for those of you who have removed your air rails, (mish, ron, etc.) how did you seal the holes in the manifolds?

 

We used to take the intakes off the car & thread the holes from the underside & install 1/4- 20 counter sunk allen bolts. This way you dont see anything & they can never back out.

 

I just tapped the holes and put in allen screws. Worked great!

 

i hope you took them off first. lol.

 

lol...yeah, I did!

 

did you end up needing new gaskets?

 

I had switched over the intakes from the original motor onto the replacement motor, so I put in all new gaskets anyway. I tapped and drilled the intakes before putting them on.

 

Yep, drilled, tapped and plugged. Gutted air pump and kept it as A/C pulley.

 

im just happened upon this thread....

is the air rail near the fuel rail and going across the rear of the valley and the air pump just an emissions thing??

what is this mod?

sorry dont have time to look into it about to leave for work just hoping for some info when i get back.

never really thought about it but always wondered wtf the "air pump" is for.

 

Yes









Removing the air injection pump and associated plumbing either to de-clutter the engine bay or to avoid repairing a broken system.

Besides clogged air tubes, burned through check valves, and broken connector hoses you often have noisey or seized air injection pumps.

Many guys dump the system if doing so doesn;t run afoul of local emission inspections.

Some dump the system in search for more power...a fool's errand, IMHO. A properly functioning system draws maybe 2 horsepower due to the belt driven pump.



It injects fresh air into the exhaust ports on a cold engine.

The pump runs at all times but at the specified temp a diverter valve opens and simply vents the pump output

Cheers
DD

 

it all adds up eventually.

 

so is the extra 20hp on the european ones just from the cats and not related to the smog equipment?

 

technically speaking the UK jags dont have an extra 20hp, rather the american ones are 20hp less potent.
smog/cats/EGR/ and the tune all play a roll in making the US spec jags less awesome.


once again, technically speaking, the UK jags are already ahead since europe has much better quality gasoline.

 

Yeah, a combination of various things....

The pre-Marelli, non-cat Euro/uk versions had 12.5 compression versus 11.5 compression. No doubt THAT comes into play, as does timing curves, etc

The cat converters themselves don't cost too much power ....providing they aren't clogged :-)

I what way is European gasoleine higher quality?

Cheers
DD

 

IIRC they run much higher octane and no ethanol.

not to mention, to achieve an 87 octane rating with 10-15% ethanol mixture (since ethanol is an octane booster) means starting out with ~80 octane pure gasoline.

 

Damn,, now in feeling left out on this thread,JEEZ.

my 1978 Euro/UK XJS , came without any CATS,, or air pumps and rails, and my manifolds and heads dont even have any holes to plug up.

now thats discrimination!!! heha

 

i tapped mine and used allen key bolts with orings like the orignal one was mounted in with, hasnt caused me any problems

 

say what you will but honestly there is no way that this




doesn't restrict power

 

no kidding. i dont bother arguing anymore, because people who say that a cat doesnt restrict power, have never removed their cats.

i had a highflow flowmaster installed in my L67 swap car right before the swap to try and pick up some power. i tracked it and i was running 16's! i had only picked up a little over a second in the quarter from my old NA engine.


i did everything i could think of, higher lift rockers, ported and polished blower casing, ehaust work, etc. and nothing helped. i was desperate for more power and busted the catalyst out of the cat.

13.84!!!!!!!!
i picked up over 2 seconds by removing the catalyst, and that was on a car with computerized Knock Retard. on a car with no KR, it will simply predetonate and lose even MORE power.

 

I gutted that cats on two of my Jags and felt virtually no improvement. I'm not even sure if the little I felt was imaginary to justify all the trouble! <shrug>

Cheers
DD