Pyro

a copy/paste from I don't remember where......... What some people will say in public. This is absolutely false, of course. Try to conceive of blowing on something hot, say a spoonful of soup, first slowly and then more rapidly. Which cools faster? For extra credit, try imagining the same spoon with first slow and then fast water moving across the bottom. Sheesh! The issue with running without a thermostat is two-fold. The first part is that the thermostat provides drag on the water flow. This drag increases the backpressure the water pump and all of the enginesees. This additional pressure, over and above the nominal 15 psistatic pressure the radiator cap sets, raises the boiling point of the coolant. The reason this is important is that it suppresses localized film boiling at hot spots such as around the exhaust port. The transition from nucleatic boiling (bubbles of steam originating from irregularities on the surface) to film boiling (where the hot surface is coated with a film of steam) is called Departure from Nucleatic Boiling or DNB. DNB is very bad, for steam is a very good insulator compared to water. Once DNB occurs, the area under the steam gets hotter because the steam doesn't remove very much heat, adjacent metal which is still wetted heats from conduction. DNB happens there. The process spreads until substantially all the coolant-wetted surfaces are insulated by a film of steam. The engine overheats. In addition, the buildup in steam pressure forces the radiator cap open, bleeding coolant, therefore making the situation worse. The second issue is that of water pump cavitation and surge. If the pump is operated at high RPM with insufficient head pressure(provided by the frictional losses in the coolant passages and the thermostat), there is a great likelihood that the pump will either cavitate (localized boiling and/or degassing on the impeller) or surge (an unstable flow regime). Either phenomena is destructive. Cavitation's collapsing bubbles act like little sand blaster, eroding away impeller material. Surge can do the same thing and in addition, can vibration stress the impeller enough to break it. Many times what looks like corrosion damage to the impeller, especially when the housing is damage-free, is actually cavitation damage. The myth of velocity originated among those unschooled in physics or thermodynamics, I suppose, because a common racer "solution" is to press a fixed restriction into the thermostat housing neck when no thermostat is desired. The conventional (but wrong) wisdom is that the restriction "slows the water" as stated by the previous poster. In reality, all it does is provide some more dynamic pressure in the block by restricting the flow. The exact same result could be accomplished (assuming the water pump doesn't surge or cavitate) with a higher static pressure (cap pressure), assuming the system could withstand it.

I wouldn't use stock 73 truck springs. However, there would be no need to do expensive head work to allow for the larger diameter springs. A set of the old "z28" springs (stock diameter) would be good enough with that cam. You could try the stock springs but I would bet there will be valve float at 5500 rpm. When you disassemble the head to change the valve springs, that would be a good time to do a little bowl work on the heads. Just spend about 5 minutes smoothing out the area where the head meets the valve seat (about 1 inch under the valve). There is typically a big edge there and some casting marks. You can pick up 20 or 30 hp on stock heads with this simple procedure. But don't hit the top of the valve seat with you grinder or else you will be getting another valve job. 7.5 psi of boost will add 50% more power. So the more power the engine makes off boost, the more power an engine will make on boost. For example, a 250hp engine will make 375hp with 7.5psi of boost and a 300hp engine will make 450hp with the same boost. That 250hp engine would need 12 psi of boost to make the 450hp. So, the power your engine can make off boost is important also. Therefore, cam, springs, intake, head work, ect, can all help make more power with boost. What transmission and rear end ratio are you planning to use? Make sure to use diesel engine oil with your new cam.

check out these turbo cams from compcam. cam number: 12-252-4 212/212, 112 LSA, 0.447"/0.444", power range 1800 to 6000 rpm or cam number: 12-253-4 218/218, 114 LSA, 0.462"/0.455", power range 2200 to 6500 rpm

Not a good turbo cam. Turbo cams have wide lobe angle seperation (112 to 116) Plus, turbo cam typically have more intake duration than exhaust duration. Go to Compcams website and check out their turbo cams for the chevy small block. If you build a 300hp engine and then add 7.5 psi of boost then it will make 450 hp. Or if you build a 270hp engine, it will take 10 psi of boost to make 450 hp.

Typically you would need to machine the head to hold larger diameter springs then use high performance retainers which normally raise the spring install height about 0.050" to 0.100". Also the valve stem seals used can effect the total lift. What heads do you have and what cam do you want to run?

I have run a lot of n20 with a dual plane intake without any problems. 150 to 275 shot. why build a 283? A 350 will rev just as high. I shift mine at 7200 rpms. You are giving up 80 ftlb of torque and 70 hp by using a 283 instead of a 350. That is 1/2 of the n20 shot you plan on using! Plus after market performance parts are geared for 350 and larger engines. Hard to build compression with a 283 with flat tops and 64 cc heads. Domes will be required and that is bad for flame travel and adds a lot of weight. And as you already know, a big port intake and a little engine kills torque even more. Let me guess.... is this a S&M thing?

