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Discussion Starter #1
Good evening all,

I have a 69 GTO with a fresh-ish engine rebuild (approximately 1,500 miles) which is not running very well, especially in gear at stop lights or when reversing (almost stalls). Runs fine when given more gas in all situations.

Background:
Carb was rebuilt a few years ago (maybe 2,000/2,500 miles ago). Car ran great last summer... engine seems to be a bit 'weaker' now, can't burnout/launch like I did last year - driver side wheel mostly. Does do equal burnouts in reverse. Also has a very strong odor from exhaust.

Transmission rebuilt a few summers ago and rear end rebuilt last summer (Posi installed with 3.23 gears). Seems to shift as expected at heavy load or being a "respectable citizen" on the road.

No leaks of great concern other than in the engine bay(need to tighten valve covers etc) and a very slow rear end leak(need to check bolts etc).

Car is stored in the winter (November to April) with fuel stabilizer in the tank - tank filled to the top to eliminate condensation. Storage could be considered heated as it does not get below 50 degrees at any time.

Things I'm going to look at, assuming I am missing something which I hope someone here can help with by pointing it out. Or maybe the order in which to process them.

Maintenance:
1. Vacuum leak at carb or trans actuator line/hose.
2. Fuel pressure/pump or fuel filter issue.
3. Check all vacuum ports/lines etc.
4. Check transmission fluid level/leaks.
Things more complicated or requiring adjustments:
3. Timing issue.
4. Tuning/carb issue.
5. Transmission issue.
6. Rear end issue (not likely).

Any help is greatly appreciated.
 

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this conversation will get out of hand fairly fast....
I am just a back yard mechanic .. no schooling just 45 years of wrenchin and a couple hundred cars n truck titles thru my fingers ,,,,my newest is my 88 454 motorhome still carbureated

K I S S keep it simple simon dad would say

start with the easy stuff.. 1.. uno.. one thing at a time

time for a set of spark plugs ,,, they will give you a real eye full of how its running,.,,
and how its burning fuel
what sistributor are you running ,,,, what plug is in it now? what are the head castings? 48 16 12 13
pull 1 at a time mark the wire for now with painters tape
and felt pen for the cylinder it comes off ... they are marked on the intake runner,.,,,
a 2" piece so you can make note on the tape also if need be...
pull the plugs ,one at a time,,, put a piece of tape on each plug and label the cylinder,,,,
measure the gap record on the plug ....
gap your new ones correctly for your hei or points ....

they are probably black .wet looking .. wipe your finger in the tail pipe ,,, is it sooty black ?

post pictures of the old plugs...

sounds like a carb issue ... vacuum leak it would idle faster and run lean,,,

time to change oil also and filter with all that gas washing the cylinder walls past the rings

and fire it back up .... then we can move on ....

do you own a timing light ?
 

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Discussion Starter #3
Thanks for quick reply...

Stock type plugs (new with engine rebuild). I think gap was set.45? (GAPped for HEI) Have a plug cleaner if that helps until they can be replaced.
Pertronix ignition (HEI)
Stock distributor - New gear/roll pin with engine rebuild.
Black soot on/in tail pipes.
Stock Heads
D-port headers
Changed oil and filter today
Yes, I have a digital timing light. Don't recall initial or total time.

So if carb issue what steps do I need to take?
New plugs after 1500 miles? Or because fouled/ruined by the carb issue?
 

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Your plug gap is too wide. Need to bring it back to .035.
Pertronix is not an HEI system but a points eliminator.
 

