I have an 84 and im thinking about gutting the cat, im not sure if the 02 sensors and what not are there, havent been in that area yet, but they were there on my 92, and im just curious what type of problems that could present if i do gut the cat.
Also, whats the easiest way to go about doing it, just take it off and shove a screwdriver in there a few times?

 

You are gonna need something bigger than a screwdriver, probably a long punch or prybar, something along the lines of that. If you can just take the cat off the car you will be better off, I left mine on halfway (other side was welded on) and would fire the car up every so often and blow all the crap out. It takes a while but you want to get every last piece of it out before you hook it back up, you don't want that clogging your muffler.

dunno about the sensors, i had a holley carb on mine so i didn't keep any of the ecm stuff.

good luck

 

Thanks man, this isnt really for sound or anything like that, i think it may be clogged, so until i get the money for a new one, or a straight pipe, and have it welded on, i havent really decided what i want to do yet, im just going to do this, my gas milage is down the drain and im trying to find out what it could be

 

Its probably that 750 Holley killin it. What kinda mods are done to the motor? A stock 350 doesnt need a 750 except to support the arrabs.

 

you may have clogged the cat w/ all the fuel you are dumping in w/ that 750 DP. Unless you are making some serious power you don't need a 750, let alone the double pumper.

gut the cat and then look into getting a smaller Holley, maybe like 650 cfm w/ a secondary metering block and jets (I forget the model #). But I would be willing to guess that your carb is at least part of your gas mileage problem.

 

Thanks guys, the sb is still currently under progress, i can hkeep the 750 and just put it back on when its needed, and get the 650 until then, i had a shop called golens build the motor for me, it was bored honed and cleaned. Crankshaft was grinded, micropolished and cleaned also.. they convinced me that installing everything of the same brand was a good idea, so everything is speed pro, it has speed pro hi-rev lifters, speed pro pushrods, speed pro double roller timing set, and some other random things like a freeze plug kit, and hi-volume oil pump

 

Right on man. With having a shop build you a motor they usually like to use the least amount of different brand parts as possible to help track them down if something was to ever happen.

But yes,definately dump that DP for a 650 with mechanical secondaries. It should run better AND be better on gas!

 

Thanks, they are the ones that suggested the 750, it seemed like they know what they were doing but aparently not, it makes sence that to much gas would be as much of a problem as not enough gas could be

 

If a lot of that fuel is passing through unburnt to the hot cat, it may have combusted in there and burnt out your fillings anyway. Totally agree: go with a 650cfm.

 

did they do the whole engine including intake and carb? i have noticed that some manual transmission cars like the DP carbs better than autos do.

which leads to my next question.... what intake are you using?

sometimes a certain carb will work great w/ one intake and poorly w/ another. huge driveability differences w/ single and dual plane intakes.

you might also not be burning enough of the tremendous amounts of gas you are dumping in, could look into upgrading your ignition to something like the msd 6AL or equivalent

just some food for thought, i went through hell trying to get the correct setup for my carb/intake, didn't have jets for my secondarys so once they opened the air/fuel went off the charts.

i know this started off as a cat question, but sometimes need to look a little further up the line to see why it was clogged (aside from age) and i think we may have diagnosed at least some of your problem, hope at least part of this was helpful

 

what kind of heads are on it? that makes a big difference in carb selection.

 

I'd say the Holley has pretty much done in the converter. Note that there are two cat. beds inside the GM converters, one in front and one in the back so be sure and punch out both. They smash up pretty easy but the big chunks are hard to get out sometimes. Best to remove it if possible when you punch it out.

 

Yes, they pretty much did the whole engine and slapped me with a $2,700 bill after pretty much telling me what i wanted, i have all the info on paper what was put into it i can dig up if really necessary, i would have liked to build it myself but i am still lacking some knowlage to built a full motor from scratch at the moment, here is a picture, not sure if youll be able to figure anything out by it though.

 

oh yeah that reminds me, there is most likely going to be an air tube running across the center of the cat. it doesn't look like you have any emissions stuff hooked up so you won't have to worry about salvaging that. clear it out so you can see all the way through.

 

Thanks jayman, Ive only had this car for alittle over 2 years, and from what somebody said if its an 84 the cat is already long blown out and such, i looked under there yesterday and it looks like there is a brand new one on there, im hopeing its a straight pipe with the cat shell welded on or something, im never usualy that lucky though, im going to go take a closer longer when i get home from wrok later