Jeff G 78

Not running super high RPM, but it does run 5000-7000 for hours at a time. Races range from 7 hours to 25 hours. Once a race starts, there is no time to check over the car. That’s why most failures are pretty ugly. Had this been a street car, I would have felt a vibration or a slight miss and looked into it. In an endurance race, if it’s turning laps, all is good. Once it stops turning laps, there is a mad scramble to diagnose and hopefully get back on track. An average race costs $3000 to $4000 for prep, entry fees, tow rig fuel, and consumables. Luckily that is split between 3-4 teammates but when something breaks and you go home early, most of the weekend costs are sunk and you are left with nothing but a parts bill and a lot of future garage time. I appreciate all the help.

I thought the same thing about the red Loctite, but the experts say it comes apart without heat. It only takes a few drops to keep everything tight. I would have gone with blue had I not read that the red comes apart well.

Same here Captain. I never gave it a second thought until I DNF'd a race, missed another race and caused hundreds to thousands in damage. After spending a lot of time on various sites including reading the links 240260280 posted, as well as rereading Frank Honsowetz's "How To Modify Your Nissan/Datsun OHC Engine" book, it sounds like the green and red Loctite applications have been in use for decades. Since the internet began, I've learned who in the Z community to trust and the common theme here is that they all agree on a quality damper, high strength bolt/washer in the right length and Loctite on the shaft and threads. I never had any idea that the bolts ever came loose, but apparently, it's super common. I guess I should have been aware and built my engine right in the first place.

Great info, thanks 240260280. Where is everybody sourcing their bolts? I see lots of talk about bolts and lengths, but few specifics and very little on sourcing. The NISMO bolt is NLA and each brand of damper appears to need a different bolt length to maximize the thread engagement. Is the KA bolt the OE one, or something else? I appoligize for sounding dumb, but the more research I do, the more questions I have... As far as installation goes, green Loctite on the bore, red Loctite on the threads and then what torque on the bolt? "How To Modify..." book states to use the manufacturer's recommendation for non-stock bolts. I've been endurance racing with various L Series engines for years and this is my first crank bolt issue. I plan to learn and eliminate this failure method in the future.

Cool, thanks. I always read your posts about Eiji and his great work, but never realized until now, that he is Datsun Spirit. Duh...

ATI Dampers for Datsun/Nissan

ATI lists three different damper for the L series and Summit sells all three. The bolt is always sold separate. ?

ARP doesn't make one and MSA only lists the Kameari bolt which might or might not be the right length.

Ahh, perfect. Do you know what model number ATI that is and what bolt you/he used?

So what brand did Eiji use on your strokers?

Thanks Guy. Do you still use stock, or did you upgrade on your latest build? BTW, do you recognize the damper in the picture?

Since my stock damper is now unusable, I need to get a damper no matter what. Since the performance dampers are known to be a tighter fit than stock, my hope is that I can salvage the crankshaft. If not, I have an old engine I can tear apart for the crank, but that one is an unknown and might need work and or bearings too. This crank is good other than the snout. My teammate thinks we should upgrade now to a better damper for (hopefully) future reliability.

Bolt came loose. From what I've read, that isn't super uncommon. I've never had one loosen before, but now I will be sure to use Loctite and check it often. The engine had 20 race hours on it before this happened.

I finally got around to tearing my race engine down after it failed the oil pump gear and I found that the root cause was a loose crank damper bolt. The bolt loosened six hours into a race and allowed the damper to walk out some. At that point, the crank gear could slide fore/aft on the crank which took out the pair of gears. Also, the damper began to wobble which beat up the crank snout and ruined the damper bore. My plan is to buy a new damper, probably an ATI from Summit Racing. Once in hand, I'll take the damper and the crank to an engine machine shop and see if the crank can be saved. I've heard they need to be sized anyways, so maybe they can take a few thousandths off the snout and salvage the crank. After a lot of research online, I see that the ATI pulley is much smaller than the OE pulley. Has anybody had an issue with cooling or charging due to the ratio change? It's an endurance racer, so charging wouldn't normally be an issue, but we do need to run several sets of headlights for night races and it will get an electric cooling fan upgrade. Next question is the bolt. MSA sells a higher quality bolt from Kameari, but I don't know if the length is right for the ATI damper which I've read requires a longer than stock bolt. Datsun Spirit sells an ATI kit with a bolt and a belt, but their price is $200 higher than the same damper from Summit and the Kameari bolt from MSA. I like supporting Datsun shops, but paying $200 more for the same part seems silly. Which ATI damper? ATI makes three different ones for the Datsun L6. One is smaller (about the same as stock) and the two larger ones are available in two weights. It appears Datsun Spirit sells the lighter of the two large diameter dampers. Summit Racing stocks all three. What bolt to buy and what is the right length? Any issues with underdriving the alternator and water pump?

Unfortunately, they are out after some sort of crash. I haven't seen any details yet, but they are okay and say that the car is repairable.

I love seeing the Z love on TV, but personally, I liked the old days of cheap Z cars. Everybody who owns a ratty Z now thinks they are sitting on a gold mine. The days of building an affordable Z are unfortunately over. I think that the skyrocketing Porsche 911 market is creating the huge demand for Z cars. Those who can't spend $50k for a 911 are willing to pay $20k for a decent Z car.

Do you have a guess for how much weight was added with all of your various sound deadening material? It looks great and would be awesome on a street Z!

I saw the TV ad a few weeks ago. At first glance, it doesn't appear that they are the usual hacks that ruin cool cars. I'll DVR it.

I tried to clean pistons and no matter what I used, they wouldn't come clean, so I gave them to my machine shop and they came back looking great. Same with the front cover.

Been there, done that. I just used a bolt and nut rather than buying another 40 year old plastic plug.

Might be 10.9, but it looks like a Chinese hardware store bolt to me.

Yeah, I immediately thought 50 was way too high, but I don't have the FSM handy, so I didn't comment on that. I knew someone would correct him if it was indeed wrong.

Is that broken bolt OE? It doesn't look like a Nissan bolt from the pic.

Nope, the brakes and struts are different too. The ZX parts are actually similar to 510 parts.

Huh?