Nope, I found that on google searching for something else Nailhead related last night. They say it was an experimental manifold. http://forums.aaca.org/f115/nailhead-prototype-experimental-292065.html
basicly what Tom is talking about is helping the fuel/air mixture turn the corner to go down into the runners.... by radiusing the shoulders inside the manifold.... but he leaves the deep side partition in there.... looks like to me that it would still flow more to cut the center partition out of there.... but you never know untill you try them side by side to see.... he may be on to something.....first time I have my intake back off , I may radius the roof shoulders like he says and just see if it makes a difference... but I dont have a manifold to experiment on right now.....
I'm not looking to improve performance (when I go to the races; I like to sit and watch). I'm keeping the stock Carter and the stock manifold. What, I'm looking for; eliminate the vapors coming under the car from the draft tube, and, to help keep the engine clean (maybe, the underneath will be cleaner, too). For 26 years; I had a 73 Olds88 455 bone stock. For me; the PCV system was a regular maintenance item. When I changed the oil; what came out, looked as clean as the new oil going in.
The picture of the 1st. one is of an Offy. They started out OK but basically made the manifold two separate pieces. The 2nd. is a Wieand. They did the same by making it two separate manifolds. We all know how they both work from Erik's dyno testing. If I remember correctly the Wieand was WAY down on the power band. These appear to be stock manifolds with no MODS. Who knows how they may work with extrude honing, spacers, etc. Who has the time & most importantly the $$$$ to play & experiment???? We know what works now & what doesn't because of all the testing Erik & I have done.
That be the case,, the easiest, least expensive thing for you to is to drill into the intake manifold in the phlenum area if possible, if you cant hit the phlenum , then hit a runner as close to the carb as possible, and then tap the hole , install a brass fitting , tube,and pcvalve to either the valley cover or rocker arm cover....or install a T fitting where the transmission or spark advance fitting is plumbed into the intake.....if you can do that , that is easiest of all.....
Tom - I do have an extra manifold that hasnt been modded, and I am running Doc's mod on my car right now, and I must of done it right because afterwards it was immediately .2 tenths faster... I'll make you a deal... I'll run the stock manifold down to you and pick it up - no shipping. You do the mods, and I'll offer up the test bed - my 65 Gran Sport. It runs very consistant 14.6's (as measured by G-tech meter) as it sits, so any difference in ET would be attributable to the manifold modifications. I'll document all runs and environmentals, and post it all here.. You in? Rhett
Rhett, right now I'm at the shop by myself. Lost a worker due to an accident. What I can offer is guidance & a place to do it yourself if your interested. A warm Saturday as you'll most likely be working outside. You supply the safety glasses & I'll supply the die grinder & carbide wheels. Tom T.
Tom - Thats a great offer and I may just take you up on it once everything melts..I've been meaning to come down and talk to you about rockers, but I've got to get gears and limited slip out of the way first.....
i just tried a 4 holer and then an open spacer. i like the open better no loss in bottom end and pulls better low-mid and top end.its just and 1/2 spacer but seems to work good. thanks for the ideal.:beer
I can think of 2 reasons why the upper plenum is cut rather than both: 1. the mixture velocity is higher as it hits the floor in the upper plenum due to the shorter distance, which makes the radius more critical 2. the upper plenum has much smaller volume than the lower, so increasing it closes the gap. I'll bet the same effect would carry over with a 1" 4-hole spacer: open only the side feeding the upper plenum.
Tom,,,, Hey, Tom,,,,I got to trying to radius the underside of the roof on my intake and I cant seem to get at it.... what is the trick???? I have a 6'' carbide burr and a die grinder but cannot really tell what I am doing,,, it is like grinding with my eyes shut,,,, you know something I dont,,,, am I going to have to make a tool to do this????
HMMM,,,aint never seen one of those burrs...... back when I was doing the manifolds, I did rig up a small light bulb that would go down inside the runner to light it up, so I could see what I was doing.....:grin:
