Pyro

vortecs flow poorly on the exhaust port so they tend to do better with more exhaust duration than intake. However, a little bowl smoothing under the exhaust valve and full length headers should take care of that and allow an equal duration cam (like a 268H). Also, vortecs are limited to the amount of lift. 0.450" is about it for the stock setup. However, a little machine work can fix that. furthermore, vortecs have fast burn chambers. so they don't require as much total timing as older style heads. This means you can run a little more compression with the same size cam as compared to older heads. Finally, the cam, compression, intake, gear, and stall (if you use an auto trans) all need to match. so, the best cam/intake combo will vary greatly. Yes, the heads are a good deal. However, they require vortec rocker arms, vortec valve covers, vortec intake manifold , and some machine work to allow for more lift. If you don't already have these things then the price to use these heads go up a lot. If you already have an intake, rockers, and valve covers then take a close look at the dart iron eagles and the RHS alum. heads (750/pair). http://www.summitracing.com

what is your ignition timing (initial, max mechanical, max vacuum advance). have you tried jetting down the carb until it complains? the jet back up a few sizes?

if you plan to use a stock cam then use a stock exhaust turbine (0.63 a/r). If you run a higher rpm spool turbine (say a T3 stage 3, 4, 5....) then the boost will come on later (3200 to 3500 rpms) but the power will still end when the cam stops pulling (around 5,000 rpm) so this setup will limit the useable power range. I know because I made that mistake. Ended up changing to a bigger cam to get a power band from 3500 to 6500. But I miss the low rpm torque of the stock turbine and cam setup (better for a street car). If you use the NA cam, then the usable rpms will be extended about 500 rpm, say to 5500 rpms. This is a nice upgrade over the stock turbo cam. I would get a turbo from a first gen 300zx because it has a water cooler center section and therefore a 360 degree bearing. This center section will take more boost as compare to the stock 280 t3 which is non water cooled and has a 180 degree bearing. You don't need to actually water cool the turbo if you don't want to. just use the stock oiling system and plug the ports. Furthermore, first gen 300 turbos are more common in the junk yards than 280zx turbos. You can normally pick one up for 40 or 50 dollars at a U-Pull-It type junk yard. But they are hard to get off due to not much room. Then get a turbo shop to replace the compressor with a T04E-50 trim. This turbo will also need a 1/2 inch spacer on the exhaust manifold for extra clearance. This turbo could easily make 350 at the wheels. Most likely the best compressor for a L28. you could run a t04b-v1 compressor if you don't want to use a spacer but it will be about maxed out at 300 hp to the wheels. I use the t04b-h3 compressor but it will surge with a stock turbine because it is to big for 2.8 liters. Works well with max boost at 3500 but any lower would cause a surge problem. Finally, don't discount the stock T3. can make 275hp at the wheels with 15 psi of boost and well over 325 ftlb of torque at low rpms. Makes a fun car to drive on the street. lots of wheel spin even in 3rd gear. but use a first gen 300 turbo with the water cooled center section for high boost like that.

I use felpros head gaskets. no problem. however, I recommend you use the nissan intake/exhaust gasket (go to your local dealer). felpro's have problems with the intake/exhaust gasket (cheap paper gasket). I use old head bolts all the time. just make sure to clean the threads very well. To clean the threads, I run a tap down the block threads and blow them out and run a die down the head bolt threads. make sure to wedge the timing chain before pulling off the head. Plus mark the timing chain location to the cam sprocket.

beat the crap out of it for years. A friend of mine is also using a P79 with his turbo. drag races it. the liners are metal. sometimes a whitish film build up on the liners. most likely burnt oil (like the white build up on spark plugs). I don't think it will hurt anything.

just get the P90 head resurfaced. 25.00 at your local machine shop. I have run P79's on turbo engines without any issues. not problems up to 14 psi of boost with a stock T3 (hot exhaust).

another option

takes time and some tweaking to get a v8 setup right. install a gm t5 from a v8 camaro.

ignition timing and air/fuel mixture are what you need to look at when going for mpg. Holleys come jetted rich. I bet your engine would like a couple jets leaner. read a plug, and make the adjustment. do a web search "how to tune a holley the scientific way". Nice write up and free. ignition timing is the next thing to setup. 48 degrees of timing going down the highway is what the engine needs for good mpg. That should be the total timing (mechanical plus vacuum advance). do another web search "ignition timing 101". you should be getting at least 20 mpg on the highway with your combo. here you go. http://www.corvette-restoration.com/resources/technical_papers/Timing101.pdf http://www.bob2000.com/carb.htm

the msd 2225 efi pump is rated to 500hp. cost about 100.00. durable and quiet pumps. The stock pump should be able to handle 300 or 400hp if it is in good condition.

Believe it or not, water cooling is optional with a water cooled center section. Just plug the holes and go if you don't feel like messing with water lines.

I prefer to place the wipe pattern closer to the valve. This makes the valve train quieter. stock lash pads are around 0.120" thick due to the recess. After market lash pad are flat on the bottom. When I setup the wipe pattern, I buy extra thick pads and lathe them down to the size I need. I also machine a recess in the lash pad (like the stock pad). Not necessary to machine the recess, just makes me feel good.

