Vintage manifolds
 

I need a little info regarding manifolds.

As I posted in a previous post, my 454/425HP motors have old 3" log manifolds right now.

I have one friend who has a stock set of manifolds from a early 90's 454/365HP, they are the stock merc 4" cast iron ones.

I have another friend who has a set of manifolds off a early 80's scarab 38. He says they are mercs PRE-Gil performance manifolds. They are cast iron, but he says they have individual runners.

Im sure either one of these manifold styles are better than what I have now, but Id like more info regarding the "pre-Gil" merc performance manifolds from the early 80's. Thanks

Re: Vintage manifolds
 

ttt

Re: Vintage manifolds
 

The manifolds that Merc used before Gil were prone to failure. If I remember correctly, Merc was swapping them out for Gils as a warranty/goodwill program.

Kurt

Re: Vintage manifolds
 

personally a wont put used manifolds on a boat, If a customer asks me to I ask them to find someone else to put them on

I do it right or I wont do it at all ( just my policy )

Re: Vintage manifolds
 

Those early Merc manifolds were prone to reversion and failure. The 420's used them for a couple of years. The 425's used Gil manifolds. They would be a good choice.

Re: Vintage manifolds
 

What if the manifold is off an engine (your own) your replacing/rebuilding?

Re: Vintage manifolds
 

The only reason Im asking is that the Early Merc Perf manifolds are available to me dirt cheap. I would have them pressure tested before installation. Would I gain any noticable power from them?