, and will remain like that till late august I'm sure. I already put a 160 thermostat in it to no avail. Aluminum Radiator? Electric fan? Different type of coolant? Fan shroud? Help me out here guys.

 

[BUZZ]

Does your oil pressure drop any? That almost sounds like spark knock or detonation to me. Normally if you have a rod knocking it knock all the time because of the amount of slack it has between the rod and crank. When's the last time you decarbonized your motor and checked the timing? That might help.

 

[TucsonHooligan]

Oil pressure is maintained, and I just set the timing recently, its dead on. That does make sense that it should knock all the time, but I figure when I accelerate, it stops because the harder force on it temporarily takes the slack out. Does that make sense? Could it be possible that at higher speeds that the vacuum advance puts it too far forward casuing pre-detination? Should I retard it and test it out?

 

[BUZZ]

I would think it would be your mec advance at high rpm but either way I'd make note of where you have it set and try to retard it a few degrees and see if it makes a change if not I'd give it a little more advance and try it there. It really does sound like a timing thing or maybe a vac leak somewhere. I also would try to clean out the cyl's with something like seafoam if you haven't done that lately. It could be just a little build up.

 

[addo]

If oil pressure isn't changing, yet the noise comes and goes - I suggest other than a rod bearing, too. Valve train is quite possible; check out all your adjustments under the rocker cover.

 

[rbohm]

8) try adding a few degrees of timing and see if it goes away. if not back the timing down a few degrees. it sounds like a spark knock to me.

 

[JackFish]

Exhaust manifold leak?

 

[fordconvert]

If its not a load O just unhook the vacuum line for a test, that will retard the timing especially at cruise.

 

[TucsonHooligan]

Its a load o matic. I retarded the timing and the knock quieted down considerably, and only shows up at high rpms. It seems almost like the timing is advancing too far at speed, because when I retard it any more at idle, it starts to die on me. When I have it perfect at idle, the knock starts to come back on the freeway. Is it possible that its advancing too far with the vacuum? If so, how do I fix that? New springs? Its better now than it was, but still not great. Also, the motor seems to resonate at speed on the freeway, like a humming that fluctuates high an low in a pattern. Don't know if that means anything, just something I noticed. May be out of balance. I plan on swapping a '66 200 out for it as soon as I can get it rebuilt, but for now, I need this to survive the summer since its my daily driver. Suggestions?

 

[66 Fastback]

Is the carb equipped with an SCV making it compatible with the Load-o-matic distributor?
Bad SCV?
You mention you set timing. Have you verified that the outer ring on the balancer with the timining mark on it has not slipped? You may need to confirm that the indicated TDC on the timing indicator is actually at TDC as determined by a piston stop or confirming that the #1 piston is at TDC position. A slipped balancer is a common problem on these old engines.
Yes, it could be getting too much vac advance, which may be causing the pinging. But if the balancer has slipped, the starting point for all the timing curve will be off. So it may not be that it is advancing too far, everything might just be shifted so that it is out of a decent operating range at the highway speed/vacuum load.
The vacuum advance is adjustable but I doubt that is the root cause in this case. I think in the case of the Load-O , you add washers or shims in the vacuum cannister.
Doug

 

[TucsonHooligan]

Its an SCV equipped carb. Haven't got into it deep enough too look into whether the balancer has slipped, was trying to get a basic fix to keep it alive, but now I guess I need to. I' set it with a timing light, but now I'm just doing it like a hippie: turning it and listening and going with my gut feeling. That way, I can get it running well even if something did slip.

Jim

 

[BUZZ]

You don't rember where your timing was set at before you retimed it do you? If so I'd go back to that point it should get you close.

 

[TucsonHooligan]

Yeah, its marked, but it ran terribly there. I got this car with no idea the history on it and had to revive the motor. I swapped out the points for a pertronix and retimed it. I think its just gonna be a trial and error experiment at this point.

 

[Lazy JW]

If it had been a rod you wouldn't even need to be asking about it by now; the "window" in the side of the block would be a pretty good clue

Rods typically manifest themselves when you back off the throttle immediately after a hard pull such as climbing a hill.

I suspect you are getting too much timing advance at speed for whatever reason.
Joe

 

[66 Fastback]

You might need to check and see if the vacuum advance mechanism is not binding and is operating. Since you don't have a timing light, disconnect the vac source to the distributor and cap off the line to the carb. Rig up a hose to the distributor vacuum motor and suck on it to see if it is holding a vacuum. If not, you need to replace it. With the distributor cap off suck on the line and see if the vac motor is turning, advancing the distributor rotor. You can also do this with the cap in place and the engine running, making sure that no hippie pony tails get caught in the fan belt. When you suck on the vac line to the distributor, the engine rpm's should increase. If not, the distributor is not functioning.
Doug

 

[TucsonHooligan]

I cut my pont tail off before I started working on the car. The diaphram is working properly, I tested it before and it was busted, so I swapped it with another I had that worked.

 

[48fordnut]

use a broom stick as a stethscope and have some one rev the eng, hold the stick to several places on the eng and listen for similiar noise.doubt a rod knock, could be a cracked piston.