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Awesome, thanks

Hi Tony, Have a read through this post, about 8 years ago, where this subject was covered. https://www.rollaclub.com/board/topic/73368-4k-change-pistons-to-flat/ https://www.rollaclub.com/board/topic/40853-what-pistons-are-these/#comment-433565 There are two types of 4K blocks. You have a simple 4K block. There is another 4K-U block, which developes more HP. I have one of those in my KE-30 2 door. There is a picture in the Toyota yellow K Series engine repair model, which shows a picture of the mark on the piston, that must be positioned to the front of the engine. It depicts two A & B type pistons; the only difference; one being flat topped; & the other is partially dished; exactly the same as your photo. The little single dot indentation in your pistons, is pointing to the front of the engine. There was also a 4K-C engine produced, that according to the Toyota workshop manual; were only exported to Australia & Sweden. The C, usually meant that the engine complied to Californian emissions regulations; as that state was, I believe; the first state in the USA, to create emission requirements for gasoline engines. Cheers Banjo

Hi guys, I just purchased this 4K with a 5 speed bolted up to it, I think it may have been in a van originally, and I thought they all had flat top pistons. Any ideas?

Well, finally got around to wiring up the COP mounting bar. I wanted to make all the wiring from the COPs hidden, inside the rectangular section of the aluminium mounting tube. However, as the COP shafts pass through the rectangular section; it doesn't leave much room to squeeze all the wires past COPS near the end where the wires, all exit from the tube. I also didn't want to squib on the wiring size, for two reasons. I wanted pretty heavy wire for the ground & +12V supplies to the COPs, as there are reasonably high currents involved, & we don't want any voltage drops. Anyway, it all just fitted, so pleased with the result. The alternative was to add another wiring conduit or tube; & that would have detracted from the clean lines of the COP mounting bracket. Have powered them all up, & had them sparking perfectly with a test circuit, to fire the COPs, one after another. I also needed to identify the 4 off trigger wires, as I used the same colour (blue) for all trigger wires Because the spark plugs on the K Series engine, were recessed into the head, I wanted to seal this area, around the COP long tube; so no rubbish got down inside there, around the spark plugs. I couldn't find a commercial rubber bung of any kind on the nett, to accomplish this. On the original K series distributor HT leads, this "seal" was moulded into the leads. I cut the ends off an olde set of leads, & with a very sharp hobby knife cut out the inner part, so it left a hole to fit snuggly around the COP shaft. Just have to now fit it to my 4KU in my KE-30, & work out where to terminate & mount a connection block for the wiring & plug & socket, so the COP assembly, can easily be removed from the engine, so the spark plugs can be removed. It may however, be just as simple, to remove the 4 off COPs, & then remove the spark plugs, without removing the complete assembly. Once I've got it on the engine, I'll make that decision. I also found that the COPs mounting bolts, & the gold COP mounting frame, were not grounded ! There was about 6-7 Megohms resistance between them & the head. The COP mounting frame, is attached to the rocker cover. The rocker cover is actually isolated from ground, via the big rubber gasket around it's bottom edge, & the two bolts that attach it to the head. I found a little earthing strap, from the rocker cover to the head, solved this issue. One of the common issues with COPs, on modern engines; is that they overheat. This is particularly common, in twin overhead cam engines, wher the COPs are "buried" down inside the head body, with little or no air flow around them. This will not be an issue, with my setup, as there wil be plenty of air flow over almost all the COP assembly. Once it is on the car & in use, I'll check the temperature of No:1 & No:4 COP bodies, & see whether there is any difference. Cheers Banjo

I have some of the Ranex Rustbuster, but my googling indicates it doesn't leave a zinc layer after it's done the rust conversion, so it's probably not suitable for leaving on for any length of time. KBS ship straight from their website too, might be worth cutting out the eBay middleman. They also have a Por-15 style primer/sealer I'm going to give a try.

Hi John, Sorry, I went & looked again, & You are right that Bunnings do not seem to stock it. My error. When I took a look again the one Bunnings market, looks very similar, in a yellow & read container, & is called Ranex RUSTBUSTER.

I got the 4 litre bottle on ebay. I've previously bought it in small bottle from an automotive paint supply place but had a couple of ordinary experiences there so went online. My bonnet had had a serious bird shit attack and the rust webs were all over it. I'v rubbed those spots down to metal and treated with KBS and it has been like that for more than two years. When ready for paint i'll strip the whole thing

Thank you everyone. I couldn't find it on the Bunnings site, but I'll keep looking. I've got Ranex Rustbuster and Evapo-Rust, but you can never have too many chemicals. I've got some Upol #2 on order.

