304 Strong exhaust smell

Paden

New member
Hey Guys,

I bought a great 71 800b 304 6 months ago. When I purchased it, it ran great, started right off every time without touching the gas pedal. I’ve driven it 500 miles or so over the 6 months. It’s been more difficult to start as of late, I’m using a battery charger to help and it finally kicks off. I live in CA so not sure the cold is the issue with starting. The idol is terrible, almost stalls even when warm. The last few times out it died at every stop. The Amps gauge is dancing like crazy. I had a guy pull up and say “cool ride but it stinks like hell” no smoke, just a very strong smell. Not a normal exhaust smell x10.

I want to do my own work and not drop it off at a shop. I’m guessing the fuel is not burning completely because of the smell, but honestly I don’t know. I run premium gas in it, the oil has been changed, put a new battery in. I’ve got new plugs and wires on the way. If you guys have any other areas to start with the search I’d appreciate the advice.
 

Scoutboy74

Moderator
Congratulations on your purchase and welcome to the forum. I have some thoughts for you. First, these engines do not require hi-test (premium) fuel to run optimally. They are low compression, low-revving, asthmatic breathing beasts of burden. With spark and fuel systems in good working order, they will deliver their utmost performance on regular grade fuel with boring consistency. Is there any way you could be more specific RE "amps gauge dancing like crazy"? Perhaps a link to a youtube clip of this would be instructive. Pictures from multiple angles under your hood with the air cleaner canister out of the way would also be helpful. For anyone to really provide any meaningful analysis and advice for you, we first have to know what components are in place atop your engine. If you are unable to provide these specific component details, this is where quality pics and/or video can do your speaking for you. There are a number of us on here who can make positive ID of things and also potentially point out issues simply by being able to hook our peepers on them. We need to know what carb you have, not only the brand of it, but also the model and the list number. We need to know what type of choke system it has, if at all, and whether or not it is functioning properly. The seasons have changed since you first started driving this rig and even though you're somewhere in CA, the ambient low temps have certainly dropped at least a little.
 

int77345

Member
is your high idle on your choke working ? to me it sounds like its idling to low, on a cold engine.

once fully warm adjusting the idle mixture i think would help also. have you ever done it before ? if not its easy we can walk you through it.

lastly wonder if the carb is a little gummy from only being driven 500 miles in 6 months ? i dont know if 6 months is long enough to cause a problem or not.
 

1975IH200

Member
It looks & sounds like the engine is idling cold with the choke fully open, causing it to idle slowly and on six cylinders.

Learn the operation of the manual choke....and check/adjust fast idle with choke closed.
Adjust curb idle at operating temp. (choke open)
Then tune up the engine as necessary.

EDITED for Typo.
 
Last edited:

Scoutboy74

Moderator
I see the carb is a list 4412 500cfm flavor. I'm assuming this was on the truck when you purchased it and not something you installed? You won't like what I have to say, but I'm going to tell you flat out that's the wrong carb for your 304. Way too big. Those 4412 versions are more geared towards engines that can turn high revs and are running them consistently, such as in circle track racing. The carb you should be running will look almost identical to that one, but it will be a list 80350 or 0-7448. Those are 350 cfm rated and calibrated much closer to what would have been on your engine originally. Like the others have stated, your idle speed sounds like it's down around 400 rpms. Too low. Should be about 650 for manual trans and 750 in Park for auto. If you suspect that your battery isn't being replenished while driving, you can buy an inexpensive digital multimeter. Probe across the battery posts with it set to measure voltage on the lowest scale while the engine is running at a proper idle speed. You should be seeing over 13 volts even up to 14.5. If you're only seeing 12 volts, then you have a charging issue. Back to your carb though, both for your long term enjoyment of the vehicle and for coaxing out what precious little fuel economy these engines can give, I don't see you ever hitting the mark with that particular carb.
 

Paden

New member
is your high idle on your choke working ? to me it sounds like its idling to low, on a cold engine.

once fully warm adjusting the idle mixture i think would help also. have you ever done it before ? if not its easy we can walk you through it.

lastly wonder if the carb is a little gummy from only being driven 500 miles in 6 months ? i dont know if 6 months is long enough to cause a problem or not.
Int, thanks for your advise, I've never adjusted anything on a carburetor before, I used youtue and figured out how to do it, all the items I ordered for the tune up arrived late Saturday. I'll be working on it this week.
 

Paden

New member
I see the carb is a list 4412 500cfm flavor. I'm assuming this was on the truck when you purchased it and not something you installed? You won't like what I have to say, but I'm going to tell you flat out that's the wrong carb for your 304. Way too big. Those 4412 versions are more geared towards engines that can turn high revs and are running them consistently, such as in circle track racing. The carb you should be running will look almost identical to that one, but it will be a list 80350 or 0-7448. Those are 350 cfm rated and calibrated much closer to what would have been on your engine originally. Like the others have stated, your idle speed sounds like it's down around 400 rpms. Too low. Should be about 650 for manual trans and 750 in Park for auto. If you suspect that your battery isn't being replenished while driving, you can buy an inexpensive digital multimeter. Probe across the battery posts with it set to measure voltage on the lowest scale while the engine is running at a proper idle speed. You should be seeing over 13 volts even up to 14.5. If you're only seeing 12 volts, then you have a charging issue. Back to your carb though, both for your long term enjoyment of the vehicle and for coaxing out what precious little fuel economy these engines can give, I don't see you ever hitting the mark with that particular carb.
Scoutboy, Thanks for your response, you're correct about the carb, I assume the PO installed it. I understand what your saying about the carb being too big. Looking at the price of the carb your suggesting made my decision easier, were going fuel injection. What I'm going to do is increase the idle and change the plugs and wires, I bought a new coil and a pertronix kit for the distributor just to be able to drive it with confidence that its not going to have a problem until the fuel injection kit arrives, I was told in takes 8-10 weeks.

Thanks for addressing the charging issue. I have a multimeter and I'll give it a go. I apricate the help.
 

int77345

Member
excellent adjusting either idle is simple ! bet that alone gets your a smoother running engine.

when you pull out the plugs check em out good, see how black they are or if any are fouled.

Pertronix is easy to install also. pay attention to where your rotor is pointing if you remove your distributor, re install distributor with rotor pointing the same way it came out.
 

Paden

New member
excellent adjusting either idle is simple ! bet that alone gets your a smoother running engine.

when you pull out the plugs check em out good, see how black they are or if any are fouled.

Pertronix is easy to install also. pay attention to where your rotor is pointing if you remove your distributor, re install distributor with rotor pointing the same way it came out.
Today I installed new plugs, wires, air filter, cap, rotor, battery, Pertronix and coil, I did not remove the distributor. I was planning to adjust the carb but it will not start, I hooked a battery charger up and the best I could get was less than a 1/4 turn of the motor and that was in boost mode on the charger. I'm loosing volts from somewhere, I can hook up the charger and get 12 volts, shut it off without touching anything and plug it in again and be at 11.5 in 10 min. It would start before I did everything today so I might have made a mistake.

The plugs were very bad, I'll post some pictures but they looked terrible to me. The Holly distributor has a keyed shaft so the rotor can only fit on in one direction so I think I got that right, I hooked up the starter and the radio condenser along with the red wire to the + side and the black to the - side. I gapped the Pertronix with the clear piece that came in the packet. I don't have enough power to turn the motor over for some reason.
 
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