Pop N Wood

I'm 43 and watch SpongeBob Squarepants... Somethings never change.

Might not be related to any of your problems. But the early Z's had airflow problems through the radiator. Datsuns's fix was to install a sheet metal shield between the frame rails that extends from the back of the radiator to somewhere near the steering rack unit. This was to cut down on the turbulence underneath the car. This is a stock Nissan part. Also the JTR manual goes on and on about installing a fan shroud. Seems likes a good idea. I don't know if anyone has mentioned this but flushing the engine block can't hurt. If you bought the car used there is no telling how many cans of stop leak might be gunking up the works. Know this one from personnal experience.

Want to second what 383 said. I have a carbureted 1970 240 that had to be CA smogged. I use to think I could lower the overall emissions by leaning out the SU’s prior to the test. The other numbers did go down, but then it failed the CO part. After a couple of tries I found the emissions were lowest when the engine was tuned to run the best. Who’d a thunk? Just keep a well tuned engine and the emissions should take care of themselves. Don’t have any experience with a 76 Z, I assume it is fuel injected. But I would say doing a complete tune up before the test is the first place to start. Pay attention to anything that could cause a lean condition (such as vacuum leaks, bad O2 sensor etc). Mine also had trouble with worn throttle shaft bushings causing a lean condition at idle. Figured this out by squirting starting fluid around the bushing while watching for a change in idle speed. One thing that did help me was replacing the smog pump (maybe not a solution for everyone since mine went totally bad). Pump enough clean air into the exhaust and all of the percentages will drop. As a guy working in a nuke plant once told me, “The solution to pollution is dilution.â€

My 70 240 has an R200 in it. When I added the new diff all I did was turn the existing front mount 180 degrees front to back. I don't even know what year car the R200 was from. Check with MSA, they may all use the exact same part.

I knew this guy who welded 2 Viper V10's together and grafted the whole mess into his bug eyed sprite....

I second Phantom's comment. My 70 240 has either 150,000+ to 250,000+ miles with a single rebuild and I don't think I have ever had an engine problem.

Yeah, Bryan is right. That was the other thing I had to do when replacing the master cylinder.. swap the break lines front to back. The early models and later models are reversed! I remember I got the directions off of the Arizona Z car web site when I was considering their 4 wheel disk set up several years ago.

I have century welder. Sorry to hear others have such a low opinion. Mine is a 220V, 145 amp DC unit. I got it close out at a SAMS club for something like $300 about 4 years ago. I have had zero problems and it seems to do everything I want it to do. Being 220V and DC means it is not exactly an entry level so maybe the quality of this model is a little better than the ones in the Sears catalogs? Of course I have never heard anyone say a bad word about a Lincoln or Miller so that says something. Would like to second all the talk about getting a gas version. It is a little more money up front but cheaper in the long run due to the more expensive flux core wire. Also the smoke from the flux core wire is a killer. Harbor Freight Tools is a good source of cheap bottles. My brother welds for a living and swears by just straight CO2 for mild steel. He got a used CO2 bottle from an old vending machine place for about $15. Also, as a fledgling MIG welder myself (I am a killer with a torch), I find getting decent welds in sheet metal is more of a graduate course than beginners. Once you burn a hole you have a problem. I have had some success filling them back in by doing short, 1 second burst just to build up metal around the edges of the hole. Once the hole is kinda goobered over you can weld through it to get a pretty weld again. Keeping everything clean (no paint or rust in the weld area) seems to help. Switching the polarity of the welder (positve to negative) seems to help but I can't remember which way worked best. One other comment about wire. My century manual says wire should be thrown out if it is left open for too long...even the copper coated stuff...or it won't feed right. I am too cheap for that so I always buy the small spools. I have noticed older wire does slip a little more causing the weld to stutter and pop. A killer when you are working on sheet metal. What is everyone's opinion of AC vs. DC welders? When is one better than the other? Also I have heard that welding on a car with a computer can kill the computer. Is this always true and what exactly needs to be done to prevent damage? Remove the computer?

SuperDan A couple of guys have posted the fix...you need to adjust the length of the rod that connects the brake pedal to the brakes! The reason you feel no breaks for 95% of the travel is it takes that long for the rod to touch the back of the booster. I had the exact same problem with my 70 when I upgraded to the later model master cylinder. On my 70 the rod is adjustable, sort of one screw inside another. It took an inch or more of lengthing to make the brakes start to work with the first inch of pedal travel.

