rossman

I was actually trying to help you out and I advised you to listen to NewZed. Grannyknot is willing to help. Heck, I will help too, but you're going to have to make an effort and collect some data as requested. We are all just guessing based on the information you've given so far. Have you bothered to check the coolant level and spark plugs as NewZed asked?

You are right, you have to start somewhere. You are about where I was 33 years ago when I started fiddling with cars. Listen to NewZed, he is helping you... Keep in mind that HybridZ is meant for people who already know how to diagnose and solve common overheating problems. It's kinda expected that those that post here have already gone thru all the standard diagnosis steps and fixes but still need help because, for whatever reason those steps didn't fix the problem. Patience runs thin for newbies who haven't done their homework, especially when they cop an attitude. Google is your friend, search something like "how to diagnose engine overheating" and go from there...

Use a degree wheel and piston stop to find TDC.

Have you seen this? I believe he will sell you a bracket separately. https://nostalgicac.com/compressors/compressors/datsun-240z-260z-280z-compressor-upgrade-kit.html

Yah, mine hasn't been broke long either. There doesn't appear to be any dirt in the joint. My boots were new so I'm pretty sure they would hold up to the few ~100 mph runs I've done. Unfortunately I didn't get a picture before I took it out, but the split looked like it was right where the tip of the LCA was closest to the boot.

The passenger side Z31 axle inner boot on my '72 240 split and slung grease all over the bottom of the car. I need some help figuring out what caused it to split so I can prevent it from happening again. For reference, my 240z is turbo'd with a Z31 LSD differential, Z31 axles with shortened shafts, 280z mustache bar, Ron Tyler front differential mount, and stock rear suspension with urethane bushings all around. I assume the boot hit passenger side LCA under hard acceleration causing it to rip. The boot is within .25" of the LCA; looking at it with the car jacked up and suspension at full droop. I assumed this was worst case. It's been awhile since I drove the car but I remember it making a metallic popping sound, kinda like an old fashioned oil can end popping in/out when I would accelerate quickly from a standstill. It would go boink, bonk every time. A while back I checked and everything seems tight under the car. Thinking about it now I've sorta convinced myself that the sound was the mustache bar flexing under load and contacting the axle boot. I am considering buying a TTT mustache bar, thinking that will reduce differential flex and fix the problem. While I'm at it, I'll shave off some LCA material near the LCA boot to give more clearance. What do you guys think, am I on the right track? Thanks, Ross

I just donated $100. I'm more than happy to donate $100 per year to keep this site going!

How about these? The on-car picture looks the same but the detail doesn't look tapered. Maybe it's just the angle of the photo? http://www.topstage.com/product/twin-aero-vents/

I set it at only 22 degrees at red line with 10 lbs of boost. The car is pretty fast even with such a mild tune. The engine is far from stock - custom high lift longish duration cam, ported head, 8.5:1 flat tops, larger intake valve, etc. I only played with the tune for drivability. One day I'll start bumping up the timing and boost but right now I have other issues to tend to.

My very stale recollection of the thread was that it recommended improving flow thru the back of the head thus removing dead flow zones. So my solution is to improve coolant flow across the head to the bypass lines that short circuit directly to the thermostat. On my setup I added a spacer between the thermostat valve and the lower thermostat housing. I then ran aluminum tube from it to several locations near 3, 4, 5, 6, as 83turbo280zx did. Basic calculations comparing the cross sectional area of the tubes to the upper radiator hose show that the small tubes combined are less than 1/4 the area of the large outlet to the thermostat. Based on that I assumed that my setup wouldn't cause dead flow zones in the front of the head. I also plugged the coolant bypass in the block and opened up the head gasket to allow more flow into the head along it's length. All that said, I'm still running very conservative timing advance.

Without going back to your original head and set up and only making only this one change it's impossible to know how much this is helping. One thing I would suggest is to increase the size of the hose and fittings from the manifold to the thermostat housing. The setup you currently have has 5 hoses coming in and one going out, all the same size. The hose between the manifold and thermostat housing is a restriction to flow. There are no guarantees it will help but it should maximize flow thru the system and improve cooling in the back of the head.