Blackroc86

Anyone have any experience porting Fastburn heads. Mine are off and it is winter here so I have the time to do them if someone could give me some direction.

rgarcia63

I didn't do the porting on mine, but I told the guy not touch the chambers except for polishing, so only bowl work was done, and the walls weren't polished either, but left with a semi-smooth finish.

paulmoore

Well, from what I have heard and read, unless the guys doing the porting is REALLY good and knows his stuff, you can and will actually lose cfm and power by porting a stock set of vortec/fastburn heads.

rgarcia63

I was fortunate to have South Texas Racer Dennis "River Rat" Rogers working at the Houston Shell Technology Center where I also work. He had the heads ported for me as will as the intake, and plenum.

Parrydise7

iTrader: (1)

Have you ported a set of heads before? Do you want to practice on a set of Fast Burns?

I saw a flow test on a set of Fast Burns. The SuperFlow came with a tube to test for vacuum, as well as a short piece of yarn on a metal rod. The guy doing the porting showed me a few places, using the yarn, where the air was actually flowing backwards from the way it was supposed to. (After this, I have to wonder about guys that claim to flow test heads with a shop vac).

And, btw, part of the work on these heads involved a $40,000 Serdi, that uses air to make sure the heads are perfectly level before the cutter is dropped into the valve seats. (Part of the machine floats on a cushion of air, just to make sure it is as level as possible). Part of the reason for this was to equalize combustion chamber volume. Luckily, you can probably get away without this particular work.

If you are actually going to try this on your Fast Burns, I'm sure there've got to be books on it (I don't remember any tech articles, but I haven't looked recently).

If you put a finger into the ports, you'll be able to tell where the rough spots are, casting imperfections, etc. You want to smooth those out.

I have to agree, though, that you really need to know what you are doing.:

Blackroc86

I know a guy that has ported lots of heads that would be doing them. I am looking for some guidance on where the work needs to be done. I have been searching the net and not finding much info other than a post that said he had his professionally ported and they flowed 298 @ .600 on the intake after.

five7kid

iTrader: (14)

Didn't one of the Popular Hot Rod magazine Engine Masters small block finalists a couple of years ago use Fastburns out of the box?

Blackroc86

I will have to do a search for that article. There is a new version of the Fastburns that flow much better than my 2 year old ones.

Parrydise7

iTrader: (1)

I tried to attach some photos, but they are too big and I have no idea how to resize them.

The heads that I saw were rough. There was quite a bit of casting flash (and very little of the "cnc machining" that GM claims in their ads).

It will be pretty obvious where they need the work, especially if the guy has done this before.

BTW, what plugs are you using?

Blackroc86

I pm'ed you my email if you want to send the pics to me. I am using AC Delco 41-629 plugs.

Parrydise7

iTrader: (1)

Thanks for the info on the plugs.

E-mails sent (hopefully with photos).

On another board, someone said that a 1 cfm improvement in flow is worth 2.2 hp! On those Fast Burns, that could be worth some serious horsepower.

83 Crossfire TA

iTrader: (2)

you _will_ loose flow touching the stock valve job, and it takes a bit of work to get it back after doing a valve job on them.



Um, use a piece of yarn? You can actually build one of those fancy velocity probes you see the pros using fairly simply, it’s just a piece of tube that you can bend and a manometer.

For that matter, this is not all that unusually near the port floors, especially on the exhaust.

Smoothing out rough spots != to porting.

The biggest hassle with these and vortec heads is not messing up the valve job, chamber and bowls. What most people would mess with instinctively would be worth nothing or worse, hurt things. The thing that even most professional porters screw up on these heads is that if you just open them up for better flow you’ll often mess up their exceptional swirl characteristics and end up slowing down the burn hurting power.

I think the actual words were something along the lines of “surprisingly little port work.” When it comes down to it, the biggest improvements on any heads involve fixing the bowls and unshrouding the valves, so I’m not sure what “surprisingly little” would be.

it’s actually about 2hp/cfm. Of course, that doesn’t mean that if you find an extra 10 cfm you’ll make 20 more hp. That means that if you find an extra 10 cfm and add a cam that spends a significant period of time in that lift range AND has cam timing numbers + matching intake and exhaust parts to turn the extra rpm to take advantage of the extra flow you will see about that power increase. On a 350 at 100% VE, you would have to turn about 5300rpm to “use all of” a 200cfm port, and about 6000rpm to do the same at 220cfm.

If I remember the stock fastburn numbers correctly, with a cam that has a peak lift in the mid .5xx” range you’d have to turn an engine 6500-7000rpm to take full advantage of the available air flow…