Any issues running flat tappet in a tubed smallblock

Looking at a tubed for roller cam block. Can i run my flat tappet cam without issues?
Its a 340 block.

I do it all the time.

Absolutely but if it is one that has just been done and never run do yourself a favor and double check their work. Make sure that all the holes that need redrilled have been redrilled. I’ve seen guys mess up doing this job.

Pittsburgh I gotta do one. Do you have any tips/caveats (for drilling the main holes out to 5/8), I wanna em straight & not mess up a block.

Thanks John
Yes its already been done by a reputable shop and been run with a roller previously since done

when the block is reamed like the factory tool the reamer it can drift to one side. i drilled a hole in lead end of the reamer and press in a pilot cone with 3 cutouts for chip relief.when the tool goes straight it cuts fast

That's a good idea. Since I have a tool post grinder I just turned down the end of my reamer to hole size.

Either way will work but I agree, it needs some sort of pilot or you have to be very careful to get it straight.

And don't forget what PBR says...make sure all the holes are drilled to size and make sure the tube isn't keeping the lifter from turning.

If the block is tubed why not run a roller cam its going to make more power then the flat tappet

Just talked to Dwayne, problem is finding springs to fit the rockers. Must be 1.500 OD.
Looked around for springs. Howards makes one, but not enough pressure to run anything worth swapping to that would make enough power to pay for springs, pushrods, roller lifters, etc. over my flat tappet. Plenty in 1.550, but those would rub.

No special tricks for me. I actually just bought a new long drill bit from Amazon because I used my old bit for 4 different block and various other jobs. I slowly hand drill around 10 inches deep from the front and rear of the block using lots of cutting fluid. Then I use 2 pieces of soft 1/2 house copper pipe driven in from the front and back. I still have the tool to drive into the lifter holes to dent the copper pipe for lifter clearance. I get out my old direct connection books for a refresher evertime I do a block and will never do another block without tubing it after seeing how much oil comes out of unbushed or untubed lifter bores. I want that oil going to my bearings. If you don’t have the tool to clearance the lifter bores round off an old solid lifter to do the job.