[96 Black]

I am confused where you are getting gasket resurfacing for the cats? Cats are easy to pull out in the event you need to. I do not resurface the gasket spots for heads and manifolds. Razor blade and scrape scrape.

Bosch used to be OEM for GM at some point I am not sure.

Replacing the O2s is good but personally another thing I wouldn't do until I start getting codes for it. Just a waste of time, effort and money. You aren't really saving or preventing any major issue from occurring in the event of an O2 sensor failure so what is the point?

As an electrical sensor communicating with the pcm to control lean/rich feed, even a wonky O2 (the terms on this forum regarding this have been 'tired' and 'lazy') will keep the engine from operating at top efficiency. Worse, it holds potential of not just damage fro constantly running lean, but relative to this topic it can cause chronic 'rich' condition. Which shoves too much raw fuel into the cats. Which destroys them. On a 20yo SUV it took just 3 short codes setting in the course of 6 months (and quickly resetting off again) for a '#3 cyl. coil misfire' to be running poorly the balance of that time for that bank's cat to puke into and take out the intermediate cat, aaaaaamd choke up the muffler. I relate the O2s as a periodic scheduled maint. item just as any other elec. component. If not just plain replacing them after oh say every 25 years or so, then they can at least be constantly checked for correct voltage as they age.

[HA!] I see Caddylack just now posted as well.

 

[Ken Hennessy]

I have been out all day and I just saw the comments about the manifold to head exhaust studs. I have reused them continuously since I bought each car. (5). The bolts all got changed to grade 8. The one on the driver side can be changed to a bolt since it is not used as a stud. I’ll let you know when one fails.

 

[shakenfake]

Lol you guys act like it is just completely open injectors. Have you guys ever watched the trims on old O2s? They are still within spec. The only time I have ever had a cat fail was when I was missing on two cylinders and SERIOUSLY dumping fuel (Engine swap with used injectors that had been sitting in the engine for 2 years so my fault lol). You are throwing money without doing any diag. Check the fuel trims, if they are super rich THEN consider replacing O2 sensors. Otherwise don't do it. Skip the voltage check, just watch the trims.

@Caddylack That flange is silly to try and machine though. I wouldn't even bother with it. Also each cat is only like $150 I think. Nothing to scoff at but I wouldn't say a ton of money either.

Source: My truck has 24 year old O2s. Trust me, I understand. The Impala also has 27 year old O2s. As far as I know neither were replaced.

 

[1996 roadmaster]

Whoa, hold up...

I know from experience that o2 sensors are a BIG deal on these cars. I consider it one of the items that you should absolutely replace preventatively, and ONLY with Delco/GM.

It's just impossible to really fine-tune anything if the o2 sensors aren't reading correctly. The dyno tuners around here expect your o2s to be fresh out of the box when you hit the dyno.

Keep in mind that changing the o2 sensors periodically will ultimately save you from that horrible torch/breaker bar job that many of us have had to undertake.

I happen to catch up with an impala SS owner today and brought up these broken bolts to him. He claims from new original owner the rear bolts on both sides were never installed imagine that.

 

[shakenfake]

Also @Caddylack If your dyno tuners are dynoing/tuning with O2s and not a wideband they are doing it wrong. Well really that is your own fault. O2s will never match a wideband in tuning prowess. Especially on a boosted app.

 

[storm9c1]

I happen to catch up with an impala SS owner today and brought up these broken bolts to him. He claims from new original owner the rear bolts on both sides were never installed imagine that.

I believe that. However the more likely case is that they fell out. Used to happen on 9C1 cars all the time. Within the first 50 miles they'd back out. The TSB clearly states they bottomed out (or weren't torqued properly IMO). Forget the "VIN breakpoint" in that TSB. Those rear bolts were an issue on every '94-96 B/D car ever made.

I've lost a few myself over the years. Along with other people's cars I've worked on. Both falling out and breaking. I'd rather lose them than break. FWIW, the original bolts stretch too much, then add heat cycles, and they get brittle and break.

Most owners/customers report this as a valve tick at idle. Which is a similar sound. But first thing to check is the bolts.

Very common issue on the B/D LT1 cars. My advice, as soon as you get a car that's new to you, or are buying one, is to feel for those bolts in the back. If they are missing, knock money off purchase price because they could be broken. If they still exist, replace with off-the-shelf grade-8 1-1/2" bolts ASAP. You can also use 1" bolts in a pinch without the spacer. Or as others mentioned, studs+nuts. However studs can make removing and installing the manifold a little more tricky. For example, there isn't much clearance on the driver's side with the steering shaft in place. On the passenger side, you got hoses to contend with, but a little more forgiving.

Addressing a previously mentioned issue of cracking, I have at least one stock LT1 cast iron manifold hanging on my wall that's cracked right between the ports. It does happen. In fact, it happened more often on the '94-early '95 runs when the "bar" was present between the ports. This bar was cut/cast out of later manifolds including the aftermarket Dorman ones. This has been discussed before as well.

 

[Caddylack]

@Caddylack That flange is silly to try and machine though. I wouldn't even bother with it.

Okay, sure. I'm not the one doing it, I'm just telling you which surface he was talking about.

Also each cat is only like $150 I think. Nothing to scoff at but I wouldn't say a ton of money either.

