Dan Baldwin

Nope, it doesn't work at ALL when I do that. When I wire it to the OTHER black/white wire (only sees voltage when key is in start), then the tach works, but only when the key is in start! Maybe some combination of resistors and capacitors between the MSD and the switched 12v black/white wire... BTW, the switched 12v black/white wire goes to the tach? Damn I'm confused. He'p!

Oh yeah, using an MSD 6AL box.

Hidey ho. I got the MSD 8920 tach adapter last night, and I'm trying to get it to make my 240z 4-wire tach work. I am CLOSE. The tach now works ONLY when I'm starting the car. As soon as I let the key go, tachie no workie. Currently (hee hee) the adapter is grounded, white wire to 6AL tach output, and red wire to the black/white stripe wire that used to go to either coil+ or the other side of the (no longer used) ballast resistor. Connecting the adapter to both the black/white and the green/white wires doesn't change anything. Anybody got an idea what I can do? I know that the ballast resistor is bypassed while cranking, so that must have something to do with my problem. Help!

The day when we're no longer able to speak freely in public is surely coming (already come?). Not looking forward to it myself. Why *shouldn't* politics/religion/whatever be freely discussed in public? Anyway, I love all you guys, whatever color you are and no matter how stupid you are. Hey, get that red-handled "fitall" away from me!

I've got a stock '95 Z28 M6 convertible. Just got it a few months back. It does have an Edelbrock muffler, sounds GREAT! Probably zero additional hp, though. I'd been looking for a coupe, but EVERY one I looked at was ragged. Looked at the 'vert for the hell of it, but it was tooo nice to pass up. Dark purple with chrome salad shooters. Never cared for the salad shooters, or chromed aluminum wheels, but for some reason chromed salad shooters look cool. Anyway, the 240 has a much better power/weight ratio, and feels a lot faster. 275hp moving 3500 lb. vs maybe 275(?) net flywheel hp moving 2300 lb. Or do stock LT1 Z28s make more like 275 at the wheels? 341rwhp in a 3400 lb. car must feel awesome!

Compared to Shane's results this might seem a little, well, inadequate! Here's the best dyno run: http://www.classiczcars.com/photopost/showphoto.php?photo=2274 And here's a link to time trial results from NHIS (only a Formula Continental was faster'n me!): http://users.rcn.com/comscc/results/nhis0902.htm The following cars are officially slower than a N/A 6-cyl 240Z: 911 Turbo (Street Prepared A) Corvette Z06 (Street Stock GT) Viper GTS (Showroom Stock U) Factory Five Cobra (Street Prepared A) So if you encounter one on the street or track, be careful that you don't run over it. Of note: Second-fastest door-slammer was an 80s(?) 911 with a 3.6, also street-driven. Third-fastest door-slammer? A Shelby Omni GLH-S! Both in my class, SPB.

Excellent! Any way to keep the torque up as the rpms go up? Or with a turbo do you have to choose between high-rpm or low-rpm torque? 436 lb-ft, that's incredible!

3L240, I guess I didn't show you what's under the hood now. I finally installed the 3X2bbl 44mm carbs. Most definitely improved high-rpm performance. I feel I could conceivably get to 250 rwhp, but the powerband is currently at 4500+. For all-around performance, a turbo would probably be a better choice. 250 rwhp N/A would definitely be a powerband compromise, but the sex appeal of having a 6-trumpet calliope under the hood is undeniable (though they're usually covered with the air filter).

It ain't cheap, but I'd recommend going to the dyno and doing some runs with the A/F sniffer going. See what your mixture is like throughout the rev range at full throttle, then also try gunning it from different rpm to see how the A/F readings respond. If the downdrafts are anything like the sidedraft carbs, they'll have idle mixture screws to control (duh) idle mixture, an accelerator pump that pisses raw fuel into the intake when you open up the throttle, a main fuel jet that controls how much fuel is metered at midrange and up, and an air corrector that prevents the mixture from getting too rich at the top end. I'm new to these types of carbs as well, but my plan is to try to get by with adjusting idle mixture screws and the accelerator pump stroke (volume) without changing the jets associated with idle and accelerator pump. The only jets I plan on changing out are the main fuel and air jets. Main fuel jet controls mixture at midrange rpm and up, while the air corrector largely only affects higher rpm mixture. I'm currently kind of rich in the midrange, and lean up high (dangerous), so I'll first try progressively smaller air jets until the mixture is somewhat the same at the mid and high rpm ranges, then reduce the main fuel jet size to bring the mixture to ~12.5:1. But I am definitely NOT an expert on these carbs, so take the above with a grain of salt. Go here for info on the DGVs from a 510 website: http://dimequarterly.tierranet.com/articles/tech_weber_tuning.html Good luck!

Go here: http://www.hybridz.org/ubb/ultimatebb.php?ubb=get_topic;f=6;t=001698 for the most recent discussion. I've got 225/50-15 street tires. very minor rubbing at the rear fender lip. I've had 215/60-15s that rubbed at the front valence at full steering lock. My wheels are 15X7 zero offset (4" backspacing). I don't think you can go much/any wider or taller than 225/50-15 without having to address clearance issues at the fender lip and/or spring perch.

