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Just cruise for now, PV tuning can come later if needed. I reckon you may need to try less jet on the primaries, say 61-62 or so. To reduce the secondary delay, you could raise the float level a smidge.

I reckon a 465 would be ideal, next step up from that is a 570 Avenger. Have you thought about a 500 Edelbrock?

64/70 jets sound about right, depending on how big their air bleeds are these days. They sound bigger than stock jets. Maybe you could drop your squirters down to 28 or even 25. 31s are a bit big for an engine that size. It's much cheaper to fork out for a spring kit than to buy them individually. Maybe go one stiffer than your silver one? Hume Performance does pretty much nothing but Holleys and will post them to your door. They've got a pretty good range of bits online. One way to eliminate the problem of your secondaries opening is to wire them shut and/or disconnect the actuator. That way you can get your primary tuning spot-on and then work out what point you want your secondaries to open up.

What size squirters are you running? You can draw out the delivery for longer using smaller squirters. Acc pump tuning is ok but using that as a means of covering up an unrelated issue is really a band-aid fix. Also note that 570 CFM is a lot for an engine that would struggle to swallow more than 400. Your carby is perfectly suited to a warm 302. I think you should keep the spring stiffer and tune the primaries ie: jet up a tad or open up the PVCR if your jets feel ok in the midrange. What jets are you running? What is the stiffest spring you've put in?

^^^ Yeah that's pretty much spot-on. The stock 570 might be a bit too much carby for a 250 so go stiffer in the secondary spring (or clip the current one at a pinch). This makes sure that air velocity through the primaries is at its max before the secondaries cut in. Jetting secondaries on those carbies can be tricky as they're a meter plate (I think) on that side. They can be drilled but once you do that and go too far you need to replace the plate. Another method to overcome secondary bog (after you've got your spring set up as good as you'll get it) is to raise the secondary float level a smidge. This gets the mains flowing a little earlier. Go in 1/4 turns of the float screw with each adjustment. First port of call is to shove a stiffer spring in. I'd go at least a purple or stiffer. Scroll down the Holley instructions to see their spring rates on a 350 CID engine: https://ac17cb7e3cc3506f0d23-7386afb7d61f5e5af0e5a817d2877bfe.ssl.cf1.rackcdn.com/199r8219-2rev.pdf Or alternately: That chart shows yellow as the weakest spring but Holley shows a white one that's weaker still. Anyway, your yellow one is too weak and is allowing the secondaries to open too early, causing a drop in flow though the primaries and leaning out.

Thanks for taking the time to do that, very interesting The higher top pivot would also raise ride height so you'd have to take that into account when spec'ing springs, etc.

Your acc pump only should relate to what's happening in the primaries. Your secondaries need to open late enough that they flip open quickly, any earlier and they'll take too long to work and with the sec throttle cracked open a tad, that's where the flat spot occurs. It's not flowing enough air through to pull sufficient fuel out. I'm assuming it's a 351, so then I have to ask at what rpm are the secondaries opening? At a glance, it sounds like you need to go stiffer on the vac spring. EDIT: just realised it's a 6-cyl, being in a 6-cyl thread and all.

Sorry forgot to explain amps and amp-hours. Amps = current flow (Coulombs/second) Its's the same as water flowing through a pipe (ie Litres/sec) Amp-Hours = battery capacity. It's like saying a water tank can hold enough water to drain at one litre per hour for X amount of hours. The reason why they rate it that way is because a battery is more like an electricity sponge than a tank, and its actual capacity can only be charged/discharged over a long period of time.

That's a great thread n00bus, answers a lot of questions if you take the time to digest it. Got another question: I seem to remember an ultra-tall ratio that came with XD-XE 351 pursuit cars. I think it was around 2.6 ratio... Or am I on drugs? Would make a great cruising ratio for a 4-speed or non-OD auto.

So the one on the left is the 2.77? Makes sense as the pinion will have a bigger diameter and more teeth for a taller ratio

Had my EF booster fail on me in traffic very suddenly... Lets just say it was lucky the centre divider in the road happened to not have any trees right at that point, as that's where I had to point the car to avoid slamming someone up the arse.... Stupid plastic boosters.

I love the smell of gear oil in my fridge in the morning

The floats aren't externally adjustable, the fuel jets and needles should be the right ones for the engine it was designed for, so once installed the only adjustments should be idle mix & speed (as with any carby), vacuum piston and secondary flap spring tension. Idle speed: if you want to run the idle solenoid then that's where you make your adjustment from. If not, you can adjust the base idle screw up so it's there all the time. The vac piston screw changes the relationship between the rods and the piston and changes the mixture under load in the primaries. It's a very fine adjustment and you can go 2 turns at a time before noticing a change. Wind the screw in to raise the needles and make it richer. The secondary flap adjustment is a little involved but from memory you back the lock nut and screw off, let the flap drop and wind it round again till the flap closes. Note where the screw is and keep winding till you reach (I think) 1-3/4 turns. Lock up the nut while holding the screw there. This controls how far the flap opens in relation to airflow over it. Tighten the spring for richer secondary mixture. If it wasn't touched during a rebuild and ran fine before then don't bother touching any of it. They're different from your normal carby and are quite specialised. You can block most of those vac lines as these carbies were designed for Mopars and a couple of Fords, meaning many of them would have been blocked from factory. All you need really is large one for PCV, small constant vac for carbon canister, and ported vac for distributor. How you tell is the first two will pull vac at idle, but distributor vac will only pull vac at above say 10% throttle. The rest are all bullshit really. That one on the top of the carby is the float bowl vent and should go to carbon canister but nobody ever bothers. There are others that go off to vacuum switches that nobody uses these days so just hook up those 3 that I mentioned and you'll be sweet. Start with your idle screws say 2-1/2 turns out and wind them in to go leaner. Best way to tell if it will work is to bolt it on and see!

