# 1970 GTO won't start after mild tuneup.



## bwayney (Apr 27, 2019)

Greetings, 

This is my first time posting. I have an original 1970 GTO with the 400 engine. The engine was running fine until I changed some parts out.

I replaced the thermostat, and the gasket. I replaced the fuel filter, and I replaced the spark plugs. I did not touch the distributor/cap, or anything else. 

The engine will turn over, but not start. The fuel filter will fill with gas clearly, so it's getting fuel. I even tried dumping some gasoline in the carb, but that did nothing. I double checked that the spark plug wires were connected, and they seem to be fine, though maybe the terminal is too far in the boot after I took them off??

I'm at a loss, and I only have basic tools (nothing to test electrical or power). I'm thinking at this point of just replacing all of the spark plug wires because they are fairly old. 

Any guidance would be appreciated.


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## geeteeohguy (Feb 2, 2008)

I suspect you messed up the firing order when you did the plug install. Verify that first. Also, you can pull the coil wire from the coil tower and hold it in place about 1/2 inch from the tower and have someone crank the engine to verify that you ARE getting a spark.


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## RMTZ67 (Mar 12, 2011)

bwayney said:


> Greetings,
> 
> This is my first time posting. I have an original 1970 GTO with the 400 engine. The engine was running fine until I changed some parts out.
> 
> ...


 These cars pretty much only need fuel and spark to start. so since you dumped fuel down the carb with no effect, check for spark at the plug end. remove a spark plug wire and connect a screwdriver into the plug boot end. Then hold it close (1/4")to metal on the on the engine,then have someone crank the engine and look for the spark jumping from the screwdriver to the metal. Be sure not to touch the metal on the screwdriver. If you have no spark look at the plug wire connections on your distributor or check your coil by using the same method.


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## bwayney (Apr 27, 2019)

I made sure I did one sparkplug at a time, so I know the order is not messed up. 

Unfortunately, I live alone and don't know when I would be able to have someone come by and help start the engine while I check for spark.

I have a feeling it has to do with the spark plug wires at the plug ends. Some of them did not come off easily and I really had to tug on them, which may have affected the terminals. 

But, even if a few spark plug wires were loose, the car should still be able to start with at least, lets say, 5 spark plugs and wires/correct? it would just run very poorly?


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## RMTZ67 (Mar 12, 2011)

bwayney said:


> I made sure I did one sparkplug at a time, so I know the order is not messed up.
> 
> Unfortunately, I live alone and don't know when I would be able to have someone come by and help start the engine while I check for spark.
> 
> ...


 If your cars in a garage close the door shut the lights and look for spark. Or set the screwdriver wire set up higher and stand outside the car while you crank and you may see the spark. Or wait till evening. Abad wire or two will run bad or may not start and backfire somewhat.


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## Lemans guy (Oct 14, 2014)

It is easy to install boots not all the way......you can re-Pull each boot one at a time and reset,..you should here and feel the click as the boot seats....just do one by one.

Also if your new spark plug gap is too wide it will cause a hard start, make sure you use a wire gauge spark plug gapped....if unsure of the gap regap....too wide and it will not crank easy


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## pcguy (Jul 7, 2014)

I'm guessing power connection to the coil. It would be easy to check with an ohm/volt meter. There are cheap ones, like $5, at Harbor Freight...


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## BLK69JUDGE (Jun 10, 2010)

https://www.walmart.com/ip/IN-LINE-...A6CIuFXnyhsR_22NrJaWv7yDZcOfow9BoCjFoQAvD_BwE

Hello ... and welcome 
I am in favor of doing 1 thing at a time if I am not confident in something ...
and just doing plugs and trying to restart is a smart idea ...

so the plug wires were tough to pull off eh ... we always like to SPIN the boot to break it loose b4 pulling it off or even to try n pull em off... if they are tuff to pull and the ones you think you may have had issue with put the light on that wire maybe first
no spark ?? move to another plug wire

DO NOT PUMP THE GAS pedal 

I would check for spark 1st with the above tool

then we can move on ... since you have fuel to the carb it sounds like.... and it ran b4
the plug change ...
this is your buddy ... I use it on my lawn mower ... chain saw ,,, neighbors rigs etc ....weed wacker or your GTO .... I have the harbour freight ones napa auto zone ...sell em too . for under 10.00 

built cheap ... but it sure is a time saver ....


