Need advice on 82 4x4 new exhaust system and part #'s

[regularJJ]

Ok so am finally resurrecting my 82 4x4 (was working out of state and it sat for 1 1/2 years). Need a lot of advice on the exhaust system because I cannot find many part #'s for this truck in autozone/oreilly/napas system.

 

First question (datzenmike?), are all the components in the exhaust system interchangeable between the 82 and 83-86? These part numbers do exist in the system, but it gives me mixed #'s for z20 and z24 so I suspect they aren't quite the same. Also, I will be either bypassing the cat or taking an old one and clearing it out. Ive replaced individual components before, but piecing together a random configuration is new to me and any advice would be greatly appreciated. One good thing is I work at an autozone hub and I can go back there with measurements and try to piece something together heh. Im going to go up there today or tomorrow and try to find the part #'s in the cross ref books but am not optimistic.

 

Has anybody experimented with resonators, cherry bombs or anything with the z22? I might also try to beef up the sound, Ive heard some of the minitruck 720's though and they sound like piece of shit Hondas, fuck that shit.

 

So far its been repainted/rust proofed, interior stripped bare and repainted black and resoundproofed with undercoating, triple layer of truck bed epoxy applied, very good trans/clutch sitting there ready to go in this weekend. Once the exhaust system is installed it will be my daily driver/work truck again and next will be a total rebuild of the 4x4 system from transfer case to cv's/hubs, so I will also need advice on rebuild kits as I cannot find any part #'s for this yet either heh. Pics coming soon.

 

And if anyone is still looking for parts, I am also finally stripping my 2wd 1982 720 KC and will have most of the parts available to sell and deliver if necessary. This includes 2 good z22 engines, all the 2wd-specific components (I don't need them), body parts, and pretty much most the truck. Update to come soon on the for sale forum with full list of parts.

 

-JJ

[Lockleaf]

Down pipes between z20 and z24 will be different lengths since the engine is about 3/4 taller for the z24. After that, you will need to differentiate between 2wd and 4wd, as well as long or short wheelbase. I know I can replace my entire exhaust system with Walker part numbers on my 85 4wd from O'Reilly.

[datzenmike]

Some may have a cat, some a resonator (or both?) and also the muffler. Automatics and Manuals might be different for their support bracket on the rear of the transmission. Emissions parts and additions was the biggest changes by year.

 

I think the 720 down pipes were 2" (at least the Z24 were) so no larger really needed. I think the 2" continued behind the cat to the muffler and then became smaller for the tail pipe. You can loose the cat by replacing with a straight piece of pipe or replace with a glass pack like a cherry bomb but you must run something after this to mellow the sound. (not DynoMax or Magnaflow ... get a turbo style that is NOT straight through and well packed and dampened, and run a tail pipe. I just run the cheapest largest pipe muffler I can find. Noise takes a lot out of you when driving. You can drive longer in a quiet car. 

[regularJJ]

Hm 3/4 inch higher, I may be able to make that work lol. Yeah for whatever reason 81-82 4x4 720 info has been lost in the recent cross ref manuals/parts store databases. When I started at autozone all the parts for my truck were in the system, but now its hard to find anything but common parts. Znet actually says the 4x4 is not equipped with cv axles, when 2 years ago there were still new+reman cvs in the system. I suggest yall get your parts figured out before the 83-86 720 info is lost as well heh.

 

I went through some cross ref books in the commercial office today and scored a very long list of 81-82 4wd part #'s I will post soon and hopefully help some people out. Unfortunately our exhaust system book had been updated to a 2012 copy that had no trucks older then ~1990.

 

Update: trans is in, everythings reconnected except the intermediate shaft found a bad ujoint and ran out of time to replace it. Hopefully all goes well when I test the trans/clutch tomorrow morning and I will begin piecing this exhaust shit together.

 

Datzenmike: Did some 720's actually come stock with resonators? Lol. I hear you on the noise, but Ive been riding in this truck since I was a baby and somehow enjoy riding in a z22-tin can. All the soundproofing and carpeting was stripped bare many years ago. Id like it louder/beefier but not trying to make it sound like a straightpipe. My mustang sounds pretty good with the shitty little v6 and 2 resonators heh

[datzenmike]

Resonators, no I don't think so. Some had cats all had mufflers otherwise

[that-son]

i got the cheapest ($30) turbo muffler installed on my truck.  now i'm looking to get a silencer for it.  between 1000 -1500 rpm the rumble is unbearable.

