Compression Test Results.......?

So what do ya think? I did a compression test recently on my 245 and came out with some iteresting numbers. First off though, the gauge is brand new and never dropped. It read accurately on my s13 when I had it. Here's the gauge. I had actually got my gauge from Autozone. https://www.amazon.com/INNOVA-3615-Compression-Tester-Plus/dp/B001QJ9JRY

Greenbook factory cylinder compression numbers : 128-156psi

I got; cyl. #1) 182psi, 2) 195, 3)190, 4)190

Now that's definitely within the 10% margin of variation per cylinder, but incredibly high over green book recommendations.
My motor honestly runs alright (to me) throughout all stages of operation with no smoke coming out the exhaust at any throttle input, including up steep hills where load is evident. Along with that, written on the hood of my car is the fact that the head was rebuilt in 2011 with new valves and what not. The internals should be awesome. I checked out he cam and valve springs, buckets and shims, too, when I was checking clearance and the were beautiful. Better looking then the dual cams of my '96 s14 (ka24de). I cant really imagine carbon build up being that epic. No seals are flying anywhere, no leaks from front gaskets. Hell, parked it on my well slopped driveway last night and drove away this morning without any signs of leaking on the ground..... for now.
Im also totally not sure how one could up the compression (not in the terms of compression ratio!!!) on the engine with the comp rings around the piston or maybe some form of head manipulation in order to up cylinder comp. I don't know.
The motor runs fine, even have a vid on youi tube(skip to 1:15):<iframe width="560" height="315" src="https://www.youtube.com/embed/ufK1p6eyYXw" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

So I dont get whats going on? Any ideas? Oh and the specs on my valves. Factory states 0.30- 0.40mm (.012 - .015) during "just a check" (adjustment) procedures.

cyl#1) Intake 0.33mm/Exhaust 0.33mm
2) Int 0.41/Exh 0.33 3) Int 0.41/Exh 0.36 4) In 0.36/Exh 0.30

I figure although there's a couple .01 over and one riding low on the line that it wouldn't just cause outlandish results. The valves actually still run fairly quieter than when I first got her (and before first oil change and timing belt job).
There it is.

Seems like things are ok for the most part mechanically. Now it's time to learn more about the kjet and maybe get it running a bit smoother at idle. You'll want to get or make a pressure test setup so you can check the control pressure, system pressure, and rest pressure. You'll also want a dwell meter so you can check the lambda duty cycle. Make sure the mixture is correct.

Has the timing belt been changed since 2011? Has it been retensioned at all? You loosen the nut on the tensioner one full turn and torque back to 36lbft. It is under the plug on the timing belt cover.

If everything is ok and you have alcohol in the gas like in my area. Cold starting is a bit more chunky than when it was all gasoline. But if you rev up a bit it clears out and runs fine after that. Both my kjet turbo and efi start a bit rough nowadays.

dl242gt said:

You'll want to get or make a pressure test setup so you can check the control pressure, system pressure, and rest pressure.

Click to expand...

TurboBricks Brand K-jet Fuel Pressure Test Equipment:

http://forums.turbobricks.com/showthread.php?t=289775&highlight=fuel+pressure+gauge

dl242gt said:

Has the timing belt been changed since 2011? Has it been retensioned at all? You loosen the nut on the tensioner one full turn and torque back to 36lbft. It is under the plug on the timing belt cover.

Click to expand...

I changed the timing belt, tensioner, and spring maybe 3 weeks ago now. Unfortunately I have no cover. I bought one but it didn't fit. I have the bolts and all, including the plug for it. My harmonic balancer was blocking it. Guess I gotta cut it without cutting off the timing marks. But my pulley also doesn't have that line on it for timing! It has the key on the back though.

