Will these valves hit my pistons??

[Spanish Dave]

How can I tell if there will be a problem with valve to piston clearence between a new pair of Edelbrock performer rpm heads with 2.02 intakes (OK I know I could bolt them on and check ... but I haven't bought them yet ) it says on the Edelbrock site that the pistons may reqiure notching if stock. The pistons have just been replaced with Keith Black Silvolite +30's flat top, but do have valve reliefs.
Any ideas? or am I better just sticking to the 1.9 valves which have no problems.
Also which would be the best rockers to use with this combo?

 

[Ronstang]

The only way to know is check. The cam play a big role here but the only way to know is check, even if your buddy has the same combo you need to check because every engine is a little different and you never know.

 

[allcarfan]

You will be able to run a 202 valve with those pistons...but it will depend on your cam also. I am almost dead positive that those pistons can take up to a 2.05" valve and .600 lift.

 

[Max Power]

If you look at the flow charts, the 1.90s flow about the same and it would eliminate any doubt. Also, I hear the 2.02s have some flow issues with shrouding against the cylinder wall. I went with the 1.90s, even though I didn't have to.

 

[Edbert]

Everyone I've ever heard said to check. Don't trust any inuendo or opinion. If they are wrong you got a big mess, if they are right you just spent a little extra time working on your car but you have the peace of mind from actually KNOWING.

 

[allcarfan]

I was quoting what I was told by Keith Black when I called.

 

[Ronstang]

I was quoting what I was told by Keith Black when I called.

No offense, but I don't care who told you that information to be perfectly honest. I was told once that a certain cam was a no brainer fit in a 302 and guess what......clink, bent valve just turning the engine over by hand, luckily running if for a few minutes solved the problem. The point is, even if you are 100% positive that a combo works you still need to check. Some camshafts are not right from the factory and have a retard/advance built in that only shows during degreeing and can have catastrophic affects on the piston to valve clearance. The big thing is the cam and timing events. Big vavles can be fine with the right cam and small valve hit with the wrong one. I lost 4 exhaust vavles in the Shelby to a camshaft that was a so called drop in. It only hit the edge of the valve relief by a few thousandths but it was enough at 7000RPM to wreck the valves.

I check every engine I build for clearance issues, even if I am 100% sure it is going to work. Usually everything is fine but sometimes you find little problems. Engines are too expensive to ruin do to laziness. Buy the components that the manufacturers/builders suggest and then STILL CHECK it to make sure. You will more than likely be fine but there is that rare chance so always check....it is cheap, quick, and can save you a ton of cash.

 

[65stang311]

I have the KB281 flat top pistons for a 302 +.060 oversize and a .594 lift cam, it cleared with out notching on the 2.02 valves, but i would check with clay anyway and mine are pretty damn close.