do you have to have special pistons to have 2.02"

murphmaster5 · Jan 13, 2006

i was looking at heads and one guy on ebay has it listed as 1.90" intake is for stock pistons and 2.02" intake is for aftermarket pistons is this true cause all i know is im getting a freshly rebuilt 306 from a guy with forged pistons will i be okay with afr 165 edelbrok or twisted wedge. can somone explain this stuff do know much in this area. also could somone explain the different pistons to me like flat top and dished what comes in a stock 302 thanks alot.

Mike92GT · Jan 13, 2006

Using 2.02 valves with stock pistons requires flycutting of the pistons for clearance. I believe the exception is TFS heads, as they have the valves positined in such a way that they will clear stock pistons, depending on the cam size. Most aftermarket pistons have larger valve reliefs for use with bigger valves I believe. Make sure that you check piston to valve clearance regardless of what heads you go with

SmockDoiley · Jan 13, 2006

Yes, you either need to flycut(notch) the pistons or go with aftermarket pistons that already have the reliefs. TFS heads cant the valves so they dont contact, but that is up to a certain lift and duration. If you call Trickflow they'll let you know what your limits are with that. Also know that not all aftermarket pistons with reliefs will work with TFS heads because the angle of the valve is different. If your getting new pistons, make sure you tell them what heads you are going with.

MatthewP · Jan 13, 2006

I ran TFS Track Heat heads with a TFS stage 2 cam installed straight up on a stock 90 5.0 block and it cleared fine. That's about the limit. With true inline heads, you will not be able to run 2.02 valves with the stock pistons.

-Matthew

pb_paulie_b · Jan 13, 2006

I had a buddy who bolted on a set of performer RPM heads without fly cutting the stock pistons. His car used to run with them until it got hot and shut off . After that he threw on a forged 347 kit to match the heads .

SmockDoiley · Jan 14, 2006

Not all RPM heads have 2.02's though.

pb_paulie_b · Jan 14, 2006

SmockDoiley said:
Not all RPM heads have 2.02's though.

I'm with you. He swore they were the 1.90's. They got beat to death by the pistons. HBH had them repaired and ported for $800. My buddy learned an expensive leason...PB

Michael Yount · Jan 14, 2006

There is not a one-size-fits-all answer to the original poster's question. 2.02" intake valves may clear a stock piston depending on the cam that's used. 1.90" intake valves in an AFR165 head may interfere with the stock piston depending on which cam is used. In any event -- the identical parts may offer enough clearance in one engine, but not another.

You must measure your particular set up to determine if you have adequate p to v clearance -- what happens with someone else's engine even with identical parts isn't predictive of what's gonna happen with someone else's combo. If you have insufficient clearance (.080"-.100" intake; .100"-.125" exhaust for most hydraulic roller street motors) you can have the valve notches altered to provide the additional clearance needed.

pb_paulie_b · Jan 14, 2006

He was running the B303.

SmockDoiley · Jan 14, 2006

The B does have a fair amount of duration, I believe 226 off the top of my head. Its designed for NA apps, and the E, with its lower duration, is designed to accomodate the blower crowd.

Michael Yount · Jan 15, 2006

The B has 224 @ .050"; the E 220 @ .050" -- however, the .006" duration is even closer -- 282 for the E; 284 for the B -- meaning the E has even lazier ramps than the B. Also the B's LSA is 112 and the E's is 110. If you look at the .050" valve timing on the cams -- the overlap on both is identical -- 0 degrees overlap at .050". Many folks look at overlap as one factor in boost compatibility -- the cams are identical in that respect.

In any event, if you're gonna invest the money for boost, you'd be wise to invest a bit more and get one of the custom cam designers to help you. No sense in guessing at an off the shelf cam when you can actually model the outcome and have a cam designed for your needs. And the specs aren't likely to be close to either of those (very old) offerings from FRPP.

ChuckFoxLx · Apr 18, 2020

hey guys im almost in the same case.

just bought afr 185cc head with 2.02intake valve and 0.600 lift with 59cc chamber

im using a f303 cam
6.25 pushrod
stock piston

do my valve will kiss my piston ? do im better to shim ? or buy some dish piston ?

i cant check ptv cose i dont have the head ..im waiting them.

and i want to drop my compression ratio a little cose im gonna install a 89mm vortech v1 s trim

what to do im kinda new in this world
thanks in advance

Foxslider · May 29, 2021

What was the word? ^^^^^

From what ive read, a 2.02 intake wont clear a stock piston with an b,e,f cam.

How much material is there. Ill just notch them myself?

HemiRick · May 30, 2021

Foxslider said:
What was the word? ^^^^^

From what ive read, a 2.02 intake wont clear a stock piston with an b,e,f cam.

How much material is there. Ill just notch them myself?

the stock notches need to enlarged 2mm I've done it w a carbide cutter on a hand grinder

Foxslider · May 30, 2021

Ok, cool. Ill look for a youtube video of it.

Im sure id be able to see it after i playdohed it.

do you have to have special pistons to have 2.02"

murphmaster5

New Member

Mike92GT

SmockDoiley

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MatthewP

pb_paulie_b

SmockDoiley

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pb_paulie_b

Michael Yount

Mustang Master

pb_paulie_b

SmockDoiley

New Member

Michael Yount

Mustang Master

ChuckFoxLx

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Foxslider

im not that much of a idiot

HemiRick

I'd be looking at jacking under the house

Foxslider

im not that much of a idiot

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do you have to have special pistons to have 2.02"

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