1984 T/A with the 305v8 with stock exhaust system front to rear.
I want to drop the exhaust pipes ( I believe that I will have to drop both sides) to remove the butterfly in the heatriser. If I remove the bolts that connect the exhaust pipes to the manifold, will the pipes drop down far enough with the cat or do i have to loosen all the hangers, etc all the way to the rear?

 

Yes. I did it on my '83 You MAY need to remove the hanger for the catalytic converter, but try it first without doing that. You do not need to loosen anything after the cat...

 

Tkx, M.L.. I am used to working on my previous car, a 1972 Buick GS with duals. New toy, new experience, but the manifolds weighted a ton. Chevy's are much lighter & smaller.

 

The '70 Buick GS is one of my favorite cars. 'Same body as the '71-'72 but I like the bumpers and tail lights better on the '70...

 

T.L. The 1970 GS with Stage 2 455 was one screaming car and has been known to beat the LS6 Chevelle. My GS was a 350 4bbl & it would go.

 

Yeah, a high school buddy had a '72 Olds cutlass with 350. All he did was add a 4-barrel & dual exhaust. While not as powerful as the '68-'70 4-4-2s, that thing had some serious grunt for a heavy car. I always liked the '68-'72 GM A-bodies...

 

IIRC, my old MOTOR manual says 500 ft/lbs of torque!

And you had better spray those bolts and studs with a good penetrating oil each day for about a week before you try to loosen anything.

 

Today I jacked up the T/A and placed jack stands under the front cross member. The exhaust manifold bolts (15 mm) were tight but with a half inch socket drive & two 1/2 inch extensions drive I was able to remove all four. I also removed the bolt that attaches the hangar to the cat. I was able to drop the heat riser & then proceeded to remove the butterfly with a hacksaw.. I filled the shaft hole with a 3/8" bolt & nut. Done.
The heat riser was partially seized and thus not freely moving. Tomorrow, I will reinstall everything.

 

I knew you could do it...

 

The exhaust is back in place + heat riser debutterflied. I also then removed all vacuum lines that were no longer required, etc., and was able to install the plugs in the thermostat housing. The ported vacuum port on the carb is now attached to the vacuum advance. Car actually is running better.