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Runs ruff in gear at stop lights, stalls in reverse, black soot in tailpipe, runs better when you give it more gas.......

first I would do exactly what Blk judge recommends, fixing any carb problem won’t work if ignition and timing are off. Also agree with plug gap should be .35.

if no Vac leaks or other major ignition issue, what you are describing sounds like an overly rich idle circuit and or retarded timing. Probably both.

the car will idle on the idle circuit, idle holes and transfer slot and run on that up until 2500 RPM’s. This would also be when the car is in reverse.

also your idle timing may be insufficient and makes the car run rough. An idle timing of 20 to 26 say with 10 degrees from vacumn advance will give a nice smooth idle, and cool.

when you rev it up it does two things it adds centrifigal timing from the weights and springs, and about 2500 it adds in the main jets with a lot more air from the throttle plate....therefore it runs better.
Q
Nowvacumn leaks or bad or no, or clogged PCV system can mess up your mixture as well, so can flooding carb from a variety of ways.

ignition, get it right clean and tight,...then timing,...then carb mixture you will get it.

a cracked distributor cap can mess up your running as well.....stay with it!
 

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Flooding. The car ran fine last year. It sat all winter. Float sticking, needle/seat not seating. Gaskets need to "swell" a little to seal better.

Check base carb nuts to make sure they are tight and not allowing air in.

If me, seeing it runs fine when you gas on it, hammer on the car a little with some good hard open runs, and burn up the gas in the tank and get fresh gas in it. These cars don't do well when they are not run and sit all winter even if you think you have tucked them away correctly. My brother has to go through this crap with his Mopar and 6-Pack each spring. He puts in stabil-360 and fills the tank. Carbs go south and he has flooding and then has to have a shop pull them apart and clean/rebuild. He finally had enough of it this year and is now pulling the carbs and installing an EFI 6-Pack set-up.

So my money is on the carb. Yes, .032"-.035" on the plug gap.
 

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Discussion Starter #8
Thanks for all the tips guys, much appreciated...

This is what I get when think of something and I post late at night without doing any research... I should have thought of some of these ideas. :)

Didn't have time to do full timing check/adjustment today so I did an experiment (KISS). I realized the RPMs were down quite a bit from last season, timing light says 300-350 less so I bumped up the idle and she acted much like she used to last year. Sooo I'm assuming the timing is off (engine is now broken in) and I most likely have a carb issue (flooding/stuck etc).

I'm going to start from the beginning and go through each step I did after the rebuild 9plugs, timing, carb, idle etc etc). found my notes from the initial setup and testing... think I will go with one of my earliest timing settings 24 instead of 22 (where it should be now.).

Need to do family things on weekends so I'll get to this during the week..."my time" while everyone else is working... being retired is AWSOME!

Thanks for all the great ideas gents!
 

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There's a million variables here that will be really hard to sort out but here's where I'd start...
Everything folks are mentioning about timing etc are all correct, but as I understand it, this ran fine when parked?
You didn't do anything to it? So the timing hasn't changed, the components probably didn't fail.
The carburetor did sit with fuel in it all winter long.
There's your problem. Winter here is 6 months long. I fix cars for a living. Every spring, we live this. Ethanolized gas is bad jujuj. You didn't mention what you used for a stabilizer, but there's a lot of types and in my experience there's a huge difference.
I used a product called Startron. It's an enzyme based product that removes the ethanol, while adding stabilizer to the gasoline.
Sounds like you have a rich condition and I'll bet you a cup-o-coffee that you have a float problem or a blocked air bleed.
 

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Discussion Starter #10
There's a million variables here that will be really hard to sort out but here's where I'd start...
Everything folks are mentioning about timing etc are all correct, but as I understand it, this ran fine when parked?
You didn't do anything to it? So the timing hasn't changed, the components probably didn't fail.
The carburetor did sit with fuel in it all winter long.
There's your problem. Winter here is 6 months long. I fix cars for a living. Every spring, we live this. Ethanolized gas is bad jujuj. You didn't mention what you used for a stabilizer, but there's a lot of types and in my experience there's a huge difference.
I used a product called Startron. It's an enzyme based product that removes the ethanol, while adding stabilizer to the gasoline.
Sounds like you have a rich condition and I'll bet you a cup-o-coffee that you have a float problem or a blocked air bleed.
Good point... more I think about it I agree. As I recollect I realized I noticed the "idle issue" late last year (October) when I put her in reverse.

