It is almost spring here in New Hampshire, although we got 5" of snow yesterday, and I am beginning to think about getting my car back on the road.

Anyway, for the past several years I have been having performance problems with my 350 - 350, with 11:1 compression engine and original Q-jet carb. I sent the carb off for rebuilding years ago and in the mean time bought a cheap rebuilt Q-Jet from the local parts store so I could drive around. The car had been having detonation problems for a while which were somewhat resolved when I started adding Av gas to the mix. However, it wasn't until I took off the camel hump heads and reduced the compression to about 10:1 that it became more civilized. Unfortunately, when I got the original carb back and put it on, I could never get the car to run well consistantly again. I have swapped out the points and put in a Petronix optical system, adjusted timing, continued to ad Av gas, but performance is so ****ty that after several trips to my local engine guy (admittedly a Holly fan but NOT the one who rebuilt the carb), we just put the generic Q-jet back on and the car ran noticably better. Hmmmm. Now, I won't go into the rebuild, but it was done by a reputable guy, and was set up with all "original spec" jetting, etc

Living up here in New England, we are now getting 10% ethanol gas mix everywhere, and even the 93 at Sunoco is a blend.

So, I am curious about how others with high compression engines are faring with ethanol in the gas, and I am also wondering if my original carb may not be set up improperly for todays low octane, ethanol blends.

Finally, I have decided that perhaps it is time for me to buy a new/rebuilt carb. Can anyone suggest a source for a quality unit for a 69 L-46?

Thanks...

Mark

 

Well......a lot of people on this forum will swear by Q-Jets. I usually swear at them. I've had much better luck with the Holley spreadbore replacement.

Anyway, the ethanol in the gas has been around for awhile and, except for hurting fuel mileage, hasn't had much affect on running. You shouldn't have to run av gas at 10 to 1, 93 octane should work just fine. There must be something wrong with your original rebuilt Q-Jet. Maybe the float is bad, or the accelerator pump. The rebuilder set it up, but did he put it on an engine and run it before he returned it to you. New parts can sometimes be bad, even though they look good.

If it's running good with the generic Q-Jet, why do you want to replace it?