Flat head info


New member
I bought a flat head and I have a few ? I think the motor is a modified I has a tillitson 355 carb has a light weight crank has 2.537 stamped on it arc rod 4.425 has ss valves that are tulip cut intake is 1.300 and ex is 1.150 cam has no numbers but looks to have about .400 lift the bore is 2.635 it has scratches in bore would like to get a new piston next size up the piston that is in there now has no markings but only has 2 rings would like to know what I have here and what would be a good piston for this thanks
You have an open class motor, with a .100 over stroke. You will need to measure the bore to see how big it is to determine what piston size you need and the piston pin height is controlled by the fact that you have a 4. 425 rod length. Hopefully it's less than .100 over as the block is starting to get thin for any more oversizes. Jon
John the bore is 2.635 what's a std bore and the crank is 2.537 this must be a stroker what is the stock stroke on a Briggs thanks for help what kind of power out put would a set up like this make it has a arc adjusting fly wheel what are the stock valve dia thanks
2.570 is standard , so your .060 over which gives you a real strong block, even .080 is a stout block. Do you have a sleeved motor ? that will determine how far you can go. The stroke is .100 over stock, and your valve size is for an all out open, they will feed it well even with a bigger bore. Depending on the cam and how hard your willing to turn it rpm wize you should make around 23 HP or so. Jon
Ok john I don't now what cam I got was going to get another one so I know what I have what do u recommend also where is the best place to buy a piston are weisco any good cuz Iam a dealer thanks for ur help
Ya, Weisco 's real good, go with it ,especially since your a dealer. Just get one for the 4.425 rod, and check their size to determine if you need to go with an .080 over bore. Cam wise , you have a few choices for an open, Percision Cams are good and so are Dyno, a serious open needs well over .400 lift these days. A dyno 126 is a bad boy, but needs to turn up pretty hard. Be sure you have enough clearance in the head for the valves at max lift. You may have enough cam, it's sounds like the motor has everything else to go hard. While you have the head off measure off the deck how much lift you have, heck you may have a 126 for all we know, they are very popular. Jon
Is it a factory sleeved (IC) or aftermarket sleeve? The factory sleeve will sometimes bore through at around .060 depending on how centered the original sleeve was.
I have 2 new wiseco .080 (1994P80) pistons that will work with your rod length and crank stroke if you are interested. -- Chuck
Don't know about the sleeve looks like the hole is centered in sleeve the block is gold inside and out looks like anodized what's up with that