Open exhaust ?_?

[66sportfury]

Okay i have a feeling this might get ugly but right know my truck has no mufflers and the exhaust is cut off right around the beginning of the cab. Personally i love the sound of it but don't care for it running like So i was just wondering how or what people do to make there vehicle even be able to rev without backfire/afterfire?

Oh and yes i realize that most people think it sounds obnoxious just like cherry bombs. Which i plan on putting on if i cant get it running right. So without just saying its horrible for your engine and sounds horrible, whats the secret???

[mopardwh]

Are you sure it's the exhaust (or should I say lack of) that's causing it not to run right? I didn't think lack of back pressure would cause backfire. I've ran open long tube headers before on several vehicles without any issues. (other than extremely loud).

[Seff]

Are you sure it's the exhaust (or should I say lack of) that's causing it not to run right? I didn't think lack of back pressure would cause backfire. I've ran open long tube headers before on several vehicles without any issues. (other than extremely loud).

i want to do that to mine when im finished with her. around here its either super loud old trucks. or quite lifted truck(which is quite stupid if i may say so) the louder the better :D

[rogerr]

If you have a carbureted vehicle that runs properly with a muffler, and you take the muffler off, the fuel/air mixture will be way wrong. Rejetting the carb is a necessity.

Same with open loop FI systems.

Closed loop EFI will compensate within certain ranges. Past that you need to redo the firmware.

[66sportfury]

Sorry for the late response but all try and list specs "that i no"
318 poly was rebuilt when i got it from towyard
Has a weiand highrise
Holley 4150 has bigger nozzles and or jets or something it was gonna be for a 500-600hp 400 mopar
When i had a fullback system with glass packs it ran good
when i cut it and put some shorty cherry bomb "glasspacks of course" and tips to go out the side it ran okay some bf around 5000rpm
When my temporary duct tape job failed to keep the mufflers to the pipes i took um of and now it runs like
I have a vid that shows it afterfiring and this was below 3000rpms, it wont go higher cause it starts backfiring through the carb and afterfiring.
Which sounded to me like the timing maybe?

http://www.youtube.com/watch?v=8gkhMNnl5lg ----yes i just noticed in the vid that its my drivers side that's running bad. And how i probably blew the powervalve in the carb. But i just bought a rebuilt 4150 from my moms friend.

[facechicken]

Not trying to be a smart @#%......but how long did the duct tape work before it failed? (just the thought of it makes me smile )

[Hobcobble]

You should put some type of exhaust system on your truck.
It might be advisable to do the following:
> run a compression check
> verify that your carburetor is functioning properly
> re-check plug wires for proper firing order
> clean up spark plugs [or buy new ones]
> make sure you're getting proper spark
> time engine with vacuum gauge vs. timing light
> re-adjust mixture on carb, provided yours has mixture adjustments

Did the yard you bought this engine/truck from give you any
receipts on the [alleged] rebuild? Some folks' idea of a "rebuild"
is a new set of spark plugs and a couple cans of engine paint.....
If you can't verify the rebuild through documentation, the compression
[and possibly a leak-down] test could be quite helpful to establish a
baseline of the engine's present "health"

John

[66sportfury]

@facechicken Surprisingly it held up for a couple of weeks! And i only gave it 2 wraps, im thinkin the only reason it broke is from how much it moved when i reved it

@Hobcobble
When i got it the valve covers were off and the heads were loose. And the yard said he lost intrest in it so they bought it from him.
1.I will when i could find my comp gauge
2. Just got a rebuilt 4150 for it
3. .......so ....... there may have been a few wires that weren't wired right, but i swear it wasn't me
4. All do that now
5. We had it timed right before i cut the exhaust, but some one may have forgotten to re tighten the distributor
All get back to you when i get the list done

[Hobcobble]

Have you ever checked/set the valve lash on this engine?
If not, add it to the list. Consult a FSM for the intake
& exhaust settings.
John

[facechicken]

@facechicken Surprisingly it held up for a couple of weeks! And i only gave it 2 wraps, im thinkin the only reason it broke is from how much it moved when i reved it

That's awesome.......ok now how bad did it smell, burning that duct tape, when it got hot

[66sportfury]

@Hobcobble We set the valve lash when we first got the truck, and to get tdc don't you just stick a screwdriver down the spark plug hole and wait for it to stop going up?