So if it's a float issue (new metal float installed 3 years ago during carb rebuild) and I set it dead-on as the instructions directed it sounds like the float isn't floating? If I take it apart I'm going to rebuild the whole thing again... wanted to get the

Sta-bil 360 is the stabilizer I used. I also used an octane booster with 93 Octane fuel (I have had mixed opinions on the use of a booster).

What steps can I take to avoid the Bad JuJu in the future - beyond Startron which I see I can get at the corner store. I would prefer not to rebuild/repair the carb every few years.

Thanks, Dan
 

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Drive it. Fuel is going to evaporate just sitting in the garage. Can lead to things sticking/clogging as sediments or other things in the fuel fall out of suspension and create problems, accelerator pump drying out, and gaskets drying out and shrinking. The Stabil 360 in the gas tank does not prevent fuel from evaporating and drying out in the carb.

If you are not going to drive it, then you should start it up and let it run for 1/2 hour each week, turning the idle up to keep oil pressure up, get the engine hot, blow out any condensation in the exhaust, and keep fuel flowing through the carb and fuel lines.

Or, pull the carb each spring and go through it to ensure all things are in order.
 

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Good point... more I think about it I agree. As I recollect I realized I noticed the "idle issue" late last year (October) when I put her in reverse.

So if it's a float issue (new metal float installed 3 years ago during carb rebuild) and I set it dead-on as the instructions directed it sounds like the float isn't floating? If I take it apart I'm going to rebuild the whole thing again... wanted to get the

Sta-bil 360 is the stabilizer I used. I also used an octane booster with 93 Octane fuel (I have had mixed opinions on the use of a booster).

What steps can I take to avoid the Bad JuJu in the future - beyond Startron which I see I can get at the corner store. I would prefer not to rebuild/repair the carb every few years.

Thanks, Dan
Probably not that the float is no longer floating, but that you have crud (dried ethanol/gas residue) holding the needle open. Pretty easy to solve. But, less easy to solve and unfortunately more likely is that you have an air bleed that is plugged with the same stuff. Trickier as those passages are TINY and often not easy to find or clean. Also, running good fuel or fuel with solvents that will get rid of this stuff will not get to it as fuel doesn't run through there, air does. Sounds like you have the ability to tear into your carb yourself. You might be in there cleaning things up. As far as what to do? I have 8 cars on the road. The number of operators in my family has dwindled, so a lot of my cars sit. My GTO sits all winter. My plow truck gets driven very little in the summer. I run a heavy dose of Startron in anything that sits. Including generators, outboard motors, lawn tractor. I don't have to mess with my carbs. I'd say it works.
You're not talking e85 right? That's a whole different ballgame...
 

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Probably not that the float is no longer floating, but that you have crud (dried ethanol/gas residue) holding the needle open. Pretty easy to solve. But, less easy to solve and unfortunately more likely is that you have an air bleed that is plugged with the same stuff. Trickier as those passages are TINY and often not easy to find or clean. Also, running good fuel or fuel with solvents that will get rid of this stuff will not get to it as fuel doesn't run through there, air does. Sounds like you have the ability to tear into your carb yourself. You might be in there cleaning things up. As far as what to do? I have 8 cars on the road. The number of operators in my family has dwindled, so a lot of my cars sit. My GTO sits all winter. My plow truck gets driven very little in the summer. I run a heavy dose of Startron in anything that sits. Including generators, outboard motors, lawn tractor. I don't have to mess with my carbs. I'd say it works.
You're not talking e85 right? That's a whole different ballgame...
And what Jim says about driving it? Some of the best advice of all!
 

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Discussion Starter #14
Mine...

No NOT using E85... Regular High Test. Can't run it all year, I'm in Northeastern Ohio. :cry:

I have to shut her down about the beginning of November. Love the Idea PontiacJim but I can't. First snow she is parked.

