Race Engine Forum UK

Hello All!
My daughter and I are building a head for her Fiat spider incorporating some of GC's techniques
Some details here:

New 2L short block with flat top pistons
maintaining stock fuel injection (possibly installing adjustable fuel regulator to increase press.)
Stock FI cams
1800 Head with some porting, polishing of the intake and exhaust ports and gasket matching on the intake side, 30 degree valve seat, valves back ground to 30 degrees, 70 degree valve throat, standard valve sizes.
We will also be installing a 4-2-1 style header maintaining O2 sensor, a low restriction muffler and removing the cat. converter (after smog test), and an aluminum flywheel approx. 9 lbs. balanced with a new stock pressure plate.

I want to match the gaskets to the exhaust side as well but the 1800 exhaust ports are quite a bit smaller then the 2 L head, Should I leave them, hog out the ports to match or just do the edges blending into the ports?
The idea of using the 1800 head was to get a compression bump without changing the pistons in the new short 2 L short block.
Thanks in advance and hope to publish some photos before the head gets installed.

Chris Saul
Oakland, CA.

Hullo Chris,

in the first instance - the ex port mean cross-sectional area should be made more-or-less the same as the valve throat diameter. Do not 'artificially' enlarge the outer section to match header or gasket.

Gc

Guy Croft wrote:Hullo Chris,

in the first instance - the ex port mean cross-sectional area should be made more-or-less the same as the valve throat diameter. Do not 'artificially' enlarge the outer section to match header or gasket.

Gc

Thanks, I will measure all throats and and match to that figure.