LeonV

DING-DING-DING!!! Precisely! We're getting a bit off topic here, but I will say that late 240Zs had side impact beams as well and I can easily tell the difference between the two (late/early 240Z). I haven't had a 260Z-specific door to look at, but I'd suspect the differences between a late-240Z door and 260Z door to be minimal. Also, I haven't noticed any signs of a "reinforced sub-frame" when compared to my 2/71. Maybe I need to look more carefully, but I've s no signs of extra metal. Right, but I covered both in my previous post for the sake of completeness. My apologies for the misquote. In the beginning, you mention not taking the magazine articles as scientific evidence. These magazines, especially back in the '70s, do not and did not account for varying conditions at the times of their tests. Who knows the circumstances between the '70 240Z "road test" and a '74 260Z one. Elevation, temperature, tires, road surface, driver, timing equipment, etc. all totally affect performance figures. You can even compare contemporary road tests in current publications and see the variance that different articles have on things like 0-60 times. The much more scientific approach would be to take a stock 240Z and stock 260Z, run them back-to-back on the same dyno and compare results. This would give much more insight into this myth, than a 40-year-old magazine article. Anyone up for it?

Carl, This is exactly what I was talking about, people quoting MEDIA figures as scientific evidence. Also, we're not talking Porsches, or Chevys, or anything else besides Z-cars. Can you explain why my US-market 260Z, and all others I've seen, say "162hp" on the engine plate? I also doubt my early 260Z weighs that much much more than a 240Z. The only real differences between the two are more heavy duty bumpers, bumper shocks, some extra wires and a rear ARB. I've yet to weigh those parts to see what they add but I can to it today, plus I've got early 240Z bumpers to compare with. The 260Z definitely weighs more than an earlier 240Z, but as you saw, it won't make a huge difference in performance. I completely disagree that "emissions equipment" took off 26hp. What emissions equipment are we talking about here? EGR only affects part-throttle performance (and actually makes it better). The AIR system was shared with 240Zs. EVAP equipment has no effect on performance. PCV is on all Z's. Throttle opener solenoids are on both models and don't affect power. So, we see that the ancillary emissions equipment has nothing to do with it. How about engine changes? Engine displacement increased by 0.2L in the 260Z. Compression ratio might have dropped a tiny bit compared to the E31 headed 240Zs, but it's the same as later 240Zs (which were rated at 151hp) at 8.8:1. Speaking of carbs, the funny thing is that the flat-tops "allow more adjustability for air/fuel ratio's (sic)," as you put it. Flat tops have separate idle and WOT circuits, unlike the round-tops. Spark timing curves did change. The 240Z had 17deg initial timing and 12deg of centrifugal advance for 29deg of total timing at WOT. The 260Z had 7deg of initial timing but a whopping 26deg of centrifugal advance, making for 33deg total at WOT. Thus, the 260Z had a more aggressive timing profile! The 260Z cam is more aggressive because of an increase in displacement. The cam did not detract from performance. The 260Z intake is said to flow and distribute the mixture better than the 240Z manifolds. I have not tested this. However, both the 260Z cam and intake are sought after by guys wanting to use stock parts to make their 240Z perform better. Do you see anything I don't see in terms of losing 26hp? I sure as heck don't! As far as I'm concerned and been able to determine, the US 260Z had 11 more horsepower than the 240Z. References: 1972 240Z FSM 1974 260Z FSM

Thanks for the mention, Blue! Mine are two stacked 12" glasspacks coming off of two separate pipes from the header. I planned out the exhaust system and had my exhaust guy weld it up and install it. The Y-junction that Blue shows would work for finishing a single-pipe system with two tips. No need for fancy "twin-stacks"!

Of course, however, the 260Z carries a certain mysterious stigma, at least in the US. Hence why I said "appreciable" differences. I'm sure there were minor spark timing curve alterations, slight differences in compression, etc. People get caught up with "emissions" equipment, but as is usually the case, that equipment does little to nothing to hurt power (and sometimes helps, i.e. EGR). Sure give or take a few hp, but I'd surmise that there isn't a seat-of-the-pants difference in driving the two. Point being, the difference between the two isn't anywhere near 26hp! I also greatly enjoy the irony of people lambasting the US 260Z, yet the 260Z cam and intake are widely renowned as the hi-po factory stuff!

Make sure that all fasteners are to German torque-specs: gutentite.

