The Dodge Challenger Message Board

gday eddie perspex is probably a trade name here in aus i think you guys might call it plexiglass its just plastic in a sheet comes in different colours people use clear stuff for windows in some aplications i think that mounting plate youre using looks like it
cheers ian

Thanks for the tip Ian. I went to Wally world yesterday and bought some Modeling Clay. 1.79 for a box of 10 sticks. I wonder what those models do with this stuff? If I cant get the adaptor plate I'll scrounge around in the Art Dept. at school, and I'll ask those "freaks"lol, if they can make it for me. (The Perspex or plexi glass adaptor plate. It will have to be pretty stout though. enough to support the weight of the head and not buckle or flex under max vacum or flow) The one we are using now is about .250-.300 thick clear plastic. It could be made pretty easy. The hardest part will befinding a clear plastic tube diameter of approx 4.375 give or take .060 most of that stuff probably isnt precision made for the perfect inside diameter, which is probably why SF offers it in Billet Alloy, but Cmon $731.00 is pretty damned high.

$731 is RIDICULOUS!!!!!

Look around. We ordered a tube of the right diameter from an industrial catalog and cut it to size. You should be able to build it for around $50.

Moparman1972 wrote:$731 is RIDICULOUS!!!!!

Look around. We ordered a tube of the right diameter from an industrial catalog and cut it to size. You should be able to build it for around $50.

Yes, it really is! I am going to submit this to our shop secretary. If they dont approve it I will get back with you on where the Industrial supply place you guys use.? Thanks

Well, the instructors approved the adaptor plate purchase. When it gets here is anyones guess. So here is what I am going to do. I am going to use the stepped bore adaptor at 4.220 which will shroud the flow a bit but at least I'll have the all-important baseline. I modeled some clay around the intake ports for an entrance radius, the modeling clay which is available at any hobby supplies store,(I used Hobby Lobby@ $1.47 for 8 ounces or 16 grams worth, it sticks to the head very well ). I'll use this as my baseline before the mods begin. The first area I'll work on is the valve opening area and the valve itself. I want to place a backcut on the Intake valve then the bowl opening, gasket match, port ect

Placed a 1 " Radius around the intake port window. I was rewarded with the foll: 80CFM at .100 lift 151CFM at .200 lift 211CFM at .300 lift 252 CFM at .400 lift 273 CFM at .500 lift 277 CFM at .600 lift,,, much better than before!! No mods, stock out of the box head.(440source) Next week the mods will commence. First will be a gasket match. Then re-tested. As usual I will post the results of the gasket matching. This was dome with a 4.220 stepped bore and at 28" pressure. It would be even a bit higher with a 4.375 bore but we dont have the adaptor plate, so this is what I am forced to use.

Porting Actually I want to smooth the bowls out a bit, then flow them after this. Hope I dont screw it up.

airfuelEddie wrote:Porting Actually I want to smooth the bowls out a bit, then flow them after this. Hope I dont screw it up.

Don't sneeze while you're holding that thing at 35000 RPM!

Don't even blink.

I placed some RTV on the seats to protect the lapped valve job. That lasted about 10 seconds. It did protect it though! I need to make some plastic rings and temporarily adhere them to those seats. I drank a whole pot of strong coffee before I attempted this. I worked 2 hours on one port and still have a long long way to go.

In a perfect world, I do the valve job after the porting. Then there's no worries, unless I am a complete hack! Which I am sometimes....

Moparman1972 wrote:In a perfect world, I do the valve job after the porting. Then there's no worries, unless I am a complete hack! Which I am sometimes....

Yeah me too Dylan Thats the way they came. Nick a seat and I'll have to 'sink' the seat to start over and you know about how wedge heads flow with a lower seat?

Neglegible unless it was quite a nick!

Moparman1972 wrote:Neglegible unless it was quite a nick!

With my luck it would be a huge 'fissure' BTW, Dylan what would you and your father suggest to protect those seats? I was pretty nervous working 'backwards like that. I checked the runout and width of the valve job. It was 'spot' on and I would really like to keep it that way. We have a new Serdi Seat and valve guide machine on order, but for now all we have to 'work with' are ancient grinding stones, that are all wore out and used up.

We do it with good old fashioned stones! We actually have a valve grinding machine, but its sitting in the corner collecting dust. Nothing more complicated than bridgeports or lathes.

I am getting scared just to look at the pic's... Keep on the nice work! I will send my future aluma heads to you for porting Ed

I'm carefully working on the first set of Intake/Exhaust ports. It's very difficult and time consuming to access the ports and bowls especially with the seats already ground and lapped. The one tool I found to be invaluable is a MAC Tools Air mini-grinder for 1/8" Collets. It's compact has amazing power,(75,000RPM), and most importantly allows access, sorry no pics this time, I havent 'removed' much material, mostly casting flash, the bowls are already at 1.900 so you want to preserve the 'venturi' effect and not enlarge the width of the bowls to the seat. This would destroy the flow. I am concertrating my work to the roof and inner wall, alittle bit at the top of the pushrod pinch, I dont want to destroy the low lift flow to gain it on top, which is what happens to removing the pushrod pinch point almost completely, it produces the same effect as a carb throttle body, it forces the air into a turbulent swirl which aids in low speed combustion efficiency, I want to preserve thios effect but also try and gain a few more CFM below .600 while I'm at it. . So I am investigating a slight tapered approach. The roof of the taper should be larger than the floor of the taper according to the experts. We had Bob Jones form Jones Engineering and he gave me a few tips. He builds Outlaw Sprint cars with 1000 H.P.and 1600 lbs.(A wild ride for sure)LOL, he says to keep things very conservative and thought the heads were excellent out of the box. He also told me that porting them fully would 'exploit' airflow above .700 lift at the sake of low lift flow. I will be no where near that lift range so being conservative is the order of the day. I will flow the ports I have been working on and post the results next week. Eddie out

Looking forward to seeing the results.

