2.02 valves on stock 302 pistons - Hot Rod Forum : Hotrodders Bulletin Board
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Old 08-05-2002, 10:45 PM
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Post 2.02 valves on stock 302 pistons

Well i finally got what i've wanted forever. Edelbrock Performer RPM heads. The only thing, is that i bought them slightly used, which is still fine. The problem is, they have 2.02 intake valves. The engine I have is an AC-Delco rebuilt (i know its weird) stock late model ford 5.0 short block (85-93). The cam i have is a roller Ford Motorsport E303 (@ .050-220 degrees in/ex, .498" in/ex) In the edelbrock catalogue it says you have to have notched pistons for the 2.02 valves, whereas the 1.90 valves are for stock pistons. My other components are RPM manifold and 600cfm carb. It will probably never see more than 6000rpms. Does this mean I have to take out my stock pistons and machine reliefs into them?? Or do you think my engine will run fine without. Any help is appreciated.

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Old 08-05-2002, 11:57 PM
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Stock flat top Ford pistons have reliefs machined into the top, they were meant for 1.84 diameter valves thus anything larger might interfere. Even the dished versions had reliefs so it is wise to check for clearance, you will likely have to enlarge the "eyebrows" on the tops but you probably won't have to deepen them with that cam.

You could bolt a head on minus gasket and then put a chunk of clay or plumbers putty on the piston and check for interference, remember to oil the valve head so it won't stick. Clearance should be around 0.050" or more, if not you could "kiss" the valve if the engine valve floats.

Machining is the professional way to enlarge them but a die grinder works just fine too, just do a nice job of it and tape the top of the pistons so no chips get in between the top ring land and bore. I usually tape the entire deck surface with duct tape and then grind through, chips in the water passages are not healthy either. Layout your lines with machinist blueing and then scribe a nice arc into the piston top, be careful with the grinder and go slow. When you hold the grinder approximate the valve angle so the groove is correct. Sounds harder than it really is, you'll get the hang of it after the first relief is done.

Good luck and wear eye protection.
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Old 08-06-2002, 05:42 AM
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The problem I see is valve shrouding at the indexed side of the cyl. 202 valves on the small bore may hinder swirl into the cyl. If any way possible try a smaller valve unless rpms stay above 3000, strip only style! The cam is a great choice for these motors!
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Old 08-06-2002, 11:30 AM
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even though it has a 4 inch bore??
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