Simple Trick To Gain 100hp+ For Less Than $200

[ShortCST]

How about changing your plugs and plug wires more than once every 7 or 8 years? This is cylinder #4, the worst of the bunch by far.

In my (very weak) defense, the headers really take a lot of the fun out of changing the plugs. Pretty much everything else gets regular attention.

[Shinysideup]

Did you mean for less than $20?
I see a tired engine.

[70STOVEBOLT]

I don't think changing the plug on cylinder #4 will make a lot of difference, I agree with Shinysideup, that looks like a plug out of a tired engine. Spark plugs do wear, and therefore need replaced every so often, but they should not look like that.

[ShortCST]

The truck sat parked for over a year while I came up with the funds to get her back on the street.

It feels more powerful now than it ever has since I owned it. A cam swap that I was considering doesn't even seem necessary now.

Also, the plug wire going to that cylinder was hidden from view, and when I pulled it out, it was taped in the middle with electrical tape. Didn't unwrap it to see what was hidden.

[demian5]

Originally Posted by ShortCST

It feels more powerful now than it ever has since I owned it. A cam swap that I was considering doesn't even seem necessary now.

Cause it needs possible rings and guides...

[Killer Bee]

every self respecting chevy engine burns a little oil.... but dang..

might want to run a compression check for top and bottom wear and proceed cautiously before demanding too much from it..

best time to do this while replacing sparking bolts

good luck!

[70STOVEBOLT]

That would explain the way it looks if it was not firing properly from a bad wire. It's always a very pleasant surprise when you do a simple thing like a tune up that makes such a big difference. I saw your other thread about the drop springs, nice looking truck.

[hewittca]

My truck went through similar maintenance a few months ago and it really livened it up and made the engine run smoother. I was ready to toss this 307 anchor overboard before I tuned it up, but it runs well enough now that I think I will hang on to it for a while.

[leddzepp]

Best thing I ever did was ditch headers and go back to stock manifolds. Easy to change plugs, zero exhaust leaks, no more burnt plug wires, able to install factory AC brackets. I'm driving a pickup truck, not a race car and there are way more advantages for me this way.

[GASoline71]

I have installed headers on every single rig I have ever owned. No probs for me.

When plugs are oil fouled... it's time to look at rings and/or valve guides and seals.

Gary

[bill3rail]

Originally Posted by GASoline71

I have installed headers on every single rig I have ever owned. No probs for me.

When plugs are oil fouled... it's time to look at rings and/or valve guides and seals.

Gary

I on the other hand do NOT install headers but your next statement is dead on! Check the cylinder/rings and valve guides/seals.

Bill

[randy500]

Originally Posted by GASoline71

I have installed headers on every single rig I have ever owned. No probs for me.

When plugs are oil fouled... it's time to look at rings and/or valve guides and seals.

Gary

I have taken headers off every single rig I bought that had them, I hate exhaust leaks...

[ShortCST]

I know that it looks like oil. But it wasn't viscous. It positively reeked of gas as soon as I pulled it out. The smell of fuel from the exhaust was dizzying. A couple of the other plugs were fouled. This one was wet.

I'll definitely perform the compression test, just to be on the safe side.

[ShortCST]

Randy, I have a set of Doug Thorley Tri-Y pieces, and they've never given me a problem. They've got really thick flanges.

[70STOVEBOLT]

It is running extremely rich then. I would bet there is gas in your oil as well. Since you are replacing plugs/wires, maybe a carb rebuild is in order as well. At the very least, a carb adjustment should be made, along with a a check and/or adjustment of the timing and an oil change. If it's been running that rich for a long time, it could "wash down" the cylinders and cause excessive wear on the cylinder walls and piston rings. That would be an extreme case, but it is possible.

[ShortCST]

Stovebolt, it doesn't smell like gas since I replaced the plugs and wires, but the idle speed is a bit fast (around 1k rpm). I wonder if the last time that I brought it in for a tune, if they just advanced the timing to try to burn more fuel, without pulling all of the plugs for inspection.

Should I still rebuild the carb? It's an Edelbrock 1406. I have no qualms, I'm just excited to drive it now that it's running so well. Hate to start the Fedex clock all over again.

[leddzepp]

If it is running well and you are happy leave it alone and enjoy driving it.

[70STOVEBOLT]

^^What Scott said.

[AnotherWs6]

Just adjust the idle screws, there are two on the front of your carb, easy peezy.

