1967 327 275hp bored .030, .010/.010 on the crank, 1967 194 heads, 3890462, new valve, guides, springs with hardened seats, Cam is a Engine Pro MC1989, right under the L79 327 cam on lift, Edelbrock Performer Intake #2703 and a 600CFM Holley, 4160-01850C all new. powerglide
Fired the engine off last week and it fired within dozen revolutions and we did the cam breakin at 1800rpm for 25 minutes as machine shop recommended, used Rotella 15-40, Crame Super Lube Breakin Concentrate, new plugs, points @ .030, cap, rotor, wires, timing @11 degrees so everything should be right but it's not. 175 miles on the engine right now.
At idle, 850rpm, it sounds like a vacuum leak, not on all eight but not a dead miss, vacuum check shows 11 inches at idle, can't get no better, sealed all lines one at a time and 11 inches is the best, bouncy, at 1500 rpm I get 15 inches but bouncy.
Under accelaration the Holley stumbles, I have set the idle mixture screw with a vacuum gage, 11 inches, right now the screws are about 1 & 3/4 turns out, when you start the car it doesn't sound like it's hitting on all cylinders but not a dead miss. Sometimes when starting cold you get a small spitback thru the Holley and at low accelration like passing a from 40mph on you get a stumble and then a spit back thru the Holley. Friday night I pulled the Holley off to replace the gasket and the gasket was wet with gas???? and the new gasket really didn't help it.
Drove the car Saturday to a show, 45 miles one way, and it always felt like it was not on all 8, but not a dead miss, muffelers just didn't sound right and one time when I went to pass a car at 55 I got a spit thru the Holley and it's real hesitant, very bad gas milage.
I'm ready to throw wrenches, been working on this engine package for a year and it's not right, compression check next???????? could the Holley have a accelrator pump leaking or vacuum leak???, tail pipes are super bright inside, oil level and smell has not changed,
OK. I've vented, any suggestions???
cw

hmmm...

I am an amateur but...

I would try a different carb.
I would try rechecking the valves...

other then that I would let the pros answer this one...

Are you 100% on the ign wires all working right?

Did you say that you set the points at .030? I thinkm that would be way to open if so. Or did you mean dwell set at 30?

I'd start pulling plugs first.

...assuming you've double-checked simple things first like firing order and points gap.

TIMING TIMING TIMING!!!!!!!/LOL!!!!!!!!!!!

1st thing with your aftermarket cam is to adv the timing from the 11 deg base its at which is substantially retarded (it's up to 7 deg retarded) to at least 16-18 deg where it will idle & run better with likley no more stuble having crisper throttle responce/better fuel economy/more idle vacuum/run cooler in traffic/etc.

Then see how it does after that that because that may clear up what you think are carb issues due to the retarded base timing causing a low idle vacuum signal to the carb.

Look for approx 36-38 deg total by approx 2800rpms with 16-18 deg base timing & vac adv hooked to ful intake vacuum for better idle.

Also check for fuel fouled plugs before you adv the base timing to 18 deg because the motor will still run poorly when base timing is advanced if it still has some fuel fouled /black and or dark looking plugs due to the retarded base timing messing up the carb signal.

Scott

Bouncing vaccum gauge may indicate a broken valve spring or a valve too tight. You can start the engine, let it run a minute or so, shut it off and spray Windex or something similar on the headers to see if all cylinders are heating up. Hopefully you have headers. If one is cold that is your problem cylinder.

Here's a really cool site I saved when someone here posted it a couple of years ago. It shows different scenerio's and how your vacuum gauge will react.

http://www.secondchancegarage.com/public/186.cfm

Good luck getting it sorted out.

Have you rechecked the valve lash? If this is a hydraulic cam, you could have overtightened a valve or two and left them hanging open. I had very similar symptoms after a cam swap many years ago. When setting hydraulics, lots of people make the mistake of spinning the pushrod to check tightness, and then doing their extra 1/2 to 1 turn after they have BOTTOMED OUT the lifter. I would loosen all of the rockers, and SLOWLY re-tighten them while moving the pushrod up and down until it doesn't move anymore. Then add your extra 1/2 to 1 turn. I had three valves hanging open just enough to make mine run horrible.

Do the easy stuff first. Sounds to me like you have a vacuum leak somewhere. Even my L79 will pull more vacuum than that at idle. With it warm and idling, spray around the carb connections, carb base gasket and intake manifold gaskets with carb cleaner. If the idle picks up briefly, thats where your leak is.

You should also check that the float levels are set properly on that Holley.

Do the easy stuff first.

