Gary M.

Searched forums and found a lot of helpful info regarding testing the cats with an infrared thermometer. Does this same procedure and method apply to the pre-cats as well? Thank you in advance and I apologize if this has been covered already but I can't find the info if it has. (97 F150)

Jbrew

No pre-cats on these trucks, pretty sure that's a Toyota thing. Anyway yea, Infrared works. Keep in mind the drivers will read higher than the pass side due to the wrinkle/crush bend at the first 90 before the crossover. The pipe reduces size a full 1/4" thru the 90.

You could always vac test for restriction or run it up to the shop for a flow test.

Gary M.

Nice. Thank you for the quick reply. I'll let you know what I found out. And maybe pre-cat is the wrong term. What are the circled items if they're not pre-cats? Thank you again.

Jbrew

Yea, these trucks incorporate 4 100% converters. They are all cat. Infact, the upstream you have circled is actually more restrictive than the downstreams. Which is why you can run just the upstreams convertors, totally delete /axe the downstreams cats and still remain within factory programed efficiency parameter margins.

When folks were converting to long tube headers on these trucks, they got a little bonouse turning their old cats in for salvage. Some were getting 200 plus for their old cats. I received 160 for mine at the time. All four are loaded with precious metals, they don't make like that anymore.

white89gt

Ford did pre-cats too. My Mustang had them from the factory. So did the Mark VII, Thunderbirds, Lincolns, Crown Vics....

In the early days of buying H-Pipes with "high flow" cats, they were advertised as being 3 way cats because of that very reason.

But yeah, I don't believe those are even made/used anymore.

Jbrew

Huh, didn't here of that. Yea,the truck lines didn't have them from 97. However, in 2005 they went with 3 way converters for a time (no pre cat). Just one converter per side.

white89gt

I know it was used on the Mustang until at least 1995.... and in 1996, the H-Pipe actually had SIX damn converters on it. Because California, they are still being made today. Not too sure if this has a Pre-cat or not.... I'm mostly familiar with the 5.0's as you know.

Jbrew

Crap! That's a lot of shiii filters. I bet it blows smoke rings at idle

white89gt

Yes it is a lot of filters, LOL. Glad Ford got it down to two cats now.....

Jbrew

They got it down to one for awhile, one 3 way cat per side. It went for one or two years , started in 05.