Topic: Intake Manifold Grinding

[mrcabinet]

While anxiously awaiting for my 62mm TB from Bounty Hunter, I've been contemplating a different way of grinding out the manifold. Using a dremel obviously works, but it seems messy and would be difficult (for me at least!) to get a nice round hole with. I have a slew of hole saws and was thinking about using the gasket as a pattern to make a jig out of MDF, bolt it to the manifold, and then cut it with a hole saw. This would be perfectly round and decrease the amount of chips flying around.

My only concern is that the closest I have to 62mm is 2 1/2", which is 63.5mm. Would the slightly larger hole be O.K.? Should I trim the gasket opening larger as well? I don't know if the slight lip of the gasket could get sucked inside.

[FourbangerYJ]

I wouldn't go larger.
The biggest problem I had with the chips was the gas that is inside the manifold. The chips stick to it so it's kinda hard to get them out. You would have the same problem with a hole saw plus you would have the MDF chips too. Just make sure you tape the inside of the opening better than me
If you mark the hole with a sharpie the dremel way can be fairly close to being a perfect circle. If there is some slight imperfections in the circle it's not going to matter that much.
The chips that get on the outside of the manifold vaccume up pretty easily. Whatever you can't get to just hose it all down once it's all back together.

[jdarg]

i'd try it, 1.5mm larger is better for flow than a rough azz hole IMHO.\

The only problem is I've never seen a hole saw that runs true. There's also some ribs in there you'll still need to deal with after using the hole cutter.

Dremel w/ stone brings the suck - very slow. Use a Dremel rasp attachment or whatever its called and then follow w/ a stone or sanding drum for evening the hole out once you have it real close w/ the rasp. Even the rasp is slow going but a stone alone would take all freaking day.

[FourbangerYJ]

i'd try it, 1.5mm larger is better for flow than a rough azz hole IMHO.\

The only problem is I've never seen a hole saw that runs true. There's also some ribs in there you'll still need to deal with after using the hole cutter.

Dremel w/ stone brings the suck - very slow. Use a Dremel rasp attachment or whatever its called and then follow w/ a stone or sanding drum for evening the hole out once you have it real close w/ the rasp. Even the rasp is slow going but a stone alone would take all freaking day.

There is 4 ribs that you get into a little.
The dremel with a rasp cuts the AL pretty fast. If you follow your line that you marked the edge is not ragged.

[stan98tj]

did you guys remove the manifold to bore it out or did you just bore with it on the engine and stuffed the hole to catch all the junk?

[FourbangerYJ]

did you guys remove the manifold to bore it out or did you just bore with it on the engine and stuffed the hole to catch all the junk?

Not to sound weird but, I just stuffed my hole 

[sharpxmen]

While anxiously awaiting for my 62mm TB from Bounty Hunter, I've been contemplating a different way of grinding out the manifold. Using a dremel obviously works, but it seems messy and would be difficult (for me at least!) to get a nice round hole with. I have a slew of hole saws and was thinking about using the gasket as a pattern to make a jig out of MDF, bolt it to the manifold, and then cut it with a hole saw. This would be perfectly round and decrease the amount of chips flying around.

My only concern is that the closest I have to 62mm is 2 1/2", which is 63.5mm. Would the slightly larger hole be O.K.? Should I trim the gasket opening larger as well? I don't know if the slight lip of the gasket could get sucked inside.

i was actually planning to do the same thing - use the 2-1/2'' bimetal holesaw - cuts fairly accurate, maybe 1/16 over 2-1/2 you just gave me a better idea how to do it with the mdf (EDIT:  ) but i will use 5/8 plywood that i have around (i was planning to try and use a flat bar inside the opening bolted thru 2 of the holes with some longer 4mm metric bolts and use it to center the holesaw, but this way is easier, it would center itself on the inside of the plywood) - if i get around to do it before you bore out yours i'll let you know how it goes

[Jeffy]

I would use a 2" sanding drum and work slowly.  Cutting it to 2.5" leaves no margin for errors especially if you're using a hand drill.

[haulincats]

I'm sorry but I have to ask........what is an MDF ?
Thanks,
Vance

[Jesse-James]

Medium density fiberboard

[sharpxmen]

like he ^ said - it is commonly used in painted kitchen cabinet doors (and even the cabinets themselves). Also, it is used for boom boxes and speaker boxes as it is very easy and friendly to the router bits (you can use routers to give it various profile edges) and it can be glued with no seam. Can be painted and also can be covered with fabric.

[stan98tj]

just the intake port needs to be enlarged correct?

[FourbangerYJ]

just the intake port needs to be enlarged correct?

Where the TB and the manifold meet.

http://4bangerjp.com/forums/index.php/topic,6008.0.html  (from the FAQ's)

[mrcabinet]

I was rummaging around in the shop today and came across a 2 3/8" hole saw. That equates to 60.325 mm. The hole will probably "run-out" some during the cut, so I'll just use that then a sanding drum to get to 62mm. Hmmm, I do have a cylinder hone. Maybe that would do for the final grind.

I have about 60 sheets of 3/4" MDF, so I'll most likely use that as my guide and countersink the bolt holes so I don't have to buy longer ones.

[sharpxmen]

like he ^ said - it is commonly used in painted kitchen cabinet doors (and even the cabinets themselves). Also, it is used for boom boxes and speaker boxes as it is very easy and friendly to the router bits (you can use routers to give it various profile edges) and it can be glued with no seam. Can be painted and also can be covered with fabric.

it's fun to quote myself - i just realized his nickname is mrCabinet -

i guess no question why the extra MDF lying around...