I would love to invest into a Fuel pressure tester kit sooner or later. But yea that does seem like something I should do. Also, when im reading in these greenbooks and manuals, it stated '79 cars without Lambda Sond have two fresh air ventilation vents. One on the drivers side by my feet and one on the passenger side in the rear letting air flow out. I don't think I have Lambda. Also, my light doesn't say lambda, only EXH something. Which I would love to replace the o2 sensor too. I wish it was that easy to mount up an AFR gauge, too. I would really like that, but I guess K-jet is real af.

I would also like to put some input on hunting down the perfect idle. Honestly, I'm not going to chase perfection with this car. I understand that this year will make this car 39 years old.... 15 years older than me. Therefore, there will always be something "not so perfect" about this car period. I mean, I'm not stressing bout it too much. It runs hella good at highway speeds and all. It's just a little bit rough on a cold idle (sometimes warm, too lol, but never pulsing).

Another example is my mileage wheel is stopped at 198K. No, I'm NOT going to rip apart the dash and all just because it doesn't count anymore. To me that's a genuine waste of money, which seems to be the marketing pitch for these vehicles currently. Chasing perfection is hella expensive. Plus, dealing with parts that are NLA, I take that approach with a grain of salt. Not planning on ripping apart fuel distributors and volumeters when as of now it's doing waaaay better than when I first laid my hands on this car. "Don't try to fix what isn't broken" is constantly banging around my head. If I had spares of all these K-jet NLA goodies, I'd be going ham like bacon just plain out F-ing around with sh*t and what not. But I don't, so I won't.

Thank you for pointing me in that direction for a good FP tester home kit. I've also searched overhauling (in my terms, just cleaning) K-jet systems. A little bit more intricate than I like, but one day I might do something ridiculous... till then.

dl242gt said:

You'll also want a dwell meter so you can check the lambda duty cycle. Make sure the mixture is correct.

Click to expand...

Just a follow up real quick on the info I found about not having Lambda. This is from the '79 manual I have:


I have both fresh air louvers. Along with the fact that my dash light doesn't say Lambda either. Not sure if that's a factor:


I also don't have a catalytic converter and I cant find the two hoses that are supposed to be coming off my intake hose. Or might I say, there are none. You can see that in this diagram coming off of item 10:


I've removed the hose to clean the volumeter before and there were no connections for the hoses leading to a vacuum amplifier. Im not sure if I have any emissions like that. Im sure I have EVAP though. Oh, and no pipe coming off exhaust manifold going towards egr valve. I don't think I have that either. Im thinking, from what I see in my engine bay, I have the valve thingy coming off the distributor, leading to #6. But on my car, it's just a t with two other hoses, one from around the backside of the throttle body area, and one going out towards something..... I'm at a lack of memory currently.

So far as compression numbers go, they may have had to face alot off of the head when it was last rebuilt. Congrats on the strong numbers!

^^^ It's nice to hear that! Someone else saying those numbers are actually strong! Also, I've never really looked into the schematics of resurfacing a head or whatever. Time to brush up on that, too.

I had a non lambda 1979 242DL. Mine had the vacuum amplifier and egr. I blocked off the egr and was going to remove the vacuum amplifier but I sold the car before I got to any of that. My car did have the two footwell vents. Nice simple Kjet basic.

But it does make it harder to check your air fuel ratio since you need a exhaust gas tester to know. Or install a wide band kit and check it that way.

Kjet basic is a good setup and once you get it so it is sorted out. It runs and behaves very well.

dl242gt said:

But it does make it harder to check your air fuel ratio since you need a exhaust gas tester to know. Or install a wide band kit and check it that way.

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Yea and I don't think I got the duckets to dish out for an exhaust sniffer thingy. How would one actually set up and AFR gauge on K-jet? From all that I've learned, it's not as simple as changing the current o2 sensor out for a wideband. I would need some sort of controller for that along with a wideband that can send a narrowband signal to the ecu. Or whatever K-jet uses.

From all that I've read about K-jet though, it's a lot more simplistic than the 0BD1 and 2 240sx's that I used to deal with. Way more fun though. I don't miss OBD at all. Your right, basic K-jetronic!