Compression with TFS 53cc heads

[flinfantryrebel]

hey all,
I am looking at TFS TW 170cc ported heads with a 53cc chamber. They would be replacing 60cc GT40p heads on a 2000 mountaineer/explorer 5.0

https://www.trickflow.com/parts/tfs-52515301-c00

how much compression gain might I expect? Any reason I may want to steer clear?

Theres a trick flow stage 1 cam in there at the moment, and a performer rpm intake, holley 650 carb

[4eyedblind]

https://www.summitracing.com/newsand...ion-calculator

[flinfantryrebel]

I’m not sure that calculator is accurate, it gave me 10:1 with my current set up, whereas FoMoCo rated it as 9:1, and with the TFS heads it’s showing 12:1 which seems just a tad high.

I was using a zero deck clearance and -5cc piston dish, which is what stock was according to my research


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[4eyedblind]

You sure it has a 53 cc chamber? TFS says 61 on the 170. Mine spec'd at ~60cc when I measured mine.

[flinfantryrebel]

That’s what their website listed. I think there are two 170 heads , with different chambers. The one I linked was part number TFS-52515301-C00, the one with the 66cc chambers was TFS-52516301-C00


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[darkd0r]

If I understand that calculator, a negative value for piston dish is for domed pistons. I would think that if your pistons have valve reliefs, you should be using a positive value.

[bkm]

You sure it has a 53 cc chamber? TFS says 61 on the 170. Mine spec'd at ~60cc when I measured mine.

The 11r 170 heads are 53cc.

[xctasy]

10:1 sounds exactly right, according to Page 12 of the Ford Parts Interchange Manual, 1959-1970, By Paul A. Herd.

The 283/284 tag J VIN code 4V 221/230/235/250 hp gross 302 4bbl engines for 1968 Fords/Mercs and 1969 De Tomasos all had 53.1 cc heads with that compression ratio, bang on it.