I need to know how much inch/pound of torque do I need to tighten up my lower plenum. When I was doin my AAM spacer. My friend tighten it up to much and broke off a screw in the lower plenum. Took it to dealer to get it out, they couldn't do it. So, I just got a whole new lower plenum. Askin to much for them to put on. This time I got a torque wrench. So, if anyone could help me. How many inch/pound of torque do I need for my Lower Plenum. NOT POUND/FEET. Inch/pound of torque???? I would really appreciate it.

 

G35 Shop manual shows 9-10 Ft-lbs. Multiply by 12 to get inch pounds. Recognizing the accuracy range of most torque wrenches, I always go with the lowest setting in the range. There's also an "order" in which these should be torqued, and it should be done in progressive steps...50% first pass, then to 100% of specification. Do a search on "G35 Frenzy" and you will find the manual itself.

 

Download the Iso Thermal installation manual from the Motordyne website. The torque spec sequence and values are all outlined in the manual.

Tony

 

for some reason, when I was doing the thermal gasket, i broke a bolt that was on the intake manifold even though the torque wasnt reached to the spec level. It kept turning and turning, then it snapped. But I was lucky enough to get it out, so i used a spare bolt that was removed from the lower plenum. Then again, it did not feel any tight but I left it like that because I did not want to break another bolt, it is still tight enough.. especially when there are other bolts holding the piece together, probably 1/2 a turn more after that was hand tight..

if you can see its tightened but if it still turns, be very careful, because you maybe twisting the screw inside.

 

Was that a stock bolt on the lower collector or a new bolt on the upper plenum?

 

I am telling you, there are a bunch of Z's out there, mine included that have crappy weak plenums and bolts. I am on a second lower plenum due to stripped out threads and today installing the second plenum I had 2 OEM bolts that attach the lower plenum to the collector snap as described above. I have a new in/lb wrench and the bolts snapped with out ever reaching the 110 in/lbs.

 

In addition to the stripped threads, I've also had problems with bolts twisting on themselves and snapping (for the ones attaching the lower plenum to the intake manifold). Helicoils wouldn't hold. Timeserts stripped out the aluminum around them. My particular intake manifold is very very soft.

I had to run a 90 mm M6 bolt with a lock nut at the bottom from the underside of the mounting surface of the intake manifold into the lower plenum area. Then I was able to tighten everything to 9 ft lbs.

DaveO has pointed out that the shop manual gives two different torque figures for those bolts on different pages. I think 9-10 is just too much for my parts.

Unless I absolutely have to, I'm no longer taking my plenum/manifold apart anymore. Everything is torqued to specs now, so I'm leaving it as is.

 

Yes. I have seen this too! I was simply untightening a stock bolt and it snapped off.
I have been questioning 110 in/lbs for a while but after seeing so much of the same issue reported it looks like 110 is just too close to the margin.

 

Does anyone have any advise on how to pull out a broken bolt? Also need to find a higher grade bolt for this manifold. Yea by the way i am nismo21z's friend and i tried the lower plenum last night and didnt even tighten the bolt anywhere close to 53in/lbs and one of the bolts broke. WTF PLEASE HELP IM VERY ANGRY RIGHT NOW!!!!!!!!

 

Sears bolt extraction kit. Or use a dremel to cut a slot in it and use a screw driver to back it out.

 

thanks man ill let you know how it goes

 

I think that maybe Nissan knew the castings were weak and in turn used very soft bolts to attach the lower plenum to the collector below. They twist in on themselves and snap at about 80 in/lbs. That was my experience at least. Fortunately I was able to get them out before they snapped. They were all twisted up and snapped when I applied slight pressure. Kind of like a dry twig!