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My KGC10-R Engine.


g72s20

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I recently had the opportunity to run the C10 on Stewart Wilkins MotorSport chassis dyno. Racing 240Z's and Nissan L6's all over the place!

Other than the obvious mods to the engine;

  • triple 44 Mikunis
  • Fujitsubo extractors and twin system
  • lightened flywheel and/ or internals
  • mild cam
  • factory electronic ignition
  • "Winged" sump (oilpan)*

..I don't know about inside as yet.

Any and all mods were done in Japan by previous and unknown owners.

It was sold at auction in Japan as having a 3.1 Litre (I.E.stroker) motor, I was told was done by Kakimoto.

To drive on the highway, this motor seems torquey and willing, doesn't get hot and has never given any trouble starting etc.

On the track, it was happy enough for a few laps but soon started breaking down if pushed. The point of breaking down getting lower and lower with more laps....nothing beyond an indicated 4000rpm. Didn't overheat, no fluid loss. Ok, back out on the highway and now it's happy to an indicated (and self imposed rev limit) 6000rpm,(3rd gear) revving nice and clean and pulling like a train!

As it is not a race car, and was happy enough on the road, I didn't get overly concerned, just put it down to fuel pump or something upsetting the ignition.

So anyway the guys run it up on the dyno a few times, 6000rpm limit. Sounds OK at first, but as the revs climb I detect "fluttering" on and off...revs still going up, now definitely running on 5, maybe even 4!! Sound like it's revving it's tits off and getting nowhere.

Have a look at the printouts, ever seen anything as crook as this:disappoin

I had a chat to the guys running the dyno, they certainly know their stuff, and seemed sure a lot more could be coaxed out of it when the obvious problem (cause yet unknown) is addressed, but with everything considered felt it wasn't major. Noted was the air/fuel figures were running at turbo type ratio (thick and rich!) I am going back to them and booking it in for a diagnostic and fix soon.

For all you guys that have played with these engines and had to interpret readouts,what's your take on what you see? Any experiences in using a dyno as a diagnostic tool? I realise guesstimates are the best you can hope for when considering a picture, but I would be interested on any and all takes on what you see. All constructive suggestions, thoughts and comments accepted gratefully. Anything else....well I got a pretty good sense of humour, Geez ya gotta have, eh!?:classic:

Jim.

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Interesting thread, did you find out what the problem was? I'd be very interesting in what parts your running in your engine. Is the head N42? Does it have L14 rods? I guess your still wondering yourself.

Regards,

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Interesting thread, did you find out what the problem was? I'd be very interesting in what parts your running in your engine. Is the head N42? Does it have L14 rods? I guess your still wondering yourself.

Regards,

Hi Gav,

Not yet. I'll know more after the comprehensive dyno work is done....and I'll have to save my pennys for that little exercise, around $400~$500 dollars:eek:

I'll check on the head for you. Rod type will have to wait....quite a while I hope!

I had hoped for a few more ideas being posted about the possibilities of the meaning of the dyno readouts....anyone?

Jim.

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If Stewart Wilkins is as good as he says he is he should have it fixed in no time. From the sound of it I think the problem would be a distributor related issue. I would check the breaker plate if it's the E12-80 module electronic distributor. It just won't let the engine advance and caused me all sorts of grief.

Seems like the old girl should be putting out more power. However if it's only had a mild port and mild cam then I guess it's probably correct.

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SWR does fantastic work.

They get the job done even if it means thinking outside the box.

Just as an aside, they had my L6 on the dyno and my initial tune looked very similar to yours.

A few hours of tuning changed the figures from [email protected] wheels to [email protected] wheels.

I wouldnt be surprised if you could get something significantly over this figure once your engine is fully sorted, seeing as you have more 'fruit' than I.

Are they happy to play around with the Mikuni's?

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Thanks for that Gav. It does have the dizzie and module you describe, and it all looks a bit tatty, but as it seemed to do the job (before I got the dyno check) I thought I'd leave well enough alone.

Hey Vincent, Good to hear from you.Where ya been? thanks for the input, that is most interesting!!. Regarding the Mikunis, the guys didn't seem fazed at all...comfortingly confident in fact. A bonus is I'm 5-10 mins from their shop!

Now your chart is more what I had expected or hoped for. Mine may yet turn out to be a lower powered package than anticipated, but to be honest what's there now is really a buzz to drive! At the risk of falling into the same trap twice,( getting all starry-eyed over what I am told) I have another triple 45 webered L6, once again an unconfirmed package, but it is rebuilt and unused, the builder garuanteed the original owner ~ 280 reliable HP, and was known for his high HP L6's. Trouble is it sat unused (well protected) for 16 years, the builder has retired to the tropics and everything about it is subject to the memories of two chaps in their late sixties. It will be torn down and inspected in time.They thought it was fitted with an option "1" box. Once that was proven wrong he remembered " Ooh yeah, that was too expensive so we got a ZX turbo box to handle the power!" well that appears to be wrong also, although it may well be a 280ZX box. This is certainly not a gripe as I was practically given the whole lot.

If the current motor in the Skyline ever has major problems I'll definitely give the other a go. I may even use the old 240K as a test bed for it:laugh:

This is great, but "need more input!" (apologies to No.5:laugh: )

Jim.:classic:

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Hi all I have 5 c worth for you on those 6000 rpm fading ignitions. my experience caused me some heart-ache on the way to Melbourne I had the MITSU distributor, and it would break down in the 5500-6000 range. I was sourced the Hitachi ran better but not everything I expected. inspection and rebuild cured the Hitachi, I stored the MITSU after its rebuild had no call to re install it. major problem with both seemed to be a sticking plate and a little shaft end play.

Also interested in that story about the two men over sixty who built that engine all those years ago, I am sure I know them, I think they built my L6, it is still going strong. Can you do an inspection of the internals without doing the tare down, it may be good if the oil was sprayed in the right way. A priming of the oil system and a bore soak may save a lot of effort.

You got to put it in the K they are just the best test beds.

As for the repairer you mentioned I have only ever heard real good things about them, and when it came to the crunch people from Newcastle have been satisfied with them.

cheers

Steve:)

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Sorry if its gone a bit offtopic,

Gavin, I've listed the mods in my photo gallery.

Jim, I've been working a lot lately, but the car has also been slowly getting some upgrades. Brakes and bilsteins being some of the latest toys i picked up on a trip to the states recently.

I'll actually be taking the Z up to SWR in a month or so's time to get a baffled oil sump made up and some other bits and pieces. Your spare engine sounds interesting- sure you don't want to run it in my car as a test bed? ;)

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Thanks for all the replys so far (hint hint!) guys. It would appear the dizzy is definitely one of the contributing culprits. Just on that area, whats the considered opinion of the distributor running with the Vacuum advance disabled? . Is this a consideration to the lack of steady constant vacuum at relatively low engine speeds/loads in an engine fitted with a combination of a large or many carbys and a cam with a big overlap? (not gospel, just my wondering)

Vincent! If you like PM me when you're coming up. If I can I'll come up and say G'day if it suits.:)

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If you are running this on the road then use vacuun advance.

Lots of carbs and a hot cam are not insurmountable - connect EACH carb to a common 'rail' from which you then take the distributor vacuum.

If there is too much interaction, put a short lenght of small bore tube in each line from the carb to the 'rail' (the restriction acts much like a one way valve).

No vacuum advance really will kill low down performance!

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Thanks Art. I just wondered what the benefit was of running without it. I'd only seen this on cars that had been modded for sport. I had an ex series production XU-1, another multiple side draught carbed straight six. Like riding in a wheelbarrow, but it could corner with you hanging on for grim life at the tiller with ya legs out the window before it would let go:laugh: . The distributor had the vacuum point blocked and the points plate spot welded to the baseplate. Mine was not the only race car I had seen with this done. Remember this was early 1970's series production racing and technology....so I guess it was of some benefit higher up the rev range?

