4K Poor Performance

[mambuking]

Hi everyone, just recently caught a ke20 with 4k engine installed.

Stock engine, I think it's a 5k carb and the distributor is still using points.

Sorted out the aisan carb idle issue, thanks to helpful topics here.

I got a performance issue though, in 1st gear it won't past 5k rpm, on 2nd 4.3k rpm ang goes lower on a higher gear.

I'm not familiar on how the 4k performs normally ( stock ), but I think this far from stock performance.

Here are the things I've tried:

- timing is now 10 deg btdc

- made the secondary open mechanically instead of vacuum activated.

- installed msd ignition box (sci)

 

After these mods, it made it accelerate faster however, I'm still experiencing the same cut offs.

On the carb, it no longer has an idle fuel cut solenoid, the points are gapped .45 as suggested.

I'm thinking of removing the msd and carb mods, as it did not help the limiting issue.

Could this be something internal in the engine? Valve springs, cam timing etc?

Hoping to heard some suggestions.

TIA!

[B.L.Z.BUB]

Maybe your mechanical fuel pump isn't keeping up?

[Taz_Rx]

What happens if you free rev it out of gear? Can you make it valve bounce?

[parrot]

Carburettor float level?

[coln72]

It's a 4K :P

 

Seriously, we had one in a ke20 and it wouldn't rev much either. Ended up doing a cam regrind.

[GJM85]

I reckon it's the old denso points dizzy and the mechanical advance mechanism is all worn out.

 

[mambuking]

The dizzy advance part I have no idea, but I checked if it was advancing while I was timing it.

It does move, without the vacuum line, while revving it.

If standing still, it seems to rev past 5k rpm, I can have it reach 6k but just a peak. I release the accelerator once it reaches 6k cause I'm not comfortable, seems like I'm pushing it too much.

I have not heard a valve float on a 4k, so I can't be sure if it was doing it.

On the aisan, this model does not have a sight glass to check the float level.

I captured it on video, however I can't seem to upload on YouTube awhile ago.

Have not checked the the pump capability on the delivery.

Looks like the mechanical advance on the dizzy makes a lot of sense at the moment.

Will try to look for dizzy rebuilding, unless you guys have some quick guides.

Very thankful for all your responses.

[tojo2]

Take off Dizzy cap. You should be able to turn rotor a bit and it should return smoothly by spring action.

 

Check rotor shaft for sideways play - indicates wear.

 

My stock 4ks have been happy to rev to 6k, hasnt been much point in going past tho.

[altezzaclub]

Do a compression test and put the results up here.

 

If its over 150psi over all 4, then I reckon the carb jetting might be the problem. A stock dizzy should pull 5000rpm, and if it does it in one gear it will do it in all. The difference of changing gears is just calling for more power from the motor, so the problem is just pumping air and fuel in and out.

[springersrolla]

Whens the last time it was serviced? So many factors, put some new plugs in, check resistance of leads, clean earths and check power to coil. Check for vacuum and exhaust leaks, clean needle and seat. So many things you can do for little cost. Then rev the guts out of it. K motors love it. can't kill em

[mambuking]

Update on the compression test:

1 = 140

2 = 135

3 = 160

4 = 150

 

From the advise of allteza, looks bad.

 

I just got the car almost 2 months now, first thing I did was give it service, change points and condenser, cleaned the carb, new plugs, cleaned the battery terminals, I can't reach the grounding points on the engine so I added ground wires. Batt to chassis, and chassis to engine.

Changed the brake fluid and serviced the brakes, drained the old fuel, changed oil and filter.

I think the only old fluid in the car are the gear oil for the tranny and diff.

Before I got the car, it was sitting on a garage and was not started, driven for atleast a year said the previous owner.