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**Brown_Muscle** · 12-05-2011, 10:04 PM

was looking at the pipes....the headers, h-pipe, and stock extensions can all be bolted securely together it looks like correct? So the only welding needed is the extensions, and if you want to the mufflers/tailpipes correct?

**gadget73** · 12-06-2011, 01:20 AM

The chrome rusts. Functionally its the same, but it will start to look shitty in fairly short order. If you can get some that aren't chrome, go for it. I had fair results using the POR-15 high temperature brush paint on the old HO headers I had a long while ago. Rattle can high temp paint seems to cook off quick, but the brushed stuff held up really well for me. I wouldn't be oppose ed to standard steel tube headers painted with that stuff. BBK headers and BBK H pipe should go together no problem. A used OEM Ford one with old converters probably will not do you any favors as far as emissions goes either. If its new OEM, you may be OK. Most of the aftermarkets I've seen use 2 converters, not 4 so be absolutely sure of what that is and it's condition before you buy it.

You can get by without any welding at all, but if you can weld the extensions onto the midpipes, it will probably fit up better. H pipe bolts to the headers and to the midpipes, pipes in and out of the mufflers clamp but they can be welded for a better look.

**johnunit** · 12-06-2011, 02:54 AM

I've got bbk headers, catted bbk h-pipe, and lengths of pipe added between flowtech mustang starter tubes and 18 inch total length offset/offset muffler.

Main thing i'd change is welding or rigging new hangars to the trans crossmember, and cutting the hangars off the h-pipe more completely. The driver's side one hits slightly. With those two changes I think i'll be happy.

I was very careful with curing my vht header paint right, in the oven, and it's held up well after a full season.

That said, it may be cheaper for you to have a custom system made.

get a new o2 sensor, and a cap for the other side if going pre-made. My old one wasn't gonna leave the old manifold and was ancient anyway. You want a universal one-wire, cut the wire to fit.

I and Nate/P72ford (on his old red 351 box) had to re-locate the check valve for the smog pump, as it interferes with the passenger side header. The mustang h-pipe also splits the air tube off for each side much closer to the cats, so the system that y's out under the bellhousing is useless if you go that route. What I did was sawzall out all of the smog pump tubing to the cats. I shortened the length of tubing on the pump/solenoid side of the smog pump check valve. This meant that it sat higher up on the inner fender, away from the header. I then ran an appropriately sized (5/8 inch?) length of high-temp tubing from there to the tubing on the mustang H-pipe that basically starts right between the cats. This may all make more sense when you're looking at the car. This is roughly mimicking what was described to me by Nate, and with numerous checks I've never had any issue with the tubing chaffing or melting on anything. It's not supported by anything but the hose clamps at either end, and there's minimal slack.

I don't certify I did anything the right way, and for sure I wish my budget involved everything being custom done and welded, but it's a running system on a car, that is emissions legal and delivered a real noticeable power boost.

Oh and one more tip: do NOT cheap out on the clamps. I've had to go back and replace the cheap ones, and the main niggling leak I still have is from the one remaining cheap clamp. Get band clamps, or at least u-bolt clamps designed so they pull inwards at the open end as you tighten them. I also found the flowtech-supplied flange with the starter tubes (I have a pair of the flowtech starter tubes for sale, btw) were somewhat flimsy, and ended up going to higher quality ones. Overall the system works, but could fit better. It seems to me I had trouble finding the S-10 extension/starter that people on here say works, and that's why I went with the mustang stuff. Whether the S-10 parts actually provide you a better fit, I don't know. maybe worth a try.

Hope this helps.

**johnunit** · 12-06-2011, 03:13 AM

posted this in my thread you found, but also putting it here just to be sure. Mostly talks about the fitment issue I had with the headers. (thanks again Nate for that, I think I'd still be in the driveway scratching my head lol).

