How to enlarge intake bore

[zane9000]

I am not really sure if this is in the right section, but I took a guess.

 

I am putting together a custom intake and I need to enlarge the bore of an intake manifold. I tried using a rotary file, but the bore is not as even as I was hoping. Is there a particular tool I should be using for this? At think point I think I may just do the best I can with the rotary file, then spend some time with sandpaper to even it out.

 

Thanks,

Warren

[piston]

have you tried porting wheels instead of rotary? im not sure what you mean by rotary file but my rotary wheels are corse and takes off bits instead of shaving.

[Killerzed]

everyone I know that ported used rotary grind stones or just regular rotary bits and just had to do their best. There could be other ways though

[kiwi303]

Try one of those bore hone things with lots of balls on springs sticking out from the shaft. Then just keep working that back and forth until you get the size bore you want.

[zane9000]

piston,

 

I assume you are talking about a rasp. That is what I tiried first, not a whole lot better.

 

kiwi,

 

I had thought about using a hone, but after looking into it, it seemed that they were only meant to take off surface rust/ imperfections. I was looking at the hones with 3 stones though, not a ball hone. Are ball hones better for this?

 

I have a metal hole saw that I was thinking about trying tomorrow, as long as I can keep it centered it should be ok...

 

Thanks for the input!

[Killerzed]

I never thought about using a honing tool. I have one that has 3 grinding stones that would proly work perfect. Bought it from Canadian tire.

[kiwi303]

Strictly speaking, hones are really only meant to do the scribing of crosshatched marks in the machined bores to provide an evenly uneven surface for the rings to rub against to seal to the bore against. But use them too freely, and you can enlarge the bore to far to get a good seal...

 

With that being so, logic indicates, use them longer still and you can gradually expect to hog out the bores of whatever you are using them in until it reaches the size you desire.

 

It would take a hell of a long time to wear away 30mm if you needed to take off that much with a 400 grit cylinder hone but if you hog things to roughly where you want it to be with a carbide burr or rotary file and then use a hone, you should end up with a usable result.

 

Besides they are available in down to 20grit size, so theres plenty of abrasive action I only use sandpaper down to 50 grit http://www.flexhone.com/flexhone%20for%20cylinders.htm

 

The reason I suggested the ball type is they can get through curves more readily as opposed to the rectangular stone types. That would make doing the intake runners from the plenum simpler, but if all you want to do is enlarge the entry to allow a larger throttle body to be bolted up, a solid mount 2 or 3 stone rectangular one should work fine.

Edited February 15, 2010 by kiwi303
Add paragraph breaks, formatting is FUBAR

[skib]

I use a carbide bit like the bottom one on a pneumatic die grinder

 

 

 

youl want the larger flutes for alum.

 

 

and as far as it not coming out as even as you want it too, well that part just takes practice

[zane9000]

thanks folks. I will be experimenting today.

[sweetleaf]

Try a flapper wheel

[piston]

honing tool is not gonna happen. you better let that sucker sit all night and hope it bores it out the next morning. flap wheels might work though!

 

on skibs pic posted, i used finer ones like 2 and 3 and it works decent, just have to be patient and move your hands constantly. im planning to do my 2jz manifold with the same ones in pic above to finish off my runners.

[skib]

on skibs pic posted, i used finer ones like 2 and 3 and it works decent, just have to be patient and move your hands constantly. im planning to do my 2jz manifold with the same ones in pic above to finish off my runners.

 

the tin flutes are for metals like cast iron ect and the wide flutes are for softer metals like alum. (alum likes to build up in the thin flutes)

[zane9000]

yeah, the hone was a no go. I managed to get by with my drill and rotary file. I used something like this http://www.sears.com/shc/s/p_10153_12605_00967037000P?vName=Tools&cName=PowerToolAccessories&sName=Drill%20Bits&psid=FROOGLE01&sid=IAx20090815x000001&aff=Y. The aluminum really does build up in it quickly though. After some practice, I was able to get it done cleanly.

 

Thanks for all of the advice.

[skib]

yeah, the hone was a no go. I managed to get by with my drill and rotary file. I used something like this http://www.sears.com/shc/s/p_10153_12605_00967037000P?vName=Tools&cName=PowerToolAccessories&sName=Drill%20Bits&psid=FROOGLE01&sid=IAx20090815x000001&aff=Y. The aluminum really does build up in it quickly though. After some practice, I was able to get it done cleanly.

 

Thanks for all of the advice.

 

ya that on a drill is sloooow goin, get yourself the wide flute carbide bit and a pneumatic die grinder and its like night and day.

 

lol first time I did anything like that I opened up my intake for a KA TB with that thing and a drill, and it sucked lol I couldnt go back to using that

[zane9000]

I was working on this at my dads house. He's moving and was cleaning out his garage. About the time I finished, he pulled an air compressor out and ask me if I had any use for it... Next time will be much easier.

[24OZ]

Most people cut open the plenum part of the intake manifold due to the difficulty of getting tools to go back into the runners, they then weld it back up once they've done their boring.

[zane9000]

I know the title of this thread was misleading, to be correct, I bored out the opening of a carb, not an intake manifold. I realized my mistake earlier, I just assumed it didn't make any difference.

[boardkid280z]

Tip: use lots of fluid like WD-40 for cooling and lubrication, then the aluminum won't gum up the bit so fast, and the bit will stay sharp longer, and everything will generally be better

[josh817]

Tip: use lots of fluid like WD-40 for cooling and lubrication, then the aluminum won't gum up the bit so fast, and the bit will stay sharp longer, and everything will generally be better

DEFINITELY agree! I used a carbide tip to rough up my ports (it wasn't as aggressive as Skib was showing) and it clogged every couple of seconds. I added some oil... well not some, A LOT of oil and it didn't clog at all. At the end of the day I'd take the tip over to the wire brush wheel and clean it out.

 

Also if you want consistency, get a valve from your machine shop with diameter you want. Slide the valve down the port, if there are any hang ups, grind there. I used an old 280 intake valve (or maybe it was exhaust, I can't remember). My dad uses a whole set of valves because the heads he ports like to be tapered. Of course it takes practice to make every port the same, and make sure they stay circular.

 

[skib]

DEFINITELY agree! I used a carbide tip to rough up my ports (it wasn't as aggressive as Skib was showing) and it clogged every couple of seconds.

 

If you are porting aluminum, get the wide fluted bits.

The flutes are wide for that exact reason.