I installed an Edelbrock 4-barrel (600 cfm carb) and Performer intake manifold on my 67 289. Now I understand that I should have used an Edelbrock 500 cfm instead. Does anyone have any information on this matter; i.e. could the jets be changed or will I have to install the 500 cfm in order for it to run right. I have not started the car since I finished the installation. Thank you
I hope one of the engine guys chimes in here, follow-up question:
I believe the Performer is a Dual Plane manifold, does that help or hurt here? Is that where the 500cfm spec is coming from?
No. I called Edelbrock in California and they told me the 500 cfm carb is the one I should have installed. I suppose the 600 cfm will run too rich. They didn’t say this. I am guessing. Thanks for your response.
You haven’t started the car at all after the install? Why not?
You should be fine with the 600, it all depends on what has been done to the motor before. Is this a stock motor or does it have a cam that is different from stock?
Changing the jets to a smaller set can be done if you find it is running rich. You have to read your spark plugs and as well, metering rods may need to be changed as well. You can get a kit with different jets and rods to bring it to where it needs to be for your motor.
if you haven’t started the car yet, start it and make adjustments. Then go from there.
The Edelbrock is so adjustable that you will be able to get it running just fine. The secondary venturis won’t open all the way so it will act like a 500 CFM carb anyway. There is a simple mathematical way to determine the largest carb you need for a given displacement, and that is what they are talking about. The carb you have came with a tuning chart for the jets and the needles and if it was rich, it would be very easy to go a couple of steps leaner and fix it. No worries.
Bill, why do you say, “The secondary venturis won’t open all the way”?
And the dual plane manifold is preferred for a regular street driver so you’re good there. It works in the lower RPM range where you’ll spend the majority of your time. Single plane manifolds really don’t start working until you get above 3K RPMs and sometimes even higher. They feel sluggish just putting around town.
Thanks to all of your for your responses. I feel better now. I will get it started and see how it runs and go from there. It is a stock 289 with 69k miles and really ran well with the 2-barrel. I just wanted a little more power and I liked the looks of the manifold and carb. Thanks again.
jbaughan
The secondaries on an Edelbrock have a weighted butterfly that only opens when sufficient airflow pulls it down. This is sort of Edelbrocks way of creating vacuum secondaries. It is also one reason why I think Edelbrocks have such a good reputation for being plug and play type carbs.
I have this exact carb on my truck. Great carb; easily tuned like stated above. Buy the tune kit, and follow the directions in the manual that came with the carb. Very, very easy. Won’t even have to take the carb off the motor to change the jets, rods, or springs… Only thing is, I learned this the hard way; if you use a spacer, use a 4 hole spacer for it. Some reason or another, the dual plane, spacers are junk with this carb manifold set-up?? Not sure why, but had hellatious time trying to tune my carb, just couldn’t get it right, then swapped out the dual plane for the 4-hole. Runs like a dream! Chirp the tires in third now… Performer series manifold…
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