Lazeum

Max 7000rpm usually means max power around 6500rpm. You're at the limit for ITM pistons but it should be fine. Think also about what you'd like to do in the future. Some, here, have some regrets because they would like to upgrade parts to get more power at high rpm but they've chosen ITM pistons, they are limited. Thinking about pistons is fine but going at high rpm above 7000rpm means also some extra investments: damper able to hold at +7000rpm, fully balance system including pistons, crank, rods, flywheel, clutch, etc. It also means camshaft able to use the power band. It should come then with special springs for high lift, lash pad with very specific thickness, major head work to be able to breath at that rpm level, lube system up to the task for rpm operation, ignition able to operate at high rpm, big enough carbs, etc. etc. My point is $600 difference between pistons is just one small parameters between many others that make an engine to cost $3000 or $10000. I've got a stock (but carefully built) bottom end with lube system upgraded (turbo high flow oil pump, oil restrictor enlarged), prep'ed head done to match my camshaft specifications and CR, good ignition system, good exhaust, sidedraft carbs. The car on open roads is really nice to drive with lot of torque and power. It is not the most powerful car in the world but it is way enough to enjoy the car and get major speeding tickets. Total cost for my engine was around $4000 starting from stock bottom end with new ITM pistons, new gaskets everywhere, port/polished/unshrouded head, Rebello cam, ARP hardware. I've bought all my parts at Clark's Discount. The guy is really nice to deal with, prices are very fair, shipping was super quick (5 days delivery - I'm in France).

ITM pistons are fine for stock rpm range. Their design is similar to stock units. I run NA L28 with max power at 6500rpm max (if not lower) so ITM pistons are fine. If you're looking for high rpm operation, you might want some lighter units. Custom forged pistons are probably more appropriate. Being at WOT or not, does not make any difference for pistons. Accel is what's killing pistons due to mass and inertia. piston acceleration is a function of engine rpm. Stress because of pressure due to fuel burn is much lower than load/stress due to inertia.

That's about right for stock pistons & rpm range.

What about piston rings? Were they gapped correctly? (if too tight, engine once hot would be damaged but I don't know if you have run it before) Have you tried to turn the cranshaft before disassembling everything? How was it?

Your comment about timing chain being very tight is suspicious also. Tension should come from tensioner, so it shouldn't be tighter than any other engine. Regarding bearings, haven't you or the engine builder checked clearances during the build? That's clearly one of the major item to control during rebuild. Either builder did not know what he was doing or you should be fine. I would suggest to turn by hand the engine with spark plugs removed as suggested below to feel rotating torque of the engine. That would help you to remove engine block from the equation.

In Europe, the only type allowed to run FIA legal events is a 6 poles cuttoff switch that would cut power from battery but also from alternator & ignition. You've got the main handle inside the cockpit and one handle outside the car in case of external support required.

Like others, thanks Chris for sharing the data with us! Like others also, I'm looking forward for future potential results with STB triangulated or not & roll cage.

I haven't seen Braap around for awhile. Not sure if he's still doing some headwork but the difference between my previous stock N42 head with stg II MSA cam & Braap's head is night & day. My ignition system allows to control every single point of timing map, exactly as you could do with EFI system. If it knocks at 3500rpm, I could reduce timing at the exact point without modifying anything else around. I've got also load controlled ignition with Webers, something a dizzy can hardly achieve.

If you can read AFR, you should be able to spot any issue with SU's. Some unbalance could create some issue but it might be big to create such effects. I guess you should also feel some symptoms at low rpm if it would be the cause. I don't think this is your problem but I'm in front of a keyboard to ptovide such info, not in front of your engine... Cam timing is a good point, you should double-check it. Regarding Unilite setup, you have to plates bolted together you can adjust to change their offset. Here are 2 shots to show you how it looks inside & how I adjusted it. My head is a P79 head prepared by Braap & Rebello to meet my expectations: Torque at low rpm, wide rpm range. I has been shaved by 1mm only but ports & comb' chambers have been modified significantly. For timing management, here's the link to my setup install. That statement is very wrong You can surely boost your engine if you'd like but bottom end has to be modified with dished pistons (at least) to lower compression ratio. You do not need forged pistons as long as you keep some hp target reasonable, stock dished units are perfectly fine.

