Thread: Kind of a Drag

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Originally Posted by 34_40

I'll add in that the better performing carb will increase your gas mileage not decrease it!

.... if you keep your foot out of it, and are driving for economy.

The better performing carb is not what wears out your tires quicker, right? It's the way you drive it with the better performing carb.

You have a vacume leak lower intake manifold by 1&3 ports-pcv feeding oil rich blowby to carb--extra gas is flowing thru gas side of nitrous system causing poor milage and running--probably leak in exhaust system letting in fresh air to gas rich/unburned fuel/oil mix and is igniting in exhaust causing popping.

over comments that lead me to suspect possibility of more vacume leaks------manifold is for quadjet and u have square bore carb plus nitrous plate??????

Jerry, I believe we're getting close and like you say there may be more than one thing.

I had to think on it a while, for it all to settle in. Remember, we're getting information in bits and pieces so it's hard to keep it all in order, not like we're there doing it.

Black sooted up carb, #1 & 3 plugs fowled, popping in exhaust and intake.

He needs to go back to cylinders 1 & 3 and compression test again. This has all the classic signs of a head gasket starting to leak between cylinders 1 & 3.

over tite valves on 50w oil, hydraulic lifters??????? flat cam lobes/lifters because 50 w oil won't flow thru bearings and sling off to oil cam--------won't flow to top of engine to oil on drain down?
1 & 3 ports--------pvc ??

needs to lock out timing advance completely and run it to see what it likes-then build curve to suit that

If spark plug wires are closenough to header to burn, they are close enough to crossfire

Hiya,

I got a metal sandwich plate between the manifold and the nitrous plate. I got a solonoid on the gas side feed and it don't work unless I use the spray, and the pvc is located on the right side rear of the engine. A breather cap is on top of 1 and 3.
The engine is got studs except for the 4 top head bolts on both sides. Heads are fresh kinda. I better do the compression test.
Is 20-50 oil still too thick?

Right now the car doesen't pop at all now but this gremlin keeps showing up like an irritating relative that clogs up the john. I'm just waiting for it to come back.

I've decided to condemn the Edelbrock and continue with the quick fuel Holley clone. I think there's something wrong with it too. The Edelbrock, not the Holley.

I've checked all the header and collector bolts. If there's a leak, I can't find it. There's NO backfire now. Or intake cough.

I will check intake bolts and compression test. PVC seems to function but I had it on for a while. Might just change it.

Question, should I replace the pvc with a breather cap and plug off the vacuum on the back of the carb? Or am I just stupid?

Ohyeah, as for the foot feed the speed shop guy says to put a piece of 2 by 4 under the gas pedal. Think it'll work? Really i'm a conservative driver. People pass me on the freeway all the time.

I like PCV systems when they're functioning correctly the motor stays a lot cleaner. Usually the valve covers have a baffle to prevent (minimize) the oil from being sucked into the PCV system. However, if the PCV is sucking oil, a oil separator maybe needed.

I'm a little suspicious of the head gasket at #1 & 3, I would do another compression test. I know it's running good right now, but if the head gasket is leaking it is just a matter of time before it mucks up this carb and your right back where you were.

But at the very least, pull these plugs and see if they're fowling again.

Though, I'd hate to see you ruin another carb for the lack of a compression test to find a bad head gasket. A leak down test would be in order too in my opinion. It would show the leakage between the cylinders that to the untrained eye may not show up well with a compression test.

The pvc side has the oil separator but the breather side does not. I took that one off because for one thing it was being hit by a rocker arm and I couldn't pass oil down it.

I just pulled off plugs 1 and 3 1 is fouled but 3 seems to be normal. As soom as I can get Mrs Goodwrench to get her clothes on I'll see if 1 is firing at all.



I can do a static compression test but I can't do a leakdown.

Should I thin out the oil some more?

Well, plug 1 is firing anyway. Next is compression test.

Carb has a slight discoloration toward the brown side but it doesen't wipe off. Not soot I guess. Edelbrock is black with soot.

No baffle under oil cap------1 & 3 get oil fouled-----maybe valve seals/guides bad and your pouring oil directly into cylinders??
I agree that low compression on 2 adjaction cylinders sometimes indicates leaking head gasket, but also on engines with the intake having 2 ports side by side that can also mean(especially on aftermarket) bad seal around those two ports plus in this case it also is running lean/whiscling?

Leaky solenoids/fittings /plates on nitous systems is quite common and is probably the only way you could kill the milage this much-unless he is mixing mpg(miles per gallon ) with Kpl(kilo per liter)

The header to head is just one of several places for an exhaust leak-------just think about how many joints are fabbed and welded and then installed with ill fitting expansion joints, flex joints, etc-

Originally Posted by Good Wrench

Should I thin out the oil some more?

How tight are the clearances in the motor?

If it's a new build with modern tight clearances, I prefer 5-30 or 10-30. If it's a new build with older standard clearances, I prefer 10-30 or 10-40 and 15-50. If it's got some miles on it, I prefer 20-40 or 20-50.

With multi viscosity oils, the first weight# is the viscosity COLD, the second HOT. In other words in your case with 20-50, at cold start the oil viscosity is 20 weight and at it's higher operating temperatures no more than 50 weight. This can vary a little depending on the temperatures the manufacturer designed into the oil viscosities.

Oh-by the way----if number 1 is fouled--------your timing light just might not work-try it off of number 6 cylinder

Originally Posted by Good Wrench

Well, plug 1 is firing anyway.

How does the plug LOOK compared to other plugs? Is it the same color as compared to a couple of plugs from the other bank (2,4,6,8)? Or it it darker burnt, oily or discolored in another way? We ain't there, you got to be our eyes, so explain it well.

We are looking for changes in cylinder 1 & 2 plugs compared to the others. Specifically any kind of fowling in or around the porcelain and tip.

Originally Posted by jerry clayton

Oh-by the way----if number 1 is fouled--------your timing light just might not work-try it off of number 6 cylinder

This is a great TIP guys, as most inductance fed lights will not read correctly if the plug circuit is fowled (spark plug completes the circuit).