Mystery 5k Motor With High(?) Compression

[emu]

Am preparing my near overrated ke30 ex grannies car for a desert rally in July

 

thought it needed bit more grunt so bought a mystery 5k motor thru the forum, then a zorst and a weber

 

a young mate corolla nut, handy with transplants is doing the changeover for me, and is finding it difficult to tune the thing

 

before i bought the 5k , i tested the compressions, which were all 190

 

only recently i owned a ke20 which had had a 5k motor fitted for about 12 years, and was probably starting to get just a little tired, and i checked the compressions on it , and they were all around 155

 

Is 190 crazy high for a 5k ? If so , perhaps it has been highly modified, which might explain the difficulty we are experiencing in tuning it ?

 

Just as an aside, it seems we stuffed up the 3k starter motor driving the 5k. I now understand they are not interchangeable, and a 5k starter motor is needed on a 5k motor.

 

What do you guys think about the 190 compresssions? I've checked the identity of the 5k head. It IS a correct 5k head

 

thanks pete

[coln72]

A 3k starter will work on a 5k.

[emu]

A 3k starter will work on a 5k.

 

Yes, Colin it worked ok for a few starts, but then locked up,..........no matter, we're replacing it with a 5k starter,........it's the 190 compression i'm concerned about............does this indicate that it's highly modded , or could it just be a recently recond engine with perfect compressions?

[camerondownunder88]

190 pfff LOW..LOL

 

I run a conservative 200 PSI in each cyclinder in my 5K in the sprinter.

 

I run a KE70 starter. 0.8KW is the KE70 one 0.6 is the 3K ones. from Early corollas. So use a KE70 starter will start easier. But mine starts fine on 200PSI

 

Cheers

Cameron

[love ke70]

what did you do to get that cameron? wasnt exactly a helpful post...

 

first thing i would do mate is check valve clearances and your valve timing. if the valves are tight, you get excessive static compression, can burn out valves and have all sorts of dramas.

is the car running and just having trouble tuning?

what exact problems tuning it are you having?

may have a cam, which can cause the upped static compression, but is more likely to lower it...but would explain the difficulty in tuning.

 

155 is about right for a standard motor.

170 wouldnt be exceptional for a standard motor.

 

how many cranks and was it throttle open or shut?

fuel connected or not?

wet or dry test (ie, oil down the bores)

[love ke70]

http://www.rollaclub.com/board/?showtopic=28267

 

motor was compression tested was up to 190psi 10.5:1 across the board.

 

 

interesting....

but theres alot more to it than static compression ratio to giving you PSI readings that you have.

valve timing and overlap, and clearances will play a large part...

[camerondownunder88]

Well my 5K was a complete mystery also was told it was fully rebuilt wich it was. That is all i know and head was shaved on mine to give it that CR.

 

4age pistons in a 5K will drop the pistons height about 5mm in the block I have looked into this and for a N/A motor would need the blocked decked to get a high CR so possibly has the block decked and head shaved mate.

 

At first my 5K didn't start seemed like it was jamming and it was :lolcry: I snapped the cam shaft in mine so look at this I found it by I couldn't time the motor. Also to get it to crank I needed all new cable to starter and all new earth cables so check all power leads as will need a lot of electrons to make it crank with a high CR.

 

 

Cheers

Cameron

[coln72]

A 3k starter will work on a 5k.

 

 

Yes, Colin it worked ok for a few starts, but then locked up,..........no matter, we're replacing it with a 5k starter,........it's the 190 compression i'm concerned about............does this indicate that it's highly modded , or could it just be a recently recond engine with perfect compressions?

 

Its a shit starter. Had a 3k starter on a 5k for over three years and it gave no poblems. If you have access to a 5k starter go for it. It will possibly be a gear reduction starter and you will get more clearance around your exhaust if it is as they are physically smaller.

[emu]

Its a shit starter. Had a 3k starter on a 5k for over three years and it gave no poblems. If you have access to a 5k starter go for it. It will possibly be a gear reduction starter and you will get more clearance around your exhaust if it is as they are physically smaller.

 

Thanks coln72

Yes, thanks for that i agree, the difference between the 2 starters is that one's a reduction gear and one's not,.......we've found that out by ruining the 3k starter.....we've now got the original 5k starter for it , so should be ok

cheers pete

[philbey]

Mine came in about 200psi on all bores. I'm at about 11:1 compression ratio.

 

Keep in mind there is no easy, linear relationship between the two, although it's often assumed there is. Durations and valves as love_ke70 will change them.

 

Mine goes well, but has some heating issues, probably due to running lean and the high compression. Still diagnosing. I also had cranking issues with a 4K starter, but that was a terminal issue, I just put new terminals on the battery and it started first kick!

Edited March 16, 2009 by philbey

[emu]

Love KE70, thanks for your help, I'll make sure we check the valve clearances and valve timing before we give it any work,....very good advice !

 

we gave it about 30 or so cranks during compression testing with the throttle shut, don't think the fuel was connected, and it was a dry test, no oil added.

 

I'm sure the mystery 32/36 carb on the mystery 5k has something to do with the tuning problem, and once we get it running well enough, I'm having a specialist carby company rejet and tune it for me professionally,............but I thought the very high compression may be causing more tuning problems than the mystery 32/36.

 

We'll see if we can get it running well after the carby tune, then I'll pull the head off out of curiosity, have a gander, and have a look at the cam too

 

thanks again , and Cameron Down Under , thank you too

 

cheers pete

[Boost+k]

youve prob got the O dished pistion 5k motor, has it got adjustable tappets aswell? mine would have about 185psi, and i use to put 15psi through it aswell, i thought it was about 9 to 1, should have reduction starter for these motors.

 

with your tuning its not a air leak is it? havent put extrators in and frgot to skim inlet manifold to match or something? you havent really said what the tuning issue is?

[emu]

youve prob got the O dished pistion 5k motor, has it got adjustable tappets aswell? mine would have about 185psi, and i use to put 15psi through it aswell, i thought it was about 9 to 1, should have reduction starter for these motors.

 

with your tuning its not a air leak is it? havent put extrators in and frgot to skim inlet manifold to match or something? you havent really said what the tuning issue is?

 

Thanks guys, we're pretty right now..........couldn't get the new 5k to run properly on either of the 32/36 webers which had ??? jetting, so drove it to Auto Carbs on a 3k carb, threw the webers at them.............they fiddled up better linkages, rejetted the better weber couple of goes, finally got it running like a dream for $200 over 2 days,.....good blokes

 

Can't believe what a great car this is now with the 5k plus weber with 5 speed box, the ke30 is a totally different car,........love it!............gotta get the extractors and 2" system on now , sump guard and spring lifters, and i'm just about ready for the desert rally.

 

thanks pete