Technical Rochester 2G to intake manifold torque spec

Thanks in advance for any help on this!!

Does anyone know what the torque spec is for a Rochester 2G carb to an aftermarket intake manifold?

My old Holley 4160 was 60-80 inch-pounds. A Google search indicates the Quadrajets get 144 inch-pounds after two passes in a criss-cross pattern.

I have a bunch of reference material on the Rochesters but can't find the info I seek.

thanks

 

My Chevy has a 2G , and it was torqued diagonally to 12 ft/lbs [144 In/lbs]which is the same as a quadrajet.
The torque specs are for correct bolt stretch and shouldn't change just because the bolt pattern is larger.

The 2G has a steel carb base so it can have a higher torque spec and less prone to warping than the aluminium base of a Holley

 

Tight?..........have never heard of torque specs for a carby base.........learn something new every day..........andyd

 

I always used a #1 grunt!

 

Not making light of the question, but I use a short combination wrench and pull it good and snug....like that. Yes, to doing a criss-cross pattern two times.

Lynn

 

If your using bolts on an aftermarket intake don't. Use studs, coarse into the aluminum and fine with the nuts to hold the carb. Never used a torque wrench. A 6" 1/2 open/box combo or a 1/4' drive ratchet extension and 12" 6 point socket.

 

I worked at the chevy dealer in the 90s and we still saw carburated trucks from time to time. Every one that came in got the carb bolts "snugged" up. We never torqued them just even tightening across the base in an x pattern.

 

Thanks Jimmy6, that's what I did with the old carb. Great suggestion for the tri-power!

 

Thanks everyone for the lightning fast responses.

If the answer isn't among the smart bunch of folks on the HAMB, it might not even exist!!

 

Can you even get a torque wrench on the nuts with a straight pull?

 

Years ago the new Holley carbs I bought came with 5/16” studs with special fine nuts that fit a 7/16” wrench or socket. I never see this anymore, so I make my own by retreading the 1/4” threads to 5/16” fine. To me this make for perfect tightness from fear of stripping alone.

 

Probably not, have to use a crows foot. Carb flanges warp because of uneven tightness, or will break if reefed down unevenly. That's why nobody uses a torque wrench, it's either like voodoo or maybe takes too long. Go real slow in a criss-cross pattern in several increments. Subtle air leaks are sometimes tough to find and loose or uneven flange bolts will do it.

 

Isn't it on ALL bolts and nuts..

You tighten them till they smoke, Then a 1/4 turn more !

 

There’s the question of the day!! Not a straight-on pull, no.


Sent from my iPhone using The H.A.M.B. mobile app

 

The complication with a crowsfoot on a torque wrench is that the scale is calibrated to its center of rotation (where you would normally put a socket), but the lever arm (the perpendicular distance from the center of the bolt to the hand grip on the wrench) will be longer or shorter than that depending on how you apply the crowsfoot. To make it just a bit more complicated, the more force you put on a torque wrench, the more it twists--this doesn't effect the length of the lever arm in normal application where a socket is centered on the rotation point, but when using a crowsfoot, the length of the lever arm could actually increase or decrease as the wrench starts twisting.

 

Install the crowsfoot at 90°, and it won't change the torque. Close enough.

 

Why didn't I think of that? Thinking outside the box works!

 

I have one head bolt behind the oil filter mount on an 8BA that I can't get to to re-torque. I had considered a "crowsfoot", but never got one because I didn't want go through the math required to figure out what the correct torque reading should be. I think this will solve my problem. I'm off to buy my first "crowsfoot".

 

If you use a standard length combination wrench, just get it tight without dropping your left nut down your pants leg.

 

If that's the case , why bother ??LOL

 

Maybe you don't understand the question?

 

How can you increase the length of the beam and not change the torque reading , that's physically impossible ...

 

Do you know what 90° means? I'm not trying to be an ass. It works. Trust Me.

I use a torque wrench because I like certain things to be evenly tightened. Especially things that might leak if pranged. Cylinder heads, or intake manifolds, whatever. I'm not worried about a couple pounds error one way or another. There is a wide range in torque specs e.g. "35-45 ft/lbs", and using a torque wrench is WAY more accurate and consistent than my calibrated elbow. Usually ends up being quite a bit tighter than I might think, though not "too tight". Almost ... you know, perfect.

I promise not to mention Modulus of Elasticity and that all that foo-foo shit.

 

Forgot all about the ,90° thing , still not the most accurate , but even using an extension can change actual torque values , I suppose that's why there's torque to yield and stretch gauges..

 

When my elbow "clicks" it's perfect.

 

My 1961 Pontiac factory shop manual says 10 to 25 ft-lb for the carburetor nuts.

 

Compared to what?? No torque wrench at all? Maybe it won't work in theory, but it works in real life. Good enough for me.