Zedyone_kenobi

pics of the tach?

That is awesome advice, and my sincere apologies for not including details... I run a Pertronix Flamethrower coil Advance Distributors rebuilt Dizzy that was recurved to close to european specs Vacuum advance plugged up. Pertronix electronic ignition installed. Taylor 8mm plug wires New NGK plugs I am running with a balast resistor with a jumper wire across it. I was looking for a wiring diagram of the 71 to find the tach to coil relationship. I have a 73 FSM, but I know they may be a bit different than the 71. Just for reference, I have a spare tach in my parts bin... but have not checked it out. Your suggestion is fantastic zkars. I will give it a try when it stops raining here. May be a couple of days. As we are getting a down pour lately.

That depends.. do you have all the lines from teh tank to the evaporator back there? When I redid my evaporator tank, I no longer had room for 6x9's back there...

I ask this as I am chasing down a very predictable miss and back fire out of my exhaust around 4000 rpm. I have been playing with mixture ratios and timing and the more I do this, the more I think they are acting just fine. Everything in the fuel and ignition portion of my car is less than a year old. Now I have seen my tach on some days just go nuts and peg at 7000 rpm when I am slowly idling in traffic, but it always returns, and there are other times when I floor it and the tack needle just swings insanely fast upwards 5x the speed my engine can actually rev. Most of the time my tach does behave normally, but it does act pretty funny above 4500 rpm often. So, I always thought my engine was not running well and my tach was showing it. However, I am starting to think that maybe my tach is causing my coil to miss fire and that is sending a lot of unburnt fuel into the exhaust causing the popping. Has anybody had any experience with this. I may try to locate the wire going from the coil to the tach, and disconnect it and then see what happens. This has been a fascinating problem to track down. And electrical problem would explain SO much with the behavior of this missfire.

I have a very recently rebuilt dizzy form Advance Distributors. I run 14 degrees static timing and max out at about 35 degrees with mechanical advance, I have tried this with both the vacuum advance on and off, and still get teh same results. Perhaps my pertronix is going bad. I have a brand new pertronix coil as well. Part of me thinks this very well may NOT be carb related.

My gosh Healy, you have had some beautiful cars!!! You got a think for the convertibles eh

UPdate, as I was starting to troll on Healy Z's thread. I used a colortune to see where I was in my mixture, and low and behold I got a nice pretty blue flame at idle. when I gave it gas I get a very orange color that never quite gets to blue again. I think I am still rich, but I am also starting to suspect other things. My dizzy is practically brand new from a professional rebuilt with new bushing/bearings, etc. All the advance weights actuate very well. I have the Vacuum advance blocked off, as I had the dizzy recurved to match the european specs. I still need to find a wideband O2 sensor that can be read real time. Then I know for sure what is going on at higher rpm.

I do have a go pro camera that could be used for this. But i would need an extreme amount of light under the hood to make it work. But it could be fun. I assume this is all under load we are talking about Blue. I find the SU a very fascinating carb. I have read quite a bit on it and I do understand its function for the most part. What kills me is when I installed these carbs from Z therapy, they performed flawlessly to 6500 rpm. I have since had my dizzy rebuilt and recurved but nothing extreme. I somehow think this is not fuel related any more. My SU's are fresh off a Z therapy rebuild and they look and feel amazing. The car idles and performs FLAWLESSLY below 4000 rpm. But its a backfiring wall at that point.

Hooked up my colortune in the number 1 position last night, dimmed the lights in the garage, and started her up. I had already warmed the car up by driving it for 15 minutes prior to this. When I walked around the car to see if I could see any flames, it was a beautiful light blue. When I revved the engine it turned very orange/yellow and bright! So, initial diagnosis. My idle mixture is pretty darn close, and any throttle input is met with extremely rich conditions. I tried holding the throttle in a fixed location, and the flames never went back to blue, but stayed orangish. I will try using the screw to hold the idle dead steady and make a note what happens. Well whatever I am I am not far off. So leaned it out a 1/4 turn and went for a drive. Car drives flawlessly up to 4000 rpm. Then as predictable as clockwork, it pops and stutters badly out of the exhaust. I am starting to wonder if my oil level is wrong or maybe I need a different viscosity SU oil. I checked my needles and they fall straight back into the jet smooth as butter. I know I have good fuel pressure, but I have not checked my float levels, but like Bruce says many times, They were set from Z therapy a year ago, and I see no reason why they would have changed. So I am going to keep playing with this as best I can. I will try to make a video of it working...if I can find my camcorder.

