H-O Racing's Tunnel Ram intakes
 

In a prior thread about H-O Racing's "Rocket Box", Tom Vaught asked about the H-O Racing Tunnel Ram intake manifolds. In that thread, I stated that I would post info about them separately. This thread is that disclosure.

Here's a picture of H-O's 326 NHRA E/MP engine with the "canted carb" tunnel ram fitted. BTW, this is 1972 tech, just so you can get your head around it.

http://www.originalho.com/TunnelRam/...acSideView.jpg

Another view of the tunnel ram
 

Another view of the "canted carb" tunnel ram:

http://www.originalho.com/TunnelRam/...iacTopView.jpg

63 SD balancer.Tom

Neat stuff Craig! A true Pontiac masterpiece. You and Kern influenced so many in the Pontiac world and am grateful to know you.

Wouldn't happen to have been Rocket Box's welded to the manifolds there would it???

More, more... very much enjoying the trip back.

I don't think there is any doubt that a "rocket box" setup would have improved the setup, but the "rocket box" was a couple years later than the 326. As is, various photos show different heights for the plenum on the tunnel ram. Changing the height alters both the volume and the "Q", which is the resonance of the manifold.

So is the base a Nash tunnel ram?

Good to see Mr. Kern Osterstock, the 'O' of H-O Racing posting here now.

:welcome: to the PY forums Kern.

Bart

Yes, it is. Also, the headers are "Headers by Ed" for 64-67 A-body with round port exhaust. IIRC, the primary header pipe size is 1-3/4in, which sounds small until you consider that this engine is the "326". Internally, it is a 1956 316 + 0.060 with 1970 RA IV (#722) heads ported by me. Valve train was Isky "Super LeGuerra" roller with a custom built stud girdle. In order to make this combo work, Kern & I had to build our own tunnel ram intake and flow bench, but this thread is only about the TR, not the 326, flow bench or other goodies. Here's another picture of the 326:

http://www.originalho.com/TunnelRam/...cFrontView.jpg

Are those 660 center squirters?
No way is that thing based on a Nash. The Nash was almost a copy of the bathtub intake. The runners were almost flat compared to this thing.
It looks like a old Edelbrock tunnel ram for a sbc that has been cut up ans re welded back together and machined to fit a Pontiac. The old Offys used to have curved runners like that too.
With a crossover cut off some other aluminum intake and used. What old aluminum Pontiac intake had one side cast plugged for the temp sender like this one appears to have.
There was a lot of hours in that intake.
Did you guys ever build and sell them to the public or was this a one off deal?

Good eye! Kern & I will explain the details shortly. Also, there was a 2nd TR built differently that we'll cover here that was meant more for commercial use, but there was no market for it at the time.

Looking closer at the intake you can see it was welded near the port flanges. You are righrt the runners don't quite look like the Nash.

Intake looks real nice. Can virtually "inspect" the runner shape from Post #9.

'72 tech eh, I was still using a cut n shut oilpan like that 'til last year!

Welcome Kern. Wish I could have made the presentations at Steve's show and met you guys in person.

Tom Vaught

...Still using such a pan. Had to run out to the garage and check to see that MY oil pan was not Thaaat oil pan in the photo. Me drain plug is in the back , not the front. Lineage was Mike Cam's Dragster (now with Paul Spotts).

Thanks for the welcome!

I can't really offer a good reason that I have not been posting here except to say I already spend to stinkin' much time at the keyboard, when I'd rather be turning wrenches!

Would be nice to sum up a bottom end build on one of these. I'm building a 347.

Some details on the tunnel ram construction:

Once Craig and I convinced each other that we could make a Pontiac turn 9,000 rpm, we faced the challenge of finding the parts needed to let it do so. The rotating components were actually easy to order, once we convince people we were serious and handed them money. But some things, like a tunnel ram, did not exist. So, what do you do? Like a lot of other parts, we wound up building it.

The first step was to take a P4b intake and cut it up so I was left with only the side flanges and the water crossover. I left to crossover in place to help retain the original bolt pattern. With the flanges bolted to an engine, I then welded a piece across the back of the manifold to keep the flange spacing correct. If I recall correctly, the runners came from an Edelbrock small block tunnel ram. The port size was close to correct and the spacing of the siamesed runners was about right for the P4B. A prime criteria was canting the carbs to keep the runner lengths as equal as possible. So, we bought a Chevy tunnel ram, which was stupidly expensive for something I planned to chop int little pieces. But I cut up the thing up to leave me only four small sections, which were the paired runners and about 3/4 of an inch of the plenum. all the rest went into the scrap. By keeping some of the plenum floor, I had material to create reasonable entries into the runners. Those four pieces were welded to the P4B flanges and then the plenum floor sections were patched together with weld and fabricated plates. Then came the first major grinding session to blend the runners to the Pontiac ports, as well as making the plenum floor smooth. After weld, it had looked more like a mound of mashed potatoes, yet needed to be very smooth with proper transition radii. That took about a week of milling, grinding and many trips to the welding bench.

Once the runners all came together with a reasonable floor, I welded a 3/8 inch plate to the top of them and created openings in it to let it be blended properly to the fabricated plenum floor as well as providing a place to erect the plenum walls. The first iteration had the walls about 5 inches high, which matched the Chevrolet design, but we found that the length from the valve head to the base of the carbs was too long for our intended 9,000 rpm target. So, I simply cut the walls down and used tapped holes to attach the manifold top.

The manifold was a lot of work, but was easy to visualize. The linkage for the offset carbs was a real PIA to build, but looked very much like contemporary offset linkage.

I ran a HC-03 cam with Rhoads lifters in my 68 Goat with there valve springs back in the early 80's. Stock head 400 and ran 12.60's @107. Not bad back then for a street car. They had a catalog back then before the net was around.