@facechicken well that one i cant tell you cause i was just smellin fumes

[surfnuke9]

Nope, that may result in being 180 out.

TDC needs both the intake and exhaust valves closed. The exhuast stroke will have the exhaust open and not develop a pressure. You want to be on the compression stroke.

Backyard method would be to put a finger over the spark plug hole and turn the engine. (not with the starter).

When the air pressure pushes against your finger, you are on the compression stroke. The you can use the screwdriver idea.

[66sportfury]

^ Is somewhat how it went... "take a look at the pic" yes i know its running real rich but its not like i drive it. Oh and to top the day off one of are dogs got fleas from the damn neighbor dogs!



And when you say 180 out what part are you talkin about? the rotor or something?

[Dood]

And when you say 180 out what part are you talkin about? the rotor or something?

Yes, he means distributor is installed 180 degrees out.

Those plugs look like it is running rich to me, or oil is getting passed the rings. In fact, is that oil on the plug itself?

[66sportfury]

sorry about the late response but yes that was oil #1 had oil and #2 had alittle...sigh it seems whenever your plan on doing something it always gets screwed up. Just wanted to sell it to pay back my brother for the power wagon, and have already spent over 200 trying to get this thing back to the state it was when i first got it running lol

After rereading my post it seems i shoulda just listened to the old sang "If it aint broke don't fix it"

[66sportfury]

"yes, he means distributor is installed 180 degrees out." I just came back and reread that. How is it even possible to do that wouldn't the vacuum advance be like pointing near the drivers side?

Also I'm putting on the new holley, new spark plugs, and 3 new wires today maybe even the exhaust. Which was at My moms friends house, cause when she sold him "the beast" she gave my exhaust that i cut off my truck to him
So me and my brother just went over there and kind ah umm hopped there fence and grabbed it than hauled

The pic is the new carb but it has a Horrible Electric choke, So i was wondering if its possible to run it without the rest of it? "what ever is missing" sorry but i don't know electric chokes, I'm a real man and i like just about everything manual

Last thing yes i realize this is alot to read but on the 4150's when you take the screw out of the bowl it shouldn't pour gas out unless you shake the truck right? Cause my front bowl i couldn't get fuel to spill out, i heard it though. Would that be the culprit for it running rich? or does black plugs mean its runnin lean? im confusing myself

[Dood]

An electric to manual conversion for the 4150 is available from Holley: CHOKE CONVERSION KIT PART #: 45-225. Or you could get a full electric kit.

Unfortunately for my odd-ball Holley, no conversion kit is available so I use the hard-core manual method: open hood and twist tie when choke is necessary.

Here is a great NGK link for reading spark plugs. At first glance it looks like the 'Dry and Wet Fouling' case to me. I'm worried about the oil on the plug itself. Like the rings aren't sealing. I could be wrong. Can you do a compression test?

As for the timing... Do you have a timing light?

[surfnuke9]

No, I didnt mean the distibutro is installed 180 degres out.

What I said was that if you just use a screwdriver and stop when it is pushed up the most, (Like you asked about) you may be at TDC of the EXHAUST stroke vice the compression stroke.

If you treated that as TDC compression, you would be timing the engine 180 degrees out.

[66sportfury]

Yes i have a timing light and was wanting to fire it up yesterday intill i went to hook the linkage up for the throttle... Which is right about when i shook my head in disappointment and anger, This d-bag that rebuilt this carb drilled the holes bigger where the little ball goes. So hopefully i could figure something out today i tried just welding some more material on the smaller one then retreading it but... ah... someone may have threw it when someone accidentally got burnt from the welder...