I just rebuilt a lg. journal 327 for my 69'. I got it running last Friday. That night I took it for a spin and it drove like a dream. I got in it to run to a car show on Saturday and it seemed like it was missing and running very rich. I've been trying to resolve the problem all week but so far I havn't been able to get it fixed.

Here are my engine specs... 327 lg journal, trw l2166nf pistons (about 10.5:1), opened up and port matched 186 dbl hump heads with swirl polished stainless 2.02, 1.60 valves, Isky z-25 solid cam 278 adv. dur--480 lift (2 degrees advanced), harland sharp 1.6 roller rockers (lift at about 512 before lash), team g 2" raised plenum single plane,750 speed demon, carburetor shop hei, msd wires, ac r45 plugs, th400 w/ 4000 stall.

So far I have replaced the ignition module in the hei, rebuilt the demon carb, and installed a fuel regulator. I have not changed the timing from where I set it (34 degrees all in). I am not running any vacuum advance, just the mechanical in the dizzy. The carb is clean, I did a very good job of making sure the orifices were cleaned out when I went through it. The float levels were pretty high so I installed the regulator and backed it way of 5.5lbs just trying to get the secondary float semi normal. I am almost all the way turned in on the needle and seat and the level is probably an 1/8 to 3/16 higher than I would like to see. The front level is good.

I just cannot figure out what happened over night. Like I said it ran perfectly on Friday night, and when I started it up on Saturday it was a completely different car. I assumed that a float stuck, but I believe that I may have had too much fuel pressure. I need to pull the plugs and check for piston to electrode contact, as that has happened to me before and it might explain the miss. The jets in the carb are 83 all the way around, but I dont want to change them due to the car running so good initially. I replaced the ignition module with an accell piece just to verify I was burning the fuel.

After rebuilding the carb an reinstalling I just cant get it to idle down below 1400-1500 without it just dying like I turned it off. I know that it is getting plenty of fuel. I smell like I have been bathing in it. I get a back fire through the exhaust at mid to upper rpm.

Any Ideas on what could have happened?

First correct the float levels, second the transfer slots should be open .020 on the primaries and secondaries, third 83 jets are too fat for a 327, you should be in the 69 to 72 range, idle screws out 1 1/2 turns for a starting point and adjusted with a vac. gauge with engine fully warmed up. You didn't specify which demon you have, does it have a choke, is it opening fully and not staying on the fast idle cam.

Dan E.
69 SS396 4spd. 4.10posi. x66 coupe

I believe I had too much fuel pressure and couldn't get the float levels perfect, but they are in the ballpark. I had the transfer slots set but couldn't get it to idle so the primaries are opened up now. I had this thing running for 2 to 3 hours the first night with out even smelling fuel out of the exhaust or any smoke, so I am hesitant to back off on the jets. Speed demons don't have a choke. I am starting to wonder if its ignition.

Is this your carb? http://www.barrygrant.com/demon/default.aspx?page=29&specs=29dd Stock jetting is 76-84. Does your carb have that Idle-Eze feature? That would get your transfer slots back to the proper size. Don't use fuel pressure to adjust float level. Separate adjustments for that. Did you check for a heavy float? They can leak and start filling with fuel and get too heavy. Probably could use more timing, too. Vacuum advance is very important for a street car. Piston to electrode contact with 10.5:1? Are these extended tip plugs?

Could the carb have a bad power valve?

I didn't get a chance to work on it today, but I plan on getting after it this week.

I believe that is the right carb. I would have to look at it to figure out the part number though. The needle and seat is screwed in to the point that I wont be able to get it backed out if I go any further, so I'm not sure of any other way to lower the float. The float is the neoprene type and I haven't heard of those failing, but it is a possibillity.

Just rebuilt the carb, and I installed a new power valve. Runs the same as before I rebuilt it. I hate to change much, I just want to figure out what changed. Its like someone swapped motors with me overnight.

You probably fouled a plug...83 front and back is huge. I have a 600 hp big block and run around 79 85 or so...(Can't remember exactly) Pull some plugs and take a look.....

As long as you have 83 jets, it isn't going to run properly; that's WAY rich. It'll be a lot happier between 68-72.

:beers:

Something else to look at in regards to the statement that you cant get it to idle less then 1500 or it shuts off.... when it was rebuilt did you use a Holley kit or a Demon kit? Was the gasket between the main body and base plate replaced? If you used the Holley kit and this gasket was replaced you'll need to get a Dmeon kit and use the correct gasket as it could be blocking part of the idle passages off.

Also as mentioned the 83 jets on both ends are going to be way big if it still has the power valve in it. The 750 Speed Demon is going to be big for that engine as well since it flows over 900 cfm and normally we will use 575's How much timing does the motor have in it at idle?

I was running this exact same setup on this motor before rebuilding it with better heads and better cam. I went to 76's in the primary side and got some nice red glowing headers out of it, 83 is what it wants. I threw on my ole reliable holley that I have had for 20 years (haven't had to ever touch it). I have been busy and I haven't had time to tear it back apart yet. One thing I want to point out is that I think this is one of the very first 750 speed demons, no idle eze and bought when I first heard of demon carbs.
I brought the total timing up to 36 with a 750 holley, and it runs great. One of these days I will take a better look.

Thanks, Ryan