Here is an interesting custom triple intake on E-bay. Has a reserve price, but so far is going pretty cheap with only one bid....

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2431460785

 

Luke,
Any guess what the "reserve" is set at? Those sure do look awwful purdy. That's the first I have ever seen for a tri system on the 300-Six.

 

That setup could be made to run great! No more fuel distribution problems. Making the mods necessary to the cast iron would not be cheap and he said the reserve was set to cover the cost of the manifolds. My guess is $200-300.

 

Thanks Joe,

That's an excellent deduction. I think the 200-300 range would be a solid guess. I'll keep an eye on them. Have you ever seen anything like them?
Are multiple carbs hard to keep adjusted?

 

I have never seen any manifolds set up like that. Most multi-carb inductions have a common plenum under the carbs that causes some problems.

Keeping multiple carbs adjusted isn't bad. Getting them properly adjusted can be a pain. These should actually be pretty easy because there is no common plenum under the carbs. You are basically tuning 3 individual 2 cylinder engines. Some of the biggest issues I would expect from this setup are as follows:

1. Getting the throttle linkage geometry correct. This is pretty self expanatory. You want all the carbs to open and close in unison.

2. Achieving a low enough idle speed. You can only close an opening so far. If you have 3 stock size openinge there might not be enough throttle adjustment to get the idle speed down.

3. The cylinders paired together are not equidistant in the firing order. This can screw up driveability, but once figured out should be OK. To make 3 carbs on individual plenums work perfectly you would need to configure the cylinder pairs as 1 and 6, 5 and 2, 3 and 4. That would create some significant difference in runner length. This will not keep the engine from running well, it just isn't perfect. Dual carb would be better because they would each feed 3 cylinders that are equal distances apart in the firing order.

I you have worked with multiple carbs before this will probably be a moderate challenge, but is doable. You just have to make sure that each cylinder is receiving the same amount of air at all times as the other cylinders. This setup will make that easier because you can adjust the airfuel ratio on 2 cylinders without affecting the ratio on the other 4. It will make it more difficult because cylinders 1 and 2 are not the same distance apart in the firing order so there might be fuel problems between those two cylinders. The same with 5 and 6. However, V-twin engines have that same issue and run well on only 1 carb.

What would be really cool would be an EFI lower modified to accept 3 downdraft Webers.

 

Thanks Joe. Once again you have give me great insight on the 3 intake issue. I think you nailed it. Although I am certainly a long way from being an engineer I believe your theory about the cylinders paired together not being equidistant in the firing order being the real issue here. It does make sense that dual carbs on dual intakes would be a better balanced system.
Thanks again for taking the time to educate me. I am sure other FTE readers would agree with your assessment.