dladow

I did some looking around at the Chevy Talk forum and its seems that the return line is generally routed through the pressure regulater, not from the carb. So you just buy a pressure regulator set up for a return line. Seems simple enough. I didn't see any references to installing an additional pump connected directly to the carb bowl, which is what Vizard seems to be suggesting. Anybody ever done anything like that? Here's a link to a site explaining fuel system design, - a grumpyvette find. http://www.centuryperformance.com/fuel.asp Dave

I was reading David Vizard's book on building & modifying carbs and manifolds, and in discussing the importance of delivering cool fuel to the carb, he mentioned installing a "smaller capacity pump" connected to the carb fuel bowl to constantly return fuel to the tank, which would act as a heat sink and help keep the fuel cooler which equals more power and no vapor lock. The 1973 240z already has a return fuel line, but Vizard gives no clue as to how to set this up. Has anybody out there tried this? I am planning on swapping in a carb'd SBC V8, probably using a Q-Jet. Dave

I just noticed that Kevin Shasteen's cd-rom book on engine building (see the forum's classified section to order) has a turbocharger calculator in it. You might pm him to see if he addresses your question in his book. Dave

Another way to handle compression is to change the dynamic compression ratio (which is really what the engine sees) with the cam. Since you are locked in with the heads, you might try different cam combinations to change when the intake valve closes. No compression occurs until the intake valve closes, and that is determined by the cam. There is a bunch of info on DCR and SCR (static compression ratio) in this forum. You might find that you can hit your compression target with the 21cc dish pistons and a cam with the proper timing of the intake valve closing, rather than changing the dish size. Dave

And I thought they all lived in Seattle! Dave

2126 - thanks for the suggestions. I also found the seats to be much higher than stock. It's no problem for me, I'm only 5'6", but my friend who is helping me is 6'3" and he is not able to get in and out without whacking his head several times. (More swearing). I like the idea of the fixed mount for the passenger seat. It could use lowering. I kind of hate to give up adjustablility on the driver's side. I might sell these and go for different seats - ones that are not quite to high, if such exists. In the meantime, I hadn't thought of drilling holes in the floor pan for access, then plugging them. That has possibilities. Thanks, Dave

Well, the seats are in. Phew, what a task. Welded in the bolts upside down as studs in the back, but it didn't help much. Still no room to get your fingers in to get the nut on. Finally succeeded after much swearing. Then discovered that the track is misaligned and the fore-aft seat adjuster won't catch. Much more swearing. Seat now has to come out to fix the track. There has to be a better way to do this. Dave

Cozy's posts on Lucas Electronics reminded me of this old joke: Why do Brits drink warm beer? Because Lucas makes refrigerators. Dave

Thanks for the suggestions. One of them ought to work. I will not be denied! Dave

It's funny (or not) how sometimes the jobs you think will be so hard turn out to be easy, and the jobs you expect to be a cakewalk turn out to be nearly impossible. So Tuesday I got my new Corbeau GTS seats and brackets for the 240Z. Brackets made for the Z - no problem, right? Nope. It is impossible to access the rear seat bolts to get the nut threaded from the bottom. Not enough room for my fat fingers. I tried reversing the bolt and supporting it underneath so it became a stud, but couldn't get it supported well enough or at the right height. Got frustrated. Slept on it. Talked to a friend of mine who used to work at Boeing putting together airplanes, and he was telling me about access problems he used to have assembling planes. He suggested gluing the nut/washer combo to the bottom of the car bracket, lined up with the hole, of course, which would hold it long enough to thread the bolt by hand to get it started into the nut. I can then access it with a wrench. I'll give that a try. If that doesn't work, I may just weld the darn bolts in place sticking up throught the car bracket so it will be a permanent stud. Anybody else have this problem? Dave

Ground Rat - Those Mickey Thompson valve covers are the same as were on my 350 when I hauled it out of the donor car. The engine is in pieces now, waiting for a trip to the machine shop, etc., so it was great to see your picture to visualize what it will look like installed. I kind of like those M/T covers. That's a cool look with that air cleaner. Must be nice to already have the V8 in place - I'm still an inliner, probably till winter rolls around. Dave

Great story! I wouldn't feel bad about putting an LS1 in that car. The 73's had the early emissions stuff and the flat top SU carbs. The power was way down that year and so I would want to modify the engine anyway. I found an automatic '73 that had been stored for years in a parking lot under an apartment building with no rust and matching numbers engine also, for $850. Someone had gotten fed up with the flat top SU's and swapped in the earlier round tops. That engine still runs really well with +120k and I am having fun driving it while I build my SBC. I just finished replacing all the bushings, springs and shocks, and it drives great. You'll have a lot of fun with that car. Starting with a rust free 240z is a real blessing. Dave

Rust bullet from the itkillrust site. I'd buy it again. Dave

I bought a quart of it and am pleased with the results so far. It sticks like crazy and only requires one coat. I applied it to floor pans, spare tire area, and to two areas on the outside of the car that are rusted through. Its been on the car for about 3 months now and it seemed to stop the rust dead in its tracks. Dave

Check with D and D Fabrication in Puyallup, just off the 512 highway. Phone number is 253.435.1616. They do great work, and know Z cars really well - they build them to race. Dave

It's interesting to think about the new BMW V-10 for the M-5, (no doubt a spectacular engineering feat) that produces about the same hp and torque, but at far higher rpm with commensurately greater stress on systems and parts. The cost of that V-10, if it was available as a crate engine, would be, what, north of $30K, $40k? I'll wager Pete won't be spending that much on his engine. Give me the simpler path to the same result any day.

