Okay, this is for my 79' F150 4x4 w/ a rebuilt 400 and C6 trans. The engine has about 11,000 miles on it now. Basically a stock rebuild, but I bumped up the cam a little and am running dual exhaust w/ stock manifolds. The intake is the Edelbrock Performer. Ignition is all stock, and timing (double roller chain) is set to about 9 degrees advanced. I have the vacuum advance running to the front of the carb on the passenger side - driver's side carb port is plugged. I am running 15x10 rims and 15x12.5x33 radials. It runs really good once warmed up, and driving around town. Here are my (2) nagging issues: 1) If you don't let the truck warm up for several minutes, or if you try to take off normally for the first few miles, it will spit through the carb. Not really a backfire, but more of a hesitation and Pfffft noise. It's fine after you initially get this first one out of the way and the truck's warmed up. The other thing it has started doing recently, is hesitating/cutting out and making the same noise if you are cruising at a sustained speed (40, 50, 60 mph - doesn't matter). Not always, but have been seeing this since I bought the truck back about 2 months ago. Anyway, these are little nagging problems that just irk me. I have tried 3 different distributors, and this is the second Edelbrock carb I have put on this truck. Just surious what I should be looking for. I have used these carbs before on Windsors and Clevelands in cars, and have had no issues with them. So, I'm stumped where to start fiddling.

 

Plug the vacuum advance reset timing with it plugged and try driving it.

 

I always do plug the vacuum advance to adjust / set the timing. It is set that way now on 9 degrees advanced timing. So for clarification, are you telling me how to set the timing for instructional purposes, or are you telling me to set it and drive it with the vacuum advance plugged and carb port plugged, after verifying timing is at 9 degrees? If so, would this be to determine if the vacuum advance itself is working? Because, I have already raced the accelerator with the timing light on the mark, and it does "curve out" and move under acceleration.

Not meaning to be a smart a**, but just want to be sure I understand what you're suggesting. And, I do appreciate the reply.

 

Try setting the choke a little richer. That "spit" is common with a lean condition. Use a thermostatic switch and plumb the vacuum advance properly also. Use full vacuum when cold and overheated. Use ported vac when warmed up to operating temp.

 

Thanks for the tip, and you may be well on to something. If you can believe it, there has been a 50+ degree temperature change in the last week and a half. We had daytime highs in the 90's, then it cooled down drastically and was in the upper 30's a couple nights, now today and tomorrow back into the lower 90's. The choke was set for a cooler temperature and I realize they are a little tempermental on these. Is this common though to run these a little on the rich side? I have set it before to where it just starts to close the butterfly, then back it off a notch (or whatever the manual recommends - not right here in front of me). It has always spit when first driven though, no matter what temp it is, no matter how long it warms up, etc. unless I take off really moderately. This is the second Edelbrock 1406 carb though for this engine, same issue. Kind of odd. They've always been sweet on other engines I had.......

 

Probably not the carb's fault. They are easy to set up if you follow the directions and tune them properly. Out of the box they are set just to "run". I like manual chokes because I can tweak them according to the weather. An automatic is just a stab at trying to find an average that will work well enuf. EFI systems that measure engine temp and air temp are much better.

 

Just sugesting driving around with out the vacuum advance hooked up to see if some of the popping or all of it goes away. I run my timing initial 20 degrees distrbutor at 8 for a total of 36 degrees. No vacuum advance at this time. The timing indicator marks on my plugs look good might need just a bit less total maybe 34.

 

I have heard that Edelbrock #1406's are setup a little lean from the factory for economy. You might want to try one stage richer on the Metering Rods.
Check the Edelbrock website or your manual for the part # for those Metering Rods. The Metering Rods are easily changed.

 

I appreciate all the replies guys. The weather is changing again tonight (cold front) and I believe it will finally be stabilizing for fall. I'll get on it this weekend. Good to have a solid base on the temps at least.

 

Make sure that you do not have any vacuum leaks that lean it out.