140f/160a. F5. 42mm. Compcams solid lifter .606. 294 adv duration, 244 @.050.
You can try 170f/200a, f5's on the track. They work on the street too but I don't think you can use all that fuel streetwise? What I do like about the 170's is how hard the engine pulls off of idle with them but they are heavy. Plugs will read dark brown.
You need to maintain those proportions of fuel to air, up and down the scale. I tested as high as 175 fuel and kept getting power increases but ran out of air correctors to match them, so I stopped there.
1.50f/2.00a is a 289 set up. The Clevelands use a different jetting ratio of fuel to air.
I did also test emulsion tubes. I like the F7s better on the street. I think there is a little more power with them on the street. The 289's don't like them as much as the Clevelands do.
I did test the F11s as well. I didn't like them at all. I thought that I lost high rpm power with them.
I stopped at F5's and left it at that. I do have sets of all of them F1 through F13 so it isn't like I didn't consider them. All the combinations get very time consuming to test and there is not a lot of difference between the three that I narrowed it down to but F11's are not the way to go with my set up and usage.
You can run the mains down as far as about 125's (with corresponding air correctors) and that will clean up the plugs. The largest effect that will have is limiting upper rpm. So I would think the 170's will help top end.
Look. This isn't NASA here. I do this by substituting jet changes and testing as best that I can for power changes. I don't have a private race track to do this on like Shelby had at Willow Springs or Ken Miles to drive it. That team was there all the time in the '60s.
Idle: .60f/.80a. You can play with the AIR CORRECTORS A LITTLE, such as substituting .85 idle holders. The 80s can be difficult to find. Look out though. Idle can immediately go lean and backfire bad.
If you haven't done the carbs already, install the third transition hole. It will eliminate the transition flat spot at 3000rpm or so. The new hole goes in the middle between the two existing ones.
It isn't necessarily the main circuit causing the richness. It's the idle circuit AND the pump jets also, since they all add fuel to the mixture.
In fact I found in my testing that the 2.0 pump jets that come stock in the carbs are only necessary to start a cold engine. I worked those down to .5 pump jets and found no power changes, just cleaning up the plugs effects.
That caused my first embarrassing moment with the Webers. I couldn't get the car started the next day with those pump jets and missed my first meet with the car as a result.
I thought that it might be possible to use the 2.0 pump jets in just one carb and in effect start the cold engine on the one carb and keep the .5s in the other three. I have not tried that yet but eventually probably will.
The best that you can tune it for is about 6,500 rpm. It will go to whatever rpm you want to provided the valve springs will take it. Those are usually only good to around 7,200rpm.
You PROBABLY can tune it for maximum power at a higher rpm but I don't know where you can do that since you are approaching 200mph with that? Maybe Lemans?
Tuning on the IDA's was and to some extent still is proprietary information and generally is not casually obtained. It isn't a video game or something that you can tune with a computer like you can with EFI.
There is some work to get the power curve where you want it with a system this old.
You need to ignore what the plugs look like as long as they aren't white or black and adjust the jetting for power. If the plugs wind up dark brown as a result, it's just coincidental. Throw the A/F meters away. They don't work with the Webers. It is just conflicting information.
I went to A3 Motorsport heads. They are about 30hp (at least) over whatever you can get out of the iron 4v heads and you need to get good headers on it.
The set of heads that I have were out of a circle track race car and had already been worked. They are "not out of the box stock heads". They have been shaved and pockets cleaned up a little. They have no cast in reducer rings like the iron 4v heads have and were intended not as street replacement heads but full competition heads.
I only got them because the PO was upgrading to later version of the heads. C302's. I know he wanted to buy them back so I would presume that he was disappointed with the newer heads?
For headers, Either Pat Michal under or 180's over. 2" primary pipes.
There is no camshaft that exists that will eliminate the reversion on an engine of your usage. On the street, you can reduce it with a "Weber cam" but essentially what it does is limit the overlap to 28 degrees. That will give away around 100hp.
It is this reversion that makes "Weber tuning experts" useless UNLESS they are experts on US V-8's. It is the v-8s with individual runners that make it complex. The Porches with the Webers don't have the reversion issues to this extent nor do the 4 cylinder cars.
A Porsche jetting is not going to work on your Cleveland.Argue if you like but why waste your time?
A 351c withe Webers is a bit of a "Horse of a different color. There's only one of him, and he's it".