Good to see someone else going round and round with Grumpyvette on this one... I've done my turn! I originally wanted to put a 327 or 302 in my Z. In the past I have had several people tell me that the light weight and narrow tires (without flares) of a Z really limit it’s ability to handle a lot of low end torque. One guy even told me his 283/auto trans equipped Z was faster than his son’s 350/4 speed Z because the smaller engine was so much quicker off the line. But a couple of things have combined to change my mind. First is the availability of aftermarket parts. The way I see it, if you want a 302/327 the options are to get a 60-70 vintage junk yard engine OR custom order a rotating assembly. Maybe these items are easy to get at swap meets but there aren’t a lot of internet sites stocking 302 cranks as standard items. Most places do stock 383 stroker assemblies thus their prices are much more competitive. The other thing that changed my mind were several comments from Grumpyvette. Build a 350 with higher RPM HP in mind and get more HP with the same low end torque of the smaller engine. Most crate engine designed for street cars use things like dual plenum intakes to boost low end torque and are being marketed with heaver cars in mind. And from what everyone on this posting is saying, a 350 can be made to rev just fine! One question for the experts: for the longest time every car magazine out there was publishing articles about modifying a 350 to use longer rods (I think 6 inch instead of stock 5.7 inch). What are the draw backs of NOT doing this and wouldn’t a 327/302 already have the more favorable rod geometry?

The 1969 Camaro had an option for a 302 rated at 290 HP (which unless I miss my quess is a 283 bored 30 over). Most publications said this was a very conservative estimate so yes, one could argue the factory made a 300 HP "283". That same engine had an option for a dual 4 barrel "Smokey Ram" intake that hung the separate Holley's to the right and left of each valve cover. Each carb feed the opposite bank of cylinders. That is still (IMO) the coolest engine I have ever seen. Also remember the Ford 289 (similar class of engine) was Shelby's first choice for the Cobras and GT40's; two cars that have nothing to apologize for. Before anyone beats me to the comment, Chevy limited displacement of the engine to 302 CI to be eligible for a specific class of racing that was prevalent in 1969. So yeah, all else being equal, you can get more HP and a fatter torgue curve out of a larger displacement engine. And yeah, in this century 350's are much more prevalent and have more aftermarket parts geared specifically toward them. So unless you have a 283 lying around it is could cost more to build. But, having said all that, a shorter stroke motor is still a very good choice for a light weight road racer like a Z. Notice I said "good" choice and not necessarily "better". Put too much low end torque in a Z and you had better have a calibrated foot to keep from spinning the tires off the line. For drag racing, go with the cubes. But then again, if you only want to go in straight lines you are missing half the fun of a Z. Perhaps an old Nova or 69 Camaro is a better place to start.

I have a century welder I bought close out at Sams club. Good welder, no complaints. They are also very common so repair parts should not be an issue. Every one from Sears to Home Depot sells them. Make sure you get the gas kit. Without the gas you need to run flux core wire which is more expensive than plain wire. Smokes like hell and splatters more also. Also make sure you get adequate amperage in case you want to weld anything heavy. Usually welders that go to very thing gages don't have as many amps.

If it is just a crack, couldn't you try brazing it? Actually the guys before me sound much more knowledgable. But WTH, if the only alternative is to buy a new one it might be worth a try.

Another problem might be something arced when the polarity was reversed. This could deposit copper/metal dust inside switches shorting them out from contact to contact or to ground. Also if you blew fusible links then there was some serious overcurrent going on. this could have overheated insulation in a wire causing it to break down. No easy answers, just need to trace the wires and check each component one at a time. Harbor Freight sells a tool that is suppose to help find shorts in auto motive wiring. Here is the link http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=33779 I have no idea how this thing works. If you buy this (only $18) be sure and let us know how it worked out. Good luck

With any of these things you're going to spend more money than you save. My 70 240 gets 26 MPG now. If you want to improve on that a cheap 4 banger is probably the answer. Shouldn't a Nissan 4 cylnder out of a 510 bolt right in? You could probably pick one up at a boat yard since about all they are good for is boat anchors (haha). No really, they should be pretty cheap. I've heard of people going the other way (a 2.4L 6 into a 510) but never the other way around.

Doesn't MSA carry points lube? Just wanted to say make sure you use a "dielectric" grease. Anything else might conduct electricity causing arcs inside the cap.

I usually go to a mom and pop style autostore. The brand names I use to get were Standard Ignition. I say avoid the chain store ones because I have had bad experiences in the past and it is a bitch to figure out when brand new parts are bad. But, it has been several years since I bought ignition parts for my Z. If MSA doesn't carry them then I am sure Nissan does.

