Please don’t bother coming on here stating I should have gone with LTs. Thanks.

A couple of weekends ago I installed a set of BBK shorty headers on my 2000 C5. I was looking for a slight improvement in both sound and performance and have since been pretty happy with both.

The install was pretty straightforward. I bought the BBKs used at a great price (thanks Mcleod ) and they came with everything I needed for the install except the bolts that join the headers to the H-pipe. I spent a lot of time trying to find Grade 8 bolts and nuts to fit my application. None of the automotive or hardware stores had what I needed. Someone finally sold me what they claim are Grade 8, but I’m questioning that. Time will tell.

Anywho, I wasn’t aware of a stock coupler piece that fits between the headers and H-pipe (about ½ inch long). It didn’t pose a problem, I just wasn’t aware that I would need to deal with it, ensuring it was seated correctly and facing the right way. One other snag is the dipstick doesn’t line up quite right with the dipstick flange on the headers. A minor issue that should be easily remdedied.

While I had the plug wires and plugs off the car, I went ahead and swapped in a set of new GM Performance wires and NGK TR55s. It seemed prudent since my car as 75k miles on it and the plugs had never been changed.

Also, I’ve never messed with fan belts before and couldn’t figure how to remove my alternator for the header install. I eventually figured it out (so that is what a tensioner is! ), discovering along the way that my belts were in need of replacement. $50 later from Napa and I replaced both belts.

Upon starting the car I thought something was wrong as I began seeing smoke coming out of the engine bay. I crawled under the car and couldn’t find anything burning and it didn’t seem to be an exhaust leak. The smoke eventually quit and I assume it was some of the WD-40 burning off that I had sprayed on the stock exhaust to break the bolts loose.

I was initially a bit disappointed that the exhaust note hadn’t changed, but I now can tell a subtle difference. I videotaped a ‘before’ of the exhaust and will try to get footage of the ‘after’ to post on here for those that might be interested. I don’t think there will be much of an audible difference though when listening through a computer.

Not sure if it’s the headers or new plugs and wires (or my imagination) but the car seems to pull a bit quicker and more smoothly. The sound of the exhaust is actually a bit louder when giving it some gas, but only marginally so. However, it is enough of a gain for me to enjoy it.

Additionally I believe these shortys are supposed to be lighter than the stock pieces. I should have weighed them but it never crossed my mind until afterwards. Reducing weight from the nose of the car (a car with a 51/49 weight bias) is usually a good thing.

I would suggest if one can get a used set of shorty headers and you doesn’t plan on putting out a lot of power, then shortys are a good way to go. Everything bolted right in and I have no codes or issues. No need for welding or tuning (though a tune may not be a bad idea, its just not something I HAVE to do). In short, I’m pretty happy.

The cost of the headers, Grade 8 bolts, and fan belts ran me a total of about $220.

 

nice write up. glad you're happy! certainly done at a cheap enough price. can tell grade 8 bolts by the number of hash marks on the bolt head....just can't remember the number, 5 hash marks= grade 8?

 

i beleive u add three to the number of hash marks on the bolt so ur right or i completly forget my airforce training

 

Really? I'll have to crawl under there and take a look at my bolts. It seemed like every Grade 8 I looked at was bronze/gold in color (I'm colorblind so work with me here ). The sales guy gave me the size bolts I needed (they were standard silver color) and when I questioned if they were Grade 8, he said every bolt they sold was Grade 8.

That seemed odd, but whatever. I'll try counting the hashmarks this weekend.

Thanks!

 

Congrats!

You certainly can't complain on the cost!

Go DBGM!!

 

BBKs are the equal length shorties right? I'd be interested to see your dyno after a tune. I always have to keep my options open in Kalifornia

 

I would like to get it tuned, if for no other reason, just for efficiency’s sake. The tune alone would probably be worth about 10 hp or more...though it will cost me twice what the header job did!

I was at 301-rwhp so with a tune and headers I hope to be around 320-rwhp. Very meager to many on this board, but just fine for my needs (daily driver).

(My neighbors keep asking me if my car is reliable since they often see me working on it. 90% of the time I'm just upgrading or changing the oil!)

 

The gold finish (yellow zinc) is usually grade 8 (six hash marks on head) and the silver finish is usually grade 5 (three hash marks on head).
http://www.unified-eng.com/scitech/bolt/boltmarks.html
In the future, you can find any fastener imaginable at McMASTER-CARR...

 

close enough guys lol. you actualy add 2 to the hash marks on the top of the bolt. make sure its not smoth cuz it might some cheap bolt thatll snap with enough force. so a grade 8 has 6 hash marks. How I remember this you ask for my age at 18 lol? simple we were also trying to find grade 8 bolts for the rear sway bar on my friends GNX. so check yours soon. grade 8 bolts are hard to find for some reason in certian lengths

 

Congrats. I'm glad someone could use my shorty's.

 

thanks hotwheels57 couldnt have said it better. you beat my response by 2 mins

 

I knew that typing class in high school would pay off someday...
BTW, I have seen some gold colored bolts that have no markings on the head. There are lots of off shore imported bolts, so beware.
Buy from reputable sources for fasteners that are under stress or shear.

 

Sounds cool bro, great price too! So is there any perfromance difference?

 

hotwheelz, thanks for the link! Now I know exactly what to look for.

 

Good evaluation of the shorties........noticed pretty much the same things when I did my B&B's several years ago. Not a louder exhaust note but more tone quality and meaner is how I perceived it. Also agree with your seats of the pants re: seemed more responsive. Despite the naysayers I still maintain its a worthwile mod and smart to change the plugs and wires while you were in there.