Yes, I've already rebuilt it once after finding a piece of cloth from a K&N filter in a jet. I'm pretty good at cleaning things so I know I can get it cleaned... I'll be looking for a rebuilt kit. Anyone have suggestions? Last time I used a Hygrade kit.

What is a heavy dose of Startron?

Oh and Jim I am using an accelerator pump made of material that is supposed to resist falling a part or deteriorating from fuel etc but I know how that goes. ;)

Thanks all!
 

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Dan - "I have to shut her down about the beginning of November. Love the Idea PontiacJim but I can't. First snow she is parked. "

PJ - Lived in CT for 31 years. Are you telling me that it snows everyday in your neck of the woods? Plenty of good days when it doesn't snow and roads are clear of snow & ice. Cold doesn't hurt a car.

Shutting your car down in November for 7 months is a choice, not a necessity. ;)
 

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Buy your kit from Cliff Ruggles. Over the counter or NOS kits aren't as good as they used to be. The accelerator pump rubber isn't set set up for todays gas
 

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Discussion Starter #17
Jim,

Yes ultimately it is a choice, there are some good days here BUT the snow melter used here is extremely corrosive. Even after the roads are dry the melter stuck to metal parts sucks moisture out of the air so corrosion grows constantly. Even if you get the dry melter stuck in a tight spot it starts the corrosion process in a matter of days.

I've spent too much time, money and sweat to expose the car to that... even though I park her she is starting to show her age, I don't think the restore done 28 years ago was done very well. Driving her in our winters would only hasten the aging process. ;)

052,

Thanks for the info. I'm on his site now. 👍
 

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I live on a state highway in Missouri and everytime the weather man sayes snow they are spraying our road with at melting slime. My new cars undercarrage looks old already. I open the garage door and a window and run her my classics for a little bit and listen to the radio (detached garage), I dont know if I do it to keep the carb clean or just for the smells and hear the motor. Frankly I like working on the motors I clean out a carb on something every year. Tiller, weed eater, chainsaw, dirt bike, four wheeler, tractor, cars, and mowers. I think its why she keeps me around. That and mowing 4 acres every week.
 

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Discussion Starter #19
I live on a state highway in Missouri and everytime the weather man sayes snow they are spraying our road with at melting slime. My new cars undercarrage looks old already. I open the garage door and a window and run her my classics for a little bit and listen to the radio (detached garage), I dont know if I do it to keep the carb clean or just for the smells and hear the motor. Frankly I like working on the motors I clean out a carb on something every year. Tiller, weed eater, chainsaw, dirt bike, four wheeler, tractor, cars, and mowers. I think its why she keeps me around. That and mowing 4 acres every week.
lol After 34 years I hope mine keeps me around for something more than just chores. ;)

Exactly! That's what they use here as well! That stuff is nasty and you can't see it on the road all the time until it's too late!
 

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Mine...

No NOT using E85... Regular High Test. Can't run it all year, I'm in Northeastern Ohio. :cry:

I have to shut her down about the beginning of November. Love the Idea PontiacJim but I can't. First snow she is parked.

Yes, I've already rebuilt it once after finding a piece of cloth from a K&N filter in a jet. I'm pretty good at cleaning things so I know I can get it cleaned... I'll be looking for a rebuilt kit. Anyone have suggestions? Last time I used a Hygrade kit.

What is a heavy dose of Startron?

Oh and Jim I am using an accelerator pump made of material that is supposed to resist falling a part or deteriorating from fuel etc but I know how that goes. ;)

Thanks all!
I live in Maine so I'm all about winter. There's no taking it on the street after the first snow in October until the roads have been washed off by spring rains in May. Just starting it will fill the bowls back up and hopefully keep the bleeds open. As I mentioned though, I do not start mine all winter long. Startron is one of several types of ethanol conditioners that use an enzyme to break down the ethanol. When I say "heavy" I mean double-triple the recommended "dose". It is safe to do so per the label.
 
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