I am using out-of-the box Edelbrock Performer RPM heads on my 400/470. The pistons are flat top and according to the stroker kit specs should be .002 below the deck. The head gaskets I used are the Fel-Pro 1009 which are supposed to be .039 compressed thickness. I am still trying to decide on the right cam to purchase and would like to know how much duration and/or lift I can run without risk of the valves contacting the piston. Is the duration or lift (or both) the critical factor for clearance and does anyone know how much duration/lift will work with my set-up? At this point I am open to either a hydraulic or solid flat tappet cam.

more likely than not those 1009 gaskets will burn thru between the two inner cylinders; don't use them. lift/duration and lobe separation angle all effect piston to valve clearance.

Prior to my buying those head gaskets, I asked here what gaskets I should get and those were recommended by several members.

The 1009 head gaskets were designed for the 383 and 426 W motors with the 4.250 stock bore size, lays yours on your block and if any part of them protrude into the bores now get another, different, set : twocents: Don't burn, torch, the heads and block up by burning those head gaskets up on your motor
Lots of other good choices out there for you

Related article:

https://www.motortrend.com/how-to/predict-piston-to-valve-clearance-before-ordering-a-cam/

I don't understand. The bore of my 400 block is 4.377" (4.342" +.035" over) and the 1009's are 4.41" bore. What am I missing?

https://www.summitracing.com/parts/fel-1009#overview

i've had to have alum heads welded back up from using those crummy gaskets. the minimum gasket i'd use is the 8519.

Locate the 1009 on the head and block and make sure that they don't overhang the bore or chamber. That's the issue with those. Otherwise an outstanding gasket in my opinion.

Duration is the biggest factor in valve clearance. If its standard aftermarket stroker forged pistons with valve pockets, your most likely ok up to the 270's at .050

The specs are misleading; the 1009 is questionable IMO on anything larger than 4.350. I've used them on 4.375", but my cylinders had absolutely no chamfer at the top that let the gasket overhang into the bores. Others haven't been so lucky and the torched gasket between cylinders is the result.

FWIW, the Fel-Pro marine gasket (17059?) has a true 4.500" bore and may be a better choice.

i wouldn't even use a 1009 on a 361 or 413.

As mentioned good idea to check that the gaskets actually fit the heads. Never had an issue with the fel-pro gaskets. BBM have 5 bolts around the cylinder they seldom blow a gasket unless mating surfaces are not flat. can be checked with straight edge and feeler gauges. what kind of compression are you running? up to 12 to 1 fel-pros have always worked good for me. Over that I use copper gaskets with o-rings. Old school I guess but top fuel cars still use copper gaskets and money is not really an object so they must be the best. And before people chime in about water leaks, if installed correctly they will not leak water. Height of the O-ring out of the block is where the problem happens on most installations that leak.

As Brad mentioned it's not the bore size that's important it's the bore chamfer size. Some have a chamfer that is big enough for the gasket to hang out. If the chamfer O.D. is bigger than the gasket I.D. then the gasket will burn and damage the block and head.

I guess I'm going to have to pull the heads back off and check as we put them on the motor about 3 years ago. The engine still hasn't been run and it is still on the stand. Being the engine hasn't been run, will the gaskets still be O.K. to use if the gasket is not intefering with the cylinder bore?

Yes

Yep. I have a 400 block that's bored to 4.375. I had to return Cometic's with a 4.410 I.D. The gaskets looked good on TFS 270's. But overhung the chamfer on the block just enough enough in most or all cylinders, that I exchanged them for the 4.5 bore gaskets.

I had tried the 1009 gasket at 4.375 , blew this gasket between cylinders . Went to the marine gasket after that , all was well . Gary

back when i was messing with a 470 i found the fel-pro 1039 to be very reliable. never a torched head with the 1039. there's a lot of work and expense in patching up this problem; so why go there?

I had a 440 block that was .030 over and I tried to run the 1009 gasket. The bore size wasn't the issue it was the large chamfer at the top of the cylinder that was the problem. They wouldn't work on that block