Yes, I will MOST definitely plan another trip for next year... i the warmer months. It will be more grand this next time, I guaranty it.

do you pop from the exhaust or form the carbs?

OOOOh data with a reference measurement.. now we are talking!!! Add a few more sensors in there, and we will start getting in to NASA levels of measurement rigor. Ask me how I know!

That band is not color related Healy Z the color of the flame is due to heat, leaner mixtures run hotter (whiter), while richer mixtures run cooler (more orange) I do not think you will go orange/blue/orange. I get my colortune tomorrow.. we can talk over the phone if you like and we can compare results and try out ideas. remember you cannot tune one carb totally independent of the other. The balance tube dictates you will get some cross talk. I have a testing arrangement in my head in mind, but I really look forward to playing with this toy. IN the end, I can easily see myself getting a portable O2 sensor, and getting fittings welded into my header. But this seems to be a great first shot. I want to echo what Blue has said in countless posts... reading your plugs is an irreplaceable tool...to knowing what your engine is doing. It is the equivalent of drawing blood and running labs. Plugs do not lie. I just need a whole day to mess with this, and I am hoping to have a week off of work to play with my colortune. Healy, PM me your phone number and we can chat if you like with our colortune experiences!

Yeah, so cars are in essence, really good for trees.

I would think this tool would be ideal. You have to set SU's fuel mixture at idle anyway, so it should get you pretty close. I ordered a colortune this week. I am hoping that at night with the lights off, I will get a good color reading. I just want it a bit blue. I still think I am running rich as I am popping out of my exhaust anywhere above 4500 rpm. That may be my needle though. I checked my records and I have SM needles in my rebuilt carbs. That may be too rich for a stock engine.

Any news on your results with a colortune?

Did you consider running a T so both carbs could help suck those fumes? Not really needed just curious. Love your car

I am going to throw some more light on the areas that have already been lit up. First let me commend you on entire engine thinking, and trying to match all the components the way you are. Good show. Now building a short stroke is a sure fire way to build an engine that is capable of spinning. The smaller diameter spinning around does make it spin easier, but another reason, that is JUST as important if not more is the angle of incidence of the rod to the piston bore. A short stroke long rod combination means the rod is never at that extreme an angle form parallel to the axis of the cylinder bore. Small block Chevy guys destroked a small block 400 by putting a 350 crank in it thus creating a 383, which would give torque and revs. A potent engine for sure. My greatest engine creation was a small block 400 with a 6" long rod kit and custom pistons with the wrist pin moved way up almost into the last oil ringland. It had the killer torque of the long stroke 400, but with such long rods (stock rod length was 5.565") it could still rev to over 7500 rpm. L28 to get you displacement is a good start. Displacement is free torque. USE IT. L24 crank to get you the smaller stroke and thus smaller angles against your cylinder bores. Good, that will make sure it can spin Rods, not sure what to tell you but get the longest rods you can fit and get custom pistons that are flat tops, the less reliefs or domes on your pistons the better. A featureless flat top aids in fighting detonation. The aluminum head will help you out as well, but I cannot quantify how much. I would not fixate on compression as much as I would about flow. Get large CC combustion chambers and get them blended and smoothed. Everything up to this point is about building revs. Keep that going with a LOT of smart head work. Does not have to be expensive, but the mods you choose must be smart. Strong valees that are large and properly undercut. Smoothed out intake and exhaust runners. Good set of springs that can handle the rpm you are looking to run. Naturally a good set of bolts and studs to hold it all together is important. Lastly, a CAM that will enjoy being up top. This usually means more duration and more lift. For a streetable car in a small block chevy, I can pick a cam rather easily, but I have no experience with L series cams. I would usually tell people to pick the smallest cam that will get you the rpm you desire. But I have heard that L series like bigger cams. I cannot speak intelligently on that. But if driveability is a trait you desire, the closer to stock the better. Lastly induction and ignition. Both must be in tip top shape whatever you choose. For an RPM engine, I would be inclined to go with triples, but I would bet a set of SU's would work darn nearly as well. I actually plan on building an RPM loving L24 one day in the future. the lightened flywheel and crank pulley will make it spin crazy fast as well. keep the weight down and your revs will climb quickly.

