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Pushrods Out Of Place In 4K- Valve Clearance?


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Hey Rollaclub

 

I just got back into a ke55!

 

When i went over to pick it up from the seller we started it and it just sounded like it was running on 3 cylinders and the engine sounded really loose/ rattly! It drove (with absolutely no power), and we were able to get it home (a 5km downhill drive home).

 

Yesterday I pulled the rocker cover off and saw that on cylinders 1 (intake) and 4 (intake) the pushrods were unseated, hence leaving the valves closed.

 

I had to take the rocker arm off to get them back in, so i have no idea how they came out. I tried setting the valve clearances to spec and they still fell out. Maybe i set the clearances wrong, but could there be another explanation for this? Engine runs better now, but still sounds wrong.

 

any tips? worn cam? valves not retracting well?

 

thanks guys

 

(4kc, solid lifters)

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Valves could have jammed open and allowed the pushrods to drop down and out. Saw that in the 1970s with an old Holden that no-one ever changed the oil on, the sludge jammed a couple of valves open. Maybe the lead supplement has jammed them in the guides.

 

Could it have been the last great thrash by someone when they sold the car, and valve bounce let the rods jump out? I'd expect bent rods or valves if things were that bad, maybe that is why its still not good..

 

10 & 12thou for tappet clearance, set them up and do a compression test to see if the valves are sealing well. Let us lnow what you get.

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Had someone done work on the engine recently ? Any chance someone had pulled the rocker gear to pieces & reassembled without the rocker shaft springs to keep the rockers apart. That would create problems like you describe.

 

I tried setting the valve clearances to spec and they still fell out.

 

If it fell out after you set the tappet clearance, something is very wrong. The round end on the end of the push rod, and the socket in the rocker are quite deep. They would both have to be very "hammered out", which should be obvious, if the push rods fall out !

 

Cheers Banjo

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Lack of oil on the rocker shaft?? That would let the rockers jam on the shaft and hold a valve open...

 

Banjo is right- if they fell out after you had the tappet gap correct something is badly broken. Check how you set the tappet gaps, making sure the timing mark on the crank pulley is at TDC and set either #1 or #4, whichever is on the firing stroke. Then turn the motor one turn and the other of #1 or #4 should be firing.

 

You can watch the cycle as you turn, the cyl on exhaust stroke will have the exhaust valve closing and the inlet valve opening at the same time, while the cylinder on the firing stroke will have neither valve moving as you approach TDC.

 

You should have the adjusting bolt & nut sticking up the same as all the other rockers, so if the bolt is screwed right into the nut or way out, it means something else is wrong.

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Valves could have jammed open and allowed the pushrods to drop down and out. Saw that in the 1970s with an old Holden that no-one ever changed the oil on, the sludge jammed a couple of valves open. Maybe the lead supplement has jammed them in the guides.

 

How would I rectify this if it were the case?

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If it was sludge jamming it you would know! It was thick like soot mixed with tar on that Holden! You couldn't touch anything under the cover without ending up smeared in black gunk that wouldn't wash off...

 

For dry, sooted-up valve guides you can check first. That's what the compression test would tell you, if they were holding a valve open you would have zero psi on that cylinder. If you don't own a compression gauge, buy one, it will last you all your life.

 

Anyway, check out Google on how to position the motor for doing tappets if what I write doesn't make sense. First, pull the plugs out. (or leave them out after your compression test)

 

Basically you have two pairs of cylinders moving up and down together, #1 and #4 and cyls #2 and #3. So when #1 & #4 move up together, one is on compression stroke, one on exhaust stroke. (At the same time the pair of #2 and #3 are moving downwards.) You can watch the one on exhaust stroke as it closes the exhaust valve and opens the inlet valve. There is about 20deg of overlap, and when those two rockers are at an equal height the piston will be on top dead center. Luckily you can check your estimation by looking at the timing mark on the crank pulley TDC mark which is for #1 and #4.

 

So you watch the cylinder on exhaust stroke to get TDC, then set the sister-cylinder which is on compression. That will have maximum tappet gap on both valves, which should be 10thou for inlets and 12thou for exhausts. (bigger gap on exhausts because they get hotter and the stem expands more)

 

Lets say #1 was on exhaust and you set #4. The firing order is 1-3-4-2 and you had #1 on exhaust. So the next cylinder on exhaust is #3, and you watch that until the inlet just starts down as the exhaust closes, and set the tappets on #2.

 

After watching #3 cross, you are back to setting the #1 and #4 pair. This time watch #4 until it crosses over and set #1, again you can check TDC by looking at the crank pulley.

 

Then do the same for the last cylinder, watching #2 for the valves crossing and setting #3.

 

I undo all the locknuts at the start, so I know I've done a rocker if the nut is tight. Don't go too stupid doing them up, and leave the ring spanner on the nut as you turn the bolt with the screwdriver, as the gap will change as you tighten the nut even if you hold the screwdriver steady. Just back the nut off a tad until you can alter the gap with the screwdriver and do the nut up again. Some take a few tries to get a feeler gauge sliding through smootly.

 

What are you planning for the car?? In other words... how soon are you pulling the head off for modifications??

Edited by altezzaclub
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Thanks so much Altezza!

Really helpful guide there!

 

Well I'm not sure that I will modify this one. I just want it to run smooth and to the best of it's current ability and then chase rego.

 

My last ke55 I had a go building a whole 5k with some machine work in the bottom end (reground cam, bigger bore and balanced crank), and the Corolla before I had a go at getting the head machined after blowing the head gasket.

 

These cars are such a good platform to learn on, and a platform I have no desire in going past!

 

I'll do my best to get it running without outsourcing, and then who knows where that will take me. I never really got to experience the fruits of building the 5k as I sold the car soon after building the engine.

 

Thanks for the input! I need it again!

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Fair enough, get it running and build a spare 4K up over time then swap them. At least you have the experience needed for doing one up now.

 

You're only a hour or two away from me if you need a hand, and closer than that to Robinson Engineering in Bathurst, so when the car is running sweetly you just do the same with another block and head for a car that goes well and is ultra-reliable.

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thanks for the great information on setting the clearances.

I had my 13yo son start my car the other day with "a little bit of accelerator"

He floored it and blew a head gasket. I took the head off and it's getting a recon now.

Next weeks job is to get it together again and working. This is pretty adventurous for me so I appreciate the great advice.

So far, apart from the skinned knuckes, it's been pretty straightfoward.

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