Thanks, Pete. But my point was that even (especially!) at the race track, destroking is counterproductive. Tomahawk, you don't know that of which you speak. My car is anything BUT a stoplight grand prix machine or dragracer. It is built for ROADRACING. Way more sustained high-rpm running than your dream road scenario. My car is WAY more a revver than a stock L24, which has peak power at or below 5000 (I know the official spec is 5500, it's also wrong). My peak power is 6500, and nobody's home below 3000. My advice: quit dreaming and get thee to a road course! Lockjaw, destroking may not be a big deal to do, it's just not a good idea. As far as torque vs. power goes, power is THE important value to watch. That does not mean maximum peak power at the expense of a broad powerband is a good idea. Anyway, the point was/is destroking is a surefire way to LOSE power in an L6. If you COULD easily build a 94mm bore L6, you'd still be better off with the stroker crank vs. L28 or L24. 3456cc, man that'd be SWEET! Anyway, point is an 89mm bore 3.1 liter is an entirely practical engine build, while a 94mm bore 3.1 liter, which would potentially rev higher and make more power is not. I didn't set out to have a 3.1 liter and then custom select my bore and stroke, I just went with as much bore AND stroke as I realistically could. Torque is pretty much a function of engine displacement and compression ratio (not really a function of bore/stroke, which is why Honda engines ain't torquey though they are long of stroke for their displacement). Where you put that torque in the rev range is up to you, via carbs/cam/exhaust. I put my rear wheel 200 lb-ft in the 4800-6200 rpm range. Wheeeee! Regarding rod length/stroke, more is NOT necessarily always better. If you follow the angle between the conrod and the crank throw, you'll see that a SHORTER rod length will actually give you greater leverage on the crank through the meat of the power stroke. But shorter rod lengths also create much greater side loads => more frictional losses, wear, etc. I remember reading an old Hot Rod where they found they made more power with 5.7" rods than with 6" rods in a SBC buildup. Something to think about, anyway.

Oops, I meant to say (regarding the old HotRod SBC article) "he decided in favor of 5.7" rods over 6" rods".

The article I'm referring to was WAY back in the 80s. Some SBC guru who'd gone through a bunch of iterations decided on 5.7" in favor of 6.0" rods. Then again I don't really recall exactly how scientific it was. Purely anecdotal. Offset piston pins could allow for greater leverage on the crank during the power stroke. I believe some I-4 motorcycle engines have offset cranks underneath the cylinder bores for the same effect, but keeping the pistons symmetrical. Seems like an idea that has some potential. I always thought the biggest advantage of increasing the rod length/stroke ratio was reduced peak piston acceleration on top at a given rpm (increased rev potential). Longer rods would tend to increase the "dwell" time around TDC, while shorter rods would reduce it. Should the piston taking more time to whip through TDC improve detonation resistance? Interesting. I only run 93 octane pump gas (10.8:1 CR). Don't think I wanna have the car rely on race fuel, but don't mind paying extra over 87 octane. Kinda stuck with the rodlength/stroke ratio I've got, but it seems to be working fine:) Going WAY back up to Tim240Z's post, I'd prefer the stroker L6 turbo option. Might try that someday myself!

I believe destroking as a performance enhancer is a myth. Haven't run the numbers for a SBC, but for the L6, no destroked combination offers enough additional revs to make up for the lost displacement. Rev limit varies roughly with the square root of stroke, so decreasing stroke 10% only gets you on the order of 5.4% higher redline, and you've lost ~10% of your torque everywhere else. Improved rod length to stroke ratio does get you a smidge more revs than the square root of stroke ratio would imply, but not much. The following combinations give the same max piston acceleration (lemme know if anyone wants to see the tedious derivation of the eqns of piston motion) L28 at 7000 rpm (rodlength/stroke = 1.65) L24 at 7320 rpm (rl/s = 1.80) 3098cc L31 at 6810 rpm (rl/s = 1.60) 2569cc destroked L28 at 7320 rpm (rl/s = 1.80) Note that the destroked L28 has the same peak piston acceleration at 7.5% higher rpm than the L31, but has 17% less displacement. Destroked L28 => 11% less potential power + 17% less potential torque = losing proposition. That doesn't even account for the KA24 pistons being somewhat sturdier at high revs than the L28 pistons Norm keeps busting. My 240SX (KA24DE engine) redlines at 6900 rpm with a 96mm stroke. In a 83mm stroke 3.1 liter, equivalent piston acceleration is reached at ~7360rpm! I've revved my L31 to 7000 (with excursions to ~7800) at ~35 track days over the past 7 years, no problems. Destroking for performance ONLY makes sense if you're displacement limited, in which case you'd want as large a bore and as short a stroke as burn rate/distance for flame front to travel will let you get away with. Of course you'd want your engine to be right at the displacement limit, if you run out of bore potential, you add stroke regardless of what F1 bore/stroke ratios are. If you're not displacement-limited by class rules, stroking makes perfect sense, and destroking would cost you torque and power. I've said this before and I'll say it again: The only quick-revving contest a destroked L28 would win vs an L31 is one where they're turned by a hand crank. Under any load whatsoever (dyno drum, 1/4 mile, roadracing) the stroker will rev up more quickly.