I guess I could live with "only" 425-450 HP. It would be a step up from the inline 6 anyway . Thanks for the info. Once again, your words speak valuable and true. This board is sure cheaper and more to the point than any Hot Rod subscription.

Grumpyvette once posted the following link which is very good: http://www.bob2000.com/carb.htm

Got on the boards late, but looks like you have it all figured out. Just wanted to say that if you are backfiring the first place to look is the ignition. This is often caused by cross firing between cylinders. The fix is a new distribtor cap, rotor and points. The inside of the cap should be clean. Any dust or brown soot is usually evidence of more than one plug firing at time. Replace the cap (and not with a trak auto cheapy). I have a 70 Z that had SU's. Another way to check for vacuum leaks is with starter fluid. Spray some around the throttle shaft bushings and if you see a change in the idle RPM, they are leaking. My Z use to need premium gas and octane booster because of leaky bushings. New carbs made it run fine on regular.

OK, one last question (maybe two). Read what you forwarded and found it very informative. I especially like the Ryan page...will spend some time on that. I am comfortable with the math and physics and already understand the concept of volumetric efficiency. From reading other postings I now realize you often recommend balancing the available intake pieces, but seem to prefer canfield heads when they are an option. But the question I still have is when is more engine too much, especially for a Z? I don’t want to build a drag racer. My car will be summer’s only street machine that will hopefully see some short slalom club racing. Thus the idle to 2500 RPM band will be more than just something to get through in the first 100 feet of the drive. Now like your articles say gearing will go a long way to keeping me in the power band, even with short tracks. But what I am trying to get a feel for is how much “drivability†can be retained and still have an awesome engine? I know this is a very subjective question. I also know money will probably be the limiting factor anyway. The thought of 500 HP is captivating and since this won’t be a daily driver I don’t mind (and would even like) a grumpy idle. But I would like to stop short of something that would be miserable to drive on a long road trip. The second question concerns your opinions of roller cams. I have noticed in several posts that you like to recommend solid lifter cams. Any particular reason? Thanks again.

Yeow! Wish my cable company returned calls this fast! Looks like I will have a lot more reading to do, thanks for the info. You seem to be saying a lot of what I wanted to hear. Most Hot Rod articles are tailored toward building torque to power heavy cars. But Z specific articles always talk about the trouble such a lightweight car has in hooking up low-end torque. That is why I keep leaning toward a shorter stroke engine. I've always wondered if just building a 350 toward higher RPM flow would do the same (and save me $ using the more common 350 internals). You are one of the first people to give me a specific combo. My immediate goals are much more modest: just find a good donor car and drop in a near stock engine/trans combo. Then, once the paint and brakes are done, start mapping out the go fast parts!

I have been reading these posting for the last week or so and I have a question concerning heads. First let me state that I have been reading about engines since the days before catalytic converters, but I have never actually built one. Years of looking at engine specs has convinced me that one of the keys to serious horse power is the heads. The problem I am having is figuring out how to balance all the advice I have read over the years. Seems like anytime someone asks gumpyvette (who by the way really explains things well ) to select between two heads, he recommends the head with the highest flow rating. Yet pick up an issue of Hot Rod and they are always talking about maintaining adequate flow velocity. Get on the Edlebrock site and they tout their "total power package" and how it matches the induction components. Now I guess my questions are: shouldn't the heads be selected with the rest of the intake system in mind? And if this is true, then wouldn’t it also be true that the higher flowing head is not always the best? If engine drivability and longevity is not totally a non-issue, then how does one scale back the choice in heads? If I decide to go with a 302 or 327 to build a slalom racer that revs, how does this affect things? When is a smaller intake plenum a better choice? GM produced a ZZ430 engine as an example of what can be built from their catalog. This engine uses their fast burn heads and HOT cam to kick out 430 HP. Seems like a pretty potent package. If I had the money for this crate engine and liked this target HP, how would I be better served building such an engine from other manufactures components? Or are you guys saying for the same money I could get a lot more engine? Look forward to any comments or opinions you guys have.

One way you might try calibrating your speedo is with a handheld GPS unit. Most of those have speed readouts which will be more accurate than anything else out there. they are popular with hunters and boaters.

Had a similar problem some years back with my 70 240. Ditto on checking the front differential mount (my problem the first time around) but don't overlook the obvious: check all the rubber pieces and make sure the mustache bar bolts are all torqued to spec.