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Have a bone stock Blue 1986 Iroc with a 305 or LB9. The drivers side tail pipe is hanging on with a coat hanger and the muffler needs replacing. Pretty sure it has original headers, catalytic converter, and possibly the muffler. I want to replace the catalytic converter all the way back so I figure lets do the headers at the same time. I want to put in a system that opens up the 305 but can handle 400+ hp down the road if I replace it.
With the price difference between them being ~$100, its negligible there. I will have to pay a shop to do all of the installations so it would be the same on install I'm guessing.
- What is the AIR and do I need it/can I use it?
- Which would better and cause less headache to fit in a stock setup?
- I've read I would need 90* spark plug wires, is that true for both?
- Would this whole system marry together easily?
- Would one of the headers work better than the other with a Magnaflow?
- Read about getting copper gaskets for the headers. Would this be a good idea and is there anything I haven't considered?
I would appreciate any thoughts on this as I'm not mechanically inclined. Thanks!
Here we are 18 months after I asked the question. Did some research and bought some merchandise. Ordered the 2044-HKR1 kit with the Magnaflow catalytic converter and cat back.
My mechanic has already installed the driver side header and it looks pretty. Had the stock A/C bracket shaved to save a bit from buying an aftermarket bracket.
Unfortunately I've run into the fun issue of the AIR tube on the passenger side header facing away from the firewall which is incorrect for a stock '86 TPI setup. Unlike most folks on here I'm planning on keeping all the smog equipment in the car as there is a possibility I may move to Cali in the future. I'm going to be talking to the product manager at Holley tomorrow. I'm hoping they will be able to get me a correctly fabricated header considering it is sold as a "direct fit" part. Attached a comparison between the 2055 (left) and stock manifold (right).
So put a cap on the tube the stock manifold connects to. By "T into the line further forward", do you mean re-route the tube that would go to the one I capped to the forward facing one? I'm trying to follow but my visual aid is in the mechanic's garage. Do you happen to have a picture of that?
I ran into the same issue. I put a short 90 degree coolant hose off the check valve pointing up along with a 90 degree coolant elbow pointing rearward and another 90 degree coolant hose back to the tee. Yes, this forms a 180 degree line (actually, 270 deg). All parts were 5/8 in. Doesn't look too bad as it all sits low and can barely be seen anyway.
That sounds like a good idea except the tube coming off the header closest to the firewall actually hits the firewall if you try to mount it in. Mechanic just let me know this so I'm still stuck.
Dropped off a beautiful set of headers with the mechanic. Dyno Don made them for me last month. Due to my situation I can give everyone on here a glimpse of Don's headers side-by-side with the Hooker 2055's.
Up top is the 2055 Header and down low is Dyno Don's header. These are both silver ceramic coated with air tubes. Here are a few comparison notes.
The most obvious difference is the air tube design. Don's much closer resemble the ones on the stock manifolds so they should fit in a bit easier. Also the threads are facing rearward which is required for my 1986 TPI. After being on the phone with Holley several times, they just don't make it like that.
Next up is the flange against the block. The 2055 is larger than Don's so a bit more weight. However, the header gasket will be covered completely on the 2055.
The piping routing itself is also a bit different as well. The 2055 has straight pipe until the collector bend which could cause clearance issues. Also the second to left pipe routes to the inside on the collector on the 2055. On Don's header this pipe routes to the outside. Not sure if that affects performance but the latter offers a cleaner look IMO.
One thing that isn't visible (that I forgot to take a picture of) is the collector opening to the rest of the exhaust. The opening on Don's header is visually larger than that of the 2055. With exhaust flow being the key performer of a header, that's a big factor.
Here are some closer pictures.
Hopefully this will help answer some future questions. Both are great headers so you can't go wrong with either. Just measure twice before ordering.
Last edited by Chris Knight; 02-06-2018 at 10:17 AM.
I'll see if I can get my mechanic to take some measurements on the openings of both types. Not sure if Don's are on the car yet. Turns out the collectors want to occupy the same space as the starter. The mini-starter we ordered for the car was supposed to come in yesterday or today. I'm not too upset about the $130 for it as the car still had the OE starter after 32 years!
The Iroc is back together and I've been driving it for about a month now. Due to how my engine sits in the bay, I ended up going with the Hooker 2055 headers & Y-pipe. They gave my 305 better clearance in my case. Ended up having a muffler shop cut the air tubes off just above the header on the passenger side and spin the tubing 180 degrees and weld it back to the header.