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## RMTZ67 (Mar 12, 2011)

bwayney said:


> Greetings,
> 
> This is my first time posting. I have an original 1970 GTO with the 400 engine. The engine was running fine until I changed some parts out.
> 
> ...


 Just curious, did you figure out your issue?


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## bwayney (Apr 27, 2019)

Sorry for the lack of response,

I never ended up getting it running, even after replacing the plug wires. I brought it to a reputable shop, and they said they were not able to get any spark period. They are going to replace the condenser, points, rotor, and distributor. They also are going to look into the timing. 

I will keep you updated.


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## pontrc (Mar 18, 2020)

I hope they are not shotgunning you b,could be as simple as no power to coil or bad coil don’t know about having distributor replaced , be careful


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## Mine'sa66 (Oct 30, 2019)

bwayney said:


> Sorry for the lack of response,
> 
> I never ended up getting it running, even after replacing the plug wires. I brought it to a reputable shop, and they said they were not able to get any spark period. They are going to replace the condenser, points, rotor, and distributor. They also are going to look into the timing.
> 
> I will keep you updated.


Condenser, points, rotor. All need to be replaced periodically. The whole distributor? Are you sure they didn't say distributor cap? Any of those could cause a no spark situation. They didn't all fail at once though. I am in the business, so I understand if they're looking at a bunch of old stuff and wanting to start with known good parts. As mentioned, these are the wearing parts so do need to be replaced periodically. Hopfully they get to the crux of the matter quickly.


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## LATECH (Jul 18, 2018)

These old cars are amazingly simple. Any Garage should be able to figure it out in around an hour , more likely less.

Its not like it has a computer or something. Wow.


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## pontrc (Mar 18, 2020)

LATECH said:


> These old cars are amazingly simple. Any Garage should be able to figure it out in around an hour , more likely less.
> 
> Its not like it has a computer or something. Wow.


It would probably take them that long to try to find the computer terminal under the dash


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## bwayney (Apr 27, 2019)

Yeah sorry, meant to say cap!

I definitely don't believe they all failed at once, and neither does the shop. Just part of the rest of the tune up and one of them potentially being the culprits.


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## LATECH (Jul 18, 2018)

look for a short in the lead from the distributor to the coil.


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## Mine'sa66 (Oct 30, 2019)

LATECH said:


> look for a short in the lead from the distributor to the coil.


Yep, and follow it down to the starter solenoid. Moving things around might've shorted/opened it.


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## LATECH (Jul 18, 2018)

I had a guy put points in a chevy years ago. He disturbed the lead wire to the coil(inside the distributor) and the rotating parts chewed through it , shorted out, and the car would not run.


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## BLK69JUDGE (Jun 10, 2010)

bad 10.00 condenser ... the key got left on ........toasted points...
I hope you have looked into new mufflers
because
when it starts up all the fuel in the exhaust is going to light off and make a nice backfire ,,,,
and might blow a muffler or 2 at the seam ,,,,

st


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## bwayney (Apr 27, 2019)

Out of curiosity, after everything is running smoothly and the tune up is complete, what performance mod would be my best bang for the buck? It's a 400 engine with edelbrock heads, and a Holley double pumper carb. Everything else is stock.


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## BLK69JUDGE (Jun 10, 2010)

433 's


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## PontiacJim (Dec 29, 2012)

bwayney said:


> Out of curiosity, after everything is running smoothly and the tune up is complete, what performance mod would be my best bang for the buck? It's a 400 engine with edelbrock heads, and a Holley double pumper carb. Everything else is stock.


Exhaust. RA cast iron re-pop exhaust manifolds, 2 1/2" duals.


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## bwayney (Apr 27, 2019)

BLK69JUDGE said:


> 433 's


What do you mean by this?


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## PontiacJim (Dec 29, 2012)

bwayney said:


> What do you mean by this?


