Iron 302 heads....aka doorstops

This is the 2nd pair of heads I have worked on. I barely did anything to the first set outside of bowl blending. This pair got extensive chamber work, work around the sides and top of the port at the valve stem, plus the bowl blending and thermactor bumps. I am getting used to my tools, and my work is starting to look better. I have done alot of reading and watched several you-tubes, and the David Vizard power tech 10 series with the iron 289 heads is what finally convinced me to try it. As long as you leave the intake port mostly untouched prior to the valve stem, and the exhaust port exit mostly untouched, I dont think you can ruin them. Dont take off more than 1/10" anywhere and you shouldnt cut through. Get some junk heads and practice on a few chambers. If you have time to spend on a low yeild project like this, dive in. My biggest problem is I like building my car more than owning it, so the closer it gets to done, the less I care about it. Grinding a junk head gets to be more fun than cruising. Yes, I am probably a few cards short of a full deck, lol.

 

Too bad we're on opposite coasts, I'd rather drive than wrench(or grind in this case).

 

Tom, I got this tool horse trading. It is foot pedal operated and variable speed. It has a cable driven handpiece kinda like the dentist and even sounds a little like that old school machine they used to polish teeth with. It really IS fun, lol. This version of the tool is obsolete.....perfect for obsolete parts.

 

I finally found someone with a "full scale" flow bench and had the 302 heads flow tested. Results are not earth moving, but very interesting:

CFM @ .10 .20 .30 .40 .50 .60
Intake 75 125 161 172 178 179
Exhaust 56 87 115 129 136 137

Compared to stock, all numbers are much higher and the low lift numbers are extremely higher. The small valves are what I think is the limiting factor in the end, but the low lift numbers beat out numbers I've found for many heads that are supposed to be better. I can only assume that having the valves completely de shrouded at low lift delivers better numbers than bigger "shrouded" valves at low lift.
I also learned that my home made flow bench predicted the rapid CFM rise from 0 to .30 and also the plateau from .40 and above, based on what my manometer was telling me......I just had no clue as to what the CFM volume might be. My next plan will be to pull my GT 40 heads and do the de shrouding and chamber work to them that I think was of the greatest benefit to these heads.

 

The low lift Increase would be great on a stock engine I'd say. Did you see the latest video with David Visard says 100 hp increase with e7 heads? Interesting stuff. My GT40 heads I flowed and ported didn't do much in the low lift areas but picked up over .300. I didn't touch the combustion chamber. Only a valve job and bowl work. I do think I may do some chamber work. What did the final product on the chambers look like?

 

Those low lift numbers are impressive compared to stock. Please post your GT40 numbers when done if possible.

 

I saw the first part of the E7TE episode and have been waiting for the dyno tests and results. Almost all the work done to the 302 heads was based on Vizard videos. He doesnt give away all the info in any single episode, but the episode 6 part 1 is very good. Also he does one that focuses on de-shrouding and what he calls "area ruling" where he takes ball bearings attached to metal rod as a clearance checker. I built myself one by soldering a short segment of .25 brass tubing to a piece of .062 music wire as I have this stuff in abundance from building slot car chassis. Look at episode 5 from 20:20 + or watch the whole thing if you have time as it is covered here somewhat.....elswhere too as I recall. Somewhere there is a 5 golden rules of porting.

