300 rebuild project

brandoncw

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Ok so i recently got a rather loud tap, not quite a knock, comming from i believe my bottom end of my 300. She has about 375k on it so anything is possible. I have good oil level and decent oil pressure. I first thought it was rod knock but ive driven about 100 miles on it and the condition has not worsened and it does not look like tinker bell lives in my oil pan. Could there be something else making the noise?

These are the conditions of the noise im hearing, it is present about 10 seconds after the engine has started cold. Immediately if it was just ran. The sound can be heard at all rpms while not under a load. But the sound is not present while under a load from something like taking off shifting through gears. If the motor doesnt last its ok cause i have another im am gonna rebuild to put in. So im really just curious of what the problem is. I will check for movement in the pistons by pushing them down when they are on their down stroke. And i will check rocker arms and pushrods for play and bending just incase that is the issue.
<edit> It sounds like it could unfortunately be piston slap. Will do some more research though.
 

bubba22349

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:hmmm: Might help to know what year engine / truck your working on! On the 300 engines cracked piston skirts often are a cause in 1965 to early 1995 engines. On an older carb type engine sometimes a worn out fuel pump lever at its pivot point can also be a cause of a knock its sound gets louder as engine RPM increases. Good luck in the hunt. :nod:
 

bubba22349

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:beer: Ok thanks pmuller9! In that case since its an EFI engine I would focus on your Pistons as being a possable cause. Personally had one 300 (high milage engine) that just about totally destroyed itself due to a stock cast Piston failing, after that I never used a stock Ford cast pistion again. Good luck on your rebuild :nod:
 

brandoncw

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bubba22349":3knza0at said:
:beer: Ok thanks pmuller9! In that case since its an EFI engine I would focus on your Pistons as being a possable cause. Personally had one 300 (high milage engine) that just about totally destroyed itself due to a stock cast Piston failing, after that I never used a stock Ford cast pistion again. Good luck on your rebuild :nod:
I did some research on that issue and the sound it makes is very similar to mine. So hopefully the engine block is still salvageable. Im gonna assume so since it doesnt look like tinkerbell had a party in my engine. I may just put my second motor in and sink some hours into this one. Not sure yet.
 

brandoncw

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Ok so the engine died on the highway like someone flipped a switch. Pulled her home and did an autopsy. This was my first clue. The ditributor rotor wasnt turning when i cranked on the engine. Pulled it out and it looked ok. Pin was intact. Then i noticed my engine cranked unusually easy. I took off valve cover and the rockers wernt moving at all. At that point i though my crank was broke in two. Lowered the oil pan to peak inside. Cranked on it and all six pistons went up and down. Crank is fine. Pulled timing gear cover and there was the culprit. A cam gear with over 1/4 of the teeth stripped clean. Could a chipped tooth have been the noise i was hearing or was it probably secondary damage from something else breaking?
Note i will be pulling the engine and thouroghly clean the inside and outside of the engine block
 

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wallen7

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When the fiber timing gear strips the motor quits running, the only thing that you realy need to pull is the pan. That is where the teeth go and the oil pump screen. If you clean those and replace the gear set it should be fine, most people get in trouble when they don't clean the screen and pan. That's when you end up with not enough oil to the bearings and start ruining things.
 

wallen7

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You could still have other problems that don't have anything to do with the timing gears, but I have seen so many of these with timing gear noises that is very probably your major problem.
 

brandoncw

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wallen7":3nybm6xy said:
When the fiber timing gear strips the motor quits running, the only thing that you realy need to pull is the pan. That is where the teeth go and the oil pump screen. If you clean those and replace the gear set it should be fine, most people get in trouble when they don't clean the screen and pan. That's when you end up with not enough oil to the beai
wallen7":3nybm6xy said:
You could still have other problems that don't have anything to do with the timing gears, but I have seen so many of these with timing gear noises that is very probably your major problem.
rings and start ruining things.
But this timing gear looks as if its cast not fiber. I may be wrong. Ill check with a magnet
 

wallen7

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The same still applies, as soon as the cam quits turning the engine stops. It won't turn the oil pump an the teeth go to the pan. Now if you replace the gears and don’t clean the pan it will suck the debris into the pump.
 

