John Scott

If your carb box doesn't see vacuum when the throttle is closed you might not have any vacuum issues with the Mallory regulator. My carb hat had a similar port for referencing mechanical pump, but ran mine from manifold with the thought closing throttle butterflys, manifold would see vacuum sooner, create a quicker signal to the regulator. Throttle spring was strong enough to shut air, but would strongly recommend a relief valve. Before I had pressure relief valve, carb hat would stay pressurized, even when I let off. In my case after WOT, too much residual fuel pressure caused carb to run very rich at idle cruise, due to overflowing float bowls. Big return line, relief valve, check valve, with line from manifold, resolved this for me. A relief valve on your carb box might do the same. Read above posts if Mallory regulator still drops fuel pressure with vacuum. The booster check valve I found was on one of those cheesy HELP displays at the local autopart store. You'll need a pump capable of delivering xxpsi over boost. I used Mallory 140 (-8 lines, will fit) internal regulator set to wide open so pump can attain 22 or so max psi. Sam at century performance gave some tips with this pump.

I always wondered this as well. V6 Holley carb was almost as long as my intake! Plugs were always on the rich side. Use was street so I appreciated the PV for driving around, ditto with my current 383. My NA drag buddies swear by the plugged pvs front and rear and square jetted. Road racing carbs generally have pvs front and rear square jetted. Always wanted to try square jetting with direct rather than progressive linkage, but never found the time. What's best with forced induction.. this is all way out of my league, so I'm outa here. John

You'd have better luck at the http://www.volvospeed.com, or some of the other volvo sites. A 300+ hp T5 would be cool in a Z. S70 owner-John

The TBs sound like the ticket!

The boost referenced Mallory 4 hole (one in, two to carb, one return) used a port at the top of the unit to control fuel pressure relative to boost. (Mallory is probably way too small for your application.) The flaw was when you set the pressure to 7 psi at 0 engine vacuum, anytime the engine would see vacuum the fuel pressure would fall to the point where the car wouldn't run, or safely so. Set pressure to work with crusing vacuum and too much pressure at low boost would overwhelm the needle and seat. Mallory was of no help, so I came up with the idea of adding a 1/8" power brake booster check valve, and put it in line with the regulator port. Now anytime the engine would draw vacuum, the valve would close and keep the regulator thinking it was at 0, rather than vacuum, thereby maintaining a constant 7psi at vacuum conditions. Testing the system, plug the lines going to the carb, (I just looped them back on themselves, the second time!) with an in-line fuel presure guage. Use another guage cabable of reading what boost you are going to run, in line with the port on the regulator. With fuel pump running set fuel pressure to 7psi, this will be the base pressure at 0 vacuum/boost. Then add pressure from hand pump or other source to regulator port and confirm your fuel pressure is rising with pressure. 7 psi on the regulator port should result in 14 at the fule lines. 15, 22 and so on. Don't laugh, but my mistake was testing this with the lines still on the carburetor and filled the cylinders and engine up with gas so fast it was running out the manifold. I ran to uplug electricals in the garage, and had quite a mess to deal with. Holley needle and seats fail around 11 psi. I was hoping that newer regulators have addressed this problem and now have check valves that don't let vacuum effect the fuel pressure. BTW I used just a carb hat, sealed choke linkage hole (JB) milled choke horn, nitro floats, same needle and seat as Turbo meister, 6.5 PV, primary jetting close to NA, plugged rear PV a few steps richer. 7.5:1 forged, cam was 232 @ .050 114 lsa, but only had 262 cu in. Start way rich. As you know, under boost by the time you found out you are too lean, its probably hurt something. Don't want those pretty new pistons to look like whiffle balls! John

dr hunt, I know T-Meister was using a referenced mechanical pump, wondering what type of regulator you were planning to use. Not trying to P!$$ with the big dogs here, but had some personal experience with my 4.3 using electric fuel pump and the Boost referenced Mallory 4 port... and how to get it to run right. Maybe the new boost ref. regulators don't have the gliches of the old Mallory and this will all be pointless. More to it than just running a line to the reference port. With the Mallory, correct fuel pressure at vacuum conditions and then having too much at boost used to befuddle me, i.e. 7 psi from vacuum to 0, AND consistant 7psi over boost to 16 psi (23psi fuel)boost. Easy to overwhelm the needle and seat on a holley. Had a crankcase of gasoline once testing the system. Stupid me. Found very simple solution to get it right in all conditions. Won't say any more if you already got this figured out. John

Dan, I had to laugh with that post, and well yes and no. If you like to just get in a go, FI is perfect. Especially for a reliable daily driver. My fantasy Z car has a twin turbo FI gazzillion HP unit, but I haven't won the lottery yet. For me on a limited budget, having FI would be a compromise in power. Not buying an expesive FI system frees up more $$ for solid roller cams and rockers, nice HP carb, etc. I'm not up on FI so I don't know if they have aftermarket systems that work well with big lumpy cams. The last shoot out I read, about 1 1/2 y.a., carburetion left the FI behind in the horsepower, but FI had a more consistant dilivery. FI is superior in most situations. If you ever looked at the fuel numbers coming off the top engine masters dyno runs, they have carburetors so well dialed in they match or surpass a FI system at all rpms. Kinda' cool thinking a person acomplished that, not a computer and O2 sensor. Some guys actually enjoy diddling with jetting, timing, adjusting, pitting their expetise against the other guy. Makes the carbureted racing series more interesting. I'M not that good, so In the meantime you can laugh at me when you start your car on a cold morning and motor off, and I can believe that dollar for dollar I have more ponies under the hood. John

Thanks Bartman, always good to see the other side, especially with a Grumpy recommendation. Wonder how they compare $$ for $$ for horsepower?

