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rebuilder86

found machine shop, where to find pistons

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Ok i have found myself a machine shop here in Cebu Philippines that i think i can trust to grind n polish my crankshaft (if my measurements and analysis deem it neccesary) and also redo my bores in preperation for new pistons, (if so required)

Now i want to get all the work done at once or else they will charge me foreigner prices. so i need to be certain i have pistons available before committing. bearings are no problem to source here.

My plan is to go back to aus for work, and buy some pistons there and bring them back here.

Has anyone personally purchased 0.5 or even 0.25 oversize pistons in australia at a parts store?

I'm hoping to find them for a 4k-u (D dish) so it may be impossible.

If i can't, then I'm not touching anything. Its just I'm seeing a little bit of blue smoke again. the last time i fixed this was by litteraly scudfing the bores with sandpaper and putting new std rings on the old pistons.

as it heats up, after about 10 minutes the smoke is entirely gone. I also have a suspicion that the amount of blowby out the oil filler is possibly enough to indicate that the seal isnt too great.

I'm getting 150psi on all 4 cylinders dry, so the point of this is really to help the oil rings do there jobs. i suspect the bottom of the bores are the problem.

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4k-u's were never offered here, so none of my suppliers list them. Which is about all of them. 

What about getting some posted to the shop from Malaysia?

Edited by kickn5k
More info

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yeh fuck. thats what i worried. internet reveals one on ebay in greece. I just don't like the idea as its quite cheap.

so can anyone tell me, what if i chose to just go to 4kc pistons. the head is the type witbout the little lugs under 1 and 4 spark holes so i think that makes it actually supposed to be used with pistons that arent dishes?? thats what i read in another post.

maybe this iant a 4ku afterall and maybe the pistins are just dished.

anyone know everything about this. there is no single post that clarifies what heada go with what pistons.

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nah thats just the rings.

I'm so incredibly frikn confused by all this flat top, dished, twin squish head and piston nonsense.

people say compression will suffer when the wrong two are paired together. But i cannot see much difference visually, looking at pics on the net, between the heads with 2 lugs (apparently for dished pistons) and the heads without.

the table here shows all 4k variants have the exact same cc capacity.

https://www.rollaclub.com/wiki/index.php?title=Tech:Engine/K_Series/Blocks

so i suspect those with dish pistons, simply make up for the extra space with the extra spark plug length intrusion and a tiny tiny bit more metal between the valves. The head with the knobs apear to have a wavy bit of metal between the valves and the heads without appwar to have pointier bits of metal between the valves. I think this image is showing both types, but i cannot tell because all forums worldwode have been struck down by this image hosting issue where u try to view the forum post and all images are replaced with an error message. fuck it makes research difficult.

https://www.google.com.ph/search?q=toyota+4k+head&client=ms-android-oppo&tbm=isch&tbs=rimg:CfcsKaxZAar2IkDREOfHPjSLrfw0yJakW6CIhzi20dBsS7cFii9OTdkiUq8_1EA-4ItiAMYs0EtuEMFLkelDIN5vXjg24KY54V4DTKhIJ0RDnxz40i60RazFQiFAmaTEqEgn8NMiWpFugiBFbRisTpK0RAioSCYc4ttHQbEu3EQnLsX0Y9Jh8KhIJBYovTk3ZIlIRW0YrE6StEQIqEgmvPxAPuCLYgBEYo3y7y1MgzSoSCTGLNBLbhDBSEW9jBEQPKMssKhIJ5HpQyDeb144RDKLKxU-ZDAcqEgkNuCmOeFeA0xFKJIlMbqwQ3Q%3D%3D&tbo=u&ved=0ahUKEwiR6cLmwODXAhVLk5QKHe81C64QuIIBCCM#imgrc=6BQsBTWNN97HQM:

Edited by rebuilder86

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Pretty much rule of thumb, if there is no lugs under 1 & 4 plug holes, flat tops are the go. Or unless your head has had a few mm milled off?

 

cheers!

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no shit. thank u. so my 150 psi is pretty damn amazing then. ok so I'm best going back and finding flat top pistons.

this is a breakthru for me and may finally be the explanation for my appauling fuel economy.

what i now wonder, is if this even really was a 4kU all along with a replacement flat top head, or if it was a 4k or 4kc (orogonally with flat pistons) with replacement dished pistons because the peraon who built it was none the wiser. or just an idiot.

any other differences or is it just the combustion chamber? i know the 4k c has california emmisions setup carb.

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Once you get the head off you should measure the combustion chamber volumes. All you need is an accurate way of measuring liquid like a burette or good scales.

Then you can calculate what compression ratio you will get with what pistons. Use petrol or turps, not water, as they have lower surface tension. There's a picture here-

https://www.rollaclub.com/board/topic/42407-the-girls-ke70/

Chamber volume should be about 31cc.

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haha there is absolutely no chance of me measuring it. haha

ill start by putting the correct pistons for the head in. I'm quite upset with myself for not looking into this further in the past. the dollars ive wasted on fuel could feed my baby boy for a year. litteraly.

this would be the answer ive been looking for, for how ive been able to drive around with ridiculous timing advance with no detonation and would also explain why i need such a big idle jet and such an advanced idle timing.

The combustion chamber is just too big.

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How about looking into a sparkplug hole with a torch and seeing which piston is in there.

You might possibly feel it with a length of wire if it is dished.

150psi is quite good, which suggests you have flat-top pistons anyway. Shallow-dish would reduce the compression by maybe 10-12%, 170psi to 150psi, so it could be those if you have a fresh rebuild, but you wouldn't get 150psi with deep-dish pistons unless you had the flat head to go with it.  150psi suggests a 10:1 compression as usual, not a over-large combustion chamber..

It will be exciting to finally find out what is in there.

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nah i rebuilt the thing (half assed ring job) 2 years ago and the pistons were out and the6 were the d dish.

thats what lead me to believe all this time that the motor was simply a 4K-U.

i never knew that a 4kU head should have the 2 lugs on 1 and 4 to go with the dished pistons so never looked into the head.

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actually from memory, the port holes were quite small compared to the 4k manifold gasket i bought aswell and the bolt holes needed a bit of cutting to make it fit. does tha suggest it might be a 3k head? 

it has the logo from Banjos avatar stamped on it and the number 70 between 3 and 4.

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ok so i just did another hot, fully dry compression test after killing the engine by disconnecting the fuel pump, so that fuel wouldnt be sealing anything.

unfortunately its now down to about 130-135 psi on all 4. I'm not uploading all four test photos, just trust me. see one below.

it used to be uo at 150. u can see evidence of this in my picture in this thread from 2 years ago. (u have to go to second page in that post for the 150 PSI test result, the pics of the 4 test reaults on the first page were incorrect due to insufficient cranking time)

and here i have 2 videos, one showing the line on the piston crown along the back of the D dish. and the other showing my crazy advanced spark at idle. (35 degrees BTC velaccum connected). it doesnt look it in the video, but thats because a camera doesnt show depth perception. it really is at 35 degrees.

 

 

IMG20171129131607.jpg

Edited by rebuilder86

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or i could just relink the old test image. here it is from 2 years ago. see it was about 150 psi. I do not think this decrease is just the gauge dying. id say sandpapering the bores is insufficient engine rebuilding haha.  So now, I'm looking forward to finding some flat top 75.5 mm pistons. can anyone point me in the right direction.post-23931-0-71501900-1456633372_thumb.jpg

Edited by rebuilder86

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