Let's make a list of non-essential parts that you can take off of an Impala and sell. Cats are probably king as far as $.

At the very least it's something to consider when a person is budgeting for exhaust mods. Some of the cost can be offset.

Source: My truck has 24 year old O2s. Trust me, I understand. The Impala also has 27 year old O2s. As far as I know neither were replaced.

I don't understand your point here.

Also @Caddylack If your dyno tuners are dynoing/tuning with O2s and not a wideband they are doing it wrong.

Okay. Call up Speed, Inc. and tell them they are doing it wrong.

Well really that is your own fault.

???

 

[Caddylack]

I happen to catch up with an impala SS owner today and brought up these broken bolts to him. He claims from new original owner the rear bolts on both sides were never installed imagine that.

That is almost certainly not true.

He probably just doesn't know any better and doesn't want to think that anything on his car is rusty or broken.

 

[shakenfake]

I knew you were telling me what he was talking about. I was replying to him not you. Don’t get your feathers ruffled here. We good

You are correct, wasn’t disagreeing just stating. The first time I started selling cats I thought I’d be making a little more lol

Talking about old O2s being lazy. The point is that in my experience they normally are fine until one day they keel over and die.

I will. Narrowband tuning is awful. Wideband is where it is at and is truly the only way to tune.

General “you” in that statement

@Caddylack

 

[Caddylack]

The point is that in my experience they normally are fine until one day they keel over and die.

I think you are wrong on this. Hopefully somebody more knowledgeable can confirm.

 

[shakenfake]

It has been my experience that is how they work as well as the fact that if they were so lazy to where they were dumping fuel you would be seeing a rich condition and codes.
Just watch fuel trims every now and then, if they are way crazy then yeah go ahead and replace. Normally they are fine though.

 

[Buda572]

I switched my bolts to stainless steel and have gone through 3 winters and salt and they are still holding up

 

[1996 roadmaster]

The fancy option: https://www.summitracing.com/parts/ARP-400-1210
The budget option: Specialty Fasteners Header Bolts - Competition Products

Taken from: Current Aftermarket Exhaust Options for 91-96 GM B/D-Body

If you need the threaded studs, that is actually a common and universal part. Farm & Fleet has bins full of exhaust studs in the nuts & bolts section.

From the forum a list including what could be needed if you R&R

• QTY P/N: Description Notes
• 6 10220453 Manifold to Pipe Studs 3ea. per side
• 6 11516072 Manifold to Pipe Nuts 3ea. per side
• 2 88891747 Manifold to Pipe Gaskets 1ea per side
• 60988 Felpro P/N (1/2 cost of GM)
• 2 12552469 Manifold to Head Gaskets 1ea per side
• ? 10231254 Manifold Bolt Spacers typically need 2ea +
• 1ea for each broken bolt
• 1 14037662 Manifold to Head Stud (FWD/R/H) Option
• 1 10055726 EGR Pipe Gasket to Intake Manifold Option
• 10 1.5” X 3.8”-16, Grade 8 Bolts Local Supply OR
• 10 88891769 GM Grade 8 Bolts Stock or “Resto” Guys $

TSB 44-67-03 lists adhesive 12345493 (Permatex®High TemperatureThreadlocker RED)



OR

OR
Get threaded rod in your choice of grade and make your own.
(If there is a reason not to do this post a correction)

View attachment 209596

View attachment 209597

View attachment 209598



Some people may misinterpret this statement.

In 1994 there was a TSB 44-67-03 the block was tapped too short and the bolts would bottom out. If longer bolts are used the user should make sure there is a allowance (spacers or cut the bolt) so that the bolt used does not bottom out.

#8 or #5 Grade Bolts for Exhaust Manifold to Head?

I just replaced four of the right hand exhaust manifold bolts on my '94 Caprice 4.3 V-8 with new grade 8 bolts; I ended up re-using the first and third studs because they are very specialized (and expensive dealer only item (for '94 only)). [As detailed in my thread about O2 sensor readings in...

www.impalassforum.com

Do you know the length of GM 88891769 ?

 

[1996 roadmaster]

Do you know the length of GM 88891769 ?

1.5” ?

 

[1996 roadmaster]

1.5” ?

Supposedly still available

 

[95wagon]

Aftermarket Exhaust Manifold Bolt Source

I found a good source for extreme-strength (comparable to Grade 9) black oxide steel flanged hex head bolts for securing exhaust manifolds. They look a lot like the high strength GM bolts, they cost less than the GM bolts (see part numbers below) I was able to find, and they're made by ARP...

www.impalassforum.com

 

[1996 roadmaster]

Aftermarket Exhaust Manifold Bolt Source

I found a good source for extreme-strength (comparable to Grade 9) black oxide steel flanged hex head bolts for securing exhaust manifolds. They look a lot like the high strength GM bolts, they cost less than the GM bolts (see part numbers below) I was able to find, and they're made by ARP...

www.impalassforum.com

[/QUOTE/ Are they holding up OK?

 

[91ss]

Pretty sure they'll hold up at least 3 years like stainless bolts as mentioned

 

[SAH62]

Are they holding up OK?

No issues for me after 2+ years.

 

[Caddylack]

Just for reference I figured I would add the current Fel-Pro part numbers for OEM replacement studs:

More Information for FEL-PRO ES75103

More Information for FEL-PRO ES75102