318 missing "COLD" but not "HOT"

[dodgit]

Hi guys here's one for you. I'm talking about a 85 D150 p/u with a 318. Today I tried to start my truck and no go ! To make it short I ended up changing the coil and it Runs BUT now it's missing on #'s 6&7 cyl when it is cold and when I let it warm up everything is Ok ! In the past I have had a bad exhaust smell and not sure whether or not it is related....Heelllllllllllp.

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72 charger
85 D150 p/u
85 caravelle

[PRO]

Its possible the smell means your too rich,check the choke and choke pull off,then replace your gas fouled plugs..........PRO......

[rumblefish360]

Do you have the rotten egg smell ? Do you have a cat? ( No not the meowing kind )

[dodgit]

Yes I have a cat and it seems to be ok, I have lots of "power" when all cyl's are working..and the smell seems to be more like gas and fuel mixture (like a skidoo smell)the tailpipe is black!!!I've changed the intake manifold gasket,rebuilt the carb,all new plugs and wires,cap,rotor,valve seals,new fuel pump and now a new coil and reset the timing,today I'm going to check the compression.Maybe I have a bad valve.???
The choke seems to be ok, it is straight up when warmed up and the pull off is at 9/32" between the choke plate and carb barrel as per rebuild instructions ????

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72 charger
85 D150 p/u
85 caravelle

[dodgit]

Well guys I'm back.....
I checked my comp and they are:
#1-150 #2-165
3-130 4-150
5-150 6-150
7-155 8-170
Now I didn't no if I should have had the throttle open or not??
I checked for vacuum leaks with a propane torch and it didn't change idle or vacuum..
Another check I done was vacuum!
at-idle (750)-22in
at-2500 24in
Throttle quick snap the readings where 0 then quickly went 29in and returned to idle readings of 22in.
Also when I slowly increase throttle the engine shakes..How do I determine if it is fuel or ignition????
One more question- How much vacuum should I have at the dist advance (at idle). I have zero until I crack the throttle and at 2500 I have 25in.
This one really has me baffled so any help would be a plus

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72 charger
85 D150 p/u
85 caravelle

[rumblefish360]

I don't know what the adv. should be at idle. But were the plugs that you took out all black/fouled. The way it sounds,well, like your rich.
I think PRO nailed on the head. You said you rebuilt your carb. Perhaps the mixin screws are a little off.
Dosn't an '85 has a holley 2bbl? I ask because i don't know. Ethier way the float must be set just so.
Is the fuel pump a high volume unit? It may be getting to much there.
What do you think PRO?

[dodgit]

Hi rumblefish
You asked about the plugs,well they where a little black,BUT the tips where greyish white..The carb is carter 2bbl (BBD)which could have been replaced at sometime,(not sure)As for the mixin screws(as you put it)well I set with a vacuum guage too the highest vacuum.(I think that was right).The fuel pump is just a stock mopar replacement(nothing special)Also since my last post I read the book on how to do a comp check properly,which I hadn't done The reading changed which are as follows:
1st stroke: Total
no oil: no oil:
#1-100 170
3-90 135
5-95 160
7-95 150
2-100 155
4-95 150
6-100 170
8-110 165

Then with oil: Total
1st stroke with oil:
#1-120 170
3-95 145
5-130 170
7-130 170
2-110 170
4-105 170
6-120 185
8-110 185
These reading where taking with engine hot..
NOW what??????


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72 charger
85 D150 p/u
85 caravelle

[rumblefish360]

Hi Dodgit;
#3 seems a little low. Not to worry. You have changed everything! Just check the fuel level in the carb again to be sure.
My Magnum was the same way. Never did a invesagation deep enuff to find out. But after 3 or 4 min's it was smooth. A little longer in the winter.
Also never had a problem with plugs. I was useing an MSD to boot. I'm also a guy to keep the plugs fresher than fresh if I can. At a buck a plug, its worth the 15min to change them out.

[turbododge]

Does the engine have a heat crossover in the intake? If it does, make sure it is working and not plugged, including the parts of the passage that are in the heads.

[rather]

MY holley did that becuase the idle mixture was out of adjustment and the distributor was also damp inside which just aggrevated the situation. A simple but effective procedure for set the idle mixture screws is written in the haynes manual for our trucks Book #30040(912) Page 4a-15 last paragraph.

Sorry I don't have the time to type it all but to me it is as effective useing the propane enrichment method preferd by ther maker. For that method I will paste this qoute from a book...

This procedure should only be used after normal diagnosis has revealed no other faults, or if carburetor has been overhauled. Idle mixture adjustment requires artificial propane enrichment. A propane enrichment tool, C-4464 or equivalent, must be used to adjust idle mixture. Before proceeding, make sure that propane cylinder is adequately filled to ensure correct propane flow.


