Hi all,

The head gasket has finally gone in my 4k corolla that I have owned for 4 years, anyways I took it off and dropped it to our local machining shop and he informs me when I picked it up that whoever did the head last had shaved 5.5 mm off the head and fitted bigger valves and double valve springs to it. Does 5.5 mm sound like a shit load to have shaved off?? It was running 2 head gaskets aswell??

Yes 5.5mm is bullshit i'd say. Usually you go 20 or 40 thou.. 5.5mm is 216 thou and the valves would be near-on sticking out past the deck

What Jono says is right...

 

Not a 3K head by any chance??

 

Measure the combustion chamber volume before you put it back on. Then you can work out the combustion ratio with one gasket and with two gaskets. You can grind a bit out of each combustion chamber to lower the compression if its over 10 to 1. It will also tell you what fuel to use to stop detonation, which destroys head gaskets... Having two gaskets leads to more blown gaskets than having one.

 

Also, timing can't be as advanced as normal with very high compression or it leads to detonation too.

is the surface of the head grinded in to the spark plug tubs? you know if it shaved a lot when it gets into them

I have uploaded some pictures to help identify the head. Even with two head gaskets you would think 5.5 mm is way past the point of just a second headgasket

Ahhh...thought that might be the case... Your machine guy is obviously comparing this head to a 4k head. What you have is a 5k head! It has been shaved maybe 40-50 thou - you can tell by the recess below the Toyota emblem in the last pic.

Oh cool thanks heaps for clearing that up, I would never have guessed that. Now I just have to figure out why there is a 5k head on my 4k haha Yeah the guy at the shop was comparing it to a 4k head which was probably my fault for thinking it had a standard 4k head on it. Have you guys ever had problem with snapping valve springs on these?

Its sounds like mine. http://www.rollaclub.com/board/topic/70614-5k-head-4k-block/

I think we can have a competition to see who blows a head gasket first. Ive been told to give it a proper warm up/cool down.

Mine's only done about 100k's since the new gasket was put on so I've got no idea how long it will last.

You can reduce the compression by cutting back around the valves. Lay a head gasket on it and draw circles where it touches, then cut the alloy out to meet the circle. That will also unshroud the valves and allow better flow.

 

If you are running a non-stock inlet manifold for better carbs, it could do with porting too. Take the ports out to the diameter of the inlet gasket. It could do with twin DCOEs, a hot cam and extractors!

 

If the rings/bore is getting tired, bore it out to 5K piston size and fit shallow-dish 5K pistons, that will also drop the compression a bit.

 

Certainly run it on 98octane only...

Or put a 3k/4k head on it and not worry about blowing a head gasket every time you go for a drive.

Some 4Ks use those heads as well. Got a pic of your pistons? Need to be dished type. Measure cc of combustion

Chamber to see what you got

Some 4Ks use those heads as well. Got a pic of your pistons? Need to be dished type. Measure cc of combustion

Chamber to see what you got

 

Called a 4ku and extremely rare in Aus

I had a look at the block last night and it has flat top pistons so I would say its not a 4ku

Mentioned the 5k heads beeing used on some 4Ks to show that pistons exist that might work with this head.

 

Guessing some $ has been spent on it and youd like to use it, could be wall to waterjacket is getting thin tho.

 

If looking for pistons don't limit the search to 4ku. Theyre also used in 4ke 4kj and here in europe regular 4K post 08-82.

To add to comfution 4ku , 4kj, and mentioned 4k also came as flatops

 

saw some new dished 4k pistons on ebay the other day