Dual Quad Engine Configuration

[alex bonino]

Other than the obvious (ie the dual intake manifold/carb set up and associated plumbing, chrome air cleaner and finned valve covers) were there other engine changes to accomodate and/or achieve the extra horse power? A different cam? Higher compression heads? Beefier main bearings? Fuel line diameter? Exhaust diameter? Something else?

thanks

alex

ROA 11550

[Guest imported_65gs76limited]

Larger exhaust,timming and distributor curve.

[Jim Cannon]

yea, all them... plus a different cam.

[alex bonino]

So, timing, distributor advance, exhaust size, and cam.

thanks for the input!

alex

[1965rivgs]

For `64 and `65 the 425 dual quad cam was the same as the single 4 barrel 425 cam. For `66 Buick detuned the single 4 barrel 425 cam but continued to use the `64-`65 dual quad cam in the ultra-rare `66 Super Wildcat option.

Tom Mooney

[RivNut]

Gentlemen;

If you want to know the real nitty-gritty about these cams, there is a chart on page 16 of Volume 5, #1 of the Riview that lists the specs for all nailhead cams used in 401/425's starting in 1959. The chart was provided by Dennis Manner - need I say more!

The last paragraph before the chart:

"The 1963-1965 425 camshafts were similar to the 59-61 401 camshaft except it was retarded 4 crankshaft degrees to increase top end horsepower. Although three different part numbers were used, the specifications for power were the same. In 1966, the 425 used the milder and smoother idling 401 camshaft. All 1964-1966 425 dual four barrel factory produced engines used the original 425 camshaft timing." [which except for the crank offset has exactly the same specs as the 59-61 401 camshaft - ER]

The chart follows.

If you're really interested and want to see the entire chart, send me a PM. I'll ask you for a home address on a SASE and tell you where to send it. I've tried scanning this before and it doesn't reproduce; it's in a small weird font and doesn't copy well. Sometime when I'm really boredand have a lot of time, I'll try putting it on an Excel spreadsheet that I can forward.

Ed

[Dales90]

Thanks Ed,

Now I understand why the distributor is different for the 64 dual quad, and one can use the unit from a 61 401 to get the 12 degree curve.

Dale