I have a 1974 jet boat with a 455 olds in it. I have recently stolen it from my dad, who's had it since the 70's.

I have a 750 Holley DP, square bore ordered and on the way. My question is will I have to have an adapter plate for the stock Olds intake? I believe the stock intake is a spread bore design if I am thinking correct.

Thanks!

 

Yes, it is not a direct bolt in.

 

What I was worried about. Dont think my rear hatch has any extra clearance. hmm

 

Why not go with a performer intake? Then you don't need a adaptor.

 

If you need some additional clearance with the adaptor you can get a drop base air cleaner to make up for the extra inch or so.

 

Not against changing intakes, but got a late start and trying to be boating this weekend.

That would be an Edelbrock I assume?

 

You assume correct

 

Will I see any noticeable performance issues using an adapter, versus the matching intake?

 

On the jet boat probably nothing noticeable.

 

The performer is a better intake hands down on a car without using adaptor for a stock intake but using drop base air cleaner. On a boat i don't know but i would say better air flow has to be a benefit!! On a side note i drag race olds cars this is why i mentioned the intake. JMO

 

Any suggestions on what timing to run?

 

I'm not sure with a boat, but on a car we look for total timing of 34-38 BTDC with no vacuum.

 

The OP is probably on the lake by now, but does a boat require an air cleaner at all? Spark arrestor yes, but not an air cleaner. I'll probably need that flame arrestor after this post.