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Recurving 425?


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I'd like to get some more performance out of my 425 without drastic mods. My '65 Gran Sport is running a '66 425 with '66 heads and a stock intake with an Edelbrock 625cfm w'electric choke. I intend to swap the stock intake for a '66 Spread Bore and a 750cfm carb. I've heard recurving the distributor can give me some more performance, but where do I find the parts? Are there any other cheap and easy mods? The Lark is currently running with a ST300, which I plan to swap for a ST400. The rear-end is stock and not posi. I think the ratio might be 3.08:1<P>Thanks for all input,

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You can buy distributer recurve kits from any speed shop and most pepboys/etc. I have never had much luck with them though. They have lighter springs for the weights but whenever I tried it they were to weak to pull the weights back in. <P>An electronic ignition conversion would give you a few extra ponies.

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Sorry, forgot to mention it - I've also got the Pertronix Electronic Ignition and the Flamethrower coil. Thanks for the tip on the speed shops. I've looked around a bit and not many of the local guys supply Buick stuff. I haven't tried TA Performance yet.<P>Dave

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Dave, make sure you keep using the ST300 torque converter if it's working ok (I'm assuming you'll be going to a variable pitch ST400, '65-'67). The ST300 converter fits perfectly and you'll keep the same stall speed you enjoy today. The ST400 converter is about an inch larger is diameter and will decrease the stall speed a bit.<P>Devon

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A good Nailhead curve is 18*-20* of mechanical advance at the crank all in by 2800-3000 rpm. Most good speed shops have a distributor machine that will allow them to curve your distributor to those specifications for $30-$50. Then you would run 12*-14* initial advance for a total of about 32* of advance with the vacuum advance disconnected and the source plugged. Find the initial advance that seems to run best when road tested (no ping- most go). Then reconnect the vacuum advance after you have found the best initial advance setting. Pinging would be the sign of too much advance. If there is too much advance when the vacuum advances is connected after the best initial advance is established, an adjustable vacuum advance may be needed. In the meantime you can run without the vacuum advance, but there will be a loss of 1-3 MPG. I hope that was helpful.

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