New Manifolds

[mike657894]

the simple stuff will get you. half the times I open my dizzy I dont put the rotor back in. open the drain on the bottom of the carb. fuel, spark, compression, the model a will run with a cracked intake and massive vaccum leaks. and over torquing will cost you. A lesson I have hopefully learned for the last time.

 

[goodcar]

many Model A mechanics references, and others, have errors.
It helps to have previous mechanical experience to ferret these out.

Andrews wants you to torque pan bolts to 20 ft-lb. Go ahead, and you'll shear them off.

The thing to remember about manifolds, especially exhaust, is that they have to live thru very wide temp swings.....from ambient to hundreds of degrees. Thus, they have to be able to expand and contract. In fact, they WILL expand and contract. If you have them torqued to 65, then they cannot move around under the special washers, and they WILL crack/break instead.

This is true for any vehicle. So, 25-30 max

A friend was setting preload on a pinion bearing (not model A) and the book said 20 ft-lb. I said, ummm, no. He did it anyway. Pinion bearings exploded at 400 miles. Book shoulda said 20 in-lbs

Ya, just like the book says to torque the axle nuts to 125 ft-lbs. Too much, damned near ruined the threads on mine. Now holding OK at 95 and keeping my fingers crossed.

 

[gweilbaker]

Like the head, try re-tightening after a few temperature cycles.

 

[BILL WILLIAMSON]

most of us like the copper gasket

Because of the EXPANSION & CONTRACTION of manifolds, there seems to be a general consensus that the LAMINATED Copper is BEST!
I have a set, made from THIN COMPOSITION material, they'd "PROBABLY" last about 27 SECONDS
Bill W.

 

[100IH]

I have gotten into the habit of leaving the bolts loose that hold the intake up against the exhaust. Mount the assembly onto the studs on the engine, then visually inspect the gasket positioning and feel for the rings between the block and the manifolds. Once the alignment is good, begin to slightly snug up the brass nuts on the exhaust studs and look at the hot-spot, space between the manifolds. I prefer the block to the individual manifolds mounting to be good before pulling the manifolds together. If the hot-spot isn't a good mate, I'd leave it un-torqued so as not pull either manifold out of register with the ports. Get the manifolds tight to 35# then just a bit at the other 2 bolts.

 

[Mitch//pa]

I have gotten into the habit of leaving the bolts loose that hold the intake up against the exhaust. Mount the assembly onto the studs on the engine, then visually inspect the gasket positioning and feel for the rings between the block and the manifolds. Once the alignment is good, begin to slightly snug up the brass nuts on the exhaust studs and look at the hot-spot, space between the manifolds. I prefer the block to the individual manifolds mounting to be good before pulling the manifolds together. If the hot-spot isn't a good mate, I'd leave it un-torqued so as not pull either manifold out of register with the ports. Get the manifolds tight to 35# then just a bit at the other 2 bolts.

I do that also then work everything together as a unit

 

[Benson]

Maybe the air leak is at the carb mounting gasket ...

I know it happened to me more than once ... crank crank crank no fire !!

It is possible to install the gasket through only one of the carb mounting bolts and have the gasket turn 60 degrees or so toward the engine where you can not see that it has turned.

The result is a large vacuum leak between the carb and intake manifold ...

The resulting leak is larger if you are using the thicker copper gasket instead of a paper gasket !!

This happens more often if you are installing carb in a dark garage!!