Nah the two manifolds look very similar but are different: BA-onwards have two inlet valves and a flat, oval shaped port, with manifold to suit. AU and before have circular-shaped ports.

Sorry we're going off topic... From what I understand, ratios up to and including 2.77 ratio use the 0575 type housing and carrier, with different pinion bearings to suit. 2.92 ratios and above use the 0578 housing and gearsets. There are better experts on here that know the intricate differences but as stated it's just easier to swap in a later 0578 housing and you'll get 4-pinion carrier and 28-spline with it too. Hand brake might give trouble though. Edited: 0575 and 0578 series instead of 075 & 078

Thanks mate but I can't take credit for it as I just copied one that I saw. So far so good for success rate anyway.

That's to remove the preload on the carrier bearings so you can get the carrier out. All Borgie diffs are that way. The pinion comes out through the back after you pull out the carrier. You can often pull apart an old diff without the spreader because the bearings are worn and the preload has been lost. Going back together you need it though, the housing needs a couple of thou of preload to be correct. You take your measurements from across the bearing caps using a dial gauge. Building any integral-carrier diff properly is very time-consuming and most folks just throw them together and they work most of the time.

From another thread: My diff housing squasher: The correct method uses a tool that locates in holes either side of the face and pushes the housing apart. Mine squashes it top to bottom for a similar effect and it (somehow) works.

Bear you beat me to it

Ok yeah sorry here's an update: It's been 3 months and the Mellings pump is performing beautifully, just as it should. I think my engine might still be a bit tight even after 30,000 k's as the pressure never drops below half even when it's hot. I took the sump off exactly as described above, sway bar dropped down from chassis, blocks of timber under the mounts, and sump came off easily... well after I loosened the engine mounts from the block (they interfered with the pan rail by a bee's dick). It all went back in without drama except for the curved rubber end gaskets. They seemed to be too big and I had to trim bits off so they'd fit. Shitloads of Threebond everywhere to be sure, hasn't leaked a drop since. I've had a good run with Fel-pro gaskets and this is the only hiccup thus far. Looking closely, they've got FoMoCo moulded into them! The old oil pump had no markings on it so I'm assuming it's a Pr-Co-p rip-off. It had lots of scoring in the rotor and relief, (possibly from the earlier camshaft failure) but I still believe there was something wrong with the relief spring to be spiking pressure like that on startup. Jacked: The lifters were pumping up due to excessive oil pressure. Think of your hydraulic lifters as tiny hydraulic cylinders that take up the clearance in your valve train. The oil is controlled by a disc valve that lets oil in as soon as the lifter sees no load, fine at normal pressure but go shoving double or triple that pressure into the oil feed port and the little valve is overcome. Then you've got unmetered oil flow pumping the lifter up and holding your valve open off its seat. Probably even worse in a stock engine with low seat pressure. No valve seal = misfire. Sometimes 7 out of 8 cylinders would be dead, and I'd have to wait for them to bleed down again before starting. Not fun when you're already late for work. I know it was spiking at least double the normal pressure at times as I blew 4 oil filters off and they're rated at 200 psi. So happy times now that I've used good quality bits. Unlike the bloke I bought this engine off. Thanks to everyone for the advice

Ported if it's a stock motor, full manifold vac if it's got a bit of a cam. Set timing with it disconnected if going off manifold

Ok we need to back track to the basics again. It has fuel, spark and compression, so it should fire. Your method of finding TDC #1 should be #6 rocking, or alternately, find #1 rocking and wind her over a full revolution to get TDC #1 compression. Even if you set it to 0 TDC, it should run ok, maybe a bit hairy. To establish a healthy spark, I like to take the dizzy cap off, and rotate the rotor back and forth on the advance springs to trigger the coil. Make sure your trigger wheel lines up with the teeth on the induction wheel. I pull the coil lead off the dizzy cap end and test the spark to earth about 1/2" off while rotating the rotor. Once you've established you've got spark, tip a bit of fuel down the carby to prime the intake. Should fire for a few seconds at least.

I'd be mindful of where the shifter sits in a Corty, as the factory single rail in the 6 cyl had its shifter mounted further forward than in a Falcon. Using a Falcon T5 would have similar issues. The easiest (maybe not cheapest) way of getting 5 speeds is to maybe use a Sierra box/bellhousing?

J3 chip eliminates the BCM problem, covered here in other threads. Eliminates the smartlock crap too, which is an issue with key coding, etc. Look forward to the result when you're done

The 6 cyl ones had shorter 1-2-3 ratios (1st was 3.47) and V8 ones had 3.25 1st. The taller the ratio, the higher the torque rating. The T5Z had 2.95 1st and was the highest-rated factory T5 made. Your engine builder should be talking in torque figures not horsepower, as it's torque that kills a gearbox. Sure it could handle 500 hp on a rotary spinning to 9 grand with fuck all torque. See what I'm getting at?