brandoncw

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wallen7":1hr40fv3 said:
The same still applies, as soon as the cam quits turning the engine stops. It won't turn the oil pump an the teeth go to the pan. Now if you replace the gears and don’t clean the pan it will suck the debris into the pump.
Ok. I already drained the oil. Tomorrow morning im gonna yank out the engine and put it on a stand. My next question is what cam can i get since im already here that would get me some extra power down lower in the rpm range 1000- 2000 and is stock ecu friendly, looking at comp 252h but im not sure if its efi friendly. And can i change my own cam bearings myself without an expensive tool? (Seen a guy do it on a jeep 4.0 with nothing more than all thread some nuts and some washers) and is the roll pin method of securing lifter studs safe? And lastly for my goal of more power in the low rpms are chevy 250 rockers beneficial or is that only helpful in upper rpms.
 

wallen7

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The Comp Cams 252H is supposed to work with all stock components, but I would give them a call to make sure. I have never tried to put in cam bearings without a cam tool, Some of the auto parts store have a loaner program for these special tools. I think Autozone is one if I remember correctly. The main thing on cam bearings is make sure the oil holes are lined up correctly and that the cam rotates easily by hand. On this engine all the cam bearings are the same as long as you get them for the right year model block. Ford made a change but I don't remember what year. Pinning the rocker studs is acceptable, but I don't think That I would use 250 Chevy rocker arms with the cam change and EFI.
 

brandoncw

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wallen7":1wd1bky5 said:
The Comp Cams 252H is supposed to work with all stock components, but I would give them a call to make sure. I have never tried to put in cam bearings without a cam tool, Some of the auto parts store have a loaner program for these special tools. I think Autozone is one if I remember correctly. The main thing on cam bearings is make sure the oil holes are lined up correctly and that the cam rotates easily by hand. On this engine all the cam bearings are the same as long as you get them for the right year model block. Ford made a change but I don't remember what year. Pinning the rocker studs is acceptable, but I don't think That I would use 250 Chevy rocker arms with the cam change and EFI.

Thanks. Ill give autozone a call. I just came across another question. In my personal experience intake valves tend to last much much longer than the exhaust. Is it acceptable to just change exhaust valves and lap them assuming the seats are straight and not pitted (correct me if im wrong but i was told lappin the valves also shows if there are any low spots) if all the intake appear clean and in good shape?
 

brandoncw

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pmuller9":19x9lfl1 said:
You don't have rocker studs.
The rocker fulcrum bolts to the head boss.
Then whats all the talk ive read about pinning them or converting to screw in studs? I mighr have been reading on a different engine :LOL:
 

pmuller9

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brandoncw":2dgp2848 said:
pmuller9":2dgp2848 said:
You don't have rocker studs.
The rocker fulcrum bolts to the head boss.
Then whats all the talk ive read about pinning them or converting to screw in studs?

Pre 1985 heads have studs.
 

pmuller9

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The stock cam has a 268 degree advertised duration and is retarded 4 degrees which closes the intake valve 68* ABDC.
The Comp 252 cam installed 4 degrees advanced (per the cam card) closes the intake valve 52* ABDC which is a lot sooner than the stock cam.
The Dynamic compression is raised considerably.
The problem you may see is detonation since you have no control over the ignition timing.

Using 1.75 ratio chevy six rockers on the stock cam gives good results.
You would have to drill and tap for studs and use a set of pushrod guide plates.
 

brandoncw

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pmuller9":2d9nt5bo said:
The stock cam has a 268 degree advertised duration and is retarded 4 degrees which closes the intake valve 68* ABDC.
The Comp 252 cam installed 4 degrees advanced (per the cam card) closes the intake valve 52* ABDC which is a lot sooner than the stock cam.
The Dynamic compression is raised considerably.
The problem you may see is detonation since you have no control over the ignition timing.

Using 1.75 ratio chevy six rockers on the stock cam gives good results.
You would have to drill and tap for studs and use a set of pushrod guide plates.

So i do know higher compression ratio translates to higher torque and efficiency. But consequently higher compression means more heat that may detonate fuel on its own. So i could run higher octane right? And since i will have the head off i can smooth edges in the combustion chamber to reduce hot spots. When i get the motor out im going to check all my cylinder bores for wear. If they look pretty worn and have bad ring groove i may just put a stock cam and valvetrain in and go with flat top pistons to bump up compression 2 points. Maybe more if im boring it. Idk how that works out there. I want to run on pump gas but still get a little extra grunt out of it.
 

pmuller9

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The Ford 4.9 works best on pump gas with Dynamic Compression Ratios (DCR) of 7.5 or less.
The stock EFI 4.9 has a Static Compression Ratio(SCR) of 8.8 with a DCR of 7.0 with the stock cam.

If you put a flat top piston in and raise the SCR to 11.0, the DCR is 8.6 with the stock cam which is way too high for pump gas.
 
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