Exhaust manifold woes... Any words of wisdom?

[Aerochez]

Well, first major unexpected problem discovered today. Took the right side valve cover off to replace a leaking gasket and discovered the exhaust manifold cracked in at least 3 places. Anyone know a good source to get a new one? I'm gonna post the question in a new thread, too. At least it looks relatively accessible. I should have looked at that closer before buying it...
Chris
1984 Chevy 454 with a.i.r. tubes.

[Full-Timers]

The problem will be getting the bolts out of the head without breaking them off.

[DriVer]

Quote:

Originally Posted by Aerochez Well, first major unexpected problem discovered today. Took the right side valve cover off to replace a leaking gasket and discovered the exhaust manifold cracked in at least 3 places. Anyone know a good source to get a new one? I'm gonna post the question in a new thread, too. At least it looks relatively accessible. I should have looked at that closer before buying it...

Absent getting the stock manifolds for that engine which appear to crack on command it would seem, you might chose to go with a set of headers which might help you - long term.

[Aerochez]

Quote:

Originally Posted by DriVer Absent getting the stock manifolds for that engine which appear to crack on command it would seem, you might chose to go with a set of headers which might help you - long term.

I had one fairly long time guy tell me some vague thing about headers not neccessarily being great for motorhomes. He is admitedly a great coach guy and not really a chassis/power guy. I can't think what the downside to headers would be unless they a) disqualify it from smog (I'll be next registering it in Colorado, so not sure what the law there is concerning exhaust mods. Here in California, it's draconian) or b) cause heat issues under the doghouse. Anyone put headers on a Class A of this vintage?
Chris

[RVhauler]

Chevy 454 are like Ford 460 in that exhaust manifolds crack frequently. One problem being that they get extremely hot during a hard pull and then cool rapidly going down hill thus cracking. Removal of studs requires liberal applications of PB Blaster or other brands several application usually necessary. A good welding/machine shop can clamp manifold in a jig and braze/weld manifolds without warpage. Much cheaper than purchasing new

[Topflite51]

If you stick with oem style, Napa should be able to supply them. Headers can be nice and they can be a pain in the A$$. With stock carb and air intake, not much to be gained with headers.

[Aerochez]

Looks like Dorman makes a replacement for the stock manifold that is rated up to 1400 degrees. I'll call tomorrow and check it out. $170 online at discountexhaust dot com.
Discount Exhaust Systems - 1984 Chevrolet P30 Base 8 Cyl 7.4L Exhaust Manifold)

[justimagination]

Your in luck, the right side is much easier than the left one, more room. You might try your local GM dealer, they should still be available. As for NAPA, I think it's going to be dealer only item. Good luck, happy trails & travel safe.
David G.

[DSouthw524]

The comment on headers not being good for MH use is correct - IF the auto designed headers are being used. The headers for MH use such as Banks are designed for the Improvement of flow at low RPM and not the high RPM that autos use for power.

[Kountry87Air]

Have you inspected both sides?

[speed racer]

I don't know about the Dorman manifolds but I do know someone makes these exhaust manifold with a stainless steel alloy in them. A guy I knew bought them and it solved his problem.

[dogpatch]

We just bought a used 2000 Winnebago Adventurer (V-10 Ford). I can hear what sounds like a manifold exhaust leak from under the doghouse when under load. It goes away once speed levels off. What's the thought from others on the Banks system? Obviously cheaper to fix the issue than the complete replacement. Does Banks make that big of a difference with towing, horsepower and fuel economy? I'd hate to have to spend $4000 on an older motorhome but ask the members advise.

[JCM]

When my manifolds popped their bolts. I went to Banks headers (didn't replace the exhaust or intake). The unit ran cooler under the hood ( I used a infrred reader but can't find the readings). I had more power from 50 - 80 mph with unreal acceleration.
I never had another problem with bolts or manifolds.
I recommend them.

[Mr JP]

I installed the complete banks kit (headers) on a 95 bounder 34J w/454. It helped allot mainly with engine heat(engine runs allot cooler) and power. I would also recommend trans fluid change over to synthetic oil I used AMSOIL and it helped the trans run cooler. Good Luck. JP