it makes it easier to tune. When you have your carbs seperated it becomes a tuners nightmare and they are more susceptable to changes in humidity and barometric pressuer. IE you have to tinker with 'em more often.
********************************************************* Hmmmmm.....Randy, this needs clarification. Are you telling me that I need a short runner intake design for racing purposes, or for street use? The reason I ask you to clarify is due to Mopar offering (as a dealer-installed option), a Hyper-Pak setup that incuded a looong runner, single-four intake in about '62. The runners were long enough that the plenum was hanging out over the steering rod coming out of the column, almost to the left inner fender well. The Hyper-pak was actually meant for the slant 6 in the then-new (and short-lived) Nascar compact class, and Mopar took the top places in a number of races that year. Roger
the longer the runner the more the torque,but the longer the runner,the lower the rpms. i built a 16'' runner intake for my 4banger,it would not pull over 4500 rph.the 10'' runner pulled to 6500rpm. i don't know what rpm you want to turn the motor,4500 is not very much rpm. who knows what nascar cars needed in 1962? maybe they knew the slant 6 would explode at rpm over 4500! don't forget,those cars were running 200 mile races with stock type wet sump oiling systems. somebody mentioned a blower manifold,runner length is out the window on pressurized systems. from what i found running a banger at b-ville i would run short runners,small pleniums with balance tubes if its a multi carb setup. randy
Randy is right, up to a point.. It has to do with shock wave tuning... Just like the soundwaves going up and down an organpipe. The trick is to open the intake valve at the exact moment the high pressure wave reaches that side of the intake. So by lengthening or shortening the distance between the two sides of the port, the length of time it takes for the waves to travel up and down the tube changes. Which means you can optimise the intake to a different RPM of the Engine. ( this goes for Tuned length Headers as well, but there you want the Valve to open exactly when the pressure is at its lowest.) I have seen some very long Intake Runners on Race engines. Like a Formula V ( German Built, if I remember correctly ), with intake tubes in the 4 or 5' range... If you want to learn more about this, get the book that was mentioned earlyer.
********************************************* Yeah.....went to the local library yesterday looking for it.....no go. Looks like I'm gonna have to buy one. Thanks for the brains, guys.....you've helped a lot. Roger
Maybe it would have... Its really cool, eventhough its written in oldfasioned stuffy English and a little hard to get through. Its awesome that you were able to move the power curve up and down by changing the intake runners like that. Do you have some pics?
Hey metal has the people that wrote the book really experienced in testing also or just design and theories? I am not trying to be a jerk by asking but I have seen some people write books on stuff that worked really good on paper but when it came to the real world it sucked. I am always tempted to follow someone who has tried and learned the hard way like randy has.
Yeah, first pubished in '62. Pretty much the bible as far as Intake and Exhaust systems go. Mine is from '72, revised and edited by Morrison. And you are right to listen to what Randy has to say as well...
The 170 slant six (lower block deck height = stiffer block, and shorter stroke = higher RPMs) is not necessarily a low speed motor, the '61 Hyper Pac motors were 6000+ RPM motors. If the Hyper Pac manifolds (currently being reproduced, if you don't want to reinvent the wheel) weren't designed for a high RPM horsepower peak (and I don't know that's true), you can bet they were intended to boost and broaden the torque curve. Chrysler released diagrams and literature on the first ram tuned V8s. With the 30" ram tubes they were said to increase the torque 15% from 2800 RPM to 3600 RPM. The later '63 and '64 Chrysler 300s with the highest output motors used rams with the runners siamesed for the first 10" from the under carb plenums, effectively shortening their length to 20", and raising the RPM torque peak considerably and increasing the overall horsepower. The short runner Max Wedge super stock plenum rammed motors of '62 and '63 were all about peak horsepower. Just a little food for thought, as Chrysler engineers were in the forefront of this technology as far as production cars go.
I made an excel spreadsheet program that will graph out runner lengths for helmholz resonance tuning in relation to your cam specs, runner diameter and rpm. If anybody wants it just PM me with an email address and i'll send it out. If you're just looking for general intake design theory I've found that the technical articles on www.grapeaperacing.com are excellent as they correspond with with my engineering books and are explained very clearly.
I've got a Speco aftermarket twin single barrel manifold for the Slant Six. I think there were a couple of companies in Oz who made them but they are no longer produced. There were also manifolds for triple SU's and triple Webers and most of the guys who race in Historic classes use the triple Webers. i did see a twin Speco for sale at a swap a couple of weeks ago, they turnup from time to time. Sorry I can't post a pic of mine cos it's in my sons garage waiting for him to polish it!! We only got the 225 out here and they were a hot item when released in 62. They came with Carter carbs then in 63 changed to Holleys then back to Carters a couple of years later. I've still got the one my Dad bought in 62. swifty
Ok I had to change the exhaust manifold on my 62 comet today, the one I was thinking of building a intake for someday. I have a problem though. It looks like the intake is actually part of the head. Anybody know anyhting about this? I'm pretty sure its the 170 cid but I guess it could be a 140. Any help on this one?
So, what cadigory do log manifolds fall into? Dual-plane, devided single plane, or maybe dual-plane tunnel ram.
The 144, 170 and 200 had the intake manifold part of the head. This was the big problem with these motors, almost no way to increase flow through the intake. Get on the website Fordbarn and look for the six cylinder page, there is a guy who has made an aluminum head for these motors, no price as of yet, but impressive flow numbers.
Okay, I know I'm late here, but if you really want to fab your own, whats wrong with a progressive tripps (six pack, tri power, whatever) setup like the McGurk for the Big Jimmy 6? One carb in the middle and one on each end. Run a progressive linkage so you drive on one till ya floor it. I seem to remeber an Offy intake ad for a similar setup on a Slant 6 not too may years ago (if you aren't set on fabbing your own). Of course that assumes you actually want carbs and aren't going to use the carbs just for throttle bodies and fuel inject it. Of course there's always Cliffords Performance .
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