I now have a set of Dyno Don's headers that are now available if anyone is looking for some, just let me know.
I kept the stock exhaust so it's probably there (a wee bit rusty though haha). Do you have a picture of what you're looking for by chance? If not I can take a picture of mine and you can let me know if it's there.
I know that the passenger side exhaust has an extension section betwen the manifold and Y pipe, but what was the factory idea with this rare connection? Anyone knows?
That extension piece on the passenger side exhaust takes the place of the EFE valve used on carbureted cars. allowed the same manifold and y-pipes to be used on both FI and carb motors.
The EFE closed to route exhaust gas through passages in the intake manifold to warm it up for cold starts.
Can I ask how much of an improvement have you experienced both in sound and performance? does it give a richer V8 burble?? and I know the seat of the pants thing is subjective, but does it feel a bit more lively? I ask with interest as I have an LB9 completely stock exhaust. Headers are here ready and my Dougs D901 Y pipe is on its way... I'll be marrying this up to the stock 2.75 inch I pipe and a high flow muffler.....until I can afford a stainless catback.
Can I ask how much of an improvement have you experienced both in sound and performance?
You just did!
Originally Posted by 91ragtopTA
Headers are here ready and my Dougs D901 Y pipe is on its way... I'll be marrying this up to the stock 2.75 inch I pipe and a high flow muffler.....until I can afford a stainless catback.
For reference, the setup is 2055 Hooker headers & wye pipe (silver ceramic), 3" Magnaflow hi-flow Cat, 3" Magnaflow stainless Cat-back (with the muffler). I ordered these parts in the summer of 2017 and had them installed roughly 18 months later. While I can understand wanting to put each part on immediately, my first Iroc taught me the value of patience. I implore you to purchase the full setup before putting it on. Once the all of the parts are put on, you never have to think about "when am I going to get that done now?" and can move on to other glorious modifications such as a throttle body air foil ($20, why not?).
Originally Posted by 91ragtopTA
does it give a richer V8 burble??
One reason I went with Magnaflow cat-back was the sound. In the videos I viewed with different exhausts on F-bodies, Magnaflow just sounded better to me. Mind the type of headers and cat (or no cat) would change the sound too. At idle in close quarters it sounds good and rumbly, in neighborhoods on lower rpms I don't feel bad driving at 6 am, and at 2,000 rpm and above it sounds good. Driving around 70-75 mph put my Iroc at ~2,700 rpm and it a great tone--loud enough it drowns out some road noise while the stereo isn't too stressed. So to this part of your question I say yes! In general it is louder and the engine doesn't sound like a stock 305.
Originally Posted by 91ragtopTA
I know the seat of the pants thing is subjective, but does it feel a bit more lively?
As for performance, the jury is still out officially due to Code 36 & 44. Code 44 is lean exhaust so the car doesn't run at peak performance currently. I haven't experienced wheel spin but also haven't tried to. When driving there's a slight hesitation/delay with the throttle but still picks up and goes out of lights and on ramps. With that being said, I've driven it once with the codes off and it does feel more like the 350 I had in my previous white Iroc. I had them both at the beginning of 2016 and could tell the difference.
Need to point out how subjective the performance is. Different parts married together will give you different results. Opening the exhaust up will improve performance, but nothing like swapping to a 383 or T56 to give you a better pull. Part of why I did the exhaust first was to experience the stock setup more efficiently. If either the original 305 or 700R4 go out on me (~104,500 miles currently), I plan to drop in the aforementioned ones in their place.
Interesting fact: The average 4 cyclinder engine in new cars now outputs ~180-190 hp. That's the same rating the 305 has for the 1986 model year
Thanks for the informative response, particularly about the various sounds and tones at different driving situations. My headers are the chinese stainless steel ones, same sort of mid length as yours I scored them locally unused thinking mainly that I'd save a bit of weight, they'd look better and to free up some of the V8 tones, sounds quite nice stock too. I'm already cat free as the car passes emissions testing here without.
Another incentive for going this route is I'll end up with a full stainless system from head to tip. Any noticeable performance gains would be a nice little bonus.
You can't go wrong scoring a local set. Saves on shipping and you get to see them in person which is always a plus. Not having that cat in place will give you more gains over my setup.