There are no appreciable power differences! Yes, it's the difference between SAE gross and net. Whatever book you referenced is right, all of them had the same power output, does it matter at this point what the rated BHP is? There is no lost power to make up for. The L26 has more displacement than the L24, and thus has more power than the L24. There are SO many misconceptions about the 260Z, many perpetuated by media (i.e. magazines, etc.) or a misunderstanding by the reader of what the media was saying. I LOVE that the 260Z is viewed as "weak and undesirable"! That means I can find them cheaper even though I consider them to be a better car (carbs can be easily swapped out although I wish there was a parts market for flat tops). They're a fun and quirky car to own since it was a 1-year-only model in the US and it's fun to figure out all the 260Z-specific aspects. Shhh, don't tell anyone!

There is no 139hp and 165hp motor, I bet you're comparing power tested under different rating systems (SAE net, gross, etc.). I'd imagine the performance differences being very slim.

A fan shroud does not fix cooling issues...

Phil, I just ran my L24 today with 120 mains (40DCOE with 30mm choke). Saw about 12:1 on AFR meter when I was looking. It was fairly cold out though, so it will be richer in warmer temps. I may go with 115s but it runs so well, I'm not in a hurry. I'd imagine at 7-8AFR, that 510 would be billowing black smoke out the exhaust pipe.

Lucky bastard... We finally dipped under $4/gal recently.

Agreed. I use Mobile 1 synthetic with no worries. I've been using it for 2 years now. I change it once a year as the Z doesn't see too many miles, maybe 5k/year.

Sounds like either a vacuum leak (likely), or timing is way out (possible).

I should be ok. The stoichiometric point of E10 is around 14.1:1 but the AFR meter normalizes what it measures to the stoich point of pure gasoline (14.7:1) since it calculates based on lambda (measured AFR = pure gas AFR * lambda). If I can lean it out a bit more, I'll be happy, and so will my wallet!

That looks awesome Captain, nice job!

Bigger is better, if your engine can support it. An L28 with an aggressive cam can easily run 45s. Basically, if (when) I decide to get some new carbs and I have the option between 40 and 45, I'm going with 45.

To recap the last week or two of my quest to rid myself of the sudden-open-throttle hesitation: 1. Tried stiffer pump springs. They seemed to help my hesitation but they were so stiff that they overwhelmed the throttle return springs (new ones) and didn't let it drop back to idle. 2. I replaced the pump springs with my old ones but soldered up my bleed back jets. The setup was 40 pumps and 55 bleeds, and was now 4- pumps and zero bleed. It drove better with less hesitation, but it was still there when suddenly going WOT and sometimes when rev-matching. 3. Keith sent me some .53mm pump jets and a drill bit to upsize to .61mm if necessary, as well as some slightly stiffer springs. Holy cow, what a difference!!! The rev-matching and WOT at low rpm hesitation is gone! Once in a while I'll get a short lag in power output because of AFR going lean, but no more bucking-bronco take-offs. Not only that, but my idle is at 14:1 and cruise is 13-13.5:1 (I want this leaner). It feels so much better to drive this car now. My current accel pump setup is stock springs, 53 pumps and zero bleed. I'm thinking I may need some leaner hypojets to get the cruise AFR where I want it. It's close but I want it leaner, at 14.5:1 or higher. I might as well try the slightly stiffer accel pump springs to see if they eliminate some mixture lag, but I won't want to use them if they mess with the throttles returning. I'd rather upsize the pump jets. All in all, you can barely tell this thing is carburetted now (especially if you don't look at the AFR meter )!

Looks awesome, Rob! Can't go wrong with Panasports...

Nice job, the modelling is coming along great!

Rob, I may be picking up some new triples in the future as well. For the L28 I plan to build, I plan to go with the 45DCOE152. Why? 'Cause they're bigger!

Those can come off in high-rpm situations, but lower-rpm situations aren't out of the question. Checking valve lash should be your first order of business. BTW, you can turn the engine over by putting the transmission into high-gear and simply pushing the car. This is how I do my valve adjustments, no tools or switches needed.

Ask Dave: http://www.classiczcars.com/forums/member7498.html

Beautiful! I love seeing the intricate details of the Z432s.

A 225/50-16 should fit fine on a 16X7 and have no clearance issue, even with stock suspension. Having the correct offset goes without saying.

I agree, I don't think flooding is a concern. I should have said, keeping the throttle closed (on a carburetted engine) while doing a compression test will suck more fuel into the cylinder. Whether that floods the cylinder or not depends on how long it takes the operator to perform the comp check. EFI and round-top SUs will not care how many times you pump the pedal between tests. Triples, 4-barrels and other carbs with accel pumps will...

Don't quote that site, there are tons of misconceptions in there, especially the Weber section.