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I’ve a 1969 hardtop that came with two l46 motors with one being original to the car. The plan is to rebuild the original to stock specs and run the other, which is in the car. Question....What is the proper way to refurbish the original intake that is flaking with several coats of paint many years of crud. A friend recommended to take it to a local sand blasting place and I did. When I got there it turned out to be a monument place....yes they make headstones. I left it there and they are gonna commence blasting in the morning. Do I need to worry about the sand blasting eroding edges on the intake? Is this the proper way to go? Please advise.
Last edited by Akroland; May 29, 2018 at 01:24 PM.
I’ve a 1969 hardtop that came with two l46 motors with one being original to the car. The plan is to rebuild the original to stock specs and run the other, which is in the car. Question....What is the proper way to refurbish the original intake that is flaking with several coats of paint many years of crud. A friend recommended to take it to a local sand blasting place and I did. When I got there it turned out to be a monument place....yes they make headstones. I left it there and they are gonna commence blasting in the morning. Do I need to worry about the sand blasting eroding edges on the intake? Is this the proper way to go? Please advise.
Sand blast it, then clean/flush it REALLY well inside/out... Then primer it and paint it with the high temp engine paint... It'll look good.
Sand blasting is not gonna hurt cast iron...at least not unless they have some kind of super duper industrial blast cannon...LOL
I had the intake blasted and today with it hot and relatively dry down here in south Florida I primed and painted the manifold. It came out fairly nice in my opinion. One thing I noticed was the port for the goose neck radiator hose has one of the bolt holes badly stripped out. How tough is it to fix this with a helicoil?
I had the intake blasted and today with it hot and relatively dry down here in south Florida I primed and painted the manifold. It came out fairly nice in my opinion. One thing I noticed was the port for the goose neck radiator hose has one of the bolt holes badly stripped out. How tough is it to fix this with a helicoil?
If your intake has a heat shield on the underside, it is critical that there is no blasting "media" remaining under the shield when you reinstall it on the engine.
These shields trap a lot of oil sludge in them over the years and if media gets trapped in there when it was blasted, some of it will find it's way into your oiling system and very likely wreck havoc on your engine. The factory shields are retained by expanding rivets and can typically be pried off and later replaced with new rivets. If there is no shield, or it was removed before blasting, you should be good to go.
Make sure you have all the grit out of the interior of the manifold as well. Far safer it to strip the manifold chemically. Hot tank at an engine builder will take off all the paint without potentially introducing grit into the engine.
Save sandblasting or abrasive blasting for the chassis.
GUSTO14.....My manifold does not have a shield attached. I looked around the venders for a short time and didn’t find any available. Is it a must item? What does it do? I’ve two engines with this one being original to the car so I want to keep this rebuild as stock as possible. Where can I get a shield and the rivets to install
GUSTO14.....My manifold does not have a shield attached. I looked around the venders for a short time and didn’t find any available. Is it a must item? What does it do? I’ve two engines with this one being original to the car so I want to keep this rebuild as stock as possible. Where can I get a shield and the rivets to install
Every manifold does not have a heat shield. Many aftermarket manifolds do not have them. I can't recall many factory manifolds that don't have them however. Does your's have the holes in it where the shield retaining rivets go in?
Finding a shield would normaly require taking one from another identical manifold. I've not seen them available separately, although the rivets are. It is probably not critical and is intended to keep internal heat off the bottom of the phlenum. If you can't find one and are concerned, I would just block the exhaust heat crossover ports to compensate. The block off plates are often included with intake manifold gasket sets.
You may want to post a picture of the underside of the manifold and the folks here can offer additional guidance. I would also post the manifold casting number as someone may have what you need on an old manifold.
1969 3927184 350 4 iron Qjet A B F X Y/255,300,350HP, srv. rep.
It is listed as a 300hp, 350hp and a service replacement manifold for your car. There should be a lot of them floating around at very inexpensive prices.
When I took my block to the machine shop, I gave him the oil pan, manifold and rocker covers. He's got some kind of super hot washer and it took all the paint etc off of everything. I don't think I'd feel confident that I could get all the sand out from blasting
Heli coil is and easy fix but should be done on a drill press so it is square.
Do both holes too......heli coil make the host part MUCH strong for fastening.....
Brodix heli-coils all holes in their heads from the factory for this very reason.
I agree on the heat shield too......remove it to clean and reattach with twist pins available at McMaster Carr.
Something everyone is not thinking about, the blocks, head and intake were all sandcast. They all started life full of sand. The key is cleaning all the oil out of the parts before blasting. This is what keep the media from sticking in the part.
Yes a hot tank is safer if it's available, but I blasted aluminum and iron parts for decades without a single issue, but I am very careful and **** about cleanliness before assembly.
Sand cast isn’t the same as sandblasted, by any stretch. Then it’s hot tanked and machined. Lots of machine oil pouring through a virgin block. No gunk, no rust scale, just perfectly clean metal. Sandblasting a manifold and installing it isn’t comparable at all.
Sand cast isn’t the same as sandblasted, by any stretch. Then it’s hot tanked and machined. Lots of machine oil pouring through a virgin block. No gunk, no rust scale, just perfectly clean metal. Sandblasting a manifold and installing it isn’t comparable at all.
Please reread the part where I say: "The key is cleaning all the oil out of the parts before blasting." If you blast a part that still has oil all over in it, you will play hell ever getting the blast media out again.
I have found sand and machining chips in new parts well as parts that have already been run. Doesn't matter if it's new or old, cleaning is one of the most important parts of engine building.
The manifold has no shield on the bottom. Two questions. Were do I source one and do I actual need it. I’m not too keen on leaving it off as this motor is going to to rebuilt as stock as possible.
I bought a wire wheel brush set from lowes you attach them to a drill , all the brushes are brass and different shapes ,after degreasing parts I just wire brush the whole thing to bare metal , I have a sandblaster but only use it on parts that get bolted on outside the motor ,too worried about sand getting in the oil.
The manifold has no shield on the bottom. Two questions. Were do I source one and do I actual need it. I’m not too keen on leaving it off as this motor is going to to rebuilt as stock as possible.
You do not need the oil splash shield on the bottom. Lots of intakes don't even have them from the factory. No aftermarket intakes have them at all. Go ahead and put the intake on and forget about it.
Proper intake cleaning