1. Remove concealment plug or limiter cap from carburetor. Refer to appropriate carburetor section.
2. Set parking brake and place transmission in Neutral position.
3. Turn off all lights and accessories, then connect tachometer.
4.0Start engine and allow to reach normal operating temperature.
5. Disconnect and plug vacuum hose at EGR valve, if equipped.
6. On models equipped with carburetor ground switch, connect jumper wire between switch and ground.
7. On models not equipped with spark control computer (SCC), disconnect and plug vacuum hose from carburetor at heated air temperature sensor, then remove air cleaner.
8. On models with SCC, air cleaner should not be removed but may be propped up.
9. On all models, disconnect vacuum hose from heated air door or choke diaphragm, then connect hose from metering valve on enrichment tool to fitting.
10. Remove PCV valve from cylinder head cover and allow to draw underhood air.
11. Disconnect and plug 3/16 inch diameter control hose at canister.
12. On models equipped with oxygen sensor feedback, disconnect electrical connector from oxygen sensor and ground connector. 13. Remove and plug vacuum hose at vacuum transducer on SCC, then install suitable vacuum pump to vacuum transducer, apply 16 inches of vacuum, and allow engine to run for two minutes.
14. On models without oxygen sensor feedback, allow engine to run for one minute.
15. On all models, open main propane valve fully. Slowly open propane metering valve until maximum idle RPM is obtained. Too much propane will cause engine speed to drop. 16. Adjust metering valve to obtain maximum idle RPM.

17. With propane flowing, adjust idle speed to specified enriched RPM by turning idle speed screw.
18. Adjust metering valve to obtain maximum RPM. If there has been a change in maximum RPM, readjust idle speed screw to specified enriched RPM.
19. Turn off main propane valve and allow engine speed to stabilize.
20.Adjust mixture screw on Holley Carburetors or screws on Carter carburetors to obtain smoothest idle at specified curb idle RPM, allowing time between adjustments for engine speed to stabilize.
21. Turn on main propane valve and adjust metering valve to obtain maximum engine RPM. If maximum engine speed differs by more than 25 RPM from specified enriched RPM, repeat steps 15 through 20.
When adjustment is correct, turn off both propane valves, stop engine and remove tool.
Install concealment plug, if equipped, then perform ``Curb Idle Speed, Adjust'' and ``Fast Idle Speed, Adjust'' procedures.

I hope this can help

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1987 Dodge D100, 2wd, 3.7 Slant Six, California Certified, Automatic A904, 2.9something rear gear, K&N Filter Charger, Jacobs Electronics Pro-Street Ultra Team Ignition sytem, Autolite Plugs #25, Basic Timing Set To 14 degrees. Chevron supreme Gasoline, Castro Synthetic 10w-30 Motor Oil, Valvoline Synthetic Rear End Oil,
American Racing Wheels AR-767 15x7, Fully Loaded Clifford Alarm System, and now at 120,700 miles

[This message has been edited by rather (edited October 11, 2000).]

[mtrv8n]

Who thought up that set of instructions? If i had that to do just to set idle, I'd get a new truck. No wonder they used to charge big bucks for tune-ups, and then get it wrong anyway.

[dodgit]

Thanks guys, I guess I will learn to live with it,until I rebuild the engine. I have been talking about this in great depth with a couple friends and we where thinking it might even be a burnt valve along with the poor comp?? Also it be maybe a bent push rod (since I changed the valve seals,without removing the heads)who knows?? Yesterday morning I noticed when I started (it was really cold out)that the exhaust coming out of the tailpipe was kinda popping (like sending smoke signals)Would this be a valve??

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72 charger
85 D150 p/u
85 caravelle

[rather]

Sorry I forgot to mention that the black smoke puffing effect when cold( other than excessive gas consumption ) was one clue that the mixture was to rich. If the propane procedure is to difficult to do or you don't have the tool the haynes manual method is not really that difficult. Just for the hell of it turn each idle mixture screw inward 1/4 turn that should make an effective change to the engine operation without cuaseing any problems.

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1987 Dodge D100, 2wd, 3.7 Slant Six, California Certified, Automatic A904, 2.9something rear gear, K&N Filter Charger, Jacobs Electronics Pro-Street Ultra Team Ignition sytem, Autolite Plugs #25, Basic Timing Set To 14 degrees. Chevron supreme Gasoline, Castro Synthetic 10w-30 Motor Oil, Valvoline Synthetic Rear End Oil,
American Racing Wheels AR-767 15x7, Fully Loaded Clifford Alarm System, and now at 120,700 miles

[dodgit]

rather-Thanks I'll try that,and yes my gas mileage really "sucks".I checked for bent push rods today and they all look fine.
Has anybody ever put water through the carb to remove carbon build-up and does it work??
I also noticed when I was looking at the pushrods that all of my exhaust valve seals where all at the top of the spring vise the bottom where the intake seals are over the valve guide and have stayed there.Is that right??
Keep the ideas coming and I'll keep trying them..Later

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72 charger
85 D150 p/u
85 caravelle