I run a 175 to 275 shot n02, on a 362 sbc with 200cc darts, shift at 7200 rpms, with MT drag slicks and a bone stock T5. best run was 10.7 at 135 with a 1.6 60 foot. I think something wasn't done right with your T5. I do shift my trans on the slow side. The only time I broke a T5 was my stupid fault when I sprayed N02 while in 5th gear. And it just broke 5th.

here you go. this is how to calculate compression with out a website. 717cc for the cylinder 12cc for the piston (standard smogger gm dish with 4 relief) 4cc for the deck height (estimate -0.020" in the hole) 8cc for the head gasket (0.040" felpro) 58cc for the head (717 + 12 + 4 + 8 + 58) / (12 + 4 + 8 + 58)= (717 + 82)/82 = 9.74 9.74:1 cr need to use a cam in the 220 degree at 0.050" range with this compression (270 advertised). will also like a 2600-2800 stall and 3.55-3.73 gear. (depending on tire size).

looks like you will also need to relocate the pcv.

never understand why people spend extra time and money building a small engine. my 362 sbc with flat top, zero deck, compcam 292H, and 64cc dart heads revs to 7200 rpm all day long. The only reason it doesn't rev past 7200 is that is where the valves float. the aftermarket is set up for bigger engines. (hence the big 64cc chambers) Plus 302 and 327 pistons are long and heavy and expensive. The piston are about as long as the rods to make up for the short stroke. You are giving up 15% more torque and hp for no reason by building a 302 instead of a 350. throw some good aftermarket 64cc heads on your 350 with a good set of valve springs with a cam in the 290 degree range. then your 350 with rev like crazy. kind of funny, but a friend of mine did exactly this to a autozone 350 short block and ran it for 2 or 3 years. he drove it to work every day and raced it at the track every weekend and street raced during the week. furthermore, he sprayed a 200 shot of N02 on top of that. He had about a 20 to 30 lbs a week n02 habit. Plus a 3500 stall and 4.56 gears. The engine revved up to 7000 easily. Finally developed a knock (hammered bearing) but only after eating 30 lbs a week of n02 for over 2 years and revving to 7 grand 20 or 30 times a day (drove like a mad man).

if you have a stock T3 from a first gen 300 turbo then it already has the 360 degree bearing (water cooled center section).

rpms also have a lot to do with it. 20 psi of boost at 5000 rpm isn't the same thing as 20 psi of boost at 6500 rpms. if you are using the stock cam (low rpms) then you can easily run more boost than 15 psi.

don't forget to take off the flexplate spacer at the end of the crank before bolting on the manual flywheel.

well, not just the auto mounts. it is also the clutch set that will be tough. need a new master cylinder, slave cylinder, and new hydro line. plus the cost of the clutch and the labor to put in a clutch pedal assembly. the hard part is to get everything in place and working correctly. modifying the 350 is the easy part. I say, drop in the stock setup then mod the 350 later. just don't expect too much power.

a th350 has a 1:1 top gear. this will make the engine rev fairly high going down the freeway. your 81 should have a 3.54 gear (since it has a factory auto trans), so that isn't as bad as a 3.90 gear. but still. lots of revs. installing a 350 trans would be the easiest. but a T5 from a V8 camaro would be better. not a V6 camaro! performance depends on the engine build. a stock smogger 350 can have as little as 150hp. Don't expect too much power out of a stock mid 70's to 80's 350. For example, a stock 73 vette engine only had 190hp which is about what a stock 81 Z had at the crank. However, add a little bigger cam to a 350, a little more compression, better heads, better intake and exhaust, and 350hp can be made even while retaining a fairly smooth idle. A v8 conversion is a tough job. Lots of little projects. it will cost at least twice as much as you think in both time and money.

3.90 gear with 26 inch tall tires and 1:1 top gear makes the car go 19.8 mph every 1000 rpms. so 70mph should be at 3,535 rpms in 3rd gear, 140 at 7000 rpms 46 mph will be 3535 rpms in 2nd gear (1.52:1)

3.36 is a 180R which is a little weak for a v8, plus not much better gear ratio than a 200r 3.54 (stock 75 to 78 diff) 7000 rpms with 3.54 will get you to 140 mph. Maybe you just need a bigger cam. A bigger cam will make the engine feel smoother at higher rpms. I helped fab a 2.87 gear (1980 vette diff) in to a 77 Z. The taller gear made the car feel heavy. your better off with adding an OD (700r) than dropping the gear ratio. A GM T5 (5 spd manual) from a V8 camaro would be a better choice than a 700r. A z should have a manual trans (imo). I ran a 700r in my V8 conversion then later switched to a T5. I enjoyed the T5 much more. if you run a 700r, make sure to setup the TV cable correctly.

thermal time switch. it is right next to the water temp sensor in the T-stat housing. the TTS and water temp sensor both have a 2 prong injector looking plug. clean both the plugs (tts and wts) and don't mix them up.

numbers look OK. compression gages can be wrong but the numbers look consistent which is the important thing. low compression numbers typically means a stretched timing chain which retards the cam timing. popping out the intake means a lean mixture and/or retarded ignition timing. a bad TTS can make it hard to start when cold. balancers slip which cause the timing mark to move, which will make adjustments to the ignition timing wrong (retarded). check for true tdc to see if the balance has moved. change the valve stem seals to stop the smoke.