you know there is a nice 72 911RS clone for sale around here.. HAHAHA

This is the issue I keep running into guys and that is why I wanted to put together the great Texas Z rally. the Blue grass 1000 is almost 6000 dollars The california MM is right at 6000 dollars Their are other targa and rallies listed on vintagerallies.com, but do not bother looking, as they are ALL about 6000 dollars. This just seems insane and keeps the little guy out of them. I don't drive a classic Ferrari and have 6000 dollars of disposable income just laying around. I put a 3 day rally together and it would cost around 400 bucks including lodging. There is certainly no reason these should cost 6000 dollars. First class accommodations for 5 days might run you 1000 dollars, and you figure 500 bucks for food for the week if you eat VERY well at every meal. Then Gas. Then a nominal entry fee. I see no reason this should cost anywhere near 2000 dollars. I realize that these events are usually for a charity, which is great, and I am happy they are doing it. But for a working class guy with a family, I NEED NOT APPLY. I am going to push forward with the Great Texas Z rally again in spring time when it gets a bit warmer, but NOT texas hot. The roads around fredricksberg are awesome and the prices are less than half of what these guys charge. Mike W actually still went this past weekend and he said everything was wonderful. I plan to double up on amenities and handouts next time and by gosh I will be going! l plan for the first few weeks in march or april and look back on this site. I will have an event worth your time and I promise you it WILL NOT break the bank! I have had a dry run at getting this together, and learned a few things. I will have something even better planned for spring! Mark my words!!!

OH thats awesome! I still have to go pick mine up. My dad has my schedule all messed up! Glad it turned out okay.

you said it had a 370 rear end, is that a Datsun rear end or did he swap a solid rear axle. Also, the Dart 2.02 heads are almost a grand by themself if they are aluminum. If he has solid lifters than he running a rather aggressive cam and valve adjustments are something you will need to learn to do. Not hard, but it is maintenance that will be required. Roller rockers are just par for the course with a large cam, no biggie there. You need to find out if they are 1.5 or 1.6 rockers for future use if you buy it, so you can more accurately calculate lift. Lets see, buy the looks of the accelerator pump diaphragm in front that is a Holley carb. Not sure if it is a double pumper without looking at both sides of it. He is running an MSD box on it, what kind of distributor does it have? An HEI GM one or an MSD one? Not the worst built 350 by his numbers, but you would need to know more about the pistons, name brand, rods, crank, cam size, etc. Are the heads aluminum or iron? THe carb is not hard to work on at all. Holleys can be tuned with great ease. And they are dirt cheap to replace. Not the best carb for fuel efficiency, but for power, they are awesome. I grew up working on Holleys all day long. I can rebuild one blindfolded. Keep one thing in mind, you will be purchasing a car that will require lots of maintenance. You have no idea of the quality of the swap, or the wiring. Be prepared to have to redo somethings. I think 5500 to 6000 is not out of the question for this car. Maybe as high as 7000 since the body appears straight by the photos, but without closer inspection I will give him the benefit of the doubt.

I agree with that so much John. There are installation and build tricks that make a motor make more HP with the same parts. Bore size and shape influence sealing. Building a motor loose so it spins faster and easier frees up HP. Custom balancing and lightening parts helps as well. Some people say money is they key to speed, but in reality, money is merely an enabler, the real key to speed is knowledge.

That is great, and I was hoping to hear that type of description of the place. I am looking ahead at the calendar to see when we can reschedule this. I am dying to driving in the Z, but my time is spent at work and at the hospital these days. I hope you took some pictures Mike! Thanks for being the brave one who did not let a little rain scare you off!

That does not sound like him.. interesting