I had the same bottom end / head combo as you but with a milder cam. I was pinging as well. Since you have a Mallory Unilite, try to lower mechanical advance. You don't need special tools to adjust it. Just get some drill bits with different sizes as template and some maths to figure how much advance you'd like. At idle, you might need around 10-14° without vacuum advance, try to achieve 30° max timing for a first start and see how the engine behaves. It means you need around 16° mech advance. My setup was happy with 30° max timing to avoid knock (around 2500/3500 rpm at high loads) but was giving up some hp at high rpm where ping vs. toning was not the issue. Since, I've changed the head & my timing management, problem are gone on my side

I'm positive they do it for L6 since the owner in Nederlands is having one in his very own 240z. He's running the Monte Carlo Classic race every winter, I've met him a couple of times. You should try to contact them directly to get some info.

You're welcome if it could help you and other people to save some time

Here's my file I had some guessing with front cover bolts regarding length, do not hesitate to get some extra bolts with shorter and longer bolts. They should cost you $0.10 a bolt, it is a cheap insurance to get some extra ones. Take everything with grade 8.8 hardware. Flywheel & damper bolts needs grade 10.9 hardware if you'd like to change them also. However, for flywheel hardware, I would follow ARP recommandations given by others. Total cost was less than 30€ on my side of the ocean for the total set with zinc plating option. To get this list, I used a thread gage and a caliper to measure each bolt I took out from the engine. Time to source bolts will be much shorter than engine rebuild, I would advice you to control them all to be sure. In the file, "Grower" is the technical name for spring washer. Inventory - L28 Motor bolts.zip

As a steering engineer (for Delphi, now Nexteer), the way splines on column are done, the answer is no. Any modification we could do will impact the behavior of the steering shaft and we have no ability to measure it and to certify that it would work. That's exactly what Tony just said. Paint on splines was reported as a "good" fix for shaft play but there's no evidence of what could happen in case of crash... For information, I've tried to replace the steering column on my car since it was having some play. Problem is I replaced it with another one with the same exact problem :/ Many S30 I've seen were having the same exact problem. Not sure if it is a factory problem or wear issue.

We're on the same page. I've got a very minor play and I can drive the car without thinking about it. However, as a former steering engineer, I know it should not be there. A fix would improve steering feel around center point (straight line and corner entrance). Track speed and time should not change, this is not the point. I'm driving a street car, not a race car anyway. Enamel point could be considered as long as both parts of the steering shaft can still slide along each other to keep the function of the collapsible steering column. My main question would be to know if the load vs. displacement curve of such modification versus nothing done to it would be negligible or not. JB solution has nothing in common with enamel paint solution since it bonds everything together.

Tony, I'm with you regarding JB Weld solution but I cannot agree with your comment about not having a perfect car and good driver definition! I've driven many Z and almost all of them were not in ideal condition (weak, soft brakes, untuned engines, poor suspension, etc. you name it), I complained about it. My car is so much more solid than this, it makes the whole driving experience much better. A friend of mine has painted the splines on steering shaft with enamel paint. I has added a layer which has taken out the play while keeping the ability of the shaft to slide back in and to collapse in case of crash . His report was the play was gone. It has been 6 months and it still goes as expected.

Hi Phil, just to make sure, car was not mine It was for sale by the owner, hopefully insurance was good and he got the money he could expect from the sale. Anyway, the whole time required to get such car is lost...

I had excessive valvetrain noise as well on my newly rebuilt engine. I solved the problem, it came from the rocker tip geometry in contact with lash pads. Here is the thread about it: http://forums.hybridz.org/topic/110671-newly-rebuilt-engine-with-loud-tapping-noise-even-at-idle/ (see page 4 for pictures)

Braap has also reported getting 260 crank hp out of a setup similar to mine with regular dizzy and 45DCOE (instead of 40DCOE in mine)

Dave has provided me thru Braap a ".487†lift tight lash grind" (0.487 lift, D50 224, Adv 276) and I love it. I had exactly the same goal with low end torque on L28 with rev limit at 6500-7000rpm. I love the combo which is plenty enough to have fun with the Z on French twisty roads.

We discussed about this issue some time ago. I created the same exact topic. My cure was to remove Avast and to switch to AVG which is also free.

It looks good! Regarding tachometer, I've plugged 12V signal from the coil pack on the black/yellow wire that goes to the tach. I've soldered the wire that goes to the coils next to the plugs below the glovebox, inside the cabin. It works flawlessly on mine. I've compared tacho and rpm on my PC, it is similar.

I see, much easier this way then. thanks for the reply!

Car was found They only took the wheels (Rota's RB from group buy) & burned the rest of the car! http://zclub.net/forum/showthread.php?t=23510&page=2

just curious (and maybe lazy :/ ) how do you intend to get your speedo working? are you going to use stock system or do you add somewhere an extra device to read speed?