400 with #16 roundports idea
 

Cut out the story, but playing around with the idea of putting SD heads on a 400. Have some parts laying around taking up space.

Cam would be HO Racing HC-02d cam
TRW domed pistons made for the HO/SD heads. Would fly cut to run on pump gas.

Can't imagine I am the first to think of this. Any feedback on this?

It should run good. My guess is that the HC-02 cam would like headers, but the SD/HO manifold would work pretty well.

Not a good idea!

And there's a reason why what looking to do has not been done!

Even if you took the Bore out to .060" over you would still only have a 412 cid motor and the size ( height ) of dome on the piston you would need to get even get a 9 .2 to 1 compression would choke off the flame travel in the chamber and severely limit HP!


If your trying to stay with a iron head then there are many D-port casting that can be ported to well over the stock 245 Intake cfm level of the 455SD heads, and the headers for such are far cheaper also!

If you went with a 4.00" stroke Crank then your idea has a chance of flying.

Can you show that pic of the flame path you cut in some domed pistons?

You will need a 4.21" crank with 3,00" mains for the pistons.

As Kenth said, the SD pistons would require a 4.21" stroke crank.

Could use a 400 high compression piston, but their dome is small compared to the SD piston dome. Or have some made up to work with the wanted CR you want.

The SD head is great for bigger CID engines, the RA IV is about equivalent to the SD except with smaller chambers.

Would work fantastic with turbos possibly in the 400.

:)

Looks like this isn't going to workout as planned. Skipped the piston pin location height on the 3.75 vs 4.21 stroke cranks.

Pistons are raw/ machined to specs TRW 2394d std bore. Bought years ago for a project that changed directions. With -19.3 cc dome, they would yield a 12.5:1 CR in a roundport 455. This would be less in a 400, however, overloooking the piston pin height throws this off.

Was worth investigating.

Actually you could use a long rod like the 6.8" (actually need probably 6.85")

That would give you the long rod plus the higher CR. (not 10.5 though)
So, find some used rods and give it a try.

(try some calcs here: Calcs )

:)

Cheaper to buy a stroker crank for your 400 block . There are domed 455 pistons to up the low compression.