swaping intake and exhaust ports

[Tim Keith]

Somewhere I read that racers sometimes converted the 25-inch six exhaust ports to intake ports as the six individual intake ports flow better after porting and that the exhaust flow isn't impacted by the paired ports. This was a mod that requires a custom camshaft and extensive reworking of the valves, as well as custom built manifolds. I have never seen any examples of this kind of work. The Chevy six had paired ports until the end, but I have not heard of that kind of mod to the Chevy. I am interested in what was done when these motors were still new.

Edited June 17, 2012 by Tim Keith

[randroid]

Tim,

I think that's an urban myth. Without a re-designed head it simply wouldn't gain anything and would lose a lot because the intake valves must be larger than the exhaust for optimum power. Not saying it couldn't be done but I think it would be a lot cheaper and easier to make it into an OHC engine, and any increase in power there still wouldn't be too great. Great topic of discussion after a few rounds of beer, though.

-Randy

[Tim Keith]

Maybe one or persons attempted swapping the ports, would be difficult. But some of the effort in remakring the Ford flathead 8 is even more extreme. That Ford inspires all sorts of workarounds which does produce big results, when the budget is unlimited. The 700 HP flathead Ford motor that Dick Landy built is only one example of the unlimited spending that the Ford has inspired.

Another claim that I read was the Tip Toe semi-auto was sometimes converted to manual shift so that it was not semi automatic anymore. The electric/hydraulic controls were manually operated so that it more resembled a regular four speed manual transmission. If that is true I'd like to hear more about how it was done. I have an extra Tip Toe tranny that I'd risk the mod if it were practical and did not require a lot of fabrication. I've also thought that a micro controller like the cheap $30 Arduino might be used to control the Tip Toe so that it shifted faster than the old analog system of valves and relays. The comparison would be the early digital computers of 1947 that use slow and noisy mechanical relays that were the clunk-o-matics of the software world. A college mechanical engineering contest might be to challenge students to take a M-6 semi auto and make it shift faster using modern controls.

Edited June 17, 2012 by Tim Keith

[grassfiddler]

I too would like to know about the transmission auto to manuel conversion.

[james49ply]

Back in the 70's they would convert a 4 speed hydromatic to manual shift, removed the converter and had a clutch. The clutch was only used when stopping. It eliminated the converter slippage and was used by racers. I have driven one and the shifts were rock solid and you had to shift each gear manually. It was fun to drive!

[Tim Keith]

I believe you can cause the M-6 to shift manually by adding a switch and a relay, not unlike the overdrives that many here are familiar with. As there are no internal band clutches as in a modern Simpson cycle automatics, I think the driver has to use the foot clutch. I think these transmissions only have a sprag clutch. To prevent gear clashes the driver lifts their foot from the throttle just as in a regular standard gearbox.

Howard Simpson tried to get other engineers to listen to him for years until his ideas finally clicked. Simpson is a major reason why Mopar went from worst to first in just a few months. Simpson quit Ford when he thought he was terminally ill. He left Ford so as to hurriedly write down his transmission theory, building many mental models that he was certain would work in practice.

Honda uses transmissions that are more like the M-6 than most autos, sliding gears rather than planetary gears. That is why I thought some smarty could rig the Tip Toe to work much better.

"Honda's automatic transmissions are unusual in that they do not use planetary gears like nearly all other makers. Instead, the Hondamatic and its successors use traditional, individual gears on parallel axes like a manual transmission, " Its like a Tip Toe with a modern controller.

http://en.wikipedia.org/wiki/List_of_Honda_transmissions