Falco

Im due to start a rebuild of a 302w in the next few days, which will be put in a '73 Falcon.

Im wanting to convert it to run fully on LPG without sacrificing too much performance.
Which means upping the compression to 11.5 or 12 dosn't it?
How would I go about that?
Which pistons, rods, heads and such?
Should I get new heads or have my stock ('74 something) heads given a treatment with HPC or something?

I'm guessing Im going to need to get a new ignition system too, what would be suggested for that?

And, last q, for now atleast...
Running it on the standard '73 falcon 3 speed manual? (heavy duty full syncro)

Or should I just do a regular recondition and keep it stock with a 2b carby?


Thanks.

EDXR8

Probably the easiest way to increase the compression is with high compression pistons. There are so many available for the Windsor engines you can basically pick any compression you want. Also a good idea to get an LPG specific cam, GRA do LPG cams for most engines I believe.

ebxr8240

If you are going to get Hi comp pistons?? Consider 289 rods [longer] and custom pistons..I don't think they are too expensive for custom, should get some off the shelf... Ask the guys at VPW.com.au .....Heads will need to be set up with hardened seats...

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Falco

Thanks for the info so far, Im definatly not an experianced engine re/builder, but I do know the inner workings inside out.
I just don't really know whats out there and how its used, not enough hands on experiance.

What are the prices I'll be looking at for this sort of mod?
Would I be better getting alloy heads or getting the valve seats hardened?
I'm on quite a tight budget so I'm not really looking for performance at all... Just enough to match the petrol performance level.

Oh, and whats the story behind the octane levels of LPG these days, last I heard or read was that the octane rating is done a few notches...

blue66coupe

keep your comp under 10.5 as current gas crops are rubbish compared to pure propane (support 12:1) most important issue with aftemarket pistons (all have varying deck heights, not much but enough) is watch your quench clearance and keep it under .060 for decent response, more power and torque and detonation resistance, make sure you allow for compressed gasket clearance as this can vary from .038 to .055 , just using 2 popular fel pro gaskets as a guide copper o-ring and standard 'blue'. Install hardened ex seats as a mater of course for all soft iron heads. Pocket port your standard heads and for more than enough airflow for stock type use 0-4500, get rid of the abominable standard valve gear and use proper rockers and keepers.

xpc66

You know if the block is a 73-76 production the deck height is slightly more than the ones produced either side. If you use the 2673 ACL pistons the piston to head clearance gets pretty close to 0.040 with the 289 rods:

Deck height 8.229
Rod length - 5.155
Compression height -1.585
Crank throw -1.5
Gasket + 0.047 ?
= net clearance 0.036

With the standard deck height of 8.206 it gets a bit too close.

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