Would run better with some 4.11's Cam looks ok. But you really should be comparing the duration at 0.050". My Z with a 292H (244/244) and a 200 shot would run 110 in the 1/8. Using less head (iron eagle), less intake (RPM), and less carb (3310, 750), but more gear (3.90) and a 5 spd. Not sure if that information helps you, but I sure like that old school 292H. Revs to 7200 rpm and is easy on the valve train. I feel those extreme series cams cause a lot of valve train problems (float and wear). In any case, use diesel engine oil with your new cam.

A mechanical fan needs a shroud. Kind of like shoes need laces. I guess you will need to run an electric fan. A ford taurus fan is a good choice. I recently helped a friend do a V8 conversion and the mechanical fan didn't work so good because the shroud didn't fit very well. So, we decided to make a custom shroud. But in the mean time, he installed a ford fan and it works great on the single core alum radiator. However, only have run it during 90F ambient and it pulls a lot of currrent (20+ amps). We also also looking into installing side vents to get the hot air out of the engine compartment. Your hood helps at idle and low speeds but once you start to drive fast, air is being force down into the engine compartment which makes it hard for the fan to blow hot air out of the area.

45C is 113F. 54.4C is 130F 45C is still very hot but a long way off from 130F. Consider installing some side vents in the fenders. Getting the hot air out of the engine compartment is the key. A V8 and a fatter transmission will tend to block the air. Also a t-stat is a must along with a tight fitting fan and shroud.

I used a regular lakewood but had to cut the entire bottom lip off for exhaust and ground clearance. Of course it doesn't pass NHRA spec anymore with the bottom lips cut off but I'm sure it will stop clutch parts from coming up into the car.

I have done two V8 swaps and three turbo swaps. A bone stock 350 will be slow. A 350 conversion is a lot of work. You need a lot of space, a lot of down time for the car, good fabrication skills, a lot of tools, and a fat wallet. Add up the cost and time estimates and double both. I did a little junk yard bolt on turbo on a 78 and spent around 300.00 and it ran a mid 14 second in the 1/4 mile at 96mph on stock boost, no ic, and just a fmu to increase fuel pressure during boost. Boost and torque is instant with the stock turbo. I didn't tune it very well and the engine was in poor shape before the swap. This was my turbo experimental car. This is as fast as most bone stock 350 would be. I also built a 76 with a bigger turbo, IC, turbo long block, and fmu for fuel enrichment. It runs mid 13's at 108 mph (bad traction) with 12 to 14 psi of boost. It is a quiet daily driver and didn't cost much to build. Has ac, stereo, sound proofing, skinny tires, ect. And still gets about 20 mpg. I also built a 71 with a 350. It went through a bunch of upgrades over the years, but my first trip down the 1/4 mile was a 12.9 at 110 mph. But the cam was very lopey and not a very good daily driver. Then I started increasing the power with better heads, better exhaust, and some n20. Then added some slicks and ran 10.7 at 134mph. But the car would break axles and not a good daily driver at all. I wish that I would had left it a 12.9 car. If you are looking for some decent power for cheap and not much work, then go turbo. The power differece with a turbo is a major difference over a stock engine. The stock turbo makes a nice street performer with hardly no turbo lag. Stock turbos go for 40.00 at my local pick-n-pull and exhaust manifolds go for 20.00. A 280Z engine already has low enough compression to run stock boost (7 to 8 psi). So, you could just bolt a turbo into your current engine. V8's are nice but take a bunch of time and money to do it right. If you are looking to run about a mid 13's at 105mph then a turbo is what you need. If you want to go faster and still retain some low rpm torque then go V8. I would also recommend to upgrade the stock efi to megasquirt before going turbo, if you decide to do a turbo.

ICEWTR, I'm just reading the numbers off my time slips. I have no need to lie about it. The difference with my car is that I use a T5 5 speed and drag slicks. I use a brake line lock to hold the car on the line and use 5000 rpm lauches with a little clutch lease before dropping the clutch to take up the drive line slop. This just about pulls the front wheels off the ground. Then I shift the trans very slow so it doesn't blow up. The slow shifts is slowing the et down. I bet I take almost a full second to shift and perform 3 shifts during the run. GM T5's are weak and don't hold up to power shifts. They are only rated for 300 ftlbs of torque and the car makes about double that with n20. My engine makes about 450hp at around 6800 rpm plus I'm adding another 175 hp with N20. This comes out to be about 500hp in a 2700 pound car which makes the 134 mph just about right. Not all cars are the same, a lot of other things effect et. Just becuase your car does this or that at the track doesn't mean all cars will do the same.