Unless they are worse than you started with.

Well the results are in. After some careful flash removal, a very small amount of grinding in the bowl area adjacent to the short side radius which I didnt touch, I got 5 CFM extra but at .500-.600 lift. The exhaust ports remained unchanged but all I did there was gasket match and remove casting flash. On the Intake: At .500 the flow increased by 2 CFM. At .600 it increased by 5 CFM,(281 total). The rest of the flow lifts matched the out of the box baseline. Next up is to smooth the ports with some sanding rolls then re-flow them. I didnt leave any 'thin spots' or profile the guide at all, I also didnt remove any material at the pushrod pinch point on the intakes.. Just some floor and radiusing of the bowls under the seat. But it's already at 1.900+ in the bowls so I dont thinks it's wise to "skirt disaster" and ruin the flow so I am satisfied with what I have now. After 'smoothing out the intake/exhaust I'll reflow and post that result as well, but I dont expect much of an improvement, I cant afford a mistake so.....no 'hoggin out' On to the next 15 ports! (4.220 bore fixture@28")

Are you going to try your hand at adding material in the port? Trying for some wedge-shaped splitters, for example? Even if you can't weld it yourself, find a buddy who can weld aluminum well and see if you can get him to throw a glob in where you want, and shape it yourself.

I think you should see far more than a 5 CFM improvement, at a much lower lift, if you added material in the right spots. This does become difficult, though, so I don't blame you if you don't want to try it.

Either way, they'll be quite the set of heads! You've done all of the detail stuff that most people neglect, and they lose the gains they make elsewhere.

man that would scare the hell out of me grinding on those heads, if i took to much off man i could'nt sleep for nights

1 other thing I want to try is to backcut the intake and flow it again. Hell, Dylan talked me into not giving up on that port. If that doesnt work I may try adding a 'wing' to help with low lift flow. Back to the grinders. (This is all your fault Dylan)

Dylan, here is what I am saying by 'backcutting' the valves. I did both Intake and Exhaust. The smaller used valve is a chev 1.5 or a Briggs& Stratten! I practiced on that before using mine.

Sioux Valve grinding&Stem machine.

Another, I was very careful not to touch the valve seat angle.

I finished it off with 400 grit. It's very smooth with no 'ski jump' not that there was a huge margin to begin with but I guess every little bit helps. I will flow this port #7 Thur. and post my results. Hopefully they wont be dismal

another

Aha! I gotcha now Eddie, thanks for the pics.

My father finished another set of heads the other night, and in addition to a wedge on the shortside radius he has a splitter blending the protruding valve guide in. The splitter was only a couple CFM improvement over just the shortside wedge when flowed. Almost not worth the time, and the port got pretty crowded for trying to shape both. Car heads would be a nightmare to try to do this on.

I still can't find my damn camera, but I will post pictures of this soon. I also found pictures of a set of Chevy 350 heads he did back in '92, I will try to scan these at work.

Eddie I have fingers crossed for big improvements for you! (If it doesn't work out, I imagine I will have to go into witness protection for sinking so much of your time.)

Moparman1972 wrote:Aha! I gotcha now Eddie, thanks for the pics.

My father finished another set of heads the other night, and in addition to a wedge on the shortside radius he has a splitter blending the protruding valve guide in. The splitter was only a couple CFM improvement over just the shortside wedge when flowed. Almost not worth the time, and the port got pretty crowded for trying to shape both. Car heads would be a nightmare to try to do this on.

I still can't find my damn camera, but I will post pictures of this soon. I also found pictures of a set of Chevy 350 heads he did back in '92, I will try to scan these at work.

Eddie I have fingers crossed for big improvements for you! (If it doesn't work out, I imagine I will have to go into witness protection for sinking so much of your time.)

Thanks Dylan!! I would love to see those ports. I re-thought the 'mods' bit after we talked. With this flow bench at my disposal I would be a fool not to try and gain flow. If I ruin a head so be it. I can buy a single head or re-weld it up. Either way no pain no gain!! I have to keep reminding myself that I only have 4.220 fixture. We are having 4.375 and 4.500 fixture made for us out of poly carbonate plastic but until I get my greedy paws on them this is what I have to work with so the flow is defintely shrouded and skews my results. But I'll post Thur. results as soon as I get home from shop.

I am having my camshaft ground as we speak.(I bought the cam only it's all I can afford before the trip)(I promise) It's a Scott Brown Hydraulic Roller with 248/258 IE@.050 and .370 lobe, so with a 1.6 ratio it should give around .590-.605 lift and 112 LSA so it will make good power, he predicts 600+ I also bought a carb 750DP #4774 for a very cheap price. I'll re-build it and re-work it for alcohol usage.