Pyro

I have a 454 in my LWB 70 c10. It has a very mild RV roller comp cam, 8.75:1 cr, 781 heads with some big valves, and mild port work (unshouding and bowl smoothing). Even with a 3.08 diff gear and 400th automatic, my 4000+lb truck kills my slighlty modified 78 280z (260 cam with crane springs, P90 head, F54 block, 5spd, 2.5 exhaust) anywhere from 0 to 125mph! However, my turbo car is a different story. I was thinking about doing a 496 cid kit but I seem to have enough power already! (I can't believe I said that!). I just use the truck to trailer my V8 Z to the track. The mileage is pretty bad at 8/12 mpg but 0-60 mph is in the 6's, thanks to the alburn LSD diff , 2000 stall, and 275's in the rear. When building a bbc it is very important to set the bearings up tight! 0.0015 to 0.002 on the mains and rods, and 0.003 on the rear main. If you set the bearing clearances on a bbc like a sbc, it will eat cams like a pig eats slop.

There could also be a bad seal on the lid of the vacuum advance canister. The diapham makes a seal with the lid and can tear or squeeze out if not installed right. I use the paper test on my car to see if the secondaries opens. Drop a small piece of paper in the secondaries and drive the car hard then look down the carb to see if it is still there. To check the seal of the vacuum canister, remove the canister and push up the rod. Then hold you finger over the port that goes into the carb and release the rod. If the rod springs back then the seal is bad.

yep. Pull out the trans again! You need that bushing! The transmission will not like running without it. The bushing goes in the hole in the rear of the crank. I bet the transmission stabbed in real easily without the bushing.

I have the black magic fan on my 350 and it works well. However, its thermostat burnt up after a year! So I had to make my own switching device with a thermostat switch in water passage and a relay. An easy and reliable fix.

Run both! Run dual 2.5" to the diff, then do a nice flowing Y-pipe into a single 3 or 2.75" pipe to go under the diff and out the back with a 3" muffler. I have dual 2.5's on my Z car but had to install a fuel cell first. Duals on a V8 z' make it sound like a mustang. Your car will make a little more power but will lose the import sound. Believe it or not, I didn't like the dual exhaust sound coming from my V8 Z, which was a big surprise to me.

This is a summary of what I wrote earlier: Don't worry about the block. Just rebuild it to stock specs using a high quality machine shop. It will be fine. Just use a good balancer. Are you planning to drag race the car every weekend? If this is a street/strip car then spend you money on the stuff that bolts to the block (heads, cam, carbs, etc) Strokers are difficult to turbo charge because the compression will be too high due to the small combustion chambers that are used on L28 engines. So you need to make a choice: turbo L28 or stroker with big cam. Don't try to build a high compression turbo. Stick with the stock 7.4:1 cr turbo compression and turn up the boost. If you don't turbo charge, use between 10:1 cr and 11:1 cr and a cam over 240 degrees duration at 0.050" lift. Don't go crazy with fancy block parts. A big cam with a good valve train setup, high compression, headers, 2.5" exhaust, with a good intake setup is all you need to make high rpm power. AGAIN, The block doesn't make the engine rev! It is the stuff on the block that makes it rev. The block just needs to stay together and the stocK L28 will handle a bunch of rpms. I say 6500 easily but 7K still should be no problem for short durations even with the stock cast pistons! Forget the block and start planning for the all the other stuff! (head, cam, valve train, exhaust system, intake system, fuel system, clutch, transmission, rear end, etc.)

It would help if you gave more car information. What car do you have? Also, what kind of rpms do you want to do? 7K is about the limit for the L28. Be careful to not waste your money building up the engine block too much. Performance rods, cranks, and pistons can really add up! The stock Z block can handle at least 6500 rpms and 350 hp without any problems. It is the cam, valve springs, head, intake, and exhaust the makes the engine rev. All the block has to do is stay together. For non-turbo: Rebuild a L28 block to stock specs with flat top pistons, add a N47 head for 10:1 cr, buy a stage 3 cam kit and a complete exhaust kit (header and 2.5" pipe) from MSA. Then you need to install a set of webers or SU's because the stock efi isn't good for much over 5500. It will rev to 6500 but I'm sure power will be dropping off. Or you can spend big bucks on a custom intake and aftermarket efi system. If you are going to build a stroker, then use a P90 or P79 head. MSA also sells stroker kits. If you want to go turbo, you need to do it from the start. Buy a complete turbo engine and ecu. Rebuild the engine and turbo to stock specs and install it in your car along with the turbo ecu. Install an IC and turn the boost up to 10 psi. Then later, upgrade the turbo, upgrade the cam, upgrade to an aftermarket efi, and turn up the boost. Stay away from stroker turbo setups because it is almost impossible to get the compression low enough to use pump gas and a decent amount of boost.

