Working to get my 77 series 2 XJ6 back on the road; I've got some simple engine questions.

If you do not have to pass emissions testing, Can I remove the smog pump and obviously plug the holes in the head?


Can I eliminate the cat?

Why does the fuel line run through an aircond fitting? I assume to cool the fuel. Is that really necessary?

Why did Jaguar mount the coil on the top of the engine? Again is this a heat issue. I want to move it.

 

Yup!


The engine will never miss the smog pump. It will enjoy the loss of the parasitic drag.


A cool place for the coil is good. O the intake is not all that bad.


Cars with no AC manage without the Ac fuel joining.


Carl

 

Smog pumps consume a grand total of about 1 HP from an engine, so there's little to gain by removing it.

Almost all engines have the coil mounted on top. GM and Ford made multi-millions of V8s like that, none of which have coil problems due to heat.

 

I remember when those cars were new we had a problem with the coils leaking oil. It turned out the coil they were using was not designed to lay sideways. Just another example of what we went thru when they were new cars.

 

its your car,do what you think is logical, and we do live in a free country!!

 

Deleting the smog pump setup is simple, just require 1/8npt plugs for the head, cleans up the area a lot.


Relocating the coil cannot be a bad thing, the reason its placed on the motor initially is for ease of packaging in the factory, so they can offer up a fully assembled motor package with the minimum of extra parts being added once its in the shell.
It would mean, you'd have to lengthen a few wires, and while you're doing that you can remove the resistor setup as its not really required (if its still fitted)


The return fuel line going through the A/C unit is to cool it down, great idea in theory, but as for how efficient it is, I wouldn't know, they thought it was required and spent the extra money to do it from factory, if you're in a hot environment or do a lot of stop start slow speed driving, I'd consider keeping it, but its main purpose is to stop fuel cavitation when it gets hot, usually caused by excess fuel returning constantly.

 

thanks all for the input.


the pump is now history and the area is much less cluttered. thanks for the tip on the plug size.


the coil will be moved to a more stable and cooler spot.


I didn't know carbureted cars had a return fuel line. this car has in-tank fuel pumps, staying cool in gasoline! all factory original.

 

My bad, thought it was a S3 for a second when I wrote that, on the EFI cars, the return line goes through the A/C setup to cool it before returning to the tank


I'd assume its the same principal in the sense that its just lowering the fuel temp before it reaches the carb, to stop vapour lock or fuel boiling in the floats

 

So I'm curious: does deleting the smog pump have any effect on emissions? Specifically, would a car still pass its bi-annual emissions test without the pump and all the piping? And, is there any other system or systems in the car that depend on the presence of, or some sort of output from, the smog pump?

It's very tempting to "clean up" the engine compartment a bit by removing all that stuff!

 

Only when the engine is cold.

After the engine is partially warmed up (157ºF coolant temp or something like that) the diverter valve redirects the pump output away from the exhaust ports and into the air filter housing.....where it can't effect emissions at all




Sure, unless...

1) Your test area has a "cold running" test ....very unlikely
2) Your test area includes a visual inspection to make sure all equipment is in place



I can't think of any. It's a stand-alone system.

Cheers
DD


PS--the above assumes a Series III XJ6 4.2 USA specification