I knew the tunnel ram idea had lots to do with tuning and velocity from its design, I had always assumed gravity helped it as well, but it would seem vertical or horizontal it should still work.  I cant wait to see it at arm drop

Thanks. Hope to give it a trial launch this week. If it doesn't bog but launches good then I am good to go as is. First race May 17  at Picton Airfield. I am looking forward to it. Here is a shot of the new headers.

don

OK, The results of the first pass. I fired the rail up . By the time I got to the line it was still running but not real happy however it staged up on the converter and left well but was not running smooth. Despite that it still ran in the ball park of normal judging from Johns Altered which I have run several times. His was BTW working well. Two things I was concerned about . One was the unusual gasket sealing technique I had used for the headers. The other was the carbs as both were rescue carbs. Boat racing champion and old friend John M told me one header was smoking black. Theoreticaly they should both be the same as carbs are the same and jetted identically. I had my pass in. There is no point beating a project to death at the track. I needed a shakedown run and I had it. It wasn't good but it wasn't bad either from an intitial trial. So after resting for a weekend I went at it this morning. First I checked the carbs and float levels to be sure something hadnt gone stupid. Both were perfect. I rechecked linkage. All Ok. I checked to see if both accel pumps were were working properly. they were although I did make a minor correction in the pump cams. I pulled the bowls and removed the jet plates. I rechecked the jet numbers . Currently 72s. That is one size below stock. Why? Because tunnel rams produce a very strong signal in the carb. Stronger then most manifolds and so tend to run richer on the same jetting that a four barrel conventional manifold. So why if everything is exact would one be running way rich. The jets were brand new so should have been right (not redrilled) Years ago I kept a set of number drills around to check carb jets and orifices. they have long since disappeared so I went to CTC in Picton today dropping the wife off at no frills for a holiday shopping adventure. (Picton is in a Tourist zone so was open) I bought a big box of drills CTC sells that includes number drills. I keep an old Holley number drill to jet size reference around I have had since the late 60s. When I got home I checked all the jets with the shaft end of the drill. They were all good. None had been tampered with. There was only one possibility left. The PVCR were not the same and had been tampered with. I had run across this before in my long career once even on a brand new carb. (An oriface had not been drill through) Oh What is a PVCR? Behind the power valve are two small holes. They provide the power circuit's extra fuel and are in a moderate 4 bbl (750 or 850)equivalent to bout 4 jet sizes. They are not real big but do the job when vaccum drops as throttle opens the spring pushes the power valve open and the extra fuel is added. So I took the first metering plate from the three good running cylinders (plugs from these looked great. Slight grey ) I remove the power valve and began searching for the drill that would fit into the PCVR. .046" was the one. Both were the same. Next I took the plate from the front three cylinders which had three sooted black plugs , very black) I unscrewed the power valve and began searching for the proper drill size. Found it at .063". That shouldn't be. They should both be the same. So now I am on the hunt for another parts carb to find a proper power plate unmolested. Why the big difference I don't know. Could be the plate is not even for this carb but someone just screwed a I can sell this together. Doesn't matter. What matters is the culprit has been found. Will that solve everything? It would be nice to think so but sometimes projects like this take a lot of rubbing on to get them right. Sometimes they never will be right. However this ol fart has been down that road a few times so I find this more interesting then frustrating. At the track I was chastising myself for taking a perfectly good working set up off and installing this untested deal however after a good rest and some careful thought I decided to press on. I should have run the car longer here under power however I don't have a good test spot. I believe however that I am on the right track. Now I have to call in some favours from my stock car friends. They all use the 500 2bbl. Someone must have a spare or rough one sitting on a shelf they will part with for a reasonable price.
I could just buy a new pair but it doesn't make sense when I do so much to them after I get them. If any want pics of the PCVR and its measurements I could do that .