Anyway I have a Crane Fireball unit not doing anything at the moment . If I can get the bits needed to set it up on the Nissan 6 I'll try that. Hmm.. I was thinking controlled dwell and all, but I might have to investigate if the unit wants the vacuum adv. or not. I'm off to do a bit of research now!

If any of you good folk want to post in a bit of free advice about the subject of ignition systems please feel free to do so:classic:

Jim.:geek:

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Interesting thread, did you find out what the problem was? I'd be very interesting in what parts your running in your engine. Is the head N42? Does it have L14 rods? I guess your still wondering yourself.

Regards,

G'day all:classic:

I checked under the bonnet Gav, it's an N42 head sitting on an N42 Block.

Today I had an over voltage problem addressed. The battery was being presented with 14-18V by the alternator!! The car was using the old "vibrator" type voltage regulator, and after ensuring the battery was still serviceable, I had the regulator replaced with an electronic unit. We had to wait a few hours for a new unit to be delivered, so I pulled the alternator and the auto sparky fella pulled it to bits to give it a thorough check. The diodes had been replaced, and thankfully everything else was fine. On the testbench the alternator was pumping out a healthy 50+ amps.

With the new regulator in place the charging cct was performing perfectly now, 12.8-14v.

I had some time to observe these guys Riversone Pde Auto Electrical at work and I recommend them highly, particularly anything to do with oddball vehicles being built. For example;Sorting the electrics for an old crewcab VW Kombi fitted with a 3.8 litre V6 Holden (GM), and a Toyota Van fitted with a 3litre twin cam Toyota straight 6!

I'm booked in at Stewart Wilkins next week...should be interesting :)

Jim.

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  • 2 weeks later...

I picked the car up this morning. Main problem was loose main jets,some were one turn from dropping out! timing was way out, advanced to where it should have been pinging its head off. No parts needed, and engine is in sound condition. Appears the head is a low compression unit says Mr Wilkins.

I thought it was OK before, but the difference on the road is amazing. Much smoother, and crisper revving, and more usable torque. Acceleration in 4th gear is great:laugh:

The attached graph says it all, better power and broader torque. Not a big numbers motor, not as much as I expected but still a fun package:classic:

1 hour on the dyno

2.5 hours labour

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What nice results Jim! All ready for the Bathurst run now I see! Just in time too. I've got new spark plugs and points yesterday, but I'm thinking maybe I should replace the leads too? Is this easy to do? Not sure what else I can do within a week to up performance a bit. Gotta keep up with those Princes...

What a difference the tune did. The dyno chart really says it all.

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If the age of the dizzy cap is unknown, it's advisable to replace it as well, include rotor button, condenser, leads, plugs. Doing it for the first time can be daunting,the right tools, specs and info are a must. Better to get an experienced friend to show the way, but once you've done it I'm sure you'll agree it's a piece of cake. The icing would be if you can get your hands on a vacuum gauge and incorporate that as tool into the job. They are a very good visual indicator of how your tune is going.

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Hi Miles,

I'd be interested to hear more about your engine. I gather it's still a 2 litre? Interesting choice for someone to add all the nice bits, like triple twin sidedraughts and a decent header/exhaust sytem. It seems to me that any of these GT's that are for sale all have had the 2.8L transplant, which makes yours all the more interesting!

Do you know what other work has been done? Any plans for it now it's in the hands of a rebuilder??

Cheers,

Jim.

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Jim,

The car is mostly unmolested. The engine is stock, save for headers (extractors) and a Fujitsubo exhaust system. The head work is going to include a mild cam re-grind from 62 to 64 degrees for better low end. I have the twin SUs that will be going in later. Other than that, no plans. You`re right that most of these cars have had the 2.8 transplant with triple webers. But the hot set up now is the 2.6 RB transplant. Will wait and see what comes after the head work.

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