I finally (after 7 years) pulled the head off my '54 Chevy to get the hardened valve seats put in and figured I'd do a little porting while I had it off. I've got California Bill's Inline 6 book, but I'd rather have so conversational input about porting this head if I could. Can anybody help me out here? Thanks, Jay
It has been over a year since I read that (what did I have for breakfast?) but IIRC there is more specific porting data in the Roger Huntington Book (he reccomends shell reamers and gives specific sizes, and diagrams). But I may have that backwards (bill VS Roger). IIRC whichever this is in has flow comparisons of this work as well, along with a warning that on anything but the hottest road engine and all out racer it's not the best plan (not in so many words, but you loose too much port velocity). No, I haven't tried this myself.
I've ported them using the shell reamer method. It works well, but you'll have a bundle in the reamers and arbors if you don't know someone you can borrow them from.
There's been major rethinking on porting since those books were written,As Nexxussian mentions it's port velocity that matters especially on a street engine. You might want to pick up a junk 235 head,lots of cracked ones around, and practice before hacking away on a good head.
I've got a couple of junk heads and a couple of good ones, too. I was just wondering how serious I have to get about the shaping and sizing if I'm not going to go crazy about performance. At this rate, I'm more interested in fuel economy! I know there is some serious casting flash inside the exhaust ports, but I really haven't looked into it any farther than that.
I also heard that unless you built a race engine, head porting and polishing is not a good idea for a street motor. Just think of the right angles of the multi-carb log type intake manifolds. They are not really built to flow as easy as possible. Some turbulence supposedly helps mixing the gas and air better below 4000rpm and burning the fuel more completely. Probably won't make a noticeable difference in mileage though. I have also seen a website and pics of a guy who notches combustion head chambers with a triangular file to get extra turbulence.
Hoe-lee-shit! Havn't heard from you in a while...how thing's going Jay? Good to see your getting back on that inline......been thinking about 235 mods myself lately..i'm getting a bit tired of the 95 hp.. Tony
Hey Tony! I sent you a PM Road Runner - I've read that it's better to have a turbulant intake flow than a nice smooth intake. That's why I wasn't really going to touch the intake ports at all. I'm not going to go too crazy with the motor, but I figured a little clean-up couldn't hurt. The machinist who's going to do the valve seats said to leave all the valves in the head, but I'm thinking I'll pull them out to do my work, then put them back in for him. Is that reasonable?
There's a lot of info on porting on the internet and books.Most applies to Chevy V-8's of course.It's quite technical work backed up by results on a flow bench and for lower speeds,port flow velocity always comes up.There's also words on not simply hogging out the area where the valves seat,but leaving a venturi shape to help air flow around the valve. 235's have a shitty head design for power that will always be a limitation. There's always the option of the great late hyper expensive after market heads built for Chevy 6's back when.
From what I understand you should be able to come up with a Wayne (or other) 12 port w/ all the stuff to make it run, for about $7K. Even then though, it's likely to be 'too big' for a 235 on the street (a stroker 261 though, that might be a different story, but still not a cheap one).
I run a 848 head on my 235. I did a serious valve job with Nuway cutters, and just cleaned up the really messy casting flash in the ports and in the combustion chambers. I Have a Offy intake with 2 B rochesters, fenton dual headers. HEI. Howard's cam. It seems to run out of power at 5000. At least that's where I shift at, shifting higher or lower hurts the ET a little. Has a rough idle, but once over 1000 it is very smooth. Drives well from off idle to wherever, sometimes I just run it up in the low gears to see how far the tach will go cause it makes so much good noise I did not do the hard seats thing when I did this engine 12 or so years ago. And have not yet had a problem with it. Twenty thousand road miles and much of that at 80-90 mph. And drag racing for the last two years about 50 runs/year. Frank
What is this in, and how did it do at the strip? Just wondering....i'd LOVE to double the hp of mine when i do it.. at 95 hp, i don't think it will be too awful hard.. And no, hot highjacking Jay's thread...i think we're both looking for the same thing Jay, got the pm and sent ya one back Tony
Tony, it's in a 54-210. When you use the weight to hp calculator it comes out to like 146 or 149 RWHP. A guy I run into at E-town with a bone stocker 49 or 50 216 stick has like 55 RWHP. (24 second car, i think) These old cars ain't as lite as the books show. That was some kinda dry shipping weight. the 49 weighs like 3650 ready to go, My 54 was at 3750. with driver. Anyhow, I run a saginaw 3.50 1st, and a 2:93 rear. Go thru the lites at 5000 in 3 rd gear. Last night at Island I ran a 17.386 and 80.09. Which is the best it's done yet, by just a little. They screwed me up a little by having a pro tree last nite. I like the old way where the lites count down and I leave on the last yellow. got 14 passes in before it got dark. Was a tenth slow on the 60 ft times compared to my good runs last year. So i maybe could be at 17.2 or 17.1. Couldn't get a good consistant launch last nite. Best 60 ft was 2.64 last night but have been 2.55 before. But even this slow, it's a blast. I get to spend a whole lot of time on the racetrack compared to the 10 second guys Frank
It really is, Jay. And i drive around all summer long with the shoe polish on the windows, too. Just to annoy the restorers. Island is having their Nostalgia Nationals on June 8th. The track manager told me that it's an open race, no club affiliation is needed. Frank
gas pumper has a good answer,clean up the big stuff & dont hog it to much just smooth it out, I like what you guys are doing,make what ya got run better! not big dollars just big fun!
I'm a cylinder head guy in a race engine shop. The best advice that I can pass along to someone when wantin' to port heads is: WEAR GOGGLES. Snow ski goggles work good they don't fog up too easy. I wear a pair of old amber colored lens Scotts. Work on the same area of EACH AND EVERY port. Then move to the next area. Example: Clean up the short turn on EACH AND EVERY exhaust port. Then do the bowl areas of EACH AND EVERY ex port. Then move to the intake side. It's easier to keep things equal if done like above. Also I've seen alot of heads where someone started out portin' them one cylinder at a time and the first port was big and the other ports got smaller as they went on. If you do the same area of every port and you get tired of it,run out of time,cutters go dull or you have to stop for any reason things will be fairly equal. Smokey
That's good advise. I've ported alot of heads and use the same principals. The 235 head design is really bad on the exhaust side. The valve is shrouded so bad by the combustion chamber I beleive most of the restriction is at the valve and seat area. You will need long shank dies to do much with the exhaust. Intake is straight forward. Smooth and blend the bowl area on the intake. The intake manifold gasket uses sleeves to locate the gasket on the head. All I would do is maybe blend the port to the same diameter as the sleeve. You really want to help milage and power mill the head. Stock they are very low compression. Milling the head .100 won't get you to 9 to one with deck clearance. You gain more decking the block if you have it apart. Jeff
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