351 swap headers - STUCK! - GrandMarq.NET - Panther Headquarters

http://www.grandmarq.net/vb/showthread.php?44331-351-swap-headers-STUCK!&highlight=

For discussions on performance modifications to the 5.0/5.8 engine. Includes engine swaps and whatever else you can think of.

One more thing while I'm thinking about car exhaust at 2am:
I've come to the quasi-educated conclusion that opening up the exhaust this much throws the variable venturi carbs for a loop a bit. It's a bit like CFI cars experience with real mods. The air fuel mixture may just be a bit off, or the bigger of the two engines a variable venturi came on with a free-er flowing exhaust than it was designed for with the hottest cam it could come with may just be flowing more air than it's capable of metering fuel for. I don't really know.

I've got a slight miss at idle, and an occasional stutter at high RPM's that I can't really trace to anything else. It's not severe, but I think it's fair to say I've left some power and a little idle smoothness on the table. I've not dealt with this because I'm planning on dropping a 4-barrel on later, but if you want to stick with the variable venturi long term you may end up having to rebuild it and re-tune it (unfortunately one requires the other anyway) for it to run properly. I've put 2000 or so miles over 6-7 months on it as is, but like I said I'm not getting all I could out of it.

**Brown_Muscle** · 12-06-2011, 01:49 PM

GREAT info guys.
Thain-Sounds like I'm better off going with the ceramic coated headers then.

Johnunit- I was definitely consider getting a new 02 sensor so i will include that as well. I can picture what you did with the smog pump tubing around the cats and the tubing on the fender liner, that new silicone based exhaust hoses are great...just used that recently to repair a hacked up EGR tube. I will definitely be finding a place to weld the extension pipes, and possibly any extensions i apply to the tailpipes. I was unaware of the band style clamps....I've used the shitty el-cheapo U-clamps before...and they leak, look messy and make disassembly difficult. How well do the band clamps seal in comparison?

I'm going to check out 86vicklylx's setup (he has the s-10 extensions)

As far as the miss/stutter, if i went with 2.25" h-pipe/cats i wonder if that would help avoid that problem? I plan on keeping the engine stock as long as i can, so if i can avoid this i'd like to.

**1987cp** · 12-06-2011, 01:55 PM

Remember kids, Walker S-10 pipes are 2.25", Maremont S-10 pipes are 2.5".

Johnunit, I assume your drivability issues are just tuning issues, since you've improved the exhaust but presumably left the carb calibration stock?

**Brown_Muscle** · 12-06-2011, 02:18 PM

http://www.summitracing.com/parts/WLK-50500/

I would get it from rockauto as it is slightly cheaper however it says stainless steel and stock fit. I definitely need to fabricated new hangers for the mufflers as they do not sit up high enough and the tailpipes as a result hang low and look horrible...

What year s-10 pipes are we talking about? Did anyone have problems with getting the manifold bolts out of the heads...I'm going to soak them in PB blaster but i really dont want to snap um off in there.

**johnunit** · 12-06-2011, 02:32 PM

Originally posted by 1987cp View Post

Remember kids, Walker S-10 pipes are 2.25", Maremont S-10 pipes are 2.5".

Johnunit, I assume your drivability issues are just tuning issues, since you've improved the exhaust but presumably left the carb calibration stock?

yes, that's what I assume too. Idle problems were expected on that basis, but I think in theory the variable venturi's computer should be able to compensate. Then again it could be a completely different issue, unrelated to the exhaust, your results may vary.

Thanks I had forgotten about the sizing difference. important correction.

**johnunit** · 12-06-2011, 02:39 PM

Originally posted by Brown_Muscle View Post

http://www.summitracing.com/parts/WLK-50500/

I would get it from rockauto as it is slightly cheaper however it says stainless steel and stock fit. I definitely need to fabricated new hangers for the mufflers as they do not sit up high enough and the tailpipes as a result hang low and look horrible...