[regularJJ]

thatson, check your ujoints on the intermediate and rear propeller shafts for damage or wear, this truck tends to vibrate/rumble very loud under low RPMs when the driveshaft Ujoints or hanger bearing(2wd) go out. And Ive found the 720 will run fine pretty much indefinitely with bad ujoints or hanger bearing, it just gets louder lol. Also check your motor mounts/trans mount even one bad one would cause abnormal vibration.

 

Swapped a bad one on the intermediate last night, 2 caps were totally blown out and no needle bearings or grease to be found. A 16mm socket is the perfect size to hammer out 1-0027DL

[that-son]

thanks for the advice.  will do that anyways however the rumble is there even in neutral.  :(

[datzenmike]

i got the cheapest ($30) turbo muffler installed on my truck.  now i'm looking to get a silencer for it.  between 1000 -1500 rpm the rumble is unbearable.

 

To be truly silent a muffler will be so filled with baffles that it will be quite restrictive. If engines were all the same displacement and ran at the same RPM a muffler could be 'tuned' to cancel out the sound. There are too many variables for any muffler to effectively silence the exhaust sound but they can cover certain ranges and be less restrictive if you don't mind some sound/noise.

 

 

The turbo 'muffler' should not be see through. It should be packed with glass and somewhat baffled. They may also be heavy from dense sound absorbing materials used inside. They are lower restriction so will be louder than a real muffler but will reduce the noise to some extent. There will almost always be some RPM range where the tone resonates and is very annoying. Car makers may even encourage a certain RPM buzz so that it can be effectively 'tuned out' with a properly designed resonator.

 

The resonator is not a muffler but a device that dampens out specific frequencies of sound in the exhaust. The problem with off the shelf resonators is will it tune out your specific range of noise? You'll have to try one and see. Generally, resonators are straight through with a perforated inner pipe and glass packing between it and the outer shell. Though not a resonator a cherry bomb style straight through glass pack should work for this. I assume that the longest you can fit will cover the largest range of annoying sound.

[regularJJ]

Hm thanks for the advice mike that definitely helps. Always wondered what the difference was with the turbo mufflers. Am thinking I might build something with a turbo muffler and a resonator. Truck is fully put together and running now, just needs the exhaust will hopefully have time to get done next weekend.

 

My 2wd 720 rumbled when I first bought it, and at the time I didn't know anything about drivetrains and thought nothing of it. Eventually the low frequency noise got so bad it actually started to hurt the ears, then it started having trouble moving into first from a stop and I finally got under there to look.. turned out all the rubber in the hanger bearing was gone, so the two piece driveshaft was hanging crooked and unbalanced. When I pulled it out to repair it I found it was only sitting in the slip joint by maybe 1/4  " and all the u-joints were bad. Truck took the abuse and was fine though, I probably put at least 10k miles on it like that lol

[that-son]

thanks!  i'll check out resonators... didn't mean to hijack the read.  lol.

[regularJJ]

So I decided my best option would be to rebuild the original exhaust system. It was broken on both sides of the muffler and about 8" into the front pipe. After tearing it apart I also found it was leaking from the gasket on both sides the cat. The only thing I could use from the 2wd was the cat, which is in amazing condition compared to my old one that was almost entirely plugged up. a 1 7/8 connector piece fits over both sides the broken front pipe perfect, am going to weld that on this weekend. I ordered thrush glasspack 24100 to connect where i cut the muffler off and convieniently it fits perfect. I will probably toss the rear section and add some kind of muffler with baffles as I suspect the glasspack and pipe will not produce enough backpressure. I also have my doubts about it sounding good at all, lol. Everything was powered brushed and painted with flat black VHT manifold paint including the glasspack and cat heat shield. If all goes well it will be up and running by this weekend.

 

[regularJJ]

Bolted everything up last night. I was absolutely shocked, it sounds pretty great actually. Sounds deeper/beefier, I suppose it's about as deep as a 4 cylinder is going to get

 

Again thats thrush part# 24100 for the 1 3/4" glasspack if anyone is interested. I will play around with the sound more as theres still space for a muffler, but its really not that loud. I think its quieter then it was with the stock muffler, but Im sure thats because it was broken on both sides and leaked in at least 4 additional areas heh

 

It runs slightly better but not much. My dumbass forgot that almost 2 years ago when the transmission jammed I was about to swap out the fuse block thats rusted to shit and a couple ignition components which is why its running so awful. Apologies again lockleaf!

 

[Lockleaf]

No need for apologizing. Nice work on your exhaust. I need to completely rebuild the exhaust under my 720 as well. Half of it fell off a couple months back....