BTW, I now have longtubes but attribute an honest 10 rwhp to the shorties when I had them That had been proven by a before and after dyno on the exact same day.

 

Just going by my 'butt meter', the car does seem to rip through the rpm band a bit quicker, but its not a night-and-day difference or anything. It should be noted that I feel like my car accelerates faster after its been washed too, so take my performance observations with a grain of salt. Waxing adds another 5hp.

I got what I was hoping for from the shortys. A bit of sound and power with minimal headaches. Also, since these bolt to the stock exhaust, this is my daily driver, and I have two little children that need constant attention, I actually installed the driver's and passenger's side several days apart.

I had a free night on Wednesday night (kids were at Grandmas) and installed the passenger side (since you don't have to remove the alternator on that side or anything). I then drove the car to work Thursday and Friday and finally installed the driver's side on Saturday. Very nice.

 

Hi FASST LN -

Cool -

I was considering those for my wifes coupe - and at that price I would have been all over it lol.....

Thanks for posting your experience and impression - good info!

As for the grade 8 bolts - if you are talking about the junction where the stock manifolds meet the stock h-pipe, those bolts only require 15 ftlbs of torque if I remember correctly.

Why did you feel you needed grade 8 bolts there?

Just for future reference, locate your nearest Caterpillar dealer - they sell many sizes and grades of high quality bolts - a Cat rental store might also have them, but I would look for a dealership. (Plug for my employer lol...)

Thanks again for the post - and congrats on a successful install!

best regards -

mqqn

 

One of the supporting vendors on the board suggested I use Grade 8 due to the heat subjected to the bolts.
Supposedly they are better adapted and won't fatigue after running through a lot of heat cycles.

Caterpillar, huh? I'm sure there's one around here. I'll keep that in mind for next time. Thanks!

 

Here's one guy's impression of grade 5 and grade 8 bolts....

Bolt Grades: My 2 cents Worth Of Comments

I will not claim to be a fasteners expert but I do have to make choices of fasteners where I work (Fortune 500 company), I started working on cars with my Dad at age 5, and Dad was the lead metallurgist for toys like the SR71 Black Bird and I learned a lot from him, and I have been designing and building equipment to manufacture durable consumer goods where I work since 1986. That said, bolt grades are performance standards and not metal alloys per se.

I see so many “Grade 8” and higher specification bolts fail, they break off, I would never use one in anything my life depended on like holding a car suspension anything. All of the texts I have read say the same thing on these higher grade bolts, use them only where very high to extremely high clamping forces are required and never in any application where the fastener will be subject to bending moments or shear, this includes large thermal cycles. Grade 8 and similar bolts are intended for applications where two pieces of metal need to be clamped together very tightly. The natural application is holding the steels together in a stamping die. Grade 8 bolts are subject to early breakage if you put them in a bend, in side load or impact. A true Grade 5 bolt, not an Asian who knows what, will bend, twist, and stretch a long way and almost always (hydrogen embitterment is always a concern for zinc, cadmium, or chrome plated carbon steel bolts and screws) stay intact.

It has been my experience the last 46 years that Grade 8 and up specification bolts fail by breaking and that Grade 5 fail by bending or stretching. If I have a choice I’ll take bend and stretch. I have worked on a variety of cars and motorcycles originally produced between 1929 and 1995. Except for special application high clamping force bolts (rod bolts, head studs, etc) I don’t recall ever finding an OEM chassis (Ford has their own specification system for critical applications) with something that would fit the Grade 8 performance standard. I have found worn, rusted, bent, twisted, and stretched bolts but they were still in place holding whatever they were suppose to versus breaking and letting the vehicle come into pieces. (I have found original British fasteners in original Cobras bent and or stretched severely but still doing the job of at least holding the car together. The bolts that hold the leaf springs are usually bent badly on a car that was ever wrecked or raced. Bent and stretched make for a loose spring, but the car is still in one piece. When I brought CSX2551 home it had a lot of bent, some stretched, and some bent and stretched original fasteners, it’s been wrecked and run hard, but none were broken. The bolts I have tested were all made of medium carbon steel and were not heat treated to a Grade 8 type condition, most were in an annealed condition.)

We had a double Grade 8 bolt failure this past week at work that cost our company about $100,000 in down time and repairs. I did the failure analysis for the plant manager. The device had two 9/16 socket head cap screws on one end. One appears to have been a manufacturing defect and it failed, snapped off in the threads at an apparent inclusion in the steel. With one bolt missing the assembly flexes. The flexing put the neighboring bolt in a bending moment and its head snapped off and shot across the room. Now we had a catastrophic machine failure. Microscopic examination indicated that three bending cycles (just three) from crack initiation to head separation was all it took. The device was ok at 07:00 in the morning and by 07:45 it was a big mess. These bolts were brand new when installed. This was their first use. Unfortunately this device needs high clamping forces so Grade 8 is the right choice, otherwise I would have Grade 5 in there. That bolt that snapped its head off in bending would have been fine in all likelihood if its neighbor had not failed. Another approach would, except there is not enough room in this device, design in a third bolt such that any two would still work.

SPS Technologies has a very thorough section on their website describing how fasteners are classified.


__________________
Dan Case
1964 Cobra owner since 1983, Cobra crazy since I saw my first one in the mid 1960s in Huntsville, AL.

 

What were the bolt sizes that you ended up using? I just purchased some BBK shorty headers without the bolts and need some sizes. It looks like the stock exhaust manifold bolts are larger than the 3 holes on the Shorty headers.