Porting Stock Manifolds with a dremel tool.

91BLOWNSC

Registered User
Has anyone ever did this? I currently have my manifolds off , and was debating whether or not to take it in to a local machine shop if theres performance to be gained from doing it myself. Just from glance, I noticed theres a decently big lip right in the inside where it connects to the downtubes...can I remove this? Basically my question is, can I do this bymyself or is better left to professionals? I do have a dremel to so it just got me thinking. And if I can do it myself, what areas are to work on? Obviously I cannot reach way down inside. Thanks.
 
You need to use a die grinder. A Dremel isn't cut out for doing the job. You can do it it just takes time. Open up the collector.

Jeff
 
Alright....

Ok, so then I was right. The lip at the bottom of the collectors should be removed; correct? It seams I can remove all of the little egde that there is on the bottom of the collector which is about a 1/16 to 1/8 of an inch or something like that. What are my expected gains and is this the only area I should concentrate on. I just bought an Air Cut-Off tool thats spins to like 20,000 rpm so I hope that sufices. What bits are recommended for this type of job?
 
carbide cutting/porting bits, you can also buy an industrial polisher/high speed grinder thats about the size of a drill, that should spin to 20,000RPM and not burn out the motor like "Dremels" do. Dremels have no torque, I seriously havent found a use for those things besides turning them on high and watching them dance on the coffee table:rolleyes:
 
the dremmel will work

it will work but you will finish after gasoline is thing of the pastand all cars are sitting in museums, I have a drill press and mounted it on press then used a 2 inch carbide hole saw, took me 30 sec,s each then just polished with wire wheel . also did some polishing on head side .remember remove oxy sensor and dont drop it or toss it its fragil,
 
I used a Dremmel :) It didnt take THAT long. I used aluminim carbide grinding stones (used about 3 of them) and to polish it off I used some sanding drums. I took them out to inner diameter of 2 inches all the way up the tube and polished everything that I could reach inside. My dremmel spins to 50,000 (supposedly) and has quite a bit of torque, so it took about 3 nights one hour each night. Painted them up with some engine enamel and they are ready to be put in as soon as i have time and money to change out the plugs and wires at the same time. If I could do it over again, I'd probably get a die grinder, but the dremmel didnt burn out and they came out nice!

Al
 
I stand corrected

didnt think it could be done with a dremmel . this shows you it can be done easily, and dont require special tools . it does add lots of umph so its def worth the time and work. al35thsc should be able to document the improvement . when he runs car at track bet it makes a huge diff, keep an eye on his E.T.s they should start to really improve esp with his exh work he has done.
 
You could use a file if you wanted to, but I think that most people would rather not. A Dremel tool is not heavy enough to handle that type of work for very long. I burn them up around here on a semi regular basis. It’s not that they break when they’re in use it seems that they fail when you need to use them again.

Jeff
 
They sell the brushes to fix them, so I'm not worried :) I guess it depends on which size/series dremmel u got too.

Al
 
Haven't had a brush fail yet just the bearings and the commutator. The one I have here is a 395 type 5. All I’m saying is there are better tools to use.

Jeff
 
hmm..

What are expected HP gains from something like this? I just spent about 2.5 hours and got 1 all the way done, and the other half way done. I removed that big bump almost on the end of the collect. Got it all smooth and nice :) Looks purrrty. Still debating what to do on the other end of the manifolds. Looks pretty tight up there also.
 
Anyone have any pics of this done? I have the heads off sitting next to the engine in the shop. After seeing this thread it looks like I may try this. Anything to look out for?
 
I start with a 7" grinder with a cone rock on it...then I use a carbide burr bit on a pencil/end grinder...then flapper wheels on the end grinder.

The ID starts at 1-7/16", ends up at 2". Just taking the raised ring out of the collector is ok but it's still gonna be just 1-7/16" dia. It's better to go ahead & hog the whole collector out to 2" since you're there.

By all means...use goggles or at the least a face shield.

'bird

here's a before/after pic:
man_pair16.jpg


Here's a "pair" :)
step226.jpg
 
well...

One more question I had regaurding porting. Which by the way I am almost done. On the ends, opposite the collector, you can see the way in which the tubes are designed that there not perfectly round and the metal is "formed" into the tubes. Well I was taking these down a little to make it a little more rounded and less protruding and I thought maybe I shouldn't be doing this. Is this a good idea? Or a bad idea? And if it is ok, much exactly should I take off. I dont' want my manifolds cracking. I would like to take more off if possible.
 
Due to possible core-shift during the factory's casting process I wouldn't get too eager in those areas. They're about 1/8" thick on average but you would do well to invest in a micrometer to keep a close eye on your progress. You can pick up a decent one at your local pawn shop for less than 20 bucks. Look for a 1" range, it'll do the job.
You can also try to weld in tubing to thicken the walls. If all else fails, just sand/polish the inlets and leave it at that.

keep us up on your progress and post some pics.

'bird
 
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