I've got 3000 miles on it in my 77 Supreme, and it still seems to idle a bit rough and lumpy, even thought its not all cammed up. Current plugs are Delco R46SZ gapped at .040.

1974 455 with E heads
.040 KB dished pistons, SILV 1630
Sealed power rings
HEI with Summit rebuild kit
stock 1974 intake with 600CFM Edelbrock 4bbl

Clevite Camshaft 229-2100
1500-4000 RPM
lift 448/472
adv dur 270/280
dur at 050 204/214
lobe sep 107/117

I was told this was built for an RV, and it has a lot of low end grunt. It doesn't get bad mileage on the highway either!

Anyone care to guess what he HP and Torque number might be? My builder guessed around 400 hp/ 450 lb/ft.

 

If it's only 450 ft lbs then yo're nowhere near 400 HP. It's just not the way Olds 455s work.

What is your base timing set to? And at what RPM?

 

I'm not sure where those power numbers really came from. I know it turns tires into smoke effortlessly, and pushes my 77 Supreme around nicely.

I've got 12 degrees timing, set with my ancient timing gun (no dial just flashes), vac advance line off and plugged when setting timing.

It idles about 750 RPM in Park, maybe 550 in D when warmed up with choke off.

I got these tune up specs and plug choice from a Chilton book for a stock 1974 Olds 455. I've got a slightly hotter cam, and HEI, and I know that there is a lot more power here if I can tune it better.

My electric choke Edelbrock has always been a good carb, just maybe a bit small for this engine.

 

With the HEI set the base to 20° @ 1100 rpm and see how that goes. And a 750 would be better for sure on that 455.

 

I've got a Edelbrock dual plane intake and a rebuilt Q-jet to install soon. The QJ was rebuilt by holley, and is OEM replacement specified for the 455 Olds.

svnt442, I'll try that tuning setup, but should I stick with my existing plugs and gap (R46SZ gapped at .040) when I do?

 

I'd gap them at .045.