Thread: Tips on Porting & Polishing!

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Any tips on this subject would be great. Put any thing from pro's to cons to what to use to do this with, etc. I think it will help not just me but others with no knowledge on this like me.
Thanks!

Shawn-

Without a flow bench, anything more than port matching and smoothing the bowl is just a WAG at whether or not you are improving the flow. JMO

I'm with Dave on this one.

I ported my first set of heads a couple of years ago.It was a learning experience and I'm glad I did it.As far as advice goes first I would first admit for the street applications you really don't have to crazy with it.Pretty much just gasket matching the intake,exhaust and head gaskets.And opening up the bowl area behind the valves,(especially when larger valves are installed).Get yourself a good die grinder and give yourself plenty of light,outside in daylight would be perfect!Also you don't need a big selection of sanding cones or grinding bits, so be selective.Be prepared to invest a lot of time in this project (I think I've got around 12 to 16 hours in my heads).I would recommend waiting until after porting for the valve job (in case you accidently hit the seats with your grinder). Lastly, read as much as you can on this subject before starting.Good luck!

Here ya go boy.
http://www.chevyhiperformance.com/techarticles/95518/

another good article...
http://www.sa-motorsports.com/diyport.shtm

Be very careful on the intake side... The
exhaust side you can grind with a little
more vigor.... Rough vs. Smooth is the
question on the intake side... "hop"

FMX---Open the ports right out to the gaskets on both the intake and the exhaust. Polish the exhaust ports---leave the intake ports unpolished. The conventional wisdom used to be that the air/gas mixture should be somewhat turbulent as it flows into the cylinder for better dispersion of the gasoline vapour into the air for an even burn with no hot spots, and this is best accomplished by flow over an unpolished surface. Although this porting and polishing used to be quite effective on the old flathead engines that didn't breath all that good anyways, I doubt that you will see much difference on an overhead valve street motor. Maybe if you have a drag car where you're trying to shave tenths of a second off your E.T., but for a steet motor ?????

Brian, thats good news to me. After I had my 882 heads rebuilt with a three-angle valve job, new guides and Z28 springs I noticed the exhaust ports were VERY rough and I paid more to have an experienced circle-track guy clean up and smooth only the exhaust ports but by that time I had spent almost as much as if I had purchased aftermarket heads and I was not very happy about only "half porting" the heads. I do know that even with extensive porting the 882 heads do not flow as well as aftermarket heads, but I was not too happy about spending an additional $200 for just smoothing the exhaust ports. Anyway your comments about leaving the intake ports rough to maintain turbulent flow in the inlet is welcome news to me. Note test No. 56 of Ryan's site:

http://www.ryanscarpage.50megs.com/combos8.html

with a mild street cam, my Crane cam has only slightly more duration and lift than the stock Chevy L69 cam so improved exhaust flow should help improve torque as shown in the Test No. 56 with 1.6 ratio rockers on the exhaust and 1.5 on the intakes. Still I have heard about "bowl porting" which I did not get, but now I can look for good low rpm torque to drive that OD 4th gear in my 700R4. The Florida room project is nearing an end soon (???) and I can get back to the roadster, but now I can hope that my "half-ported" heads are maybe an improvement over stock 882 heads, thanks. But is FMX messing with Ford heads? If so, I guess Ryan's data on SBC does not directly apply, but maybe the general principle of smoothing the exhaust and leaving the intake rough still applies as Brian has said?

DonShillady
Retired Scientist/teen rodder

Thanks a lot for the info guys! I don't plan to do this for my Ford really, I really want to do it to my 48 since it will be a pro street car. Also I do not plan to start doing it on my own heads anytime soon since I don't even have the frame done or nothing on the 48 at the moment but that is why I am asking these questions, etc early is so that I have plenty of time to practice, learn and whatever else and then when it's time to port and polish I will have more knowledge of how to do it.
I try to think ahead as best I can.
Thanks a lot for the info and HWORRELL, thanks for those sites, I haven't read all them yet but they seem to give some good info. You guys just now taught me about 6 things or so just by reading your posts that I didn't even know so keep them comming because they are going into use here and it's not a waste of your time... Well maybe it is but heh, it's helping me out at least. haha.

Wadda you all think of the importance of CCing the chambers?

kcress... in my opinion, unless you're racing in a compression restricted class, cc'ing is a waste of time.

Shawn, the guys pretty much covered everything I was going to say... keep the intakes a lil rough. We get $30k, 775-800 hp, 9000rpm 350's and 380's and the intake ports are by no means mirror smooth. Gasket matching is definitely a good thing. Pay attention to the bowl areas, much can be gained there.

Also, whatever tools you use on iron heads, make sure you don't use on aluminum heads... you can embed iron into the aluminum, which can cause galvanic corrosion and lead to gasket leaks.

So what kind of heads should I use if I plan to build a real high performance engine, aluminum or iron? I plan to get about 600 HP at least. And like I said before, I don't plan to even start doing this anytime soon, this is going to be one of those slow, try to do most of it right and good kind of projects.

Thanks again!