Will this combo work 454 gen 6 with 188 heads???
my other option is 781 with small valves, what do you recommend and any technical input helps thanks.

Without doing a bunch of research what are the 188's specs, large ovals, rec's, what size valves and what gen ? I think the 781's are large oval small valve's.

Rectangular, 2.19-1.88 open chamber 118cc, mark lV.
I always heard they are hard to find.

781's are ovals , small valves, 113 open chambers

Interesting test.
http://www.maliburacing.com/ovalvsrect.htm

What pistons do you have and compression ratio are you looking for? What are the goals of the build? Mark IV heads will work on a Gen VI block but not vice versa.

Motor is at machine shop now getting bored out should be around .040 will hear details today going with new cast pistons, rm cam, stainless marine headers, edleboc intake, and well see if the 750 holly can handle it.. I understand the compression ratio will be determined by the heads, smaller chambers more compression, but the guy with the the 781 wants 900 and they have the small valves, the guy with the 188s will take $750 hell put the harder springs and the marine valves both have new valve job.
What do you think is better for my application? im looking for mid and top end speed but i guess budget is controlling this head problem

Very good article Piclenjim, but let me ask you this what do you choose when the 781 have smaller valves and not the same 2.17-1.88???????????????????

Cool,

Sounds like you will have a good runner, who is doing the machine work? Sorry I havent called back, been so freakin' busy lately. Probably gonna run with FMO March 6th over near Sanibel.

Whats up man, no problem at least you have plenty of work going, this head thing has been driving me crazy trying to find the right set and then having to replace the guts out of it anyway.. Never ends.

Hoping all goes well should have back this week...

What size props you have to test?

Great article Jim. I knew that to be the case, but I didn't have any flow #'s to back it up. On a 502 or 496 stroker motor you'd see different results, but on a 454, in a marine app, large ovals are the way to go unless you're getting radical.