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4.2 petrol carby options

Posted: Tue Nov 23, 2010 12:04 pm
by Quigga
Heya guys,

New to these forums but been around on others for a while.
Just need some quick suggestions to get some more beans from the carby motor without spending big, So far i have have come up with a few ideas but nothing really in concrete, for now it has to stay carby and internally stock (may port head if the time comes) for class rules but may efi/turbo later

retain stock carb but take out restriction plates and rebuild and rejet to suit a meth/tolulene mix

use a holley or webber downdraft carb (dont know sizes that would suit though) also will use a fuel mix there too

upgrade to electronic ignition with beefier coil and leads (possibly petronix )

any links or guidance would be appreciated

Re: 4.2 petrol carby options

Posted: Tue Nov 30, 2010 10:46 pm
by Quigga
bump it up

any suggestions guys

Re: 4.2 petrol carby options

Posted: Wed Dec 01, 2010 5:59 pm
by 351ciofgrunt
What class rules says it needs to stay internally stock?

To get some decent power out of a normal atmo TB42 will take alot of money, it's a very heavy rotating assembly, with a tiny cam and no compression.

Save your money and go down the efi & turbo path, very impressive power

Re: 4.2 petrol carby options

Posted: Thu Dec 02, 2010 8:49 pm
by PGS 4WD
Quigga wrote:Heya guys,

New to these forums but been around on others for a while.
Just need some quick suggestions to get some more beans from the carby motor without spending big, So far i have have come up with a few ideas but nothing really in concrete, for now it has to stay carby and internally stock (may port head if the time comes) for class rules but may efi/turbo later

retain stock carb but take out restriction plates and rebuild and rejet to suit a meth/tolulene mix

use a holley or webber downdraft carb (dont know sizes that would suit though) also will use a fuel mix there too

upgrade to electronic ignition with beefier coil and leads (possibly petronix )

any links or guidance would be appreciated
Do the ignition, good intake, extractors and exhaust. A dynotune with premium and some cary adjustment can get from about 75 to 85-90 rwkW in a manual.

Re: 4.2 petrol carby options

Posted: Sat Dec 04, 2010 7:09 pm
by Quigga
ok appreciate the help so far but im assuming there isnt or is very few who have actually tried to develop this motor so it looks like ill have to just trial and error it :lol: ill do a write up of sorts anyway so the next person isnt greeted with the usual stuff
intake, zuast, ign, tune
it must stay internally stock for the class rules (it says so in the cams licence for the class all parts are to be engraved and pics taken prior to installation) the turbo route may happen next year but with a 4.6 later anyway if we move up a class (or 2) with some tricks i know from building 25/30's and 26/30's it should be making around 500-600hp with like well over 1000+ torque

btw ive already changed to some 3inch extractors and made a custom pipe to dump behind the diff (so far biggest gain)
made a custom intake and snorkel setup (response and bay temps went down)
got a petronix on order

oh and im gonna use the stock carby, it has restrictor plates and fairly small jets so ima change it accordingly and run it on a 10-15% meth mix to run a whack more timing which the petronix with help with(so far with the math its looking at an extra 50-90hp just with the carb so much more with the juice)

anyway still welcoming ideas as it can never hurt