351c 2v open or close chamber diff

[luvsit]

Hope you guys can help,run a 351c with 2v close chamber heads,like to know if open chamber heads will make a difference in flow rate and give more hp or torgue.I have to run steel 2v heads in my class of racing.Just thinking a bigger chamber might make a difference,or is ther any other 2v head i can use with standard valve sizes. Will be much appreciated.

[MrPbody]

luvsit,

Define "closed" chamber. The only 351C heads I've ever seen that WERE truly a "closed chamber" were the 4-bbl. "quench" heads for '69 and '70. ALL the 2-bbl. heads I've ever seen were "open". That is, the entire chamber is open to the top of the bore/piston. the "closed" chamber resembles a triangle, with the spark plug at the point in the center, where the two "short" sides meet.

Perhaps we're talking about apples and oranges. Do you have any pics?

Jim

[luvsit]

thank you for responding Jim as Im thinking of putting another engine together,you are correct with the chamber sizes.In australia the 302 cleveland came out with close chamber and the 351 came with open.Im running closed to boost compression on my 351,what I would like to know will open chamber heads flow or burn the fuel better then closed,and maybe give more hp.cheers!!

[MrPbody]

If your octane rating is up to it, the smaller chamber will produce more power. Compressiion IS power, up to the point where the fuel cannot support the compression ratio. Rule "of thumb" is to multiply the octane rating by 10, and that's the highest compression you can run. Example: 93 octane, x 10, equals 9.3. Well, we know 9.5 is the "practical limit" for 93, so it isn't EXACT, but it's close! And that's the rating system used here in "the States". Yours may be different like Europe. There, their "98" is roughly equal to our "93".

Will the closed chamber make power? Not unless the compression increase accompanies it. It should have little or no effect on flow. Some engines do, but not the Ford "Cleveland".

Jim

[Boss351]

If you have to run Iron 2v heads, the Aussie closed chamber are the best. If you need to lower your compression (due to octane) used a dished piston. Open chamber Cleveland heads tend to ping due to poor combustion chamber design. The higher compression you can run, the more power you will make.