Cam choice 425

[Bob]

I would like to hear what you did. I am doing a 1966 Riviera GS 425. It has a good exhaust system and will have the addition of a set of 2X4s. Original appearance is important. This car is equipped with A/C so idle quality is important, but we don't want to loose out on any performance.

That is one of the reasons you will find the OE cam chart here:
http://www.teambuick.com/forums/cont...-425-nailheads

It would be nice to have some of these cams measured at .005" and .050"

[telriv]

Bob, the "hottest" of those cams measured at .050" was around 208* intake & 209* exhaust. To keep idle quality & not limit the flat torque band & not limit the "useable" RPM's is to have a lobe separation of at least 114*. Also the "ramp" rise has much to do with this. The stock rockers play a HUGE role that hinders performance also. They just don't allow the valve lift nec. to help the asthmatic breathing nail the air required to perform. I know the 2x4 is definitely eye candy, but one BIG single 4 will almost always out perform the dual quads on the street. I could talk about this ALL day.

Tom T.

[Bob]

Thanks Tom, I am well aware of the "eye candy" aspect, and feel that an original Riviera GS just needs that "eye candy". I not interested in hot sounds or lumpy idles. I am just trying to make the best decision I can for a good running car that doesn't stall at stop lights because the air is on, but runs strong.

I have always run and recommended single quads. I personally like the Holley spread bores for street use.

[nailheadnut]

Does your car have the MW or MZ engine code. Three were only a handful of '66 Gran Sports built with the two four barrel option; most Gran Sports came with the single Rochester Quadrajet. The Gran Sport option for '66 included that big pancake air cleaner that was chrome plated. You won't be off building a correct GS with a single four barrel.




Ed

[Bob]

It is a '66 GS, but not originally a 2X4, we just want the "eye candy". It is just like your photo with a good load of options but no bucket seats, although if we want them I have a parts car with them.

[nailheadnut]

The picture I sent was of a '66 GS as it came from the factory - one Rochester Quadrajet 4bbl.

Besides the fact that this air cleaner is for only one carb, you'll notice that the shape of the lid and breather is different from the 2x4 cars and it has only one snorkle on it rather than two. Nice eye candy, still an original OE Gran Sport, but just one carb.

The thing that helps motivate the GS is the BS code transmission and the 3.42:1 posi rear end.

Here's what the Super Wildcat air cleaner looked like. Notice that the sides are more square than rounded at the top, and the lid is stepped rather than smooth. This picture is from a '65, ALL '66 Riviera engines are painted red.

[Dr. Frankenbuick]

Bob here is TA's specs on the nailhead cams. Poston and KB are out of the picture, but they had some nice grinds in the day:


http://www.who-sells-it.com/cy/ta-pe...-fullsize.html

[Dr. Frankenbuick]

Bob,

I scanned and uploaded the KB and Poston Nailhead cam specs and descriptions:

http://www.fileden.com/files/2006/9/...0NH%20Cams.jpg

http://www.fileden.com/files/2006/9/...0NH%20Cams.jpg

I have the KB C114A in my 66 GS, but it has never moved the car. I did run it in, and the idle is a little lumpy. It has a 4-speed, and this means I do not have to be concerned with converter stall or off idle issues.

[wkillgs]

It would be nice to have some of these cams measured at .005" and .050"

I carefully profiled a stock '66 401 cam. These are the results:

Duration at 0.002" lifter rise:
309 deg Intake/ 298 deg Exhaust

Duration at 0.006" lifter rise:
271 deg Intake/ 266 deg Exhaust

Duration at 0.050" lifter rise:
209 deg Intake/ 208 deg Exhaust

0.006" rise is generally used by most manufactures for 'advertised' duration.

Lobe separation was 114.5 deg, with intake centerline installed at 111 deg and exhaust at 118 deg.