carb backfiring

[PetesPonies]

To surface the base of the carb I glue a sheet of 200 grit to a good flat piece of plywood and carefully surface the base until it all shines the same usually the ears just need to be knocked down a bit.

OMG don't do that. Use the tabletop to a machine or a clean counter, even a piece of glass . . not wood.

 

[BLOODBANE]

Doesn't the 2150 use a power valve as well. it can get FUBAR'd when they backfire through themselves and cause havoc.

 

[kimcrwbr1]

Mine ran pretty good off manifold vac but I had problems getting it to idle slow my pedal would stick when the butterfly was closed too far I`m pretty sure it was a cable binding thing it works just fine with ported vac. I allways wondered if a holly carb would work on the 2.8. My guess when get it dialed in it wouldnt hurt to try some smaller jets if you find it drinking alot of fuel. I`m running #43s and getting between 16 and 18 mpg. 15 inch B-II wheels and 3.73 LS rear.

 

[kimcrwbr1]

If you have a auto choke make it turn off as soon as possible!

 

[cammeddrz]

I personally run all my vehicles, that have vacuum advance ,off of manifold vacuum. I want the advance at cruise, when my foot is out of it. It help MPGs greatly. YOu can tune for it. However, as I said before, don't want to confuse you when you are having hard enough time getting your engine to run correctly.

this statement had me curious, the entire point of vaccum advance is to improve driveability, and mileage. are you saying that you know more than the engineers who designed the system?

 

[PetesPonies]

You need to investigate more. Manifold vacuum is a way of running advance. I'm not a lone wolf here. But there are factory systems that use manifold vacuum. Ford even did it. If you are capable of following vacuum diagrams, you can find them yourself. But as I said, not trying to start a big deal here. You, since you are curious, look into manifold vacuum and what its benefits are. I know what they are, having been using it for a long time. And advancing the timing when at part throttle cruise is one way to gain MPG. It is also used with very radical camshafts . but I'm giving away too much here. remember, I used to teach all this stuff . . done teaching.

 

[PetesPonies]

I will give you one more thing to think about . . in reference to tuning your advance. What is important is total advance. Not how you got there, but the amount of it at any given situation. So if you have the advance you want, at the situation you want . . makes no difference how you got there.

 

[lmtpop]

ok, i rebuilt the carb according to the RS instructions, so is there anything in the rebuild that would cause the high idle? my plan this evening is to increase throttle idle screw while retarding timing to try to get below 1000 rpms then to adjust idle mixture screws to lean out the mis. currently the choke is disabled ( if that matters).

 

[PetesPonies]

A high idle is almost always a vacuum leak. This is assuming there are no mechanical problems with the linkage or butterflies.

 

[kimcrwbr1]

I fought with vacuum leaks for a bit with mine there is a port on the back of the egr spacer that points straight back at the firewall that is easy to miss. The top of the egr spacer where the carb mounts on the passenger side it is inset for the throttle position sensor plus the heat factor if you havent done so yet get the carb spacer felpro # 60529 it will seal the base of the carb and insulate between the carb and egr spacer.
http://www.ebay.com/itm/Fel-Pro-605...Parts_Accessories&hash=item2a11f7d0a4&vxp=mtr
they probably have one on the shelf at your local parts store.

 

[Brownie Mobile]

I've recently had timing woes and i almost gave up, but then it hit me my engine runs well when hot and at the proper timing, but it wont run cold and at the proper timing ( had to get out every morning turn the distributor just so i could get to school) I realized what needed to be done my high idle needed to be turned up it wasnt even touching the high idle speed cam. IDK if that helps but it sounds like something similar.

 

[lmtpop]

well it has improved somewhat. compared the bottom of the old TFI carb to the 2150 i am using and they are not the same and i was reusing the insulator block that originally came on the B2. Swapped that for the one for the 2150 had to use 2 due to the length of the studs on the intake. idle smoothed out but is still high around 1200 rpms will work on the fast idle came adjustment as it seems to idle down better once it is hot.

 

[lmtpop]

where do you hook up the electric choke to? power source?

 

[kimcrwbr1]

On your alternator is a terminal not being used. With the engine running you should get around 8 volts coming out and nothing when the engine is not running use that to power up the choke thermostat. You can also use the power to the ignition coil but try the alternator terminal first it is the white wire with a black stripe it terminates at the 8 wire connector by the coil.

 

[kimcrwbr1]

well it has improved somewhat. compared the bottom of the old TFI carb to the 2150 i am using and they are not the same and i was reusing the insulator block that originally came on the B2. Swapped that for the one for the 2150 had to use 2 due to the length of the studs on the intake. idle smoothed out but is still high around 1200 rpms will work on the fast idle came adjustment as it seems to idle down better once it is hot.

If your still having problems stop F`n around and get the proper spacer felpro # 60529. Make a gasket for between the spacer and the carb never I repeat never reuse any carb gasket you will allways have a vacuum leak. You probably bent the ears on the base of the carb, surface the base of the carb install the spacer and carb gasket then slowly snug the carb down, Using two of those phenolic spacers it will allways develop a leak down the road. Been there done that!