PVCR = power valve channel restriction

-- Edited by Don on Monday 19th of May 2014 05:21:19 PM

-- Edited by Don on Monday 19th of May 2014 05:25:57 PM

-- Edited by Don on Monday 19th of May 2014 05:37:58 PM

Ok. I supposedly found two brand new plates part #134-137. That suits me then I would know for sure they are right. Supposed to have them by the end of the week. If that doesn't work out I will take you up on your offer. meanwhile let us know what your plates check. I would be curious to know what the actual difference is with those two carbs.
don

BTW I am severely colour blind. This site with its shades of blue is almost impossible for me because I cant see a lot. Like the up and down spot etc. Anyone know how I could customize that for me from here.  Things I cant see. yellow or red writing on a blue background. Shades of blue, white on blue and blue and green. Now this site is so good and the people so great I am going to struggle thru it anyway but if someone knows how to change even to black and white that would help. 

Went after that small fuel drip. It was a stubborn deal but I finally found it and cured it completely. One of the big problems with aging is eyesight. Stuff you would pick up in a mili second at 30 becomes almost undetectable at 64. During the drip fix I noticed on the gasket register that the accel pump holes , bowl to jet plate did not line up to well so I fixed that while I was there. Then with all well I ran the car on the trailer for a few minutes with the air cleaners off. I do this so I can look for pump nozzle drip or pullover and also booster drip. Pump nozzle drip is most often caused by a poorly seating pump discharge needle. Sure enuf the rear carb had a drip when idling for awhile. You can sometimes hear in the the headers as it is a slight but intermittent pop in the header at idle. The primary cure is to lightly reseat the needle in its seat. Luckily for me that was all this one needed. I let it run for a fairly long time checking everything over again and again. |I think I have it all good now. I put the air cleaners back on and am ready to go I think. Bring on the dancing bears!
don

Generally speaking, the tunnel ram works in the higher rpm.
Oh OK. The range in RPM a tunnel ram or any ram manifold works at is related directly to the runner length. The first serious ram manifolds of any kind were the early 60 long ram manifolds on Chrysler products. With a carb sitting out over each exhaust manifold they were reportedly tuned for about 3400 RPM Shortly after the separtion in the passage was opened up and the range raised to a much higher figure. That was kinda of a fudge deal and eventually we got to the Max wedge crossrams which were tuned for around 6000. About 1971 Wiend cam out with a super stock manifold for the six pack 440 cuda that has no equal. It was also tuned for around 6200 RPM and had long runners the crossed under each other to get the length but still kept the height and port angle close enuf to stock specs that the manifold was allowed for NHRA super stock. I have spent a lot of time playing with this manifold in the past eventually making a plywood test top and after successful testing had a 2X4 bbl manifold top cast for it. That manifold project appeared in Chrysler Power magazine back in the day and it currently out west on Paul Amatos winning 440 Dart in Kitamat BC. What you said generally is true but not by virture of the fact that it is a tunnel ram but rather by virtue of the runner length used by the designer. Rule of thumb I use is the desired RPM in thousands divided into 90 gives the length in inches from the back of the intake valve to the plenum. So if I want peak at 6000 I divide 90 by 6 (six thousands) and get a length of 15 inches. Most manifolds of any design for 440s have far too shor a runner and I have reworked even single four single planes with good improvement in et and MPH. Dualplanes though often have good runner length although some are too wiggly to be of any value. Performer RPM Is a notable exception.. This slant six is cammed to peak about 6000 RPM so the manifold and the headers BTW are also tuned for that RPM
don

-- Edited by Don on Wednesday 18th of June 2014 02:55:17 AM

However thanks to my fiend Steve Sheehan and his phone I do have one run. You can hear the burble at the top end of first as the bowls starve for fuel. That I believe has now been dealt with. End of the run is out of sight and sound.

don

http://youtu.be/Psfeh8qvkro

I have some with you in it I believe. Email Glen and ask him. He will say it isnt edited but that isn't important. He will put them all on a stick if you supply it.

don