Thread: carb set up

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As most of you know, I'm running a tri carb set up on my 315(bored 305 engine) and need some info. I'm running progressive linkeage and it works great but here's the problem. If I floor it all 3 carbs kick in which floods the engine and makes it hesitate. When crusing about 40 and I floor it there's no hesitation because the RPM'S are up. What I would like to do is keep one carburetor with no idle circuit and replace one set up like the middle one with idle circuit and make a linkeage that would open the two carbs at idle and one at half throttle. I feel this way I would be running a true 500 cfm( the 2 barrels are 250cfm each) and when I punch it I shouldn't have the lag I did before. Does this make sense ?

Denny You might be on to something there. I had a HEI and changed to a MSD because the last carb would't fit on the old HEI. The old dist. would always loosen up after a few runs and I would constantly retighten it. The new MSD does the same. I can crank the hold down so the distributor doesn't turn, but after a few runs my engine start pinging and I can turn the distributor by just pushing it with my finger. I don't know how to keep it locked down.

sounds like something isn't running smoothly #1.. and secondly, try and put some thread locker on that hold down bolt after you've tried a thicker gasket

Don't know what carbs your set up for 3 bolt or Rochester, but it sounds like 2 things are happening, your over-carbed at wide open throttle (WOT) and your end carbs are coming in to fast. If it was me, the first thing I would do is slow down the opening and limit the amount of opening of the secondary carbs. For what it's worth, this is the way I set up a Tri-Power.

This is a picture of my SBC tri-power linkage. I have run this set up on a 307, mild 327 and a 383 stoker (It's currently residing on a 350 LT1). Once I've got it to the point it will idle and run, I set the adjuster on the end of the top piece of linkage to start opening the end carbs at a certain speed so I can comfortably cruse on the center carb only. I usually use 80 MPH on a flat stretch of road as the tip in point (the interstate speed where I am is 75 MPH).

On the 307 and 327 I used the upper hole in the front carb linkage because it caused the end carbs to open slower and in that case the end carbs would not completely go to WOT. The total CFM at WOT with all 3 carbs is around 900+ CFM which was entirely to much for a small CID (which I think is the problem your having). It could be slowed/limited even more if I had moved the linkage higher on the front carb or lower on the center carb.

ON the 383, I used the lower hole which opened the end carbs faster and wider (but still short of WOT). I think you'll find that for your 305 the end carbs will not need to be open very far (with the center at WOT) for it to be effective anything else is just over-kill.

Mike and all others who have responded I thank you for your input. First of all I need to take care of mu distributor problem and then Mike I will follow your input which makes sense. Since I made my own progressive linkeage I'll have to do some more adjusting.

Thanks Richard. I'll give that a shot. Did you get my E-Mail I sent you yesterday? Bart