What caught me in your post was cheap. I would go with the engines that are popular, have a big aftermarket following.... like a chevy or ford. Check what Summit or Jegs carries for 99% of the magazine. Looking for performance parts on an obscure engine can be tough. There are some Cad sites that cater to these old beasts, but I bet they are more expensive than the tried and true. The old way of hp rating 365/535 hp and tq ratings dipped to 285/385 when they converted to net hp and tq. Big cubic inches don't always equate into high horsepower. Looking to be different? Don't let anyone stop your passion, but IMO a more common engine will be $$ and horsepower ahead. John

Wow .6 is a big gain, especially getting into the 11s! Timing, jetting, adjusting, and then, at least around here, you get a completely different weather system and get to start over. Thats the sport of it. Changing around the hard parts, headers, cams, rockers, seems like more permanent gains, but can be a bit harder to play with for finacial reasons. I know my headers are going to stay put as are nearly everthing else. When I get the money I'll talk you out of your twin turbo...once you got it dialed in John

FI guys and other experienced tuners can laugh, but we all find "new to us" discoveries that make our day worthwhile. I fell into the rut of going with Holley recommendation of 1# down for every 2000' etc, then never changed the jets. Don't go to the drags lately, so what I didn't know didn't hurt. I don't know why I never did this before, but doing a web search I found a density altitude calculator http://wahiduddin.net/calc/calc_hp_dp.htm and plugged in our local conditions. Die hard racers already know this, but its amazing how much a change in temperature, humidity, pressure effects the air. At our 4662 altitude, the altitude density on a 70 degree day, typicall humidity (dry) and pressure, results in a 6000'+ density altitude. Yesterday even though it was 46 degrees, altitude density was still 5500'. Bandimere Speedway at 5800 feet sees over 10000+ on summer days. Makes you really appreciate those 10 second street cars that drive to the track! Recently changed my valve stem seals on the AFRs, and jetted for 6000'. I also read less air, more timing, so bumped it a couple more to 40 degrees total. No detonation, crisp. BINGO! I could always roll on a 1st, 2nd, sometime 3rd, burnout, never had instantaneous punch to redline bouncing off the 7000 limiter. "Like being on ice" doesn't even come close to describing the responsiveness. It puts the tires up in smoke so fast there is little thrust forward. I'm checking on track tune days so I can really play with this, but still have 2+ months to go before opening day. Live it up in the Sunbelt! John

Ahh, the good old days. Back when you could be a hero with a jetting recomendation, blower pulley update, or TV cable adjustment. My interest comes and goes, usually acording to my income, but to HybridZ's credit, (administrators, moderators, die hard fans), it has grown into a phenominal site with more talented...( and scary fast) members than ever. Still the only real source for this nasty addiction. I'll stay off the site and out of my car for weeks, sometimes months, then after a drive, get reinspired. I feeling like I had to sell mine a year ago, but still manging to pay the bills. John

Lee, gald to hear you are still around. Always looked forward to reading your posts in the days when HybridZ was small. Guys, this is the founder of the F150 clutch master swap for T5s, aftermarket T56s! Brilliant! Good luck! John

I can't afford to fill mine with gas lately...but even if you can't throw your money at your Z the way you'd like its great following the posts of the "first drives", the latest best e.t., and heck we have two more twin turbo V8s coming!

I was told by my last builder to let the head airflow pick the cam. Go custom grind. Wondering if the CC custom billit cam has the option for a cast gear for traditional distributor gear use? I didn't like the idea of pulling the distributor on a regular basis to change out the bronze. Isky had this option when I orderded my solid roller...I though all SOLID roller cams were billit?? Enjoy hearing the progress. As in Finding Nemo: "Dude, you got some serious thrill issues!"

Let us know, hopefully a day when the roads are dry and other HybridZs can come. Can't wait to see it, though it will send my Z home with its tail between its legs. John

Thanks for the reply. Yeah, $70 or so is alot for a few decibel reduction... But if it would keep me from getting pulled over.I looked into some perforated sheet metal suppliers, but was boggled by the assortment and didn't know the ideal open hole to surface area. I guess I could stuff a big spud or maybe my wifes panty hose in there

Yes. From over head view, similarly, engine can be offset left or right as long as the centerline is parallel to the centerline of the differential. John

Or a 10 second car. I hoped I worded that further into my post well enough not to appear to be recommending the stock 200 for a 9 second car, just that it was amazing how the stock rear was holding at these extreme levels. Anyone remember Nosz 350's 60'? His old video looked like the front tires were still touching, barely. John

No wheelie story, but how soon we forget. See below. 1fastZ ran 9.71@147, NOSz350 9.28 @153. Two of our fastest members used STOCK R200s. Thats with U joints, boys. If my math is correct more than 750 hp! I recall 1fastz started blowing his with abusive shots of nitrous. This isn't saying they lasted forever, but the fact that they could pull those times at all on a stock rear is amazing. I know the solid axle is stronger and safer, and yeah I hear the stories of all the blown rears with stock L6s, but minimize your rear squat, the binding angles and u joints are pretty damn strong. http://forums.hybridz.org/showthread.php?t=68008 John