intake manifold questions

[Cptkid570]

I received my new 350 long block (pre-1986 Mercruiser 260) from Rapido Marine. I’m very please with the service & you can’t beat the price. (I'm going to be asking a lot of questions over the next couple of weeks)

Anyway, my current intake manifold is pretty rusted & corroded looking. So, I’m trying to figure out what to do with it and I have a few questions:

1. When a machine shop “hot tanks” the engine block & parts, what type of liquid does it soak it in?

2. Could I just soak my intake manifold in a bucket of muratic acid and then repaint it?

3. I could get a cast iron intake manifold off of a truck/van at the auto junk yard for $15, but they have an EGR valve. Does anyone sell a plate that would block this off? If I made a plate to cover it up, would it affect the intake’s performance? Could I just plug up the egr valve?

Thank you for any responses.

 

[Rigidtool]

Re: intake manifold questions

As far as I know it is just a very heavy degreaser that is heated and circulated through the tank. you could always have it bead blasted, just make sure you cover the mating sufaces with a heavy masking tape then take the thing down to get it hot tanked so they will clean out any sand or bead particles that may have gotten inside.

 

[bjcsc]

Re: intake manifold questions

Does "rusted and corroded looking" mean there is loose scale? If so, I wouldn't take any chances with that manifold. I would only reuse parts that I knew were 100% on a longblock.

The good price you got won't be so good if you have to buy another one...

 

[95yj]

Re: intake manifold questions

My stock '97 5.7L 2bbl Merc cast iron intake manifold has the EGR opening and a plate and gasket covering it up. I would think you might find this at a Chevy dealer or maybe at Merc.

Instead of mucking around, you might want to just get the performance gains out of an aluminum manifold. You'll either want closed cooling or I've heard some people say they screw an anode into it and they hold up fine.

 

[Cptkid570]

Re: intake manifold questions

I run in salt water, so I don't want to take the chances with an aluminum manifold. I found that NAPA sells an EGR block plate for $10, so I think I'll just get a manifold from the junk yard and get the block plate for the egr. Looks like I could make a block plate pretty easily too.

 

[95yj]

Re: intake manifold questions

You'll want to clean the used manifold real good and paint it to stop corrosion. Same with the block off plate.