dapiper

Positive stop must be right length (long) and very strong steel to avoid bending and/or breaking. Do not put too much force on crank; remove plugs and rotate slowly. Mechanical advantage is high and angle is shallow enough to cause pos stop to bend, fatigue and break. Bummer if it breaks off inside your cyl.

The important thing is to assure that cyl #1 at TDC, that the cam sprocket notch is aligned with the oblong groove on the cam thrust plate. Alternatively, the two bright links on the chain should be aligned with the dimpled marks on the sprockets which should also correspond to the above condition.

In 10 years I have replaced one coil (stock, they dry out being mounted horiz), three trigger pickup coils (vibration intermittant), and two MSD 6T boxes (?).

Motor will meltdown if attempting to tune each cell on boost, or it will take a very long time, since you will have to wait for motor to cool. We tuned the 100 kPA cells up to 6500 RPM and coolant spiked to 220F and caused coolant weepage, resulting in replacing head gasket, so watch out, take care, beware. Make sure your shop has a really big fan.

Actually, start lurking on the MegaSquirt forum and any other forums that specialize in EFI, maybe even the Haltech site. The MS is so basic that you can learn alot. If your EFI is map based, you tune to your vol effy curve based on a target AFR and compare to actual from WB AFR, such as LM-1 ($350). Set up target spreadsheet with suitable number of cells, eg 16 Load (kPA, psia) X 16 RPM. Just begin tune by monitoring AFR while driving to get a feel to where you can make improvements in drivability and performance, then later dyno tune to optimize. Same for timing. More power from timing than AFR. Be conservative. Get the LM-3 ($250) to datalog and study sessions later in comfort and safety of your garage. Get the XD-1 AFR gauge for readout capability, but much slower response that available on datalog. I prefer the hands on approach, alternatively you can take the EFI University course. Or just hang with those who know. Maybe your local dynoshop will let you lurk. All you really need is the desire to learn and take some measurements. Don't be intimidated at the start and soon you will be comparing techniques like a pro.

Also consider exh leak and rich.

I am going thru the same thing with my N42 and 86.5 mm bore custom turbo with RaceWare studs. See my other posts re head gasket, but just now pulling head for third time since Aug. Will try one last time with stock gasket and then its new motor time. Builder admitted to not decking block after cracked head in #4 cyl. I suspect this is problem. Did you? Even had OEM original gasket with contact adhesive and asbestos construction weeping on plug side. Once they begin weeping, its all down hill. Mine happened on dyno while tuning and holding cells on map up to 0 boost and 6K RPM. Never did weep on road, however. OBTW, stock gasket $88 at dealer, but looks very much like MSA. Inspected FailPro today at parts store and found fire rings quit narrow at 0.080" on block side. Did have nice adhesive though. This would not allow sufficient area for my block o-rings to engage fire ring. Stock and MSA were 0.160", quite a difference. Did not have luck with NAPA, had a smooth brown coating that leaked even when just adding antifreeze. Considered HKS metal, but was told that their 91 mm bore just too big. Block and head need to be lapped for metal style to seal. What is your bore? This time using OEM and Hylomar spray coating, like Copper-Coat only will fill up to 0.010" gap. These new OEM style are graphite and have no contact adhesive.

Now involved in rebuild of standby trani acquired from Cherry Ave Towing in Birmingham bone yard for $250, but needs reverse gear set and shifter forks. Negotiating adjustment. Guess the PO tried to power shift or crunched shift style. Box only had 100K mi, supposedly. Yeah, got same issue about "crushed syncro", whatever that is. Heard from Dave at drivetrain that they have a retro kit to replace reverse gear set with 21 tooth. Considering cryo treatment. Anyone tried it? Cost? What year is that box? Is it FS5W71B?

Most ECU's have at least 2 ign outputs so can use waste spark. If u have only one, then need multiplexer, mucho $$. I'm also on fence re DIS with my autronics ECU, which has 4 ign outputs, but still requires waste spark. I have some LS1 coils (inductive) I will try, but now running on dizzy with MSD 6T. Have heard more power with timing than AFR optimization. CDI best with turbo. LS1 coils may not be up to firing my turbo but I guess I will find out. LS1's are a cheap DIS alternative. Will advise by next week, if you can wait that long. I couldn't wait, so I just tuned fuel on dizzy. I know I will have to retune.