This is what I did today and still no luck, first I pulled the plugs and they all look good and I could not see any cracks in them. Called my buddy at local parts store and told him what was going on and he said to remove all ignition parts bring them in and he would replace them. So new points, condensor, rotor, cap, and wires, set the dwell at 30* and reset the timing to 12* btdc, fired off right away, but still not right. Reset timing to 14* and really no better, vacuum was 11&1/2 to 12&1/2 inches @ 775 rpm, at 1000 rpm the vacuum pulls to 15 to 16 inches but bouncy. Did not drive the car tonight. One thing, the car was at operating temp with the air cleaner off and I put my hands over the carb and the engine died. I did this three times and it took about 5 to 7 seconds to kill the engine each time and I could not hear any type of whisle like a air leak.
I'll try something else tomorrow
cw

FYI,the base timing is still way too retarded,the 12 you were is way too retartded for base timing with that cam let alone the 14 you advanced it too.

14 base timing isnt much better & is still significantly retarded,you need at least 18 deg base timing with the cam you have. Then if it still has issues with stumbles etc from carb after getting base timing adv to 18 deg then go after the carb tuning like accell pump etc.

A good starting place for timing is with your setup is approx 18 deg base + 18-20 deg mech all in by approx 2,800-3k rpms.

Then 18 deg base + 18-20 deg mech = 36-38 total by 2800-3k rpms.

IMPORTANT,MAKE SURE YOU HAVE IDLE LOW LIKE 600-650 RPM(vac adv unhooked & plugged too) WHEN SETTING BASE TIMING BECAUSE A HIGH IDLE CAN ACTIVATE MECH ADV IN DIST WHEN SETTING BASE TIMING WHICH WILL MAKE IT INCORRECT/END UP SIGNIFICANTLY MORE RETARDED THEN YOU THINK IT IS.

Also as already suggested by others dbl chk firing order and also maybe run motor at night in dark area with no lights and pick up hood and look for wires arcing ,cracked dist cap,etc.

Scott

CW,

Any updates?

Hey Tim, no update, here in Texas a little east of San Antonio we are right in the middle of a very bad drought. We have rain forcast for Sunday so I have been in the fields getting them ready to plant if it does happen. We are going to need lots of hay for next year because it looks like we will be feeding for some time this spring.
One thing by riding a tractor all day and most of the night is being able to rethink things and be damx if I can figure what is going on with the engine. As soon as I get back to it I'll post a update, two things that still get me, the wet carburator gasket and the spitting thru the carb under normal passing.
By the way, I did do a double check on everything, wires, dwell, timing advancement, hoses, and checking at night for sparks, nothing
cw

CW,since you said you checked everything then what exactly was the base & total timing and at what rpm was the total fully in at?

Scott

Finally got back to the car and we, not I, found the problem, Scott you hit it with the timing. The harmonic balancer timing mark is off about 1/2 inch, pulled #1 plug and stuck a screwdriver in it and run the piston up three times and each time the timing mark came up at the 10 degree advance mark, about 1/2 inch off. So now I have a close timing mark and it will do for a while. Scribed a new mark a 1/2 inch from the old mark and have set the timing @ 10 degress advanced and the car is running fine. I'm going to put some miles on the new engine before I tackle replacing the balancer.
How do you check to see if your balancer outer ring has turned by looking at a balancer? I have been told that the key way on the inner hub and the timing mark on the outer ring should always line up????????? A lot of time and worry and $$ went into finding this problem especially when you assume (yes I know) that this part that starts the whole timing cycle was right.
Appreciate the help an support guys
cw

Glad you got the problem solved. Sounds like you put a ton of work into the motor and now just enjoy driving it! Every time I have a problem with my 327 I tell the guys at a local garage that I want to sell the car, forget the whole thing.... But then one nice drive with everything fixed and I'm hooked again... I'm new to this sight and the guys have helped me out a ton already. Enjoy your 327!:hurray:

CW,glad to hear you got it all sorted out.

But just an fyi,if your running any kind of non GM non stock aftermarket cam(even a very mild one) they can use at least 16 deg base timing so the 10 deg your running it still very retarded.

So try 16 deg base timing to see how it responds to it,if good great but if it pings then back it off to 14 sand try that.

Look for approx 16-38 total by approx 2800-3k rpms.

Scott

I know I'll probabaly get flack for saying this, but a newer HEI setup can be easier to work on and much more effecient at delivering a good spark. They can be picked up fairly cheap. Maybe you should try one

IF the outer ring moved on the balancer, JUNK IT NOW.
Ask young Paul "65lkey" what happens when you have balancer failure....his came apart!!!
Luck nobody was hurt, nor was his car with a very frikkin nice paintjob!