Intake Manifold

Hey folks, two part question for the PCM guru's. After talking with Tim B. there seems to be two different stock intake manifolds for the 351w (marine). I will refer to them as the 12 bolt (mine) and the 16 bolt. Does anyone know the history? The tag on my engine block indicates a 1983 RH. The problem I encountered was an interference with the water neck stub and hose to the left exhaust manifold and my new DUI dizzy. The original dizzy was a Prestolite with a 3 inch diameter body. The DUI has a 5 inch body.

Everyone I have talked with, which was confirmed by internet researches, have not had any problem with fitment on the 351w and the DUI. My guess is they have the 16 bolt manifold. Mine is the 12 bolt.

My options are to return the DUI, and they will make me longer (above the the engine) dizzy so the body clears the waterneck. That is going to take time and another $75. Time is my issue right now. I am going to look at the water neck to see if I can modify it to gain some clearance. My other option would be to pull the manifold and replace it with an aftermarket. I am looking for recommendations on the manifold. [/IMG]

I'm curious how this plays out being that I'll be switching to a DUI in the next month or so.

This doesn't make any sense at all. Several here have had no clearance issues installing a DUI in a 351.
Keno is absolutely right. The dizzy mounting location and height can't possibly change.

A quick search at Edelbrock indicates that the 12 bolt intake will fit an older 16 bolt head as long as you have a 16 bolt gasket. Don't ask me how the hell this works because I have no idea. This is exactly why I'll take a Chevy any day. Ford's make absolutely no sense to me.
If this is true, your 12 bolt vs. 16 bolt theory is moot. It's the same intake no matter how many bolts it has.

Are you sure this isn't a 302? The 302 intake isn't nearly as wide as the 351 so the location of the water neck will be considerably closer to the dizzy.
Another option might be to use this time to install a new aftermarket aluminum intake and get rid of that POS stock one. The water jacket housing might be just different enough to clear. I'm guessing that most everybody has done that when upgrading to a DUI anyway. At least that would make the most sense to me. DUI instructions specifically state that they won't fit with an Edelbrock Victor Jr. but nothing mentioned about any other intake.

Sorry I'm not more help than that.

Damn, Tim has beat me to the punch again.

I concur with him obviously. Edelbrock Performer with stock heads.

It seems like an easy solution would be a spacer between the thermostat housing and the manifold to move the whole housing forward enough.

You'll then have clearance with any manifold you want to use.

You'd need a couple of longer mounting bolts, a gasket for each side of the spacer and somebody to machine the spacer.

He could use the gasket as a template.

It would affect the alternator alignment due to it's bracket bracket mounting to the housing but some washers could easily remedy this.

KenO

I wonder if the Thermo housing is the wrong part. There is a casting number on it. I'll take a look. Dan

So, I am going to take the thermo house off and see if I can get the clearance by elongating the holes. If that is a no go, I have a chunk of aluminum that I have been itching to do something with. Might machine my own spacer. I'll keep you posted. Dan

Hi Dan

Hope the project goes well for you.

As an "oh by the way", if you had a 351 with an Indmar conversion instead of a Pleasurecraft, there is plenty of room for the DUI distributor because the thermostat housing setup is completely different.

But that's mostly on them M..m..m..mastercrafts

Ken O

Useful comment Mr. Gun

Well I guess I wanted to replace the stock prestolite that was bastardized. Marine distributors are not cheap, since I was going to make the investment I figured I would get something that was highly recommended and made in the US. I also figured on taking it with me to my next boat. Besides a good strong spark can't hurt an old tired boat.

Also this upgrade was supposed to be fairly painless, meaning less time lost on the water. All in all, I don't think it the purchase was a waste of money. Of course, you can disagree, I just wanted you to know that I had thought about where I was going to spend my boat money this year. Thanks for your concern. By the way, got basically the same comment from my wife.

I picked up 200rpm in both holeshot and wot when i put a DUI on my otherwise stock 90. I couldn't see spending $100+ on another junk EI kit, so I understand the rationale. Room for growth!

There's definitely something oddball about the housing or that particular intake...

If he went with the Mallory electronic distributor, the extra 100 bucks plus that he would have saved would put him close to half way to a better intake and get rid of the "boat anchor" intake he's trying to use.

TX Foilhead wrote: Mallory stuff isn't an upgrade anymore, it's junk.

Junk really!!
I guess I got lucky then as mine has worked flawlessly since I installed it a couple of years ago.

More data. Found there was not enough play in the water neck to squeeze the hose on. Going with a spacer. Found I had a piece of 1/8 brass plate. That with a couple of gaskets and I should be ok but it will still be tight. Here is a picture of my water neck.
[/IMG]

Probably too late to notice now, but was the alternator bar aligned properly before?