351 swap headers+ exhaust questions

[johnunit]

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*

I don't remember how the plugs looked, sorry.

Yeah the exhaust sounds incredible when you get on it. It just drones a lot, but that's with it dumped before the axle. Hopefully tailpipes and 3 inch tips will reduce the drone while keeping the overall volume at full revs.

It's not a BIG thing when it happens. I'd say I lose maybe.. 20% of the power? If I had to guess it's only 1 or 2 cylinders actually misfiring per rotation.

[Lincolnmania]

use mustang aftermarket mids with extensions flowtechs are around 50 a pr

[Brown_Muscle]

If i do that though then i will need extra clamps or welding. and these are less expensive then the mustang mids with extensions: http://www.summitracing.com/parts/IMM-339221/

I know it says cherry bomb, however they look the same and have the same part number at the maremonts.

[gadget73]

Regarding throwing the VV for a loop with exhaust flow, that does make sense actually. More air out = more air in, so you'll need more fuel to keep the mix correct. I dont honestly know what the O2 sensor thinks its doing with a VV engine since as far as I'm aware it doesn't have any electronic control inside the carb. You may have to open the carb up and put a larger main jet in there. Atl east thats what you'd do with a normal carb. The VV, NFC. I dont know if its as simple as swapping jets to fix a lean condition.

[Midnight Drifter]

OH! the air injection pipes....i have to pass NJ inspection. how would i reattach those to the mustang pipes? or does that have to be fabbed as well??

Don't even worry about that, just delete that shit completely. I thought it was GAME OVER when the state inspector popped my hood, but didn't even notice the PCV to atmosphere, disconnected smog pump and random emissions equipment just strewn about under the hood. Sheeit, they didn't even check the underside for cats. You're good man.

[johnunit]

Don't even worry about that, just delete that shit completely. I thought it was GAME OVER when the state inspector popped my hood, but didn't even notice the PCV to atmosphere, disconnected smog pump and random emissions equipment just strewn about under the hood. Sheeit, they didn't even check the underside for cats. You're good man.

he's got tailpipe emissions to deal with, and considering the only thing needed to RETAIN it is basically running one line of hose that costs 10 bucks, it's simpler to retain it.




@Gadget I don't think there are replaceable jets per se. I think you can screw adjust the mixture in some way, but I'd have to look over the info I have again.

[Brown_Muscle]

If i recall correctly the adjustment screws are capped in some way, and they may require a special tool to adjust them... and even if you could get to them i hear they are very finicky. There was a manual on ebay for the VV's. they have service information, also there are several dealership VV carb kits for sale as well. i believe it would pay for me to get them...assuming it's not too advanced for me to work on (i'm sure i can figure it out)

[packman]

As far as teh air tubes from the smog pump to cats go, I plumbed it together using copper tubing from Home Depot. I then transitioned over to 3/8" rubber fuel line and connected that to the air tube on the cats.

I know it's hard to find a shop that does inspections these days (especially for our cars because in NJ, 1995-older vehicles use different inspection equipment), but you may want to spend a little time searching a shop out. Even though you're paying money, it's worth not having the aggravation of dealing with the state.



Packman

[gadget73]

Mine hasn't had air injection pipes or an air pump in years, passes no problem. They don't look at that crap. If its got converters, it'll pass the visual.


Not sure about VV internals at all, but on a carb, the screws only mess with idle mix. The VV is entirely it's own beast though, so no clue what the hell they may use for main fuel metering devices or how you'd go about enriching it. I just know that more air in needs more fuel to keep the A/F ratio correct. Exactly how you go about doing that with a VV is beyond me.

[Brown_Muscle]

i know they use needles like in motorcycle carbs, they should be attached to the black squares (VV valve) If the needles are adjustable that would also allow for main jet adjustment. if i order the manual ahead of time, i will know it advance!

http://books.google.com/books?id=EgEAAAAAMBAJ&pg=PA78&lpg=PA78&dq=variable+venturi+carburetor&source=bl&ots=IYvtmi1aFU&sig=oPyzO_23sif9kZoXiIoRLU1hMhg&hl=en&ei=LvDfTsy8GarW0QGR6YnSBw&sa=X&oi=book_result&ct=result&resnum=6&ved=0CFwQ6AEwBQ#v=onepage&q=variable%20venturi%20carburetor&f=false

some excellent diagrams there even though it's the 2700 none feedback and not 7200 like mine...

*edit* looking over the diagram it almost appears as though the main jet can be turned in or out...which would lean out or enrich the mixture... how you get to it to make that adjustment i don't know...but it may be possible.

[gadget73]

well, most things with metering rods you can change either the rod itself to one with a different taper, or the seat (jet), or both. If its an actual taper instead of just a step like the Carter carbs have, then having a jet that screws in and out would alter your fuel mix too. the AFB metering rods are more of a rich/lean switch than a real metering rod.

[1987cp]

"Real" metering rod, meaning something tapered instead of stepped?

IIRC, Quadrajunk rods could be had in three-step or maybe even four-step configurations ... interesting, anyway.

[Brown_Muscle]

If it's like a motorcycle VV carb it should be tapered....

Okay so i guess my only 2 questions before i order everything (next wed) would be: That cherry bomb pipe that has the same part # and picture as the maremont pipe, i suppose i'd be safe to assume it is the same thing? As i cannot find maremont anywhere online...? It would be nice not to have an extra connection and clamps to worry about if i could

http://www.summitracing.com/parts/IMM-339221/?rtype=10

And the others:

http://www.summitracing.com/parts/BBK-15110/

http://www.summitracing.com/parts/BBK-1563/?rtype=10

http://www.summitracing.com/parts/CTO-O2-1/

http://www.summitracing.com/parts/SUM-G2990SS-1/

[Brown_Muscle]

I was looking through the forums a bit today...and noticed that Nate and perhaps a few other people with the 351 had problems using the mustang h-pipe... this makes me a bit worried. Johnunit, do you have any pictures of your setup?

[johnunit]

I'll get pictures tomorrow.


The issue I had (and I imagine others have) boil down to two things:

1. a hanger has to be added as the stock mustang h-pipe hangers are useless. you have to weld something on right ahead of the cat and then attatch it to the trans crossmember.

2. if you mount it at an angle where it isn't hitting the trans crossmember, the h-pipe will sag a bit heading towards the back of the car. It's not severe, I'm a long way from hitting speed bumps, but it's lower than stock for sure. It only hits on the driver's side pipe, because it's too close to the center of the car instead of being centered in the hump on the crossmember. Moving the driver's side h-pipe tube outward (cut and weld?) would allow the h-pipe to be put at a good angle, I think.


I had no problem, however, actually mating the h-pipe to the headers. No leaks, no overly difficult bolt placement, etc. Even the oxygen sensor was still in an ok spot.