Well, it was a big week-end for the 73 Z – it’s off the jack stands! Yeah! I finished the suspension refurbishing – springs, struts and bushings, new brakes, cleaned and painted the parts. I actually got to drive the car for the first time in two months. Wow, what a difference. I drove it down to Mt Rainier on back roads – what a blast. No body roll, no squeaks, rattles, groans or clunks. And I got it up to 80 mph without scaring myself. Right now I still have the L24 with rebuilt round top SU’s and a free flowing exhaust. From what I’ve read, I’m guessing it’s about 120hp to the wheels. Pretty spanky in that light car, and that is a really smooth revving engine. And the turbo muffler gives it a nice growl. Still, I can’t wait to get the V8 in it. Even a mild SBC build up will be one hell of an adrenalin rush. But first, I have to put the interior back in, fix the dash and heater core, seats, etc. Then enjoy it for the rest of the summer, maybe take it to the test and tune just to see what 1/4 mile times I can do, and build and swap in the V8 this winter – just in time for April’s Hybrid Z meet. Seattle to SF’s not THAT far, is it? David

Lots of food for thought. I definitely want peak HP to be below the 5500-6000 range - probably closer to the 4700-5000 range. I don't have a feel right now for what different combinations do to the HP and torque curves. Sounds like I should get myself some computer dyno software and model a few combinations just to map out the relative torque and HP curves. Any suggestions on what software is the best? At the moment, it seems like the constants will be the Vortec heads, dual plane intake manifold, 600 cfm carb, and 12cc dished pistons, with a .040 quench (.025 deck plus .015 gasket). This gives me an SCR of around 9.6:1. I live in the cool Pacific NW, and that together with the optimum .040 quench should let me run on 92 octane pump gas. Now I need to make some cam selections that will give me a DCR of between 7.5:1 and 8:1, then model them on dyno software to select the right RPM range for peak HP and torque. Am I missing anything? Dave

Thanks Kevin and Grumpy for the thoughtful replies. On the advance issue, I might be misinterpreting Kelley's program, but he asks for the lobe separation and the intake lobe centerline, and then the program calculates the opening and closing points plus overlap and cam advance. In order to make the opening and closing points correct (i.e. match the cam card), I had to enter the lobe center as stated in the catalog or on the card, and then enter 4* less for the intake lobe centerline. You added 4* to go from 112 to 116. I can't get the crower or comp cam sites to come up, so I'll use the crane cam site. Crane cam #113931 has adv duration of 262/268. The card doesn't show the lobe separation, but the PAW catalog lists it as 114* Putting those figures into the Kelley program, I have to set the intake lobe centerline at 111* to get the opening and closing degrees to match the card. Intake open and close is 20/62 and ex open and close is 71/17 with an overlap of 37* The dynamic stroke length is 2.76782 and the DCR is 7.8490:1 (with an SCR of 9.6:1 with 12cc dished pistons). It is interesting to compare this to the Crower 270HDP. Both have the about the same intake closing degree (62 vs 63), but the Crower has 49* of overlap, while the Crane, (due, I think, to the 114* lsa) has an overlap of only 37* The Crane has about .06 more DCR than the Crower (7.85 to 7.79). Another interesting comparison is the Crane 113941 to the Crane 113931. cam # 113931 113941 Adv dur 262/268 268/280 overlap 37* 50* lsa 114* 112* intake close 62* 63* DCR 7.85 7.8 Based on grumpy's comment, the 113941 would be the better choice for me, because it would make more power in the 3500 - 5000 rpm range. I don't need much low rpm power because the Z is such a light car. It's kind of fun to build on paper, because I can change my mind. One of these days I am going to have to make a decision and stick with it. Thanks again for all your help. Dave

Hi, Kevin - My goal is street driveability with a punch. I plan on making this my summer car and driving it almost daily during the summer. I will take it to the drag strip to tune it, but am not building it to race. Thanks, Dave

