[crm318]

I just acquired the correct stock iron intake for my 1970 GTO and I did some extensive porting in the carb area (removed the lateral dividers all the way down). I noticed the inside of the intake is filled with rust and other hard crusty substances. What's a good way to clean it out throughly? I was thinking off blocking off the ports and filling it with vinegar overnight. It may require something more effective.

[54nomore]

Vinegar is cheap, you might as well give it a try. It certainly won't hurt anything and all it will cost is a little time.

[lugnutx2]

I have the machine shop hot tank and or bake the manifold, that usually does the trick. If it still has some rust in the runners, I'll hit it real light with the glass bead.

[b-man]

Vinegar will attack machined surfaces, either soak it in molasses (feed grade) or give it a thorough bead blasting.

[Toms bird]

Home depot sell prep and etch it's for etching concrete. It's a phosphoric acid you can use full strength or dilute with 4 gallons of water to 1 gallon acid. It's under $20 a gallon. The stuff is amazing what it will derust. Just dont put greasy or oily stuff in clean first.

[Formulajones]

I use evaporust. Block off the ports and fill it up. Sit for 24 hours and it looks brandy new inside. Plus the stuff is reusable. I filter it back into the jug for the next project.

[beertracker]

Originally Posted by Toms bird

Home depot sell prep and etch it's for etching concrete. It's a phosphoric acid you can use full strength or dilute with 4 gallons of water to 1 gallon acid. It's under $20 a gallon. The stuff is amazing what it will derust. Just dont put greasy or oily stuff in clean first.

I have used that stuff & it works great. Also sold at Lowes as Crud Rust Buster.

[STEELCITYFIREBIRD]

A bigger production machine shop will have an oven bake, steel shot and shake set up. Will look like a fresh new casting.
Likely cost you about $25-45..... and none of your time materials for a perfect job.

Glass bead is a viable option if you have access to a cabinet, the man time it takes a shop to cabinet blast it will likely cost you more than a bake and shake... for a machine shop to do it.

[GRX]

x2 on bake & shot peen for that fresh clean look.

x2 on feed grade molasses if above is not an option.

[dataway]

I just dropped mine off at the industrial sandblaster and told him to run the nozzle into the runners .... came out super clean of course.

[steve25]

I hope you are not looking for good bottom end responce with that divider removed?

Those stock iron manifolds will support well over 500 hp in stock form and surly your set up / Cam will not get you near that level of power!

[A.J.]

Citric acid. Cheap and can be found in your wife's kitchen.....

[steve25]

Cleaning , if you have a big enough Gas grill, then heat up the manifold to 160 and spray it down with oven cleaner then in 30 minutes hose off where you don't mind your grass going dead and replete if needed !

[rohrt]

I use the phosphoric acid and Evaporust.

The phosphoric acid is some harsh stuff but works pretty quickly.

I have 2 gallons of the Evaporust in a big plastic container and drop pieces in it overnight.

[crm318]

Thank you guys for the ideas. All very viable options. As far as the intake divider goes. I cut it down to look like a performer RPM. It is still 180 degree divided with a smidge taken down by the secondaries.

[77 TRASHCAN]

Originally Posted by crm318

Thank you guys for the ideas. All very viable options. As far as the intake divider goes. I cut it down to look like a performer RPM. It is still 180 degree divided with a smidge taken down by the secondaries.

Looks good!
I have used Lysol toilet bowl cleaner on metal parts. It's fairly strong, so I don't let it set very long, depending on what I use it for. It's good for getting corrosion out of carbs, but he EXTRA cautious using in carbs. When using to de-corrode a carb, I don't let it sit more than 5 minutes at a time. I rinse it out w/ water to see how the de-scaling process is doing, then add more if needed, wait 5 more minutes....repeat again if needed...

[dataway]

I'm telling you .... have an industrial sandblaster stick a 1" nozzle in there and blast those babies out ... they will be cleaner and smoother than any other way.... although my guy charged me like $40 to do it.

[HoneyHush]

I've done 3 in my little harbor freight sand blast cabinet in the past year. All of them turned out like brand new.

[Grand73Am]

I sandblast and then blow it out, and then run some high pressure water through all openings to be sure no sand remains. Then dry with a towel and finish blowing out and drying with air.

[Doug]

electrolysis rust removal

battery charger
30 gal plastic trash can (something big enough for a manifold to go in)
washing soda
water
piece of scrap iron for grounding piece