Running Rich

[stock93]

I have a 250L6 w/Rodchester 2se on it. Do these have a common problem that makes them run way rich? It has a clean air filter so thats not it. Timing is spot on and I just put new plugs in it. I'm going to pull if off, clean it out, and put a kit in it. Any ideas?

John

 

[diesel4me]

they suck.....

I've had 3 of those 250 "camel humper" sixes with the 2SE carbs--only one ran halfway decent--the other 2 had severe hesitation when accelerating and a "lumpy" feeling at part throttle,like it was surging--I rebilt both of them,new accelerator pumps,floats.etc--no improvement--the 2SE is just a complicated peice of junk in my opinion--
I ditched the one my 79 C10 had and made an adaptor to bolt a 4bbl edelbrock performer on it,and I disconnected the secondary barrels,so it ran only on the primary barrels--it ran 100 percent better and got better mileage to boot,but the motor lost the top of the #6 piston after 2 years(but I dont think the carb was to blame,I have seen several others sixes do the same thing--I think the lean mixture of the 2SE is whats to blame,and maybe blocking the EGR valve off didnt help)...

If your six has those pipes coming out of the valve cover and go to the exhaust manifold passages in the head,the "check valves" in them can leak and let soot and carbon into the air cleaner and carb--this screws up the fuel/air mixture and causes poor running--it also can let exhaust heat into the valve cover and burn the paint off,and carbonize the oil in the valve cover and the top of the head,where the rockers and valve springs are--this is another bad thing,it keeps everything from getting the correct flow of fresh oil to them,causing excessive wear...

I took all the pipes off mine and plugged the openings,but I dont have to get mine emission tested--your state might be different..It ran better with them plugged,but one hose that goes to the air cleaner is a breather and must not be plugged,or pressure will build up in the cranckcase..stuff a "bowtie" filter in it,like the one inside the air cleaner housing..I still didnt like the way mine performed,so I spent 2 days making a carb adapter and getting the throttle cable and detent cable to work again--..

Good luck with your 2SE carb,maybe the "check valves" will be the source of your problems,they make it look like its running rich due to all the soot from the exhaust going into the carb via the air cleaner...I liked the older 250's with a one barrel carb and a "Non Integreal" head--I think they were much better than the 2 barrel "camel humpers"---my 79 now has a 305 in it from an 86 van,and its like a whole new truck compared to the way it was with the 250 in it...

If your really stuck,I still have the 2SE carb,air cleaner and snorkel out in my shop--I kept it in case my carb adaption didnt pan out--and I have no use for it anymore,since the motor went to the scrapyard...

 

[stock93]

Thanks for the ideas and opinions. I dont have any lines running from the valve cover to the filter housing. I guess I'll find out more when I tear it apart. It does hesitate some and doesnt want to pull hard at interstate speeds. I think this is mainly due to having (original) 3.73 gears w/36s.

John

 

[diesel4me]

Overload!

Yeah,3.73's are good gears--for stock size tires--but even a V8 would be straining some with 36's!...

I had tried a lot of things to make the 2SE carb run better,the one thing I did that helped a lot on my 81 G10 van that had one was to disable the secondary barrel (the BIG one!) by disconnecting the vacuum pull off hose that operated the air valve on it,and plugging the hose,thereby making it a one barrel--it seemed to have more power than it did with both barrels working--my truck felt like it slowed down when the secondary barrel kicked in,it went better if I held back on the gas pedal rather than flooring it!---after I "unplugged" it it seemed more powerful,and didnt tend to "bog" under acceleration as much..

.The 2SE carb was a thorn in many a GM mechanics side,from what I learned asking older GM techs about them--they are a hard carb to adjust right,you need all kinds of angle gauges to set the linkages up right--I had mine done by a pro who knew them real good,and it still didnt impress me much--just a crappy design,its like a Q-jet someone sawed in half,a GM "mistake" --I wish they had put EFI on the straight sixes,and kept using them--I'm not a fan of V6 motors...

I still have that carb adapter too! It looked like an abortion,but it ran a lot better with the 4 bbl with the rear barrels disconnected--I think a small 2 barrel like the old 318 mopars used would have been plenty of CFM for a 250,the edelbrock I used was a 600 CFM,but it was a 300CFM after I disabled the secondaries!--and even that felt like a little too much....