557 TFS Domes

I was shopping bottom end parts for a new build and settled on a diamond piston # 40724. 4.44 bore 6.8 rod 14.5 cc dome, I called Diamond directly and was ready to purchase when the guy told me that this piston would not work with an 18 bolt head. Their catalog plainly says it's for use with TFS race heads. . What am I missing? Did I get a rookie phone rep who didn't know his own catalog or is this true? Part number for my head is TFS-5451T802-M87.

I was under the impression that the 340 cc 10 bolt and the 340 cc 18 bolt were the same with exception of the extra bolt holes.

It is possible that he may have mistaken it for an 18 degree head!!

I don't know, he said he knew which head I was talking about. I tried to give him the part number to look up but he didn't bother, said all 18 bolt heads had a different shaped dome. If I remember correctly?

I stopped by my local speedshop/machinist to get his input after I posted here. He seemed to agree it was going to require a custom piece but he is going to do some more research before we buy anything. I was confused by the wording in the diamond catalog. I guess that part umber may be for an older obsolete style "race head"?

Their are some different combustion chamber shapes on the A460 stuff depending on the part number, try ordering from Lem he has a few part numbers that already have what you need

10-4. Thanks.

stanger68 wrote:I don't know, he said he knew which head I was talking about. I tried to give him the part number to look up but he didn't bother, said all 18 bolt heads had a different shaped dome. If I remember correctly?

I stopped by my local speedshop/machinist to get his input after I posted here. He seemed to agree it was going to require a custom piece but he is going to do some more research before we buy anything. I was confused by the wording in the diamond catalog. I guess that part  number may be for an older, obsolete style "race head"?

Come on man ... this is like believing that a C460 head is not a "race head" BECAUSE it only has provisions for 10 head bolts; they are certainly not obsolete.
A current 10 bolt A460 head definitely IS a "race head".