What year s-10 pipes are we talking about? Did anyone have problems with getting the manifold bolts out of the heads...I'm going to soak them in PB blaster but i really dont want to snap um off in there.

I don't have any experience with trying it, but I'm not sure the 2 1/2 inch ball flange on the headers would play nice with the 2 1/4 inch h-pipe.

My studs came out incredibly easily, but I attribute that partly to oil from a valve cover leak. If your engine is dry, PB blaster is a good idea.

Also, I hacked up the metal sheet that wraps around the exhaust manifold to supply the hot air/stove pipe, and strapped it to the header with header wrap ties. The originaly stuff was too large to get it tight around the smaller header tubes. I'm not sure how well this would work normally, because I wrapped my headers, and in a rather unorthodox way. The idea was to, at a glance, make them look like newly painted exhaust manifolds. I was somewhat successful but it added probably 70 dollars to the project. Makes checking plugs on a hot engine much easier though.

I was also able to verrry carefull move the dipstick out of the way once it's support bolt on the manifold was removed. It's just resting with slight tension against the header, and has caused no problems yet. Again, I can't guarantee that would be the case resting against a bare header. Someone will chime in with what they've done.

**1987cp** · 12-06-2011, 03:07 PM

What year S-10? Dont' remember. Pretty sure you get different PNs for different cab and bed configurations, too. Anyway, the Walker PN is 43281, Maremont is 339221, IIRC both are long enough to reach a 14"-case muffler from the shorter end of the Mustang crossover pipe. I found the Maremont pipes cross-referencing from the Walkers, then noticed a) they're bigger, b) they're cheaper, and c) they include the flange clamp thingy (which admittedly has to have its bolt holes slotted, but the Walker individual flanges are annoyingly expensive), so I rushed out to Murray's, had a look, and bought the one they had and asked them to order me another one.

**Brown_Muscle** · 12-06-2011, 03:28 PM

Duh, as far as the collector. guess that limits me to using the BBK 2.5" catted h-pipe (eek expensive!). Gotcha as far as the dipstick, I'll figure something out for that.

Sorry for all the questions but with these s-10 pipes, no mustang extension pipes are needed, and if my mufflers are of correct length will reach them AND will be able to bolt up to the h-pipe if i simple make the bolt holes slotted to a larger(longer) size? that would greatly simplify installation.

**Brown_Muscle** · 12-06-2011, 03:30 PM

Johnunit- have you considered putting some sort of baffle or small-well designed obstruction in the exhaust to see if it helps with the miss and stumble? just a thought

**johnunit** · 12-06-2011, 04:31 PM

Originally posted by Brown_Muscle View Post

Johnunit- have you considered putting some sort of baffle or small-well designed obstruction in the exhaust to see if it helps with the miss and stumble? just a thought

No, I haven't played with that to see if it's the issue. I've basically left it alone because if all goes right I won't have a variable venturi on the car at all next year, and it's being mothballed as soon as I buy a winter car. It's a pretty intermittent issue to test, too. In seemingly identical conditions, I can sometimes hold it in first and second north of 4500RPM, and other times it will start to sputter at more like 3500rpm.

In this video you can hear it happening at 1:05, 1:27, 1:55, and a few other spots. at 5:35 you can hear it's mostly gone.
It's audible as a sort of thump-thumpthump sound

Personally I'd do it again, with the same parts (minus the tweaks I've mentioned) even if I was keeping the VV carb. I'd just be aware that tweaking of the carb may be in order.

**Brown_Muscle** · 12-06-2011, 05:15 PM

I love the exhaust note...so sick.

I can just barely make out the sound your talking about. It does seem pretty minor though no? Have you checked the spark plugs at all to see if it is indeed running lean? I notice you seem to get on it right when it happens....too bad Nate switch to 4BBL, cause it would tell us if this was a normal issue, hopefully i will be exempt from the problem haha *crosses fingers*

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351 swap headers+ exhaust questions

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