Power difference between heads with 2.02 vs 1.94 inch valves

There are way too man variables to figure that out.

what heads are you looking at? The twisted wedge heads have 2.02s that you can run with the stock pistons

Heard a few stories of Twisted Wedge heads cracking in the spark plug area and have also heard some racers talk about getting valves too large for the 289/302 engines.

Mine are Edelbrock RPM.

HistoricMustang
www.historicmustang.com

From what I hear, the power/airflow difference between 1.90 and 2.02 valves is not much at all.

You can run larger valves without special pistons if your cam lift and timing allow.
Like said, there are way too many variables to post a yes or no answer.
It is one of those deals where you have to mock up your engine and check valve clearance.
Technically, to build a performance engine properly you are supposed to check valve clearance regardless. If you have clearance issues, then you either use a smaller cam, shorter rocker ratio, or mill the pistons. Then you check clearance all over again until you get it right.
As for power...
It is all relative to your rpm.
Larger valves will make significantly more power, but depending on variables, it generally doesn't show up until higher rpms.
You can also lose lower rpm power, depending on your combo, if you go too big.
The difference between 1.94" and 2.02" intake valves will be minimal though. I am sure it could be as much as a 10-15 hp difference at 6000 rpm, but much less at street revs.
Dave

HistoricMustang said:

Heard a few stories of Twisted Wedge heads cracking in the spark plug area and have also heard some racers talk about getting valves too large for the 289/302 engines.

Mine are Edelbrock RPM.

HistoricMustang
www.historicmustang.com

Click to expand...

A lot of them crack in the spark plug area but it doesn't affect their performance.

I've had them all except for canfields and brodix heads.

I'd be more concerned with the cracks that occur inbetween the valve seats. Since the seats are cut so much it creates a weak point where the two seats overlap.