Finally pulled cam sprocket to check timing and found short chain; during engine assy, had advanced one tooth to allow cam dowel to index with crank at TDC. Same head, same cam tower shims, same block. If anything, head may be thinner a few thou. Did replace chain and sprockets with MSA parts, but used ArizonaZ adj cam sprocket, which was fine, except way it's made could not check alignment of notch with groove. With crank at TDC and cam indexed to sprocket on #1 hole and notch centered on oblong groove, I could not install sprocket with chain onto cam nose. Had to advance cam considerably, later determined to be 10°. If I retarded cam one tooth, cam was excessively retarded; notch aligned off left end of oblong groove. Finally had to retard one tooth (-18°) and use #3 hole on cam sprocket (+8°) for total retard of 10°. The only explanation is the chain is too short. Watch out, take care, beware of certain aftermarket parts. The L28 will run with 18° adv, but power down 20% at 5300 - 6000 RPM. Nice wide power curve, just too low. Lift is 0.485" at valve with 11cc dished pistons at zero deck. Try dyno again tomorrow.

Considering the HKS metal head gasket on 86.5mm bore, since Cometic has as yet not delivered. The HKS is 91 mm. Is it too big? Should I just leave the block o-rings? They are inside the 91 mm, well actually just inside and extend about 0.012 above deck.

Call local hose distributor and get oil resistant hose, probably be 2-ply but not really required for low press in crankcase. Use 3/4" or largest possible and straight run to help drain back. Use heat shield (Design Engineering) over hose.

Just talked to Cometic and they have no plans to fab our gasket unless we have order for 150 or more.

Still need pix, dimensions? Count me in for quantity two for 86 mm bore and 1mm thick and one 89 mm.

Thanks for the link. My app is N42 custom turbo with old Racer Brown turbo grind. 236°I/246°E @ 0.025" lift on 110° lobe ctrs and 20° overlap. Lift is 0.485". Also using ArizonaZ adj cam sprocket. Thought maybe installed one tooth (9°) advanced, but cannot see notch with ArizonaZ sprocket. Might try replacing with stock sprocket to check, but hassle removing cam trigger. Retarded cam 5° crank and seems to pull better, but getting knock while developing boost. OK once at boost. Boost limited to 15 psig. Will check on dyno Monday. Anyone know max retard without piston clearance problems? Using 8:1 CR and 11cc dish. Might try another 5° retard if improved.

Anyone have experience with L28 cam timing; advance and retard impact on peak power/torque @ RPM?

Nismo makes retainers for 43 mm spring height, so you don't have to machine the spring pockets and Isky makes the springs that provide 110 lb on seat and 260 lb at lift for these retainers.

Observed wierd power band on my custom turbo. Peak torque occurs 300 RPM lower at 4400 and power maxes out at 5300 RPM and is flat up to 6000. This cam used to be 4700/6200 RPM for peak torque and power. Peak torque and power were always equal, i.e. 330 ft-lb and 330 RWHP at 13 psig boost. Now peak power is only 300 with the flat curve. Anyone ever observed this limitation and what can cause it? Increased AFR from 10.8 to 11.8 and improved midrange but did not change max figures. Acts like some big restriction. Air mass sensor maxed out at 5300 RPM also whereas used to keep increasing. Could cam be that retarded? Cam set at 0 adv, but has been refurbished and using adj cam sprocket. TDC chks OK. Maybe cam has been ruined when refurb?

Thanks one and all! I found bone yard item and will probably have to rebuild, nice to know it's possible.

I used 280 tank on my old '73 turbo conversion, which has larger outlet for pump. Any old Bosche pump from an EFI car, i.e. rabbit, golf will support over 400 hP. Check bone yards. OK to use 3/8" alum tube line for supply and 5/16" for return. I also used stock rail and reg for a while, but not ideal, since much pressure fluctuations on small 5/16" rail.

There is one for sale in classifieds.

Measured 5.5" center distance (3.680" between pin and journal OD). Are these 240Z rods?

My LHS (driver's side) upper door hinge is worn. Tried MSA. Replacement source? Are these hinge pins servicable? Terrible wind noise at speed. Door is sagging rendering top seal on window frame ineffective.

I measured 38 psi on turbine side with 18 psi boost (380 RWHP) and then changed out Flowmaster for Dynomax (all 3") and achieved 410 hp at same boost. Exh BP went from 7 to 2.5 psi. L28E N42 with Turbonetics H3 and 0.69 A/R. Cannot find run data to determine change in turbine BP, unfortunately. I thought you divide boost psia by effy to calc turb BP, i.e. (21+14.7) / 0.7 = 51 psia = 36 psig.

Golley. What kind of timing could stand 23 psi on 94 octane? Please advise. Fuel pumps?