I finally got all my pipes, mufflers, another Cat, and headers for my '81 F150 I-6 (it's a California model). Now I just noticed the EGR valve has a big metel pipe connecting to the exhaust manifold. I want to order the Offenhauser intake but that will be in a few paydays from now. What problems will not having an EGR valve cause. How do you normally install the headers? Just plug the EGR? or remove it?

Thanks,
CR

 

No EGR, more than likely means not passing emissions. You'll probably have to have a small hole drilled in the #6 tube and a bung welded to the header so you can hook a line up to the EGR.

 

I think I'll be Ok with the emissions laws. I live in Texas and the truck will be exempt next year or I can get another waiver. But I am still looking into it to make sure.

 

Lets not forget the EGR valve effectively lowers tempeture at which combustion occurs. I have an CEL genereated from "insufficient EGR flow" right now on my Ranger. You want to talk about a cruddy ride. I will fix mine Sunday. If this ride is going to be a street ride, I don't see how you can do it with out the EGR. I would definitely suggest you weld a place into those headers.

 

When guys install the offy intake manifolds I think they leave off the EGR. There is no way to hook it up unless they have the stock manifold. Is this correct? The EGR is only there for emissions.

 

With a carb you can easily tune around the EGR system being gone. It is there to decrease emmissions and increase mileage. If you don't recalibrate the carb after disabling the EGR system it will probably run lean and knock at part throttle. You will have to rejet for the headers anyway, so it's really no big deal. My truck runs fine with no EGR and it's EFI. I'm sure I'm losing a little mileage, but that's no big deal. I am in the process of fabricating a new EGR tube to work with the headers so I can get some mileage back, but I've gone 5 years without it.

saintthomas,

You are having issues with yours because it is OBDII. Code P0401 is usually not set by a problem with the EGR system; it is usually rotten hoses going to the DPFE sensor which measures EGR flow. When the hoses leak the DPFE falsely measures no flow, so the PCM commands more flow until the EGR vavle is wide open. Engines run like crap with the valve wide open. Rarely is more than 50-60% flow ever commanded by the PCM in normal operation. The earlier truck used an EGR vavle position sensor that just made sure the valve was opening and did not measure flow. Since the DPFE actually measures flow it is not easily fooled.

 

Thanks Silver Streak. If I get the intake now and recommended Holley 390 CFM and install all at the same time, will I still need to re-jet the carb? Is this something a noice can do?

 

Basic jet, powervalve, and secondary spring changes can be done by a novice, but advanced tuning practices are best left to an experienced tuner. There are tons of books available on carb tuning that will show you the basics. As usual, experience is the best teacher, but a good book will get you started.

Part of any performance upgrade should be a trip to the dyno to make sure everything is working properly. Lots of people I have worked with on engines have initially balked at spending the money on dyno time, but it is probably the best money you can spend to improve performance. I got some good ammunition for this argument at a dyno day I did for the Tulsa Lightning Club last fall. One of our members brought his 69 Cougar with a 351 Windsor to tune. It seemed to run great on the street and he had no complaints with its performance. Initially on the dyno it made 280 or so hp, but on the graph you could see that it quit pulling about 3500 rpm. He spent about $150 on dyno time and he left with nearly 320 hp after we worked on the carb and ignition curve. You won't find a better deal than 40hp for $150. We could have found more, but he was having a fuel supply problem and we didn't have all the tuning stuff we really needed. I think his charts are posted at commercial link removed.

I guess the point is that you should at least check things after any major change, and adjust as necessary. If you do all your mods at one time you only need to tune it once.

 

Just as a side note, the major catalog suppliers sell a spacer with the EGR hook up so that you won't have to get creative on the intake side. As for header, I would aslo weld up another bung or two and get a fuel/air mixture meter hooked in. That should help keep the emmisions "in sight" and keep the mpg's up.