As I mentioned before I feel my original 2180 heads have to many issues to rebuild. So, Im looking for advice on a new set of heads. I had a great conversation with Joe at Revmaster but like many other sources for heads, the lead time to get them is as much as 12 weeks. Im going to try to get some clarification from Joe tomorrow on their lead time. Mofoco has a 12 week and I was told they supply Aerovee with heads but they don't look like the Aerovee heads I have seen. Mofoco has a 12 week lead time. Empi has a set of heads part number 98-1431-B that seem to have the correct specs.at 94 mm with 40x35.5 mm stainless steel valves but they are dual springs with 64 cc combustion chambers which I feel are too large. Here is why. Someone check my math. For the Empi 98-143-B heads you calculate the following. If you take 64cc x .0610237441 equals 3.91 CI. Then 24.27 + 3.91 รท 3.91 gives you a compression ratio of 7.2
For the Empi GTV-2 part # 98-1335-B heads with the same 40x35.5 stainless steel valves dual ports you have 56 cc chambers and the math comes out to 8.1 compression ratio. Which to me seems pretty spot on perfect head. Correct me if I am wrong. For the Revmaster REV049 heads they look like a hemispheric combustion chamber dual port, dual plug of 58cc combustion chamber which comes out to 7.8 compression. Very close to the just above Empi head. The REV049 also has the 40x35.5 stainless steel exhaust valves. Here is a few side notes I would also like feedback on. I'm pretty sure I can get the 56cc chamber Empi heads now. Not yet sure on the lead time on the Revmaster heads but most places I have checked are 12 weeks out. Also, there are some heads out there with larger exhaust and intake valves. That means a bigger air pump meaning more power. What might be the trade offs of gaining that power ? One though would be potential for stress cracks and potentially more heat which is the last thing we want. But with the bigger exhaust valves would it actually cause greater heat. I run a 4 into one exhaust thats jet hot coated. This should help with scavenging heat. I know when I built my 455 stroker 496 I chose bigger valves and long tube headers to both increase power via longer tube to the collector will help with impulse timing and heat scavenging and all of that creates more power (torque) at lower rpms which in my application I was looking to build peak torque between 1,700 to 3,500 rpm. Almost exactly where I believe we need it in an airplane. By the way, in my 496 it worked amazingly well and now pulls a 12,000 lb motorhome far better, safer in the mountains and increased my fuel economy. So, some of you probably think I'm nuts trying to compare what I did with a water cooled terrain based vehicle to an air cooled aircraft motor but I think its somewhat comparable. Start the Jeff is nuts comments starting....... now ! But. I work at Valvoline corporate and have access to some wicked smart people in the lab which many have doctorate and PhD in their titles and they are the lab for many tests for our race car engines and they loved my weird 496 build so I think they will enjoy this too. Plus, I got to make my own oil cocktail of special blends for my 496 so I'm sure they will let me do the same for my 2180. Well, when I said they let me make my own blends they actually did it. I just got to sort of watch and help. Ok, be in the way. Jeff York
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