Thanks Pete ! I must have been living under a rock; as I've never come across KBS Rust Blast previously. Sounds like good stuff. It's even available at Bunnings, apparently. This is what Google says about it . . . Thank You for that pointer. I'll try it out very shortly, as my bonnet has a few sections that need treatment. Cheers Banjo

This is mine more than a year after stripping all the paint off with stripper and a flap wheel where necessary. I then treated the whole area with KBS rust last. Any areas that showed any sign of colour where then treated again. The coating I’ll wash/ neutralise when I spray epoxy sealer hopefully soon

You can check out cashforcarsadelaide for good wreckers in Adelaide that deal with rolla, Toyota, and other car bits. 4.1-mini

Get some Upol #2 weld-through primer in copper, we use it all the time on race car fabrication. Its a lot more expensive than the zinc, but they are rubbish to weld through, its just like welding galv pipe. I'd use paint stripper to start with, get all the paint off as there will be little rust-worm trails under paint that look fine from the outside. We took the driver's-side top surfaces back like this, even if the paint looked OK for 99%, underneath were little rust trails heading off in all directions. I figure it spent its life in a carport up against a wall on the passenger's side, so the drivers side was weathered.

Thanks Banjo, I have a few Rotisserie videos in my queue and I'll add those. In this case I'm focusing on the bonnet for a few reasons. 1. They are in demand, so if my build goes nowhere they still have value. 2. The bonnet is in my garage but the rest of the car is 500km away. The bonnet (and guard) are from Captain Kerolla, so their condition is not reflective of the rest of the vehicle. I'm going to school on these parts, and I can get them up on the bench under my workshop heater. John

Glad You are into it ! Hope is addictive, & not too despressing. I'd really be concentrating on the structural bits first, as they are the most important, after all. Shame to do all the surface & visual pieces, & then find later on, that there is a structural section, beyond repair, & that all the visual; non structural clean up, was in vain. A simple rotisserie would be good, so it is easy on your back. No fun working upside down, when You get to the underfloor area. Metal Rotisserie Wooden Rotisserie Cheers Banjo

Hi Everyone I'm still working on my bonnet but I feel like I'm chasing my tail a bit with the rust removal. I've de-skinned the bonnet to get at the surprises underneath. Lots of pinholes I couldn't see from the top. I've been using a combination of stripper disks to remove paint and Evapo-rust to get in to the nooks and crannies. This works (pitting and blow throughs expected) but because I'm just doing an hour here and there I feel like the surface rust is back as fast as I remove it. Should I be hitting sections with a weld through primer as I go? Can I leave paint in place where it's clear the metal beneath is good? Will that impact the final finish in a big way? Thanks for any advice.

Sure, we have it hosted here- https://www.dropbox.com/scl/fi/kxtqr769ojtetah/downloadfile.jpg?rlkey=ulck2pyqn6u8nd163h0awrj7w&e=1&dl=0

Can i get one too please?

Yes Kieth ,ask me how i no😂

Ok cheers, thanks mate

Hi Tony not sure about the dellow bellhosings ,but K-T housing it was better with TA22 because of the more forward shifter position. The ae71 and ae86 T50 s had there shifter towards the back of the extension housing. Hope this helps a little rob

Hey guys, 30 odd years ago I put a Celica 5 speed box in my 3K KE20, using a Dellow bellhousing. However I can’t recall what model box it was as I bought it second hand with the adapter housing. Does anyone know what it may have been or what to use for a similar setup?

Hi Tony, My guess is; that now You will want to calculate the new "compression ratio", of your 60 thou bored engine. This is a little more complicated, depending on whether you have flat top pistons; or pistons with domed or concave top faces. This calculation, should also take into account the thickness of the head gasket, once torqued down, to be truly accurate. Here is a variety of sites tackling this question, if Your interest requires this information. How to Calculate the Compression Ratio Obviously, if you bore the engine, & leave the combustion area in the head untouched; the compression ratio, will increase. Question is; by how much ? This link here on Rollaclub, from over a decade ago, might help ? https://www.rollaclub.com/board/topic/69246-4k-engines/ Cheers Banjo

I appreciate your response and info, much appreciated mate, cheers

The volume of a single cylinder is Pi x r squared x the stroke. 22/7 x bore/2 x bore/2 x stroke. For a standard 4K engine, the bore is 75mm & the stroke is 73mm Substituting these into the above equation give (22/7) x (75/2) x (75/2) x 73 = 3.1429 x 37.5 x 37.5 x 73 = 322638.33 cu mm Divide that by 1000 to obtain cubic centimeters & you obtain 322.64 cu cm. That is for one cylinder. To calculate that for 4 cylinders, simple multiple by four. 322.64 x 4 = 1290.56 cc, which is what the good book says the capacity is for a standard 4K engine. Now simply add 1.524mm (60 thou) to the bore dimension, & recalculate. 3.1429 x (75.00+ 1.524)/2 x (75 +1.524)/2 x 73 = 3.1429 x 38.26 x 38.26 x 73 = 335.85 cu cm Multiple that by 4 & you get a new volume of 1343.4 cc. Subtract the original standard volume = 1343.40 - 1290.56 = 52.84 cc. or an extra 13.21 cc to each cylinder's swept bore capacity. Yep, basically, the same as Simons calc. Cheers Banjo

75mm stock bore, + 1.5mm (60 thou). 73mm stroke. That's all you need to know to punch into a displacement calculator 😉