[ShortCST]

Originally Posted by AnotherWs6

Just adjust the idle screws, there are two on the front of your carb, easy peezy.

Thanks for the tip! My pickup definitely isn't burning oil or smoking at all, doesn't smell like gas anymore, and is certainly now producing power close to its factory rating ('67 L79. 325hp), which it hasn't done in the past 10 years.

I do want to fix the idle speed, though. Today. Mostly just to wring as many miles per gallon out of the 327.

Two related questions, and I'll be out of everyone's hair:

1. Does idle speed affect mpg much? Both city and highway, or just in stop and go?

2. Are the idle screws the only/best place to turn the engine speed down a notch, or does the ignition timing change that as well, and how do I know which to change, without an exhaust gas analyzer?

['68OrangeSunshine]

Originally Posted by ShortCST

Thanks for the tip! My pickup definitely isn't burning oil or smoking at all, doesn't smell like gas anymore, and is certainly now producing power close to its factory rating ('67 L79. 325hp), which it hasn't done in the past 10 years.

I do want to fix the idle speed, though. Today. Mostly just to wring as many miles per gallon out of the 327.

Two related questions, and I'll be out of everyone's hair:

1. Does idle speed affect mpg much? Both city and highway, or just in stop and go?

2. Are the idle screws the only/best place to turn the engine speed down a notch, or does the ignition timing change that as well, and how do I know which to change, without an exhaust gas analyzer?

1] Yeah. Sort of. You will be burning more gas waiting for the light to change running 900 RPM than 650 RPM. On the highway, you won't be idling much, unless coasting down hills, so it's not so much a factor.

2] Back in the day -- when we just clubbed and skinned a dinosaur for its gas rather than squeezing its juice from the pump, long before EGAs, A/F meters or OBDs -- we used a device called a 'vacuum gauge'. It's T-ed into the vacuum line from the distrubutor to the carb and reads in Inches of Mercury [X''Hg] . When adjusting the carb set screws, you want the highest number reading on each screw. For my 292 L6, 17-18''Hg is nominal. Easy analog gauge to work with, not hard to find, doubles as fuel pressure meter too, in some applications. Not expensive either. Also an in-dash Vacuum Gauge can indicate best gas-mileage while running, decelleration, bad valves, sticky valves, poor compression, etc. And just looks cool being there.
Big trucks have them as standard.
Tachometer is also handy tune up tool. If you have points, you need a Dwell Meter, too. They used to sell Dwell/Tach/Voltmeters.
Yes, timing affects engine speed.

[ShortCST]

So, after just having come back from a drive, I realized that:

The truck idles at 750 rpm in Drive when warm.

It idles at 1000 in Park or Neutral when warm. Even if I stab the throttle. Settles back down at 1000.

Sorry for the sophomoric questions. Do the above numbers sound right?

[AnotherWs6]

Originally Posted by ShortCST

So, after just having come back from a drive, I realized that:

The truck idles at 750 rpm in Drive when warm.

It idles at 1000 in Park or Neutral when warm. Even if I stab the throttle. Settles back down at 1000.

Sorry for the sophomoric questions. Do the above numbers sound right?

No they don't I don't think you should be idling mire than 750-800 in neutral. The old school way off getting your timing roughly dialed in - loosen the dist clamp and turn the distributor slowly advancing it. Idle speed will increase. Keep turning it until starts to slow down then back it off a bit.

Do the same thing with your mixture screws, one on each side, one at a time. Your looking for the highest idle speed and then backed off a quarter of a turn. Once you've got that done you can adjust your actual idle speed to where you want it. It's a screw on the far right front of your carb.

[ShortCST]

Originally Posted by AnotherWs6

No they don't I don't think you should be idling mire than 750-800 in neutral. The old school way off getting your timing roughly dialed in - loosen the dist clamp and turn the distributor slowly advancing it. Idle speed will increase. Keep turning it until starts to slow down then back it off a bit.

Do the same thing with your mixture screws, one on each side, one at a time. Your looking for the highest idle speed and then backed off a quarter of a turn. Once you've got that done you can adjust your actual idle speed to where you want it. It's a screw on the far right front of your carb.

Is that for sure an accurate way to set it? I'm so nervous now about messing it up and fouling the plugs all over again.

[ShortCST]

Tim, I love the performance of my headers (huge, noticeable improvement in power), and have had zero leaks in almost ten years.

It's just that they've made it SO difficult to get tools on the plugs securely.