[TedRamAirII]

Originally Posted by ScumOne

I did a mild buildup of my 400 in my 69 Bird last year...10.6: 1, Kauffman heads, recommended cam/roller rocker arms, RA exhaust manifolds. Went to the Holley 750 with vacuum secondaries instead of the Q-jet (since rebuilt by SMI for 5500 ft elevation).

The Holley is just a gas hog, plain and simple. The Q-jet got 11/12 mpg around town and 15 mpg on the highway doing 80 mph with the AC on.

The Holley was so bad I did a test driving 52 miles, 1/2 city, 1/2 highway. I drove like an old lady. And I mean slow AF. It was torture for me to drive the Bird that way for 52 miles. I filled it up after that and it took almost 7 gallons to drive, which was 8.3 mpg.

The Bird is back in the shop to get that dialed in. My mechanic hates Q-Jets, but this Holley has been a huge disappointment compared to the Q-Jet. The Q-Jet was better on mpg and it launched and accelerated quicker at high speed, too.

Just my .02

Jim

Maybe check the sparkplugs color and a jet change. go at least 2 sizes down.

[ScumOne]

Originally Posted by TedRamAirII

Maybe check the sparkplugs color and a jet change. go at least 2 sizes down.

Did that already, still no joy. I think there's a leak somewhere in the fuel system. I can walk out to the shop and it smells faintly of gas even in the car has sat for a few days. It's maddening.