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Old 06-07-2019, 05:53 PM
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question on timming

ok I have a 454 converted to 427 .040 over , 480 lift cam with long duration of 56 , when setting the distributer by ear, at idle , adjust to best running . ok then accelerated to 2000 rpms to finish setting timing. as i em turning the distributer the rpms goes up a lot . ok left the timing like that but at idle it runs like ****. was wondering if i should get a msd ignition. or is thiis to do with the curve of distributer ? any ideas oo and the vacuum lines where on

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Old 06-07-2019, 06:29 PM
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You'll never get it right by ear....what sounds best at idle will be too much timing by the time you get to 1500-1800 rpm and way too much above that rpm. Get a timing light on it so you can map the timing curve and see if a recurve kit or other mods are going to be necessary.

An MSD distributor is going to require the same set-up steps, checking curve and changing springs. etc.

big cam is going to require these distributor mods no matter if it is a stock distributor or an aftermarket, all have to be tailored to fit the engine specs.

Also, timing is set with vacuum advance unplugged from the carb and the carb nipple capped, then reconnected after you are done timing the engine.

The ,480" lift is pretty small in a BBC, do you have the intake and exhaust duration numbers??
"Long duration of 56" is pretty meaningless, doesn't tell us anything at all.
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Old 06-07-2019, 07:07 PM
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COMP Cams Xtreme Energy 256H Hydraulic Flat Tappet Camshaft & Lifter Kit Lift: .480" /.485" Duration: 256/268 RPM Range: 1000-5200 I have the iron heads so wasnt thinking of high rpm . yea i will get a timing light
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Old 06-07-2019, 08:00 PM
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Timing light is certainly helpful but you can also set the timing by ear but not sitting still. Go back, unplug the vacuum line and plug the hole providing the vacuum - golf tee's work well - set the timing to where the engine idles pretty good and about where you want it. Take it out for a quick spin, get on it a bit and listen - if you're not hearing any pinging, then you can move the timing up a bit. You might have to reduce the idle speed back down by tweaking the idle screw on the carb. Take it back out and see if you get any pinging again. You might have to go back and forth like this a number of times but once you get some pinging, go back to the previous setting - that's going to be the best timing for your combination. Yep -it's old school but it works.
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Old 06-23-2019, 08:11 AM
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My biggest question is why make a 454 smaller by installing the 427 crank??? No substitute for cubic inches.....
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Old 06-23-2019, 09:08 AM
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low rpm torque
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Old 06-23-2019, 09:25 AM
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The 454 will make more power than the 427 will. Including more torque...cubic inches always win....
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Old 06-23-2019, 10:08 AM
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Quote:
Originally Posted by russ55 View Post
low rpm torque
You went the wrong way if you wanted more low rpm torque.....the 427 stroke is shorter(3.766") compared to the 454 stroke(4.000").

You gave up torque by shortening the stroke AND you gave up torque by losing 27 cubic inches.

If torque was the focus and you were going to change cranks then the aftermarket 4.25" stroker crank would have been the smart move, makes 482" @ standard bore, 489" @ .030 overbore, 496" @ .060" overbore and 505" @ .100" overbore.

In the days before aftermarket cranks became relatively cheap, the 427 was somewhat popular and was known for its high rpm capability compared to most 454's, due to the shorter stroke.....the same guys who thought the 427 bested all due to RPM's were the same guys still hung on the 327 SBC besting all small blocks due to RPM......sun has set on those days a long, long, time ago.
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Old 06-23-2019, 11:08 AM
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Yup....what he said......
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Old 06-23-2019, 11:19 AM
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Big thing to understand is that engines produce torque, and HP is a mathematical calculation of how fast it can perform work. Four different ways to increase the output of an engine:

1. Increase engine size. Given no other changes to the platform, a larger engine will make more power (torque) than a smaller engine. This is due simply to it ingesting more air and fuel. Burning fuel is the only thing that makes power in an engine, nothing else. A larger engine can consume more air, so you can add more fuel.

2. Make the engine more efficient. Make it so it can intake more air per intake stroke, so more fuel can be added, and it will make more power per unit of fuel burned. The other side to this is to make it so it more completely burns the fuel it takes in, there will be less wasted fuel, more heat produced, and more power made. Both of these factors usually go hand in hand.

