Support mods that I think are important for this level of motor.
Big exhaust! You have DOUBLED the heat output; you need a serious exhaust to not "back up the sewer" with heat.
Raby himself suggests 4 into one with short collectors for his stuff.
@Literati914 has a nice set of short collector 4/1 set up that I'm hoping he will post a pic of.
Then there's the Tangerine stuff...
https://tangerineracing.com/shop/ols/produc...eet-system-1-58His systems are what is referred to as tri-y and have two distinct collectors 2-1 than 2-1 again. There are good reasons to do it this way. You end up with two negative pulses at the exhaust port exit this way at different rpm ranges.
Pricy but very nice! I'd go Tangerine is cost wasn't an object.
That used set up was a good deal!
There is a BUNCH of good stuff out there! You CAN use the normal SSI heat exchangers, but they will be a bottleneck at high flow rates.
Because of doubling the heat output, you also need good temperature tracking.
Oil temp is important. Don't trust the original gauges. An accurate temp gauge is a requirement long before ANY oil cooler is warranted. You MIGHT need the cooler as well; the gauge will let you know if you do.
More important is cylinder head temp. Best to have sensor around #3 spark plug.
Lots of threads on here, many different was to go. I actually bought a 4-channel gauge from a member on here as I'm prone to gather WAY MORE data than I really need.
Then there is wide band O2 sensors. If you're not using these, you are back in the stone age of reading plugs for tuning data. Wideband is PARAMOUNT in any build IMO.
Oil mods, your oil pump can be a weak point. I'm an absolute bitch about "sucking air" which is possible with a stock oil pump. Pumps are made with dedicated O-rings that stop that shit. Lots of threads about pumps as well.
Then there's the oil pick up. A "tuna can" is the minimum IMO. Lots of threads again...
Fuel supply, you need to be able to deliver at least 200hp worth of fuel at all times.
At this level of engine, I'd be running a 7-8psi pump under the tank and a fuel pressure regulator to reduce this to 3 psi right before the carbs.
Overkill, but if you run lean EVER it will GO BANG and you will be sad.
Ignition: No points for this, modern electronic distributor. Many are available but the current "King of the hill" is the 123 blue tooth model.
I'm actually a fan of full-on stand-alone modern EFI with sequential injection and sequential coil on plug but you already have the proper sized carbs, and this jump is every bit as big a jump as the 1.7 to 2.255 jump you lucked into.
Even I would fire what you have on carbs first.
Talking about that...
I'm using the lowest of the low induction system for initial run in/cam bedding.
My 75 came with a brand new progressive 2bb. This is a single carb in the center over a plenum that feeds all 4 cylinders. This thing is SUCK CITY for performance but it is beyond easy for initial set up.
I'd use the baby single Weber to get the engine through the first CRITICAL run in period. I'd bed the cam and make sure the thing is proper before trying to add ITBs.
The ITBs can have initial teething issues and I don't want to be jacking around with that type of shit while the cam is bedding in.
Baby Weber for an hour and then the REAL carbs...
You shouldn't have to purchase this puppy, lots of us have one and most would be willing to let you use them for a short period of time as the ONLY time we use them is for run in as I have just described.
They REALLY do SUCK but they are drop dead easy to make work!
Enough for now...