Z-Gad, I see. stroker mph...... But still good numbers for a L28. 300+ at the wheels is still a very fast Z! Bastaad525, Sounds like your engine is falling off too fast. Should make good power until 4.5 or 5K (just like you want). Maybe stronger valve springs or some 0.040" spring shims would help. Play around with the ignition timing. A little more advance will give you a little more rpm. Is your fuel pressure maintaining during high rpms? Another stock pump in parrallel would help keep the pressure up during high volume demand. Are you using the stock wastgate? I feel the stock wastegate is restrictive as compared to a striaght pipe off the turbo used with an external wastegate. I think you could get the stock T3 running much better.

Turbo cams typically have less duration on the exhaust and more on the intake. This is opposite in a NA or supercharged engine. So, it makes sense to me to leave the stock exhaust valves in place for a turbo engine.

Good post and good numbers! If you are using weak springs, I'm sure you will gain even more HP at higher rpms with the proper springs. That 122mph trap speed is impressive! That is the speed of a 400hp engine in a 2800lb car! The dyno must be way off. However, can't argue with the 1/4 mile dyno. I have always believed the turbo also needs to match the cam. Especially after changing over to a T3/T04b-h3 wheel and liking the new turbo less than the stock T3 which was a good match for the stock cam. So, I installed a MSA stage 1 turbo cam (made by schneider cams). 114 lobe centers, 260 intake, 250 exhaust .450 lift. A real turbo cam with less exhaust duration and wide lobe seperation. I'm also using the crane springs and retainers and 0.160 lashpads. Had the rockers resurfaced at DeltaCams for 3.00/each. (350.00 cam swap) The MSA turbo stage 1 cam kicks in about the same time full boost hits at 3500 rpm (14psi) and pulls to hard 6500 rpm. The engine makes 5 psi at 3000 rpm. The old T3 would full boost by 2800 rpm which was perfect for a cam that quit pulling at 5000 rpm. And I still miss the torquey t3 with stock cam for pure street driving. Idle vacuum droped from 19 to 15 and engine is much smoother driving down the highway and has a slight lope at idle. Good job! Keep us updated. Have any 1/4 mile trips planned in the future?

A 400 to 425 hp 350sbc with not normally have a smooth idle. It takes a long duration cam to get that power. If the idle doesn't bother you then you will be ok. I have had all kinds of cams in my 240 with a 350/T5/3.90 gear. The small cams are nice at the stop lights or sitting in traffic. But the rpms are greatly reduced which is a bummer with a big engine in a small car. By the timing the tires quit spinning it is time to shift. (bummer) The cam I enjoyed the most was the compcam 292H. Rough idle but cleaned up right off idle and reved to 7K with heavy valve springs. At least a 400 hp cam. A long duration cam but with wide lobe centers (114 to 116) would smooth out the idle of a big cam while maintaining high rpm potential. Would also would well with efi. Would make a very long but lower torque curve. Good for a V8 Z street/strip car. I never tried that combo because I have always ran a carb but I'm sure it will work great with efi. Of course, cooling will be the biggest issue. The stock mechanical clutch fan with a custom shroud on a HP cross flow radiator will work the best. If you go electric fan, get the most cfm possible.

Yes, heat shields work. Ugly but functional. I build one on my 76 retro-turbo around my turbo and a little bit under the intake with 1/8" alum. plate. No vapor lock problems now and the intake has uniform temperature from front to back. The intake was 50 degree hotter on the back half of the engine (under the turbo), but not anymore. I would get vapor locking during long idle periods or from a re-start after a long drive. I always heard fuel rails make more vapor lock problems? The big mass of aluminum fuel rail gathers and holds a bunch of heat. That is what I read but have no first hand experience. You are not overheating right? Just vapor locking, correct?

