I want Revs!! --(Mal)

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I currently have a G200Z in my gem. I can really only get it to rev to 5000 - 5500rpm max. The crank has been reground, balanced and the flywheel has been lightened.It's running around 11:1 compression with a shaved 1600 head ported etc, the vavle gear will hold up.But I would like to find out is there any other way you can get it to rev. Also I've heard the G180 is a pretty good motor, what's it's strong points? thanx

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what size cam and do u have double valve springs?? (rr4?)

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what sort of induction
G200 /G180 only nead to rev to about 6200 / 6500
this is easly done with twin carbs
std carb will not let it breath

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I've got twin sidedrafts and a 30/70 cam.

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put and air ram on it, then it will breath!

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cool thanx I might give it a go, see what it does

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check your fuel and ignition, had a g200 that would easily rev to 7000 with the niki carb

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When you say it won't rev, do you mean that the power drops off or it physically won't rev, either way, something is amiss. Don't go spending more money on modifications (eg. gene's air ram... ugh.) until you find what is wrong...

I had a very similar setup, G180 bottom end (same stroke as a G200) bored to two litres (so the same bore as your engine), ported G161Z head (only 9.5:1 static compression), 30/70 cam, lightened flywheel... but I was running a port matched factory inlet manifold and niki carb, my engine happily pulled to 7000rpm (when I was driving) or 7800rpm (when my father drove it, never let other people drive your car). Your combo with the higher compression ratio and twin webers should be making a lot more power and pull happily to 8000rpm... what valve springs are you running and what is the spring tension at installed height? The only other thing I can think of is that your cam has been installed one tooth retarded. Just had this problem on a U12 nissan pintara. What about your ignition system, have you checked all the usual suspects there?

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Ok. I found out it's the G200Z Jackaroo motor. As far as I know it's been rebuilt with a reground crank, new pistons rings etc. It's got the 1600 head shaved 30thou, double valve springs, 30/70 cam, twin sidedrafts, extractors and the distributor has been regrafted. It just really seems like a torque motor rather than one that is gonna give rpm. It sits you back in 1st and 2nd but I can only take it to 6500rpm cause it sounds like something is gonna give way. I can feel it still wants to pull. When at idle it has a very slight knock kind of tap in the bottom end, it's not to loud though. I am really thinking about rebuilding it and getting it fully balanced and making the bottom end basically bullet proof. What is the rpm duration of the 30/70 cam? Does a high compression motor have any problems later down the track because of the compression? Like bending valves or a limited engine life? Thanx 4 your help much appreciated.

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You might want to check how much total timing your engine is running. Too much ignition advance can help kill your big end bearings and journals. I was running about 54 degrees total on a 1600 of mine, many years ago. It had a big end not, unsurprizingly. I didn't realise that distributor degrees is half engine degrees. In other words, my dizzy was set on about 18 degrees of mechanical advance, which I later found out actually meant 36 degrees of mechanical advance, relative to the crank. I was also running about 15 degrees static.

Use a timing light that lets you dial in the timing, so you can see how much total advance you have when its all in.