Hello all,

I am doing some work on a B20F that I am going to be putting into my 145 and I had a number of questions related to the cylinder head. First, a little history. The engine I'm working with is a B20F that I am pulling out of a running donor car. The engine ran fine and tested good with 150ish compression across all cylinders. My current plan is to pull this engine out, do some work to replace worn seals and parts (water pump, oil pump, clutch, etc) and create a solid runner for my 145. I am not really looking to significantly increase performance but rather just create a solid, reliable motor with stock performance. I am planning on ditching the fuel injection system and going with a set of HS6 carbs for simplicity. The biggest question I have is the head...the current B20F head is (to my knowledge) completely original and not rebuilt (haven't had a chance to pull it off yet). However, I am also in possession of B20 head that was supposedly previously rebuilt. The head looks to be an earlier, carburetor head. My problem is selecting which head to use and I have a number of questions:

- In general, it seems that the "E" fuel injection heads have large valves and have better breathing than the carb heads. Is this also true for my "F" head?
- For both heads, is there an easy way to identify if a head has been fitted with hardened valve seats? I have heard that these are needed to run with unleaded fuel for reliability reasons. How important is this? If the F head turns out to not have the hardened seats but does have larger valves, I may have tradeoff between performance and reliability.
- When I get a chance to pull off the B20F head and place it side by side with the carb head, do you guys have any suggestions on things to check out / tests to do on the two heads?
- Finally, looking into the head gasket to pick, I see that IPD/CVI sell a number of different gaskets with varying thicknesses, resulting in different compression ratios. As I mentioned, I am more looking for reliability but I am planning on running only high octane fuel in these cars. Any recommendations on which thickness to go with? Is the IPD "low compression" kit reliability worth the reduced performance if I am using 92 octane? Finally, can any of the head gaskets be used w/ either head or are their differences in the FI heads vs. the carb heads?

As always, thanks in advance for all the advice! This is my first time doing significant engine work like this so any advice would be appreciated!

Brian