Hi all, looking at putting 302C heads on a 351C with flat top pistons, will this combo work, not sure where the compression ratio will end up.

All thoughts welcome.

Cheers

hi, welcome to fordmods.

yeah the compression will be about 10.9 to 1 with the 302 closed chamber heads
not a problem generally, get a mild cam, carby, exhaust and dizzy recurved to suit.
i have this combo in my xr and in my f100 too

The set up I have is;

bored 030
ICE ignition
eldebrock with 600 holley
mild crow cam
roller rockers
4 bolt mains
running straight LPG


Not sure what sort of HP it should pump out.

in my xr i have roughly same with

mild crane hydraulic cam,
stock crane rockers (deburred)
high flowed 750dp holley,
holley blue pump with 1/2" lines from tank
holley street dominator manifold,
accel electronic ignition,
ported 2v heads,
manley stainless 4v valves, retainers/collets etc
prepped rods and crank,
arp rod bolts,
flat top pistons 020,
tuned length pacemakers,
match ported intake, heads, exhaust,
top loader 4 speed,
xtreme lightened chro-moly flywheel
xtreme bf turbo clutch
4.11 9" lsd

i put it on the dyno last november and it made 234 rwkw / 320 rwhp on premium ulp

i built my motor as a nice daily driver

On dedicated LPG it will be great. LPG is naturally about 100 octane. I run 302 heads on all the street 351's I build. The general rule of thumb for petrol is 220° @ 050 is the smallest cam that will allow a reasonable spark advance curve with the 302 heads on a 351. LPG with it's higher octane rating means even a small cam will allow the engine to run without detonation.

If you are upgrading in the future, your carb is a little small if your LPG injection point is before the carb. LPG takes up about 15% of the intake air volume, so your carb is really only a "510cfm of air" carb. You could also use a bigger intake manifold for the same reason if your "edelbrock" is a performer. LPG is already a gas so there are no atomisation issues with running a big intake and carb.

I'm looking at putting it togather to produce reasonable HP, Plan A, is to replace the 302C already fitted to the short wheel base ford maverick and then plan B, refit it into an early mustang.

Now back to the topic, I guess to increase the intake are we talking carby spacer.

Cheers

more a higher flow manifold like Weiand X-Cellerator (sic) or funnel web style i think, yeah LPG loves compression used to run a ZD with 351 w/ 302 heads hated petrol but give it gas and she loved it!
351 over 302 anyday!

Use a single plane intake for a dedicated LPG engine. And don't make the cam too small. Remember you need to move 15% more air/fuel mixture into the chamber than a comparable petrol engine.