All,
Just finalized the tuning on a Holley List 3795-1 for Steve Jonas a member on this forum. I have done about 6 of these specific carbs lifetime and 100’s of others. 1968 was an early year in the emissions battle. Holley must have worked with Ford to produce this specific version that also includes the List 3796. These carbs are specific to the Ford 390 Cougar and Mustang models. The 3796 being for the auto trans and the 3795 the manual trans.
I am supplying a link to the California Special Website for information on these carbs. Specifically 2 of them that I have ran into has a second set of idle mixture screws in the front of the throttle plate assembly. The link shows clear pictures. In both cases these mixture screws were almost bottomed on the driver side and totally bottomed on the passenger side. The carbs exhibited flat spots off idle and poor idling characteristics. I perform the Ford TSB modifications 1283 enlarge the secondary idle discharge ports form .022 to .028, but it did not sole the problem. I have performed this modification on carbs without these secondary idle mixture screws with great success.
Wonder how many of you are driving early 1968 390 Cougars that idle poorly and have a large flat spot off idle? This maybe the cause. first thing to look for would be the holes that these screws are in. They are pretty easy to see once you know where they are. Scroll down to todays post on the link below.
Rob
http://californiaspecial.com/forums/showthread.php?p=116009#post116009
Robert you are right this is a common problem. There is also a 3794 for a 67 390GT auto thats california emissions issued.
Robert that just blows me away. I have never seen those screws. Now I have to go check
I would not call this common. I see you have a 67 390 Cougar. Does it have these screws in the throttle plate? xr7g428 has two 390 cars of this era. wonder what he will find.
Rob
xr7g428,
Very curious as to what you find out? This helps me in my rebuilding and tuning hobby.
Rob
Both 390 cars appear have the wrong carb on them. I will see if I have any of the correct carbs on the shelf.
Here are some pics I took of mine when I got it back from rebuild and just before I had it installed on my S code XR7-G.
It looks like it has this adjustment screw.
It apperars the base on my 3794 has the boss"s for the idle screws but there not drilled. I never have noticed them before even after 16 years.
Phillip,
How does it run?
Rob
I am with you. These were unnoticed by me until the one carb that I got that ran like doo doo. One side was completed shut off and the other side nearly shut off. Got those little dudes out and opened them up a bit and everything perked up and ran great.
I have another throttle plate that looks just like yours. The area is cast in, but not dilled out. I believe it is from a 735 Holley as it has huge holes for the idle circuit. But I cannot confirm.
Rob
Was checking a couple of our core Holleys at the shop. Could see holes, but not see the idle screw heads. I could see and feel the points protruding inside.
It has been on the car a couple of years now and it runs and idles fine. At least that’s the way it seems to me - could be that someone with the skills could improve it some but it’s all good as far as I’m concerned (“knocks on wood”)…
The ability to feel them protruding is a sure sign from what I have experienced that the screws are all the way bottomed. The two I experienced were further in on the passenger side and the normal passenger side air mixture screw did nothing.
I would warn anyone who purchases these carbs that they may have to “adjust” these screws out to get the car to run correctly. And adjust means removing and it is no picnic! The one on Sheryl’s (GT/CS website) car ran very bad until this was done. Also they may need to secondary discharge passages enlarged from .022 to .028.
Rob
