lpg_250":1uz9kt3f said:
Thanks for the advice xtaxi.
Alot of great info there much appreciated.
I will now look into everything and start getting prices.
Just a few more questions though if you can help.
What do you advise I use to avoid rocker stud stripping?
What do you advise for the lifters?
How do I find what convertor I am running on my LPG system? (L series or E series)...
What diff ratio would you suggest for daily driving and casual 1/4 mile?
Does a 3.9 sound about right?
What stall speed would you recomend for the auto with all the above?
Does a 2500 stall convertor sound about right?
Rocker stud stripping? First option is easy. Limit revs to less than 5400 rpm. More expensivley, posi lock 7/16 studs on the head, and go YT roller rockers. Even more expensive, the latest SVO AVESCO racers fix it by making very trick location spigots where the 7/16 stud would go, and then peg the rocker with two smaller studs each side.
lifters Check
Dynoed250's posts. He places flat grove in each lifter to bias the oil flow.
L series or E series Look closely at the converter. The L-series is marked L=series on the converter.
The L-series is Lozenge shaped, has EFI XE/XF Falcon style cross hatching on one side.
The L-series always has an EC-1 port, while the E-series often missed out on it, and has a priming spring.
The E-series has water inlets on opposite sides, while the L-series has water inlets on one side only.
The E-saeries is circluar.
The E-series can be marked EB or B2.
The E-series was made in Aussie under licence for a while.
What diff ratio Diff ratios can be compliacted. Car must be pulling 10% above peak power revs through the traps at a 1/4 mile, and must not run
off the converter on the open road.
Generally, get a TE 2.92:1 diff from a 3.3 Cortina 6.
If your car has 370 hp at the flywheel, run a 3.23:1 diff
If your car has 300 hp at the flywheel, run a 3.08:1 Commodore VN diff ratio.
If your car has 200 hp at the flywheel, run a 2.77:1 diff, and take it to the limit in second Optionally, you can run a 3.7:1 TE 4 cyl diff then trailer it to the meet. 3900 rpm at 110 km/h is not going to make your six last.
The non turbo 250 Falcon likes similar 3.23's. Turbo Falcons in the 11's run 3.7's, and seldom see over 6 grand at the traps.
The Cortina needs a
taller ratio to alow for smaller tyres. My friends 5 speed EFI TE car runs the 2.92:1 diff, and says he wants a 2.77 or 2.54 diff!
Traction with a well set-up Cortina is better than a Falcon due to weight transfer. Be very carefull!
TF's don't run BW 78 diffs, they run the smaller 7" diff found on Oz RWD Toyota Coronas, Sigmas and Bluebirds. It won't take the heat! I like the bulletproff Limited slip SR5 Hilux truck diff, but they only come in 3.9, 4.1, 4.3 or 4.88 ratios. It allows you to get great drum brakes, Falcon 5-stud pattern, and the best axles for dollar you'll ever get. The hassles of welding the upper and lower links, and shock mounts are worth it! With is about 1390 mm, so its narrower than the 1420 mm of the stock diff.
What stall speed
A 2500 stall convertor sound about right. You'll find the engine will make a huge amount of low end torque, especially with two stage boosting. Stock aftermarket C4 converters, such as Kyver, are cheap, and run about 2350 rpm. Must V8 converters sit at 1650 rpm for a stocker, 2350 rpm if its an FMX 351GT. The price goes up and up from there.
At 110 km/h, a Cortina with 600 mm tall tyres and a 2.92:1 diff would give about 2800 rpm, so a 2350 to 2500 rpm converter is just fine. If you lower the diff ratio to 3.9:1, it would be pretty useless. Bob Pinelli, a 302 Cortina racer, found the 3.23 ratio ideal if you have big tyres. I'd just opt for 2.92:1 for a start, and concentrate on getting the basics of the turbo delivery right.
A drag Cortina will eventually rip the a$$ out of the stock floor. Inital issues are the rear window falling out under load, and then spot welds popping. ( Spots were only 80% complete at best in the factory). The four link rear is quite a good thing, but 300+ hp will tax it a little. You'll need compromise on the front springs and dampers to launch well. 90/10 shocks may help drop your ET's, but you'll never want to play cat and mouse around the streets.
Best wishes.
x
