Thread: High Comp 4.6 Straight Gas. What to use to return to straight fuel

As stated above I don't know how to do it but the ignition timing will be advanced a long way to run straight gas to its best benefit.

You would have to make sure the ignition timing was returned to standard to make it work properly. That is if they had advanced the timing.

Cheers

Mike

What manifold system does it currently have - can be almost anything?

Without the information ,

i`d pressume it is running a form of injected lpg because of the question ?

If so it is probably piggy backing the petrol ecu ?

The std 3.9 Rover ecu can be modded for a 4.6 if the need is felt .

Our RRC with a 4.6 has a 14CUX that has been altered by Davis Motor Works

The ECU alters fuel and not ignition so i`d consider to be worth while it would need to be used pretty hard , or do alot of heavy towing ETC .

If it`s basically std Rover and it has a distributor and as has been suggested the advance has been altered for lpg , it would need changing back to a petrol curve .

I guess 5 is beside 4 on the keyboard ?

Oops yes a 4.6.

Std 3.9 Manifold with gas injection in injector location.

LPG makes sense but not available in the bush.

Will get more info.

Ok so if it has the 4Cuix system I guess they also put the 3.9 dizzy and timing cover on the front.

Then as suggested by PLR, the 4CUIx ecu is probably there some where, if not source one and get it chipped for the 4.6. I am also guessing you will need to get injectors etc. You will need a MAF as well etc. Timing at around 9-10 degrees BTDC will work with both gas and petrol but the new tuning process will sort that.

Guessing a bit as specific details of what you have is still not totally clear.

As a suggestion - why not take it back to dual fuel - Put the petrol injectors back where they belong and get the manifold modified to take the gas injectors - best of both worlds.

Garry

Would prefer straight fuel for availability and one system

Motor is a fully rebuilt 4.6 block with shaved 3.9 rebuilt heads and running straight LPG.
Bottom end was rebuilt by Speed Works in Ringwood. It included brand new High comp pistons (almost the last ones you could buy in AUS), all new conrods, and new bearings.
Heads were reconditioned by Fred Smith and shaved so the bowl suited the 4.6 and compression was not lost

Injector holes were blocked up, I think resin or sikaflex or something permanent so that might not be possible. Putting it on carby would work but not very efficient.
If you could get fuel rails, injectors in you would still need all the sensors ( I think there were 3 or 4 that are necessary) ecu and all relevant wiring.

Sounds like a very nice engine. Maybe one of these on it would be great fit modern simple and would go well. The second one that does ignition timing as well

fitechefi.com/