It's not a lot of trouble to build a stroker. Not all that much more than a generic rebuild. Pretty well worth it, I'd say. I believe the cranks still go for $250, and get sold pretty quickly. Mystique? Anybody that mods for that reason is an idiot (not saying there aren't any about). That's whay 3x2 carbs were the LAST thing I did to my motor, not the first.

I've got a Pertronix Ignitor in the distributor, and an MSD 6AL, w/ MSD Blaster II coil. No problems except my '71 current triggered(?) tach doesn't work. I really need to address that...

I always did just fine at the track with Nissan shoes. They might have gone to a new non-asbestos compound now, though.

The cam is from Sunbelt in Atlanta. 302 duration/.550" lift. Designed to use relatively light valve springs. They did the whole valvetrain setup when the rebuilt and modded the head. Previously I had a Schneider 290/.503" that seemed to work fine as well. Neither of these cams does much below 3000 rpm.

What's a much much better tire than a Bridgestone S03, BFG KD, Pirelli PZero, or Dunlop SP9000? Several max performance tires available in 225/50-15 these days. Michelin Pilot Sport is the only tire of note available in 16 and 17" sizes but not 15". It was outperformed by the S03 in wet and dry conditions in a Tire Rack test. Also, how do you figure it's cheaper to go 17"? 16" tires will save you about $50 vs. 17s, and 15s are $70 to $100 cheaper than 16s. 4x225/45ZR17 S03s = $620, 16"ers $564, and 15"ers would be $492. For KDs, that'd be $780 for 17s, $752 for 16s, and $648 for 15s (yes, I *should* be working right now). Oh yeah, in my previous post I mentioned 225/45-16s on a '72, they were really 225/50-16s. Nice to have ye aboard, 3L240!

That'll be interesting to see, for sure. Of course the only valid test would be to dyno the same motor first with one head and then with the other, with the same valve events and timed the same. Not something I believe anyone's prepared to do. Anyway, it's my belief that there probably ain't much between the two (shaved P79 and N42). I'll have to come and see you guys sometime, I have family in Birmingham (Birminigham?).

I know 225/45-16s require bending the fender lip back on a '72 lowered a bit more than mine (~2.5-3"). 225/50-15s fit with minor rubbing at the stock fender lip on my 1971 car, lowered ~1-1.5". 225/50-16s *might* fit on a moderately lowered car with the fender lip rolled back. Dan "not cool enough for 17s" Baldwin

Dude, give it up! I know you *think* N42s are utter crap, but until you show us a 12-second or 235 rwhp N/A P79 car, you can't seriously expect anyone to believe the P79 is any better AT ALL. Until you provide some EVIDENCE, you don't have a case. Please note I am NOT saying that the N42 is superior, it's just what I would recommend to start out with, particularly for someone who is new to Zs, and possibly to engine work. Stock N42 on a stock flat-top bottom end. No machine work required. No chance for the monkeys to screw it up. My engine was WELL on its way to 185-190 rwhp at the dyno last year with a totally stock N42 and a 290/.503" Schneider cam (only made 177rwhp due to a busted spark plug causing power to break up above 5000). With headwork, new cam, and 44mm triples, it's at 235rwhp. So, why the regarding the N42? I'd be happy to post images of my dyno results if someone would tell me how.

Note, this is my OPINION. I wouldn't run 17s unless I was trying to fit 275s (N/A for 16s 15s 14s). I mean, what good is it doing you to run 225 17s? Higher c.g., greater unsprung mass, greater polar moment of inertia, taller overall gearing, reduced braking gs/pedal effort relative to 225/50-15s. I run 225/50ZR14 Hoosiers at the track, and 225/50ZR15 B'stone S03s on the street. Only reason I'd go taller would be to fit wider tires.

The old Chev 302 was a destroker to meet CID limits for Trans Am. GENERALLY, you will lose hp destroking, because rpm limit doesn't vary linearly with stroke, it varies with the SQUARE ROOT of stroke. I.e., reduce stroke by 10% and you only increase your redline by about 5.4%, not enough to make up for the lost displacement. Even accounting for improved rod length/stroke ratio, destroking almost always loses, and stroking almost always wins (I know this is true with L6s, haven't run the numbers for SBC). Plus you improve torque EVERYWHERE up to redline with a stroker, whereas with destroking you reduce torque everywhere for only a minimal gain in redline rpm. One more thing, the idea that a destroked motor will rev up more quickly than a stroker is a myth. Unless you're talking about revving them with a hand crank.

I called the Ferrari dealer before I had my car painted back in '95. Glasurit 300-12 is the bright red they use. Looks great!