I am putting my engine together for my 73z and am puzzling over how to pick the optimum compression ratio. My goal is to build a mild performance street motor for the Z, that will spend most of its time in the 2000 – 4500 rpm range. Here is what the engine/drivetrain looks like on paper. SBC 350 block bored 30 over; 3.48 stroke; 5.7 rod length Vortec 64cc heads machined for higher lift, with stock valve sizes Performer RPM manifold Carter 600 cfm carb Quench .040 1 ½ shorty headers into 2 ¼ single exhaust turbo muffler 2004r auto tranny with 2000 stall I can vary the SCR using KB dished pistons, and vary the DCR by the cam timing of the intake closing degree. I am not sure what the practical effects are. For example, look at these two Crower cams, which appear to be pretty close in specs, but have very different overlap and DCR numbers. 267HDP – adv 267/272 .050 210/216 112 lca 4 deg advanced; 38 deg overlap; intake closes at 56 deg. Using P Kelley’s calculator, I get the following CR’s by varying the dish size in the pistons. 12cc: scr 9.6/ dcr 8.2 18cc: scr 9.0/dcr 7.7 22cc: scr 8.7/ dcr 7.4 270HDP – adv 270/276 .050 214/218 112 lca 4 deg advanced; 49 deg overlap; intake closes at 63 deg 12cc: scr 9.6/ dcr 7.8 18cc: scr 9.0/ dcr 7.3 22cc: scr 8.7/ dcr 7.1 I am not sure how to translate these numbers into drivability and power characteristics. I assume that higher SCR equals more HP, and the 270 cam will shift the power curve upward and presumably make more power at higher rpm. Any thoughts? Dave

I ran into an unexpected problem over the weekend in the midst of rehabbing my rear suspension on my ’73 240z. I was working on replacing the bushings in the rear control arm. After hearing all the horror stories about removing the spindle pin to replace the outer bushings, I was expecting a long tussle to get it out. But the spindles, both sides, came out clean – no rust – and with minimal effort. (Better to be lucky than good). When I tried to dry fit the new inner metal tube (that goes inside the new bushings) on the spindle, it was clear the spindle diameter was a smidgen too large to go through it. OK, fine, I’ll just use the stock metal tubes, right? Nope, because they had too large an outside diameter to go through the bushings. (Fortunately, the bushings themselves fit fine in the outer control arm holes.) Hmmm. What I ended up doing was taking my right angle grinder and cutting through each of the replacement metal tubes lengthwise, so they could expand to fit the spindle. That way, I could still get the tubes through the bushings and the now the spindle fit through the tubes. The bushings and tubes came from the Energy Suspension kit, and everything else has fit perfectly. But this set for the out rear control arm bushings were simply the wrong size for my spindles. Has anyone else run into this problem with the Energy Suspension bushings for the rear outer control arm? David

I am wondering what others have done about outside rear view mirrors for the early Z's. I don't want stock mirrors, and I don't want fender mounted mirrors. I did a search and found Pete's write up on the Tercel mirrors, and saw some references to M3 mirrors and 84 300ZX mirrors. Just wondered what choices people have made for their cars. I bought a pair of Vitaloni baby turbo mirrors, but because of the angle on the top part of the door, the mounting angle for those mirrors is not satisfactory. Has anyone used those mirrors without fabricating a mounting piece to change the angle? Thanks, David

I used edead from elemental designs. It is reasonably priced and easy to use. It seems to be pretty effective as a dampener as well. Here is their web site. http://www.edesignaudio.com/ David

I'm less than two months into my Z car. After I was able to buy a rust free car for $850, I thought I might be able to do the swap and finish the car for under $5k. Hah! But I didn't know enough to create a realistic budget. As it is, I still may be able to get the basics done for under $7500, excluding paint. I am building a street GT car with a mild SBC. I chose the SBC because it has to be the most bang for the buck of any engine on the planet. Something that has helped me immensely is that I have a friend with knowledge and tools who is guiding me through this. It has already saved me from making mistakes and wasting time going up blind alleys. Still, there are lots of compromises involved in that $7500 figure. That means the stock diff, not an lsd. It means no headers, no rear disc brakes, no cross drilled front rotors, no aluminum heads, no roller cam, no Autometer gauges, no coil overs with camber plates, no 16" Panasports, no roll bar, no spoiler or front scoop or flares ... But, it does get me a self-rebuilt mid 200hp very torquey engine, nicely dressed, a 2 1/4" exhaust with a great sounding hi flow turbo muffler, auto tranny with aftermarket shifter, decent aftermarket seats and steering wheel, new carpet & sound deadener, 4 piston front calipers and new stock rotors, new bushings all around, tokico struts, power steering, and a simple cd head unit feeding two very nice 6x9 speakers. The way I look at it, its a work in progress. I hope to get things mostly together by summer, enjoy the heck out of it, and then take my time fulfilling my wish list. I'm sure that several years from now, I will have doubled my investment, but it probably won't seem so painful since it will be done slowly over time. And it will be fun doing it. To me, the hybrid 240Z is the perfect project car. It is very good as is; the sbc is a simple and beautiful engine with tons of cheap aftermarket parts; and its all simple enough that a newbie hobbiest like me can eventually figure it out, especially with a little help from my friends and this forum. Dave