[TWF79]

Heard a strange noise, did a quick inspection and could not see anything. I took the heat shield off and look at what I found.

The bolts have never been turned, what kind of head ache do I have?

What are my options for replacements manifolds?

[bigborehunter]

There was a manufacturer making replacement bolt on stock cast iron exhaust manifolds. The company was called Hermanns or Hermoff. Check with a big dealer that works on used cars. Hermoff is the name. Just found them online. They're being bought by an Asian company.

[b-man]

Shouldn't be too hard to find good used replacements if you post a 'parts wanted' ad in the appropriate classified forum here on PY.

Spraying down the bolts with a good brand of penetrating oil (Kroil or PB Blaster) and letting it soak in for as long as possible would be a good start. The back side of 2 of the bolts on the end ports are easily accessible for oiling up, and if you don't mind removing the two head bolts on the ends you can access the back of the other two end bolts as well. After you're done simply reinstall the two head bolts and torque them down to 95 ft/lb after oiling the threads and under the bolt heads as well using 30 wt engine oil, head gasket seal won't be affected..

Often the bolt heads themselves will 'shrink' in size from rust and corrosion over the years. Perhaps to try using a 6-point 14mm socket or wrench that's normally a tight fit on a 9/16" bolt head would be wise before rounding them off.

[TWF79]

b- man is the FN390 the correct part number?

[Grand73Am]

What engine do you have? I see 79 in your user name. So, that makes me think you might have an Olds 403. If so, you could get some Thorton manifolds for Olds.

If you have a Pontiac engine, there are the exhaust manifolds from Ram Air Restoration Enterprises. These are 2-1/4 outlets. They also have 2-1/2 outlets available on another page:

http://www.ramairrestoration.com/pon...y-headers.html

These(and others like them) will be better than your stock manifolds, but the outlets are probably in a different location which would require some exhaust pipe work to hook them up to your existing pipes.

[TWF79]

I have the 400 with 4 speed.

[TWF79]

I'm looking at FN390 and FN393. I sent a request to tech to make sure it will fit my motor.

[TWF79]

I received the answer from Adam the FN390, FN393, and FN406F are needed to replace the broken manifold. I will start soaking the bolts tonight.