Hand made cast 351C intake

Link is not working. Can you please repost?

Larry

https://www.hemmings.com/stori...yrofoam-and-patience

Here

I'd be curious as how the length of the runners were determined.

Around 50 years ago the distance from the throttle plate opening to the valve was determined to be ideally 4.5". On the dyno. Extensive dyno runs, etc.

These are pretty long and I wonder why?

That manifold was built by Kelly Coffield, a Pantera owner who is on this forum but I have not seen him post recently.

here is a link to his YouTube channel, that shows this manifold and others that he has made. Truly a amazing designer and fabricator.

https://youtube.com/channel/UCSTKBcCz9pD_MC0l_ZarxhA

Larry

Ah yes. I remember it now. I always wondered where he got that dimension from and the obvious answer to me was that he put the mounting flanges where he wanted to and whatever the runner length came out to be is what it was.

I had not seen this previously - it is brilliant.

Now where the heck can I put the furnace ......!

Doug, I suspect Kelly C was trying to fit 48 IDAs under the engine screen, or maybe under a Mustang hood. As you probably remember, decades ago there was some unhappy talk about having to cut the deck lid edge to accommodate Webers on 'factory' or Hall intakes, or with some EFI throttle bodies for 8-stack injection. D Quella once had a Weber manifold that tried to address that problem, too. Really, it only affects cylinders 4 and 8. Nowadays, the best fix iseems to be a fiberglas decklid that can be cut (or patched) without wasting a steel stocker.

FWIW< the small diameter spouts on the core would probably connect to the water jackets on a 302 or 351-W for heater hoses or something similar.  Haven't contacted Mr Coffield for 5 or 6 yrs- my bad.

Kelly’s manifold is made for 2 x Autolite inline 4 bbl carbs.

Kelley is quite the expert on the Autolite four barrel in-line carburetors. Check out his website here:

http://inlinecarb.com

Larry

Those are two different manifolds shown here. I should mention that there is at least one more, the Doug Nash split manifold which is not shown.

BW, the Gp.IV cars did not notch the decklid and I will add that it appears that I was too quick in notching mine since it APPEARS that the Webers will JUST clear the window opening, but I saved the piece I cut out and it can be dimple welded back in.

The purpose of the runner length is to make the induction system come into Helmholtz tune at the desired RPM. Helmholtz is the same principle used in designing and tuning pipe organs and musical instruments. In automotive circles it is also known as the ram effect. The pressure wave from the valve opening and closing travels at the speed of sound and reflects within the runner. When the valve opening is in time with the reflection (resonance), that pressure wave can further pressurize the air/fuel charge, increasing charge pressure up to 10-15% as a natural form of supercharging. For American V8s, the length runner necessary to achieve this on the first reflection would be 30 feet! Since the pressure wave goes both up and back in the runner, that immediately halves that figure. Luckily, the same effect can be realized on subsequent reflections with the 4^th to 6th harmonics being common depending upon runner length and RPM and reduces the runner to more practical lengths

The runner lengths on this intake are very similar to those in the CrossBoss plenum intake (ala Bud Moore Maxiplenum for 351C) except they have carb flanges instead of a common plenum. The runner lengths are actually in a very inconvenient position for packaging. Three of the manifold mounting bolts on each side need to be installed through the carb openings and you can see the cylindrical bosses for them on the exterior of the manifold. On an 8.2 deck intake, everything thing is tight. The design of manifold casting, linkage, and carb positions were a real challenge. It also uses a custom timing cover like several of the old TA Boss 302 intakes that positions the cam forward and uses an extension to drive it. A friend and longtime B2 enthusiast is building an engine around the system. It will fit under the hood of a stock Boss 302.

More here at the B302 Forum. Someone started a thread with a catchy title there :-)

https://www.boss302.com/smf/index.php?topic=88291.0

More here for anyone with an interest in lost foam casting.

http://forums.thehomefoundry.o...pendent-runner.1692/

In the future I may have some 351C intakes of interest to the Pantera community.

Best,

Kelly

Kelly,

Nice to hear from you. It has been a while.

thanks for the teaser on future intakes. Looking forward to see what might appear

Larry