intake manifold

This may be stupid on my part but I do not think you will be able to use a torque wrench on the intake manifolds nuts (maybe a couple here and there).
I just reinstalled them and had to use a variety of tools to be able to tighten all the nuts as well as a good amount of contorsions.
I just tightened them as well as I could just by feel and by how much juice I could put on the wrench.
My car is an 81 GTSi with the air injectors still in but with the manifold shields removed and ceramic coated.

Flame suit on....

 

Using creativity and a variety of 3/8" drive extensions / u-joints on your torque wrench, you should be able to reach all the nuts (assuming the air plenum, throttle body and linkage are removed first). The factory manual does not specify torques for either the exhaust or intake manifold nuts. If you are using a gasket sealant (which most shops recommend) the torque required is low --- 15 to 20 ft-lbs max. However, if you want to really gronk them down, I would use the same torque speced for similar fasteners (M8x1.25 into non-helicoiled aluminum) on the engine. An example would be the waterpump housing-to-block fasteners. Don't overdue it -- the manifolds are not a structural joint so high torque is not needed.

 

greetings,

As my HERO (Carroll Smith) once said, "While it is true that all nuts and bolts deserve to be torqued to specification, it is also true that it is frequently impossible to do so).
So, faced with this stressfull moral and physical delima, (sp), I suggest the following:
1) Practice developing a sense of "torque", (not by listening to our sage lord, Flush Limbaugh), but by locating a similar ACCESSIBLE fastening situation, i.e. a similar nut stud combination holding a casting to the block, like a water pump attachment bolt. Because of the relative importance of things like Ferari intake manifold nuts or distributor fixing nuts, I recommend you develope/practice on things that really don't matter like maybe an international harvester fender attachment nut or a chevrolet bumper fixing nut or maybe GW's left nut - if it brakes, no big deal. Loosen it. Then torque it to what ever spec you find for the intake manifold nuts, then grab a wrench or ratchet and lean on it untill it just perceptibly moves. you have just exerted, essentially, that same bit of torque.
2) There are and infinite number of refinements to developing this "personal sensitivity", like wrench length, the angle of pressure relative to the wrench and fastener, the phase of the moon, ect. but you get the general idea.
When practible, I go for the torque wrench, when not guestimate.
3) a small side note for those not having done a lot of wrenching, it is fairly important to "sneek up on" the torque by progressively tightening manifolds and other bits going across the major axis of the part in a criss cross pattern to secure the part without distorting it and causing a leak.
4) Enzo would probably smile on you, metaphoirically speaking, if you cleaned the nut and bolt and applied locktite just prior to the aforementioned tightening phase.

regards,
chris

 

chris makes some good points ---

Also, remember that even in ideal scenarios, "torque" is far from an exact science. There have been many foraml Engineering studies done on torque applied to achieve accurate fastener preloading --- and the results are surprising. Even under perfect conditions (access, accurate tools, good lubrication, etc.), torqueing fasteners is very imprecise --- most torqued joints end up at the target value plus/minus as much as 20%. So, don't sweat it too much ---- get as close as you reasonably can, and call it good.

By the way, you want to make sure to do a proof test (pressure check) on the coolant circuit once you get everything put together BEFORE YOU RUN THE ENGINE!!!!

If no leaking, you should be good to go --- remember, that a hot, running engine will only tighten these joints and seals.

 

F1 DONT TORQUE UP DRESS UP ENGINE PARTS,so chris is spot on,just tighten it,use NO jointing compound on inlet and ex flanges,smear on water joints is ok,use a good quality rtv rubber setting compound,i use wynns silicone black,
and use a very small amount,its good for keeping the water off the mating surfaces,and keeps corrosion at bay,if you torque up the inlet bolts/studs recheck them after a few hot runs out,they will come off the torque you applied,

cheers
Dale.

 

Ok, I AM stupid. I was thinking of exhaust manifolds.

 

I did use grey RTV for the gasket, they leak otherwise.

For pressure test, you actually do have to rig up something fairly custom. Preferably, you do this with the engine on the stand. The factory called for doing this before the transmission is attached. They did not say how to test.

I tested before the water pump went on the engine, filled the engine with water, blocked the water intake, rigged something to apply pressure to the water exhaust port, applied 125psi. Wait a few minutes, checked to see if water leaks anywhere at the head gaskets, or down the cylinder walls, or the intake gaskets etc. A small bubble or two is OK, more than that is not.

You wrench for a living, I won't have to tell you to be careful with 125psi. Things can fly off under that pressure and ... injure someone.

 

Yes, the intake manifolds also form a water seal for the heads --- you must use RTV or they will leak. This can be diasasterous because the coolant can leak into the intake / cylinders. The pressure check is accomplished by attaching a pressure pump to the header (overflow) tank. You can buy a coolant system pressure pump at the auto parts store (they are not cheap!!).

 

By the way, the pressure relief cap on the header tank is set to open at around 1.3 or 1.7 bar (look on your cap, the value will be stamped on it). No need to go anywhere near 125 psi ---- 2 bar is about 30 psi --- and testing up to about 30-35 psi is plenty for these seals. When pressure testing the cylinder o-rings (as yelcab was doing) you have to go higher. I don't know the spec of the top of my head, but 100 - 125 psi seems reasonable.