Porting suggestions/pics for 3x00 heads

[3400-95-Modified]

Is anything I did bad?

I just matched them, intake side only, which wasnt much.

[IsaacHayes]

Touching them kills the velocity eh?

[SappySE107]

I can't stress enough how little you should touch the 3500 heads.

[IsaacHayes]

I noticed the casting on my 3400 lower was smooth like smooth garage floor concrete. The casting on my 3100 lower was rough like rough driveway concrete. I didn't polish the 3400 insides because it was all ready pretty smooth. The 3500 plenum was rough inside though but I couldn't really get to all of that.

[Superdave]

I don't have any final pics of my combustion chambers but i did round off the parts around the spark plug, then sanded everything to about 800 grit and used the crossbuffs to get them very shiney.

my exhaust ports were opened up to a little bit under the 3400 gasket port size (since i used 3400 header flanges). I didn't go all the way because i was worried about losing port velocity.

my intake ports were matched to the LIM gasket with a little "fluff" room for the gasket crush, same as my LIM lower ports. i sanded the intake tracks in the LIM to about 800 grit all the way to about where the injectors were then crossbuffed to a shine. The intake ports in the heads were sanded to about 120 iirc.

Upper ports were matched to the 3500 metal gasket like you've done, same as the plenum, and i rounded off every sharp edge i could reach in the plenum.


I use a carbide cutter for most of the shape work then sanding cones to make everything blend in nicely, then crossbuffs for the bling.

mine will be coming apart this winter, i plan on stripping the heads back down and doing a little more work to the intake ports.. (with a few other small changes to the engine)

[IsaacHayes]

Ah yes that tape will work. Even when I had to go back to clearance my LIM for my rockers some more (since I did it first by eyeballing pictures online) I covered the ports, and coolant jackets and valve cover areas. A slip going that far would be a stretch, but I didn't want to chance it.

[ForcedFirebird]

If the mark isn't all the way across the gasket surface area I wouldn't worry about it. Just as long as the rubber seals it. I'm using 3400 upper gaskets and they are paper on the bottom with silicone on top. The paper style will melt into stuff like that better. You can take some RTV and use a razor blade to wipe it across it to seal it though no problem. I actually did that on my pitted LIM on the 3100 once and it held great on the coolant jackets!!

Yes, it went all the way across, but with hardley any pressure on the stone - just enough to scratch it. Like I said, not overly concerned because it's between the UIM and LIM. I'm going to follow your advice on the tape for the bottom side - we all know we don't need any help with leaks there . I'm going to use some silver tape (aluminum) that I have for sealing A/C plenums, this way one layer is tough enough to take a little abuse.

[IsaacHayes]

If the mark isn't all the way across the gasket surface area I wouldn't worry about it. Just as long as the rubber seals it. I'm using 3400 upper gaskets and they are paper on the bottom with silicone on top. The paper style will melt into stuff like that better. You can take some RTV and use a razor blade to wipe it across it to seal it though no problem. I actually did that on my pitted LIM on the 3100 once and it held great on the coolant jackets!!

Thanks for the info on the rasps.

For the central pneumatic die grinder, it has a safety catch so it doesn't turn on if you drop it. I took some masking tape and wrapped it flat to defeat it. It's so much easier to use then.

[ForcedFirebird]

Those rasps suck, tried them. I should take a pic of what happened when I just touched a piece of scrap to check them out. I picked them up when I went to HF today. Just ended up going back to the sphere.

The RotoZip is nearly impossible to stop, and doesn't even slow much when pressing hard.

I touched the gasket surface once at the top of the LIM, but not too bad. I think a little RTV will make it OK, but may go ahead and take .010" off the top before assembly.

I only got one more top port on the LIM today. The wife had me working on the washer for a while, then the kids came home from Aunties house, and have been hanging with them since.

[IsaacHayes]

There was a cheap set of carbide metal rasps at harbor freight, but I was told it would clog up on aluminum and you need special ones. They looked like they had huge spaces between the cutting parts, I should of got them I doubt they would have clogged like the stone wheels.

The dremel just didn't seem to work well. If I used the die grinder bits on it the glue would let loose due to the heat. The die grinder worked good as long as it had air. I would push hard to take off a ton of metal before the tank emptied. It chews the stone down fast that way, but was quicker to get it done. The stones didn't clog since it didn't sustain power long enough to get the aluminum hot and sticky. Plus pressing hard helped clean the stones and large chucks flew off the stone a lot.

Yeah my dremel is the craftsman one. Two speed. I used the low speed.
My air die grinder I got for $7 at harbor freight with a case and stones included.

I wish I had tried those metal rasp bits. Oh well all the sweat and work is done. The stones I found the red and black ones worked well, but the white was too soft and basically disintegrated. Only good for polishing.

I do like air though because if it gets stuck it stops. Electric motors when they get stuck they slow down and the torq goes crazy and then it skips across a gasket mating surface!!! I always put like 3-4 layers of masking tape on the sealing surfaces as insurance. I had a few slips and the tape was enough to save me.

[ForcedFirebird]

It's made by central pneumatic and is smaller than your rotozip. I got it from harbor freight for like 18 bucks. It came with a bunch of stones also.

When I ported mine, I found that the carbide cutter worked great in the dremel because I had a much steadier hand. I came back behind it with a stone and sanding drums.

I have a Dremmel also (just Craftsman's version). All the tools/accessories from Dremmel fit it.

[ForcedFirebird]

I used a dremel with a carbide burr tip, took the inital amount off beautifully, and then I went at it with a 120 grit flapper wheel and then a 80 grit

looked very similar to yours.

This was done in one step with the stone. Just had to get more and they are on sale for $3.99 for five assorted

[whitelightnin04MC]

I have 25 gallons of air, but like you say, I just turn it on and go. This thing sounds like a router, but is small enough to hol in one hand.

It's made by central pneumatic and is smaller than your rotozip. I got it from harbor freight for like 18 bucks. It came with a bunch of stones also.

When I ported mine, I found that the carbide cutter worked great in the dremel because I had a much steadier hand. I came back behind it with a stone and sanding drums.

[3400-95-Modified]

I used a dremel with a carbide burr tip, took the inital amount off beautifully, and then I went at it with a 120 grit flapper wheel and then a 80 grit

looked very similar to yours.

[ForcedFirebird]

I bought a pneumatic die grinder for porting my 3500 upper. After the third port, I switched back to my dremel. Our air compressor doesn't have a really large holding tank and the compressor was running almost non stop. The dremel was much better for me because there wasn't a bulky trigger that I had to hold down. With the dremel, I just set the rpm and went to work.

I have 25 gallons of air, but like you say, I just turn it on and go. This thing sounds like a router, but is small enough to hol in one hand.