Not guesses. These are et's and traps that I have run in my car. Traction was not too bad but shifting slow with a weak T5 slowed the car. 0-60 ft in the 1.5 range with MT drag slicks. My best time was 10.7 at 134mph with 175hp shot or 11.7's at 120 on the motor. 6.9 1/8 mile at 110 on the bottle. With an automatic times would be better. Running N20, I was only getting about 5 or 6 passes before breaking something in the rear (r200, 3.90 gear).

As you know already, with only 285hp at the wheels you aren't going to beat everything on the street. However, you still have a fast car for very little money. And that mild engine makes a nice driving street car. Installing a huge cam and 4.56 gears and a 4000 stall will make it much faster but at the expense of drivability and durability. Maybe some better cylinder heads (195 afr's) and a slightly bigger cam will get you into the 320 rwhp range (low 12 at 115). Then spray a little 125 shot of n20 for a true 420rwhp Z which should get your car into the mid 11's at around 125 mph. That should be enough to beat most cars and is at the limit for Z axles and half shafts

re-check the firing order. Glowing headers or exhaust manifolds is a sign of a rich mixture and retarded ignition timing.

It is a 153 tooth flywheel. A lot of cars came with that flywheel. Mid to late 80's camaro's and mid 60's nova's, for example.

this works good for me

Cam lift rates are being increased for more power and oil antiwear additives are being reduced for emissions. This has lead to a lot more cam failures when aftermarket, high performance cams are used. You should use diesel engine oil even after break-in with flat tappet cams if an aggressive cam prolife and stronger valve springs are used . Can't rememeber where I read it, maybe hotrod or a chevy high performance magazine. But the article was called, "When good cams go bad".

10:1, 3.90 gear, and a manual trans. I would recommend an old school 280H compcam. Or a cam with about 228 to 232 degress on the intake and a little more exhaust to help out the weak vortec exhaust port. I don't like comp's XE series cams. Sure they make a little more power, but at the cost of quicker lobe wear and extra valve train noise. Plus there will be much less tolerence to any valve train issues which can lead to instant lobe flattening. Avoid 1.6 rockers, sure they will make more power but again, at the cost of quicker cam wear. Don't get caught up in dyno numbers and tricks to make just a little more power. You should also be concerned about cam life. When a cam goes flat, the cam and lifter metal eats up engine bearings. Use diesel engine oil with the new cam, as compcam recommends.

Just FYI. My basic 350 (362 cid) in a 71 240 makes great power all the way to valve float (7200 rpm). Using MT drag slicks, run's 11.7's at 120mph, 10.7's on N20 at 135 and 6.9 at 110 in the 1/8. Low 12's on street tires. engine specs 11:1 cr, KB Flat tops, zero deck block, 2 bolt mains, steel crank, stock rods with arp bolts, balanced, 200cc Dart Iron Eagle heads (64cc chambers), Compcam 292H (244/244, 0.501", 110 LSA), Performer RPM intake, 750 vacuum secondary (3310), GM T5, 3.90 gear. Need to shift slowly with a GM T5.

Nice to see another V8 project! However if you don't mine me saying, it sounds like too much stall for the cam, not enough cylinder head to make over 400hp, and low on compression for that cam. Would also do better with more exhaust duration. What are the exhaust plans? Need to use a 153 tooth flywheel to clear the frame rails so a bolt on external balanced counter weight should be use or have the rotation assembly internally balanced. A stock 400 flywheel (168 tooth) is too large to fit in the car. You also may have clearance problems with the large 8" counter weighed balancer. Use diesel engine oil for break in and from now on with an aftermarket cam.

Nion, I used the mount as a template to drill the holes. It would be better to drill those with a drill press to keep the holes straight but it can be done with a hand drill using some care and help from a friend to eye ball the drill bit straight while drilling. The holes end up being right at the edge of the crossmember. Also, the hump on the cross member can be hammered down a bit so the rubber mounts don't ride up on the curve (like Team Zleep mounts). The hump doesn't need to be hammered in that much, just a little around the mount. It also took a few more washers, more than shown in the photo, placed under the lower mounts to raise the diff back to stock height. I used a 0.406" (13/32 drill bit).

Sway bar link kit. Bushings top and bottom.

I think I have seen a smaller externally balanced damper but I haven't seen a 153 tooth, externally balanced flywheel or flexplate.

If you are going to build a stroker sbc, plan on getting the rotating assembly internally balanced so you can run the smaller 6 inch balancer and 153 tooth flywheel to clear the Z's engine compartment.