final pic. In the 289 video there is mention of "Hipping the ports" without details of what that translates to. I was afraid to cut into the exhaust as much as I cut into the intake at the sides of the guide boss, but the intake starts out looking like a shelf and I cut enough out to make it look more like a ramp, keeping the recommended bias of 60/40 to the cylinder wall side of the port. The last bit of the original "shelf" is still there as a small triangle pointer. I used my finger to check the size uniformity from port to port. Sounds lame, but you can feel pressure that a size difference would create if you concentrate on what you feel and where. Is there a better tool in your arsenal? lol...use your best tool or combination of. I did almost nothing to the intake runner as according to Vizard it is not a restriction. Is it now? If so, the best way to remedy that is a head with bigger runners to start with. GT40 heads have much bigger runners, bowls, and valves. This head might be only as good as a stock GT40 according to a flow bench....but the engine may see it differently. The engine builder with the flow bench did make two remarks about these heads 1) the numbers never declined at higher lift 2) The exhaust flowed at 75% of the intake. He said they behaved very decently for what they are and I told him that they were Vizard inspired. The guy had 4 complete boss 429s in his shop....one was built to the exact spec of a nascar motor from 1969 right down to period solid core spark plug wires. He had a complete Gurney/Westlake motor.... I felt like I was in a museum. Oh, I also "back cut " my intake valves and radiused (slightly) the corner of the face of the exhaust valve. Vizard talked about that somewhere too.

 

Nice! I will watch more of his series and probably spend a little more time on my gt40's. I wish I'd seen more of his stuff before I did my bowls and valve work on my heads but they did pick up 25 cfm on the exhaust and 23 on the intake. I'm kind of excited to see what they do on a 351w I'm building.

 

I just saw the episode released a week ago, and in it he talked about a "max effort" E7TE porting project he will cover. I assume this will include some porting techniques. I cant say that I am done with anything until I see that! lol. Vizard says good low lift numbers translate to an increase in the ceiling of a power curve. Of course, the low lift numbers are seen by the engine twice, and getting the charge moving sooner has to help the high lift be all it can be and continue to ram in air at the end of the cycle. And if he can get 100HP out of garage sale iron, I gotta see it.

 

That garage sale iron has 1.6 exhaust valves and 1.97 intake. Lol....not exactly low budget stuff. The mods will be very interesting to see if they are shown. GT 40 heads start with 1.54 E and 1.85 I and bigger ports out of the box..... so I wonder what they are really capable of? Someone, somewhere with nicely ported old school 351 windsor heads probably knows.

 

I didn't even think you could put 1.6 valves in those heads... Interesting.

 

1.97 seems too big to me.....and the valve size is visible on a written description that is momentarily visible on the screen in the dyno room. If you stop the video, the specs are there. These specs are not mentioned and people might think they can learn how to port heads to get these numbers with stock valves? Ya wanna sell tuition to port grinding seminars??? lol. I eagerly wait for the presentation....getting +100 from garage sale iron will have my attention even if they are hiding a little of the path.

I pulled some C8OE 2v 302 heads from my old engine. The chambers cc @ 65. They looked bigger, but 65 cc was it. The chambers were different than the C9OE (cc @ 58), and the naturally unshrouded valves flowed better. The stock heads flowed as follows on the pressure drop bench:
................... .1..2..3. .4 .. .5. .6
stock C8OE 45 27 21.5 21 19 17 65cc
stock C9OE 46 32 23 23 23 21 58cc
ported C9OE 41 24.5 17 15 14.5 14 60cc after chamber mods

NOTE: in a pressure drop flow bench, lower pressures = better flow.

 

Really all we did in the 1980's was get rid of the smog bump in the exhaust port and smooth off the casting texture. We left the intakes and everything else alone. That was basic HS kid 101 stuff. I don't care about all the other stuff because at that point just buy some brand new trick heads... but getting rid of the smog bump is easy and that's what I'd like to see numbers on. Before and after with nothing else done but the de-bumping!

 

So did the chamber mods actually hurt flow on the c9 head?

 

No. I think they were the biggest plus. That 68 head has "chamber mods" as cast compared to the 69. The comparison flow numbers for stock heads is on my shop-vac powered flow bench which can only measure a pressure drop Via the manometer. The vac pulls 64 inches of water with everything closed. As the valve opens, vacuum in the chamber drops accordingly to how well the air moves through the port, and this drop is measured through the spark plug hole by the manometer. So, The ported head beat both stock, but the stock with as cast chamber mods beat the stock small chamber head.