I'll just enjoy the fact it will be legal in Cali and avoid the possibility of a future headache. IMO, the whole point is to enjoy driving the car. I can hammer it up the on ramp, wind through all the gears, and arrive at the posted speed limit without being sideways. And do it over...and over...
As for performance, the jury is still out officially due to Code 36 & 44. Code 44 is lean exhaust so the car doesn't run at peak performance currently. I haven't experienced wheel spin but also haven't tried to.
I had some similar issues with running lean after I first put headers on. I'm not sure about your headers, but mine moved the O2 sensor down to the collector. If you remember, on your stock manifold, the O2 sensor was much closer to the heads. With headers, the higher flow and distance from the heads makes it harder for the O2 sensor to get hot and stay up to the correct temperature. I switched to a heated O2 sensor and haven't had the lean issue since. It is super easy to switch to a heated sensor. All you need is the heated sensor and the wire kit to convert it. I found mine on ebay. The sensor p/n from AC Delco is AFS-74 IIRC.
Thank you for mentioning this blacksunshine'91, I'd have been at the mercy of a mechanic for this one. Didn't realize the location of the O2 sensor would do that since it's a closed pipe system. I figured it had something to do with the flow rate but never thought about the temperature. Certainly an easy oversight on my end and appears I'm not the only one to have run into it. I'm not great at the hands on wrenching (shame on me) but something small sounds do-able.
The current O2 sensor hasn't been in place but for a few hundred miles, hopefully it won't require heating to come out. I had a chance to read a few posts on heated O2 sensors now. Several folks suggested hooking the power wire of the adapter (pink w. black line) to the fuel pump power wire. This makes sense as it comes straight from the battery through a relay that could handle the power. I think any ignition on power source would be a viable candidate. Saw comments where a pair of these ran through a 10 amp fuse on cars, but they could run fuse or unfused.
Unfortunately, a previous owner bypassed the fuel pump relay on my vehicle. There's a wire coming straight off the battery and jammed into one of the spots on the plug that would go into that relay. I haven't removed the tape to see which one as it works currently and I don't want to upset the magic. I do suspect that may be related to the Code 36 I'm getting though (check my post here: https://www.thirdgen.org/forums/elec...ll-relays.html). I think I will instead run it into the cabin and utilize a 10 amp fuse.
Yes, that is the adapter and sensor. Aside from the issue of the hacked up wiring from the previous owner, there isn't any "wrenching" involved. Its literally plug and play. I used a ground already in place on the firewall, tapped into the fuel pump hot wire, and that was it. Even using a mechanic, it shouldn't cost too much. Hope that helps fix your issue.
Heated O2 Sensor: This appeared to fix the lean exhaust code I was getting, thank you for the recomendation blacksunshine'91. It seems that the SES light will blip on for a a few seconds every once and a while with the code but that's pretty much it. More like a "remember me?" reminder at this point .
Code 36: Tracked this down finally. Turns out there is a in line 20 amp fuse that had blown and the previous owner didn't know it existed either. Hot wire comes off the positive battery terminal and went to this inline fuse between the battery and passenger wheel well. The wire from this fuse then went to the MAF, MAF burnoff, and Fuel Pump relays. Also turns out the picture I found online mislabeled my relays, and the hot wire the PO installed was jammed into the MAF burnoff relay (not the Fuel Pump relay), hence the Code 36. Replaced the inline fuse, put the plug back in the burnoff relay, and no more code! Only took four years to figure that out...
Performance: Now that I've been able to drive without codes, I can give my opinion. Under normal around town driving, the engine just sounds deeper and more powerful. At highway speeds it's louder with a desirable sound. *Still* haven't experienced wheel spin with brand new BFGoodrich tires. It does puller harder now out of a light from 3,000 - 3,500 rpm it sounds fantastic . It does feel more like the 350 I had in my previous white Iroc.
I had a code 36 after I fixed my wiring I fixed my exhaust went back to factory manifolds and a magnaflow mandrel bent y-pipe. A 3 inch cat delete with 3 inch cat back magnaflow. Still a code 36 and after months of searching and a custom burn with burn off request turned off I found the damn issue my pcv valves kept popping up and pulling in fresh air when the O2 sensor reads the excess fresh air trips the code 36 so check for leaks at the egr the exhaust manifold and other places
06-08-2016, 01:13 PM
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. It does feel more like the 350 I had in my previous white Iroc.
