SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: BDK on August 03, 2021, 10:26:39 AM

Title: Intake Manifold for 1981 HM 454?
Post by: BDK on August 03, 2021, 10:26:39 AM
Greetings, first post.  I did search for my topic, didn't find it.
I inherited my Dad's 1987 Miller Mini-Cruiser.  Its a beautiful boat full of family memories.  Its been sitting over six years.  I got it running after changing the oil, all the filters, the plugs and draining the gas tanks.  It runs strong, but I have sent the carb to a hot rod friend to be rebuilt because I didn't want to take the chance of a clogged port burning out a piston.  It has a Holley 3310-2 750 on a 1" adaptor plate.

The engine is a 1981 HM 454 that was gone through right before my Dad started declining so it has maybe 20 hours on it, and one trip to Havasu.  It has a mild cam, not sure what it is and I couldn't locate any paperwork.

It has the OEM intake manifold on it.  Since I pulled the carb, a hot rod buddy who was looking the engine over suggested I get a nice dual plane intake manifold to wake that engine up a little.  Nothing too crazy, its a covered engine and needs to stay that way.  Maybe 2" over the stock intake would be fine.  It was suggested I call Edelbrook and use their recommendation but its hard to get ahold of them lately.  I am looking for something that would produce a little more power but not use much more fuel.  I was thinking a modern intake manifold could do that.  Would want to keep the carb it has on it, and I would like to stay under $400 if possible.  The boat has never been in salt water and never will if that matters.

Any suggestions would be appreciated?
Title: Re: Intake Manifold for 1981 HM 454?
Post by: Grimpala on August 03, 2021, 10:33:29 AM
Nice looking boat, sorry to hear about your dad.

I run an Edelbrock RPM on my 454 in my Rogers and on the 383 in my Chevelle and love them for single carb setups.  The one int he boat is a standard and the one in the Chevelle is an airgap, either one will work.

https://www.edelbrock.com/performer-rpm-big-block-chevy-2-o-intake-manifold-7161.html
Title: Re: Intake Manifold for 1981 HM 454?
Post by: FordLover on August 03, 2021, 11:12:23 AM
Welcome! Beautiful float!

Sent from my LM-Q730 using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)

Title: Re: Intake Manifold for 1981 HM 454?
Post by: mash on it on August 04, 2021, 08:20:21 AM
I run a Victor Jr air gap on mine. Dog house clearance might be a problem for you.
Jets don't really need extra torque down low... That's what a dual plane manifold is for.(motorhomes and tow trucks).
A compromise is a Eddie performer rpm (or similar) with a 1" open spacer (linkage wouldn't clear without it anyways). Clearance might still be a problem. I can check the height differences this weekend. Vic Jr vs performer rpm vs a stock iron truck manifold.

Dan'l

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