ttodhunter

Thanks NewZed and madkaw!

I have to ask... What is the tap-and-rotate alignment?

I just went ahead and put helicoils in and put it back together only to find another stripped. So I helicoiled them all. Quick note- if you mess up on a helicoil, if you can pick the end out and grab it with a needlenose, you can pull the whole thing right out.

Hey all, I'm assembling the top end and came across a couple of stripped bolts in the cam towers. These are the bolts directly next to the head bolt, so I'm hoping they are just there for assembly purposes. With the head bolt sharing a deck less than an inch away, does anyone know if these bolts are necessary? Part of me thinks they are there for a reason, another part thinks the head stud will apply all the clamping force necessary. Thanks!

So, I took #6 to the machine shop to check for straightness. He put it on a template and found it slightly off, put the crank end in a vise and a dowel on the pin and did a few rounds of hammer blows. He got it to 'as straight at he could get it'. I took it home and put it in the hole, and it now measures F +4, R +3. This appears to be the root of the problem. The question now becomes: do I have him repeat for all cylinders, or do I get new rods. Would you all have concerns with rods that were bent being straightened in this manner? I worry, and I'm no metallurgist, that when they heat up, they may bend back to their previous state. Or, perhaps, that their strength has been compromised. He did note, as he was hammering, that they were very tough rods. Thanks again.

I went and measured all pistons, Front and rear: #1 F -1.5, R +13 #2 F +3, R +8 #3 F +3, R +8 #4 F -1, R +10 #5 F +3, R +8 #6 F +10, R -3 I swapped #1 and #6, and the readings remained unchanged with piston assembly #1 in hole #6 reading F -1.5, R +13. Same thing for #6 in #1 hole. I am now suspecting that the rods are bent, so I will take them and get them checked out. I'll post results, but it may be a while. Any other comments or suggestions are welcomed in the meantime. Thanks for all the input so far!

Just got back home and will now put some time in. Yes, probably not a machinist grade measuring device, but you can feel the piston over the deck on the rear. These are the ITM pistons. I'm really hoping it's not the rods... I'll post back with results.

Yes, higher in the back than in the front. I'm going to spend a little more time with it today and will try swapping #1 and #2 to see if the problem is with the rotating portions or with the hole. Thanks for the reply.

Hey all, I'm putting back together my motor and have found that (especially) the #1 piston, at TDC, is above deck at the rear and at deck at the front. I am measuring approximately 15 thou above deck, but only at the rear of the piston. I don't have a mechanics straight edge, but used a framers square across the top and can't fit a 10 thou feeler anywhere along the deck. I plan to use a standard FelPro HG which should still leave 20-25 thou clearance, but not sure if that's enough. I also worry that there is a problem somewhere that once I fire it up will reveal itself. Has anyone else come across a similar situation? The block was not decked since rebuild. Feel free to make me look dumb. N42 Block P90 Head L28+1 dished pistons Thanks for your input!

Depending on your head, I'd go with +1mm flattops, you can get them at rockauto for $33/ea with rings. I run them on my P90 head turbo setup with no problems, but had lots of detonation with an N42 head.

Hi Pallnet, It's probably about time to upgrade my fuel system. Looking to use FAST injectors with an adjustable FPR and a gauge. What have you got for me? Any other information you need from me? Thanks!

Hi All, I have a 76 280z with turbo and a mild cam and recently have had a problem with power braking. About 1/4 of the time, I will step on the brakes and they are rock hard. This happens while cruising at light throttle, or after I've let off the gas and have ~15" vacuum. I checked and replace the check valve, but still have the problem. If the brake booster failed, would it fail all the time or sporadically? What else could cause loss of power braking - sometimes? Thanks!

I built my N42/N42 with flat tops, ported head and 270/280 .464" cam. Calculated compression was at 10:1. With SDS programmable fuel/ignition, I was still having detonation issues and had to back the timing out quite a bit. Power-wise, it was decent, but not what I wanted and I ended up lowering compression and putting a turbo on. Lots of people say "just drop an L28ET in" and I wish that's what I would have done

I've got a N42/N42 motor I initially built naturally aspirated- +1mm flat tops, ported head and a Delta grind 270/280 .464" cam (don't remember LSA). Originally had it at 10:1 CR but wasn't happy with performance so got a Cometic gasket that brought it down to 9:1 and put a turbo on it (stock boost, 6-7psi). With SDS fuel/ignition and Methanol Injection, I can almost keep detonation at bay. My question is: If I switch to a turbo cam (stock turbo cam for now), would I be more likely to detonate or safer? With less overlap, would that lead to increased cylinder pressure making it more prone to detonation? Or would less exhaust gas reversion lead to cooler cylinders? What other physics are at play? Thanks for any input!

IIRC, The 75 and 76 are full size spare tanks, 77 and 78 are for space saver spares and wont fit properly. 280 tanks are for fuel injected setups and have different ports and design. These are used for FI conversions which makes them more sought after and expensive.