Sure, the T3 will work better in a L24 engine at higher boost and at higher rpm levels as compared to a L28. It comes down to the air flow capacity of the turbo and flow requirement for the engine . However, hp is hp, and the super t3 is good for 300 hp max.

Just paint the tank black and smooth out the rear panel with some good body work. I could send you some photos on my car done that way but I'm not sure how to post a photo here.

Buy a GM T5 5 speed from a V8 camaro. The shifter is in the perfect position. Plus the extra gear is nice. The T5 will handle a 283 with no problems.

CRAY Z Or for you engeering nerds 3.141592654

I have a stage 1 turbo cam from MSA (Schneider). Then I had the rockers reground at Delta Cams. Then I used crane springs and retainers from summit racing. Then I used 0.170 lash pads from courtesy nissan. I would had used a delta cam but they didn't have the extra wide lobe seperation required for a turbo. Idle is smooth but not as smooth as stock. Pulls to over 6500 rpm.

I think studs are more uniform in clamping force as compared to bolts. Also having fresh threads and a lubed up nut will have less losses to thread friction and more clamping force/torque ratio as compared to a traditional head bolt. Especially an old bolt in an old block.

I used them on my JTR conversion. However, it took a lot of bending, tourching, and welding to get them to work. In the end, I feel that I should had built my own headers. Sanderson headers also have some interesting headers. They have a block hugger with full length tubes that looks like it could work. But don't know if anyone has tried them on a Z.

Yes, I have kill many BBC flat tappet cams during break-in. The BBC is the best cam eater ever made! However, it seems some specific engines do it more often than others. BBC are also known to have lift bore alignment issues which can make the problem even worst. I have a 454 that ate 3 cams during break-in so I ended up installing a roller cam to fix that. But, I think the problem was rooted in large main and rod clearances. It seems the two machince shops I had used to rebuild the engine both wanted to set the BBC clearances up like a SBC. And after doing a little research, I found that the BBC needs to be set up much tighter than a SBC. For a BBC, 0.0015-0.0025 on the rods and mains with the rear main set at 0.003-0.0035. This will keep the oil pressure up and slinging correctly on the cam.

If you didn't wedge the chain before taking off the cam gear then the tensioner sprung out. Start removing the timing chain cover if you what to get the chain back on. If you did use a wedge on the chain then use the big cam bolt to pull the gear onto the cam.

My 240 with a 362cid ran 11.7 at 120 mph without N20 (MT 26x8 slicks, 3.90, T5 5speed). It took a 175 hp shot to get it to run 10.7 at 134 mph (1/8 mile: 6.9 at 110). I sprayed the N20 right off the line. So, maybe you should up the N20 a little and use it off the line if your traction is good.

93 octane with 15 psi of boost but have done a few runs at 17 psi without problems. Stock turbo motor with t3/t04b, spearco ic, all 1976 efi stuff and fuel pressure ramping up to 100 psi at full boost. 20 initial timing, 28 total, plus 14 more from the vacuum advance during off boost driving. PS. a 454cid in my 70' c10 chevy makes close to 400hp/500 ftlb on 87 octane.

SS was never intended to be a retirement program for all the people in the country. But somehow it developed into one (sort of). It was intended for widows and people who lived a few years past the average life span. Lets face it, it is welfare program paid for by more income tax. I wish the government would just drop SS and increase income taxes to pay for this welfare program (SS) and quit promising everyone a retirement. Then maybe people will get the idea that they should plan for their own retirement instead of letting the grovenment do it for them.

There is a weight stuck on the balancer and flywheel of stock 400 sbc and 454 bbc. The external weights (out of the oil pan) are required to bring the engine into balance so these engines are externally balanced. All 350's are internally balanced (no extra weights on the balancer or flywheel). In strick engine balancing, the entire rotating assembly needs to be balanced together (crank, flywheel, and balancer), However, this is overkill in 99% of the cases.