What did I forget? I'm doing something wrong and I can't figure it out

[quietdad]

69 Roadrunner 383. Getting it out of hibernation and after putting in a freeze plug and a new carb (repleced Edlebrock 600 with an Edlebrock 750) I'm trying to get it tuned. Bone stock except for the carb and maybe a mild cam (never had it opened, but it sounds like that) I cant get a tune on it. No matter what I do it sounds good idling in the driveway and the throttle responds ok, but the minute I put it under load it pings to high heaven, almost like a low octane fuel issue, which I know is not the case. I've adjusted the valves, set the timing and I have the carb right with the "instructions" and tuning with a dwell/tach and such. Could it be starving cause the bigger carb wants more fuel than the stock fuel pump want's? Gonna replace the metal line with a rubber one tommorow just in case but I'm getting crazy on this. I've been doing mopar motors for a long time and well, I've never been this stupid, or maybe I've just been really lucky.

[rumblefish360]

Getting it out of hibernation

Theres the problem. Gas went south a bit. Try new gas or feed it some race fuel. Thats what I did when I took my car out from under the tarp.

[dave571]

It could also be carbon build up. Try spraying combustion chamber cleaner in the carb while running.

Another good cleaner is water. Use a mist spray bottle. Spray a mist over the carb(with the car running at idle), so it get's sucked in. Steam cleans the inside of the engine. Perfectly safe, as long as you use the mist method. Don't pour water down the intake.

Modern induction system cleaners do the same thing, simply suck the into the intake through a vacuum line(manifold vac, not port)

[Larry S.]

You might also check to make sure the advance mechanism in your distributor is working freely.

[AceVeres]

not trying to doubt you dave, but is the mist method really safe--any second opinions? i always figured that water and engine don't mix. if so, how many sprays with the bottle?

[polarapete]

Yes it really does work! I have used this method several times to clean out carbon. A little goes a long ways.

Actually, GM used this on the turbocharged Olds 215 V-8 about 1963 as a means of preventing detonation under boost.

[6pakman]

the man is right. absolutly right!!

[dirty dan]

All the previosous i deas are good ones here is some more fuel for thought. Ihave seen this with cars that have spent a long time in a holding patern. Pull the float assem; from the gas tank. I know it sounds like work . but I have seen them 98% cloged with nastyness and still run good in the drive way. I dont know how long yours has been off it`s feet but it may pay to clean it out any way.

[quietdad]

Update on the car. Watered the carb, put a can of "miracle" cleaner in the gas tank even borrowed a distributor thinking mine wasnt advancing....
Nuttn.....

Being I had just done an oil change, using a 30W I tried again going to a 40w just cause its what I had and I threw a Quart of Marvel Mystery Oil in the crank just to loosen it it up. Well, It must have been a gunked up lifter cause all's well again

Now lets see what else I can break..........

[gsmopar]

Everything sounds good to me, but there seems to be a smoking gun in your description that we might have missed.

You mentioned that you put on a new Edelbrock 750. When those carbs first came out (yours may have sat on the shelf a few years) they came with an ultra restrictive fuel filter right inside the fitting for the fuel line. For $hits and grins, pull out that screen filter and try again. Be sure that you're running a inline filter elsewhere in your system.

Let me know if this works!!!

Later,

Greg

[fourspeedlarry]

I noticed that you did some work on the freeze plugs, which means you probably moved the sparkplug wires. Follow them to make sure they are connected correctly. I have seen where 3 and 5 are crossed and it won't backfire - but would run rough.
Good luck.

[quietdad]

The screen was the FIRST thing to go on the carb. Never touched the car. I also replaced the hard, kinked, steel fuel line with a new hose and a new filter when I put the carb in. Freeze plugs went in without a spark plug wire being removed.

Again, it seems my problem was a bad/gunked up/possessed lifter cause once I got the right oil and cleaner in it the car came to life.

Debating now to throw a new set of lifters in it anyway but we'll see where that goes.

[fourspeedlarry]

Glad you figured out your problem. Seems like you enjoy tinkering with engine. If your wires aren't 8mm - you might want to replace them. The biggest improvement I made to mine was to install the Taylor 8mm wires. Even when I put in new plugs - it really didn't do much until after I upgraded the wires. If you have already done this - great.

Enjoy cruisen.

[quietdad]

I don't know if I "enjoy" tinkering, but I was a mechanic/wrecker operator (5 ton) with the Marine Corps (2 active , 8 reserve) and used to fiddle/race a home grown hemi 68 Sattelite (mid 11:00s) and this Roadrunner is my mid life crisis. If I'm gonna own it, I'm gonna drive it and If I'm gonna drive it, it's gonna be the best it can be (wait... thats Army....) and I can't see giving the 20 yr old APEX Tech "mechanic" who ponders how to find a 69 Roadrunner in his computer and where to hook up the comp to the car the $$ for something I can do myself. Besides, when YOU do it, YOU know what the car is and what it can do. There's no finger crossing....

Current car is "stock" 383 with only 8mm wires, 750cfm carb, adjustable rockers and a cam (I think....unverified, but sounds/runs like) replaced. Being a #s matching car I'm doing my best to leave it alone, but we'll see.......