Carb tuning - Starting
12-16-2013, 05:19 PM
#1
Staging Lane
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Carb tuning - Starting Ok guys so this is my first carb motor I've owned other than my karts that I race, heh!
So there are a few things that I've noticed and maybe it's in the carb tuning, wrong carb for the motor, or something unrelated to the carb all together. Any input into the following things would be appreciated.
1. Cold starts. In the summer, 2 pumps of the gas it it seems to fire up just fine. When it's cold outside or sometimes in the summer weather it takes 5-10 and it takes a while to crank over.
2. Hot starts. Drive the car for 20min, say to Subway to get some lunch. Now just run in to grab a sub and when you come out it's not really wanting to crank. Or it will, but you just gotta crank it a few times and give it a little gas.
3. The smell. This is also my first classic car, it's a 68 Camaro. Now this might not have anything to do with the carb, maybe it's just the exhaust but a 5min drive and anywhere you walk into they'll be able to smell the fumes.
Are these all normal things that you just have to deal with in a carb motor? A couple of these reasons are making me really want to do an LS swap and go fuel injected haha
The car is going to be used for weekend/nice weather, track days/time trials, and autocross. The wife loves it too and would like for us to take it out more but we don't always want to smell like exhaust at dinner! haha
Thanks in advance!
So there are a few things that I've noticed and maybe it's in the carb tuning, wrong carb for the motor, or something unrelated to the carb all together. Any input into the following things would be appreciated.
1. Cold starts. In the summer, 2 pumps of the gas it it seems to fire up just fine. When it's cold outside or sometimes in the summer weather it takes 5-10 and it takes a while to crank over.
2. Hot starts. Drive the car for 20min, say to Subway to get some lunch. Now just run in to grab a sub and when you come out it's not really wanting to crank. Or it will, but you just gotta crank it a few times and give it a little gas.
3. The smell. This is also my first classic car, it's a 68 Camaro. Now this might not have anything to do with the carb, maybe it's just the exhaust but a 5min drive and anywhere you walk into they'll be able to smell the fumes.
Are these all normal things that you just have to deal with in a carb motor? A couple of these reasons are making me really want to do an LS swap and go fuel injected haha
The car is going to be used for weekend/nice weather, track days/time trials, and autocross. The wife loves it too and would like for us to take it out more but we don't always want to smell like exhaust at dinner! haha
Thanks in advance!
12-16-2013, 05:30 PM
#2
10 Second Club
You are used to cars with catalytic converters, so any "old car" without cats (or newer ones that removed them) has that "gas smell".
You can (and will need to) tune the car better....check the timing, adjust carb, and you could even add a fragrance to the fuel as a last resort
What flavor the little lady like....LOL 
http://www.amazon.com/s/?ie=UTF8&key...l_66w8z9zlia_p
You can (and will need to) tune the car better....check the timing, adjust carb, and you could even add a fragrance to the fuel as a last resort
What flavor the little lady like....LOL http://www.amazon.com/s/?ie=UTF8&key...l_66w8z9zlia_p
12-16-2013, 06:53 PM
#4
Well, the main issue is tune, the closer to 14.7 at cruise the better but a cam that has plenty of duration just doesn't burn completely. Another issue is a old car with poor sealing in the trunk and other area with dumped exhaust will always cause issues of fuel smell.
I deal with it and do what I can to make it the best I can, but I always have that hot rod car smell.
Tail pipes are the best thing that can help. If you have them then the trunk area probably has bad seals as well.
This is all off the top of my head, hope it helps.
I deal with it and do what I can to make it the best I can, but I always have that hot rod car smell.
Tail pipes are the best thing that can help. If you have them then the trunk area probably has bad seals as well.
This is all off the top of my head, hope it helps.
12-16-2013, 07:15 PM
#5
Staging Lane
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Timing is something I didn't think of, I'm not use to dealing with this kinda stuff, fun though! haha!
With that being said here is some info that might be helpful.
Here is the motor 350 SBC:
Eldelbrock TEC 200 Aluminum Heads
COMP Cam 12-612-5 Solid Lifter Cam
Roller Rockers
Ceramic Coated Headers
Holley Competition 750 cfm
MSD Ignition
OEM Forged Crank
OEM polished rods
TRW pistons w/ floated wrist pins
Balanced rotating assembly
ARP Head Bolts & Fasteners
And a pic:
Also for timing this sticker is under the hood, was there when I got it earlier this year.
With that being said here is some info that might be helpful.
Here is the motor 350 SBC:
Eldelbrock TEC 200 Aluminum Heads
COMP Cam 12-612-5 Solid Lifter Cam
Roller Rockers
Ceramic Coated Headers
Holley Competition 750 cfm
MSD Ignition
OEM Forged Crank
OEM polished rods
TRW pistons w/ floated wrist pins
Balanced rotating assembly
ARP Head Bolts & Fasteners
And a pic:
Also for timing this sticker is under the hood, was there when I got it earlier this year.
12-16-2013, 07:59 PM
#6
Forgot to mention, if cold starts are a issue you want to solve and don't mind losing a couple HP, the carbs with a choke are made for that. I have thought about getting one for winter and one that I ready have would be for the rest of the 11 months in Texas that isn't cold.
12-17-2013, 05:18 AM
#7
You really shouldn't come out of the car smelling like exhaust. Probably bad seals like Zones said. Also check for exhaust leaks.
I see breathers on each valve cover, does the car have a PCV hook up? That will make a difference.
Cold starts, a choke helps tremendously. In fact, if you have a chokeless carb and it isn't hard to start when cold then you are almost certainly tuned too rich. That could contribute to the smell problem.
Having grown up with carb'd vehicles I can tell you each one seems to want a different combo of throttle movements to start. What often works when cold is two pumps to the floor then on the second pump hold the throttle half way open. When hot, maybe just open the throttle half way when cranking. Too much gas can be as bad as not giving it any. Getting the right tune will make all the difference. Considering getting a wideband O2 sensor or taking it to someone who has one.
I see breathers on each valve cover, does the car have a PCV hook up? That will make a difference.
Cold starts, a choke helps tremendously. In fact, if you have a chokeless carb and it isn't hard to start when cold then you are almost certainly tuned too rich. That could contribute to the smell problem.
Having grown up with carb'd vehicles I can tell you each one seems to want a different combo of throttle movements to start. What often works when cold is two pumps to the floor then on the second pump hold the throttle half way open. When hot, maybe just open the throttle half way when cranking. Too much gas can be as bad as not giving it any. Getting the right tune will make all the difference. Considering getting a wideband O2 sensor or taking it to someone who has one.
