Pre cats

Author
Discussion

assynt road

Original Poster:

361 posts

126 months

Friday 15th March
quotequote all
Just how hard is it to remove the pre cats with the manifolds off the car guys. Do you have to be Conan the barbarian with triple jointed forearms?

latham91

77 posts

42 months

Friday 15th March
quotequote all
Use long masonry drills and just keep drilling through then use, chisels, screwdriver, crow bar, preferably something bent and eventually after 30-40 mins you'll lever one of them out ... then start again on the other side...

Use a dust mask and do it outside since it is messy...

enjoy!

Dave85chim

133 posts

25 months

Friday 15th March
quotequote all
I did mine last weekend, certainly not the hardest job to do- I would say easy just time consuming. Hammer drill, prize bar, and hammer.

Get yourself a mask, gloves and enjoy!

assynt road

Original Poster:

361 posts

126 months

Friday 15th March
quotequote all
Thanks chaps, sounds like fun!

Dave85chim

133 posts

25 months

Friday 15th March
quotequote all
Do a bit, and come back after a coffee it gets a bit tedious.

Once removed- just get some small wire brushes and be sure to get any small bits still left inside.
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sparkythecat

6,752 posts

194 months

Friday 15th March
quotequote all
I've currently got the manifolds off the car and the precats look quite healthy, so Im trying to decide whether or not to remove them.
Clive Ford the manifold guru suggests that this is a worthwhile mod, but someone on another forum said their car had failed the mot on emissions after the precats were removed.
Does the fuel map need modifying to compensate if you take them out?

Dave85chim

133 posts

25 months

Friday 15th March
quotequote all
Have only heard the benefits of removing the precats myself, I would think as long as you have a spin round the block before to warm up couldntsee it failing as long as you have the main cat?

Dave85chim

133 posts

25 months

Friday 15th March
quotequote all
Have only heard the benefits of removing the precats myself, I would think as long as you have a spin round the block before to warm up couldntsee it failing as long as you have the main cat?

indigochim

730 posts

69 months

Friday 15th March
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sparkythecat said:
I've currently got the manifolds off the car and the precats look quite healthy, so Im trying to decide whether or not to remove them.
I didn't want to do anything none reversible so I bought a spare set of manifolds. From experience check that any you plan on re-fitting don't leak, fill them with water to see if any runs out from anywhere but specifically between the joints where 4 become one. Mine (spare replacements) did and unfortunately when I had them cut to weld up the welder didn't quite align them 100% subsequently my local TVR garage worked crazy hours (all through the night x 2) to get the car back together before last years Le Mans classic. They still leaked as they no longer mated properly to the elephants trunk so this year I bought my 3rd set I wish I'd splashed out on the clive-f ones in the first place it would have been cheaper.

sparkythecat said:
Does the fuel map need modifying to compensate if you take them out?
I'm very interested to know opinions on this too. how about for when all cats are removed.

latham91

77 posts

42 months

Friday 15th March
quotequote all
Took mine out a couple of years ago and has continued to pass MOT's - no changes to mapping etc... The precats are mainly for when the engine is cold so provided it is warmed up the main cat does the job.

Classic Chim

8,788 posts

88 months

Saturday 16th March
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There will be more under bonnet noise (drone) from removing pre cats which then gets worse if you go full de Catt so just be sure you can handle the extra noise.
If you do lots of long distance cruises as opposed to short blats it’s not necessarily the best thing to do but that’s about the only downside.
There will be less under bonnet heat too smile

blitzracing

5,587 posts

159 months

Saturday 16th March
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sparkythecat said:
Does the fuel map need modifying to compensate if you take them out?
Dont forget the lambda probes will correct any minor shifts if fuelling pattern anyway, so I would not worry about that.

SantaPod

52 posts

136 months

Tuesday 19th March
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+1 for checking they don't leak before refitting...... been there done that.....

mk1fan

9,411 posts

164 months

Tuesday 19th March
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Buy a spare set of manifolds. There's a few available at the moment. Check for leaks. Clean up the messy / poor welding - along the headers they seem to be very poorly cut tubes and welding in the ones I've seen. Enlarge headers assuming they are '400' manifolds. Knock out the pre-cats. Get them ceramic coated.

Main cat will heat up quicker.

Remaps can be beneficial - ask Mark Adams. Wouldn't bother unless everything else is tickty-boo in the management wiring / sensors which is unlikely given the age, quality of the factory installation and the basic system.