3. Force feed the engine. This can be done by supercharging, turbocharging, or nitrous oxide. All methods here put more oxygen into the engine than it can take in on it's own which allows for more fuel to be added, increasing output.

4. RPM. Turn an engine faster, it will take in more air, and can burn more fuel. This is the least desirable method however, as valve train design becomes paramount. Higher rpms also mean shorter engine life due to frictional wear....

Out of the ones mentioned, cubic inch displacement is the easiest way to increase output. Second would be by force feeding the engine. Increasing the efficiency requires redesign, and is out of the realm of most people with the exception of installing better parts than original such as cylinder heads or intakes.
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Old 06-23-2019, 11:22 AM
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One thing I didn't mention is fuel. Changing the type of fuel can effect engine's output. Oxygenated fuels will produce more power than non-oxygenated fuels but it comes at a price of lower fuel economy. With oxygenated fuels, they carry an amount of oxygen with them in a chemical form that's released during combustion. This additional oxygen allows more fuel, which allows more power. But as stated it comes as a price.....so pick your poison....
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Old 06-23-2019, 12:03 PM
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well i read the charts that i could find and they say a 427 has more torque at start then a 454 both stock .i took it like a ten speed bike im in first gear
going up a hill and your in second i will get the jump on you but long run you would win i didnot have the money for a high rpm rig so went this way
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Old 06-23-2019, 12:45 PM
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Quote:
Originally Posted by russ55 View Post
well i read the charts that i could find and they say a 427 has more torque at start then a 454 both stock .i took it like a ten speed bike im in first gear
going up a hill and your in second i will get the jump on you but long run you would win i didnot have the money for a high rpm rig so went this way
It all depends on the build. Intake, cylinder heads, camshaft profiles, compression ratio, all come into play. The 427 did not share the same parts as the 454 when it came to cams, compression, etc....Depending on the year, the heads were different, intakes were different, etc....Most 454's had more hp and torque than the 427's, and usually at a lower rpm. There were numerous versions of both, but eventually the 454 took over because it simply made more power, and both engines, with the exception of LS 427 and LS 454 (both high compression, solid lifter cam engines with larger heads and intended for racing), both engines made best power until approx 4000 rpm, where they were pretty much done in stock trim. Below that however, they were beasts. Don't forget to account for the 427 truck engine, which utilized a taller deck, taller 4 ring piston, and very small intake ports on the heads. These engines were built for heavy duty use and very low rpm. Still got smoked by the 454's though, even though they saw substantial use until the mid 1980's. A 454 doesn't have to be a high rpm deal either, with the right parts they can be very powerful engines at very low rpm. It's all about the combo.

Best of luck with your build though, when you do them yourself and have good results, that's always a positive!
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Old 06-23-2019, 01:28 PM
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Quote:
Originally Posted by russ55 View Post
well i read the charts that i could find and they say a 427 has more torque at start then a 454 both stock .i took it like a ten speed bike im in first gear
going up a hill and your in second i will get the jump on you but long run you would win i didnot have the money for a high rpm rig so went this way
I don't know what chart you looked at but it is completely wrong. The only way a 427 has more power at any low rpm than a similarly built 454 is if the 427 has a higher compression ratio or better flowing cylinder heads.
What you posted is actually the complete opposite, the 427 needs lower gear just to match the 454 in second gear is how that should read. The 427 IS the high rpm rig in this comparison, that's what you've got backwards.

Care to point us to this bogus chart so we can see it??

If you were comparing 1965-1970 427 specs to 1971-up 454 specs you were duped by the fact pre'71 was SAE gross rating, and post '71 was SAE net rating.
Gross rating is engine, no accessories at all, not even water pump,.... net is as installed in car, waterpump, steering pump, alternator, fan, belts, smog pump, exhaust manifold and y-pipe.....makes a 70-100 Hp difference on BBC's.
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Old 06-23-2019, 04:21 PM
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i dont remember where the charts are but this was my first so i did do a lot of reading . but money and i worked with what i had, corvettes had a 427 thought it would be cool to say 427 just sounds better lol heack i got it running sounds good 10.1 compression i think . used the 702 iron heads and a a small dome piston mild cam . here in my town you fart and get a ticket
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