Blown 454 Manifold Gaskets

[Dolores]

Morning from the UK.   I've done a search on your Forum but couldn't really find an answer to my problem. You got too technical talking about Headers etc which I don't know what they are...     Got a 454 V8 engine. Had the manifolds taken off and new gaskets replaced about 18 months ago. It only lasted 6 months and only a few hundred miles before it started blowing again. Got worse ever since, now the drivers side is blowing badly and the passenger's side beginning to blow.  I've been told that  'all V8's blow....'   Is this a common problem?   Is it worth me buying new manifolds and gaskets and getting them fitted? And hoping it won't happen again?  Or having the old ones 'faced', new gaskets and then re-fitted?  What do you think would cure the problem once and for all? 

[kattkisson]

all 454's don't blow.

there are 2 ways to approach this problem depending on cost and preferences

1. Reface the present manifolds and use gaskets.  during this process or after there is a modification that GM came out with that can be done with a hacksaw  that allows the manifold to conform better when heated.  Look it up . When I had mine done they had to remove almost .100" for it to be flat.

2.  New manifolds with gaskets.  They will probably have the modification mentioned above.  Note that most of these engines came from the factory without gaskets.

In my case it was only about $100US difference between machining and new.

[tiinytina]

Or if you have the funds to do it... headers can replace manifolds.  The cast iron manifolds on the 454 are known for issues.. Ours had an accordion like flex piece that finally blew out completely when the engine backfired.  Banks is the header system many including me have switched to once the old manifolds cracked.  $1200US when I bought them.. kit is complete with every bolt etc needed and also has designed in the hot air return to the carb.  Depends how much you want to spend.  Performance definitely increased with the headers though no increase in kpl/mpg and Gone sounds like a pack of Harley motorcycles with a deep rumble. 

[Rickf1985]

A lot of the time the fault can be because of an ill fitting exhaust pipe. If the pipe is putting strain on the manifold it will eventually cause the manifold to warp and leak. The longer it leaks the worse the damage since the flame is eating away at the metal of the manifold the whole time. The later manifolds with the bellows in the center are made out of stainless steel and not cast iron. I had to weld a bead around the flange on mine and file it flat again to get it to seal. A member here sent me a better used manifold that I am going to replace it with though. My reccomendation is based on how much you want to spend. The route that Tina went is top of the line and will last you a lifetime but is pricey and labor intensive. The facing and gaskets will work fine as long as it is all done to spec and the bolts are tightened evenly and quality gaskets are used. The exhaust pipes have to fit up well also.