LOL, you need to get out more often. Any Pontiac enthusiast knows what 4:33's are. They are the factory mandatory rear axle gear ratio on the 1967-'68 Ram Air powered GTO's, and optional after that. All out racing gear and not great on the highway. Will wake up any engine due to the acceleration factor they provide. So cheap means to go fast, but gas mileage is non-existent, uncomfortable RPM's on the highway, adds additional wear to the engine due to use of hgher RPM's at lower road speeds, may whine, probably will have traction woes, but...........your car will scream when you can hook-up.


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## Mine'sa66 (Oct 30, 2019)

bwayney said:


> Out of curiosity, after everything is running smoothly and the tune up is complete, what performance mod would be my best bang for the buck? It's a 400 engine with edelbrock heads, and a Holley double pumper carb. Everything else is stock.


If you changed the heads/intake/carb, but didn't get a cam to go with it, you will probably gain one heck of a lot from that.
As mentioned, freer flowing exhaust will help a lot. The RA manifolds are a great choice. Of course headers are going to give you the best flow, and they're so darned easy to install on a Pontiac (sarcasm font). Before you change the cam, you'll need to decide what you're going to do for exhaust because that should be taken into account when you select your cam.
4.33 gears will feel like +100 HP, but you only want to go there if you're wanting to be in "on" mode all the time. Particularly if this is an automatic. You will be screaming RPMs just to go 60mph.


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## bwayney (Apr 27, 2019)

The car has the 4-speed manual close ratio. I mostly drive this car on the streets, so RPMs won't bother me. Where would be a good place to find 4:33 gears? Ames performance doesn't seem to have anything. I'm very interested in a cam as well. What cam would you recommend with the performance mods it currently has? I would have a shop install the cam.


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## pontrc (Mar 18, 2020)

I would go after a ram air spec cam first and try that don’t worry about the 433s


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## bwayney (Apr 27, 2019)

So after completing the tune up, they are able to get spark just fine and dandy but they are having a fuel issue now. They believe its my Holly carb.

They can either rebuild it for $350 dollars, or we can put on a new one. They are recommending a Holly 4777 650 CFM. My question is, if I'm going to spend $500-600 on a new carburetor, is this my best option for performance? Or is there something better you would recommend?


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## Lemans guy (Oct 14, 2014)

I would check out Quick Fuel Technology carbs....Holley owns quick fuel, it is almost identical only much more tunable.

their 650 street brawler carb is like $370 ,...you can buy direct from factory or JEGS, summit whatever....when you have a QFT you can curve the fuel mix, but mainly if you are having any idle problems the air bleeds can be changed with a screwdriver.

you have to have a shop that knows how to do it, but easily done. Check them out.


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## pontrc (Mar 18, 2020)

What did they determine about the no spark issue and if you don’t mind what did that cost you?


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## O52 (Jan 27, 2019)

If the engine is stock, get rid of the double pumper and put the quadrajet back on for a smoother, better running car. The Q-Jet was good enough for the Ram Air IV so it will do the job even if you put a big cam in your engine. A Q-Jet rebuilt by someone who knows what they're doing will run you about $4-500, but is well worth it. 

Unless you're driving on the track all the time 4:33s are a little extreme. With a 4 speed close ratio you more than likely have 3:90s now. (That is if the close ratio transmission came with the car originally) and thats close enough to having 4:33s. 
3:55s would be a great all around gear set for highway and street driving and will work behind the close ratio trans.


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## lust4speed (Jul 5, 2019)

Am I the only one that puckered up when he said the shop wanted $350 to rebuild the Holley? Maybe I'm out of touch but that seems terribly high.

650 CFM is a nice mother-in-law carburetor, but going the wrong way for performance. Maybe something in the range of a Holley double pumper -- oh wait!

Car probably came with 3.90's from the factory, but I've seen quite a few 3.55 special order rears. Pretty high ratio for performance work with a close ratio trans. Figure the 3.55's and close ratio is about the same first gear ratio as a wide ratio trans with 3.08's.


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## pontrc (Mar 18, 2020)

lust4speed said:


> Am I the only one that puckered up when he said the shop wanted $350 to rebuild the Holley? Maybe I'm out of touch but that seems terribly high.
> 
> 650 CFM is a nice mother-in-law carburetor, but going the wrong way for performance. Maybe something in the range of a Holley double pumper -- oh wait!
> 
> Car probably came with 3.90's from the factory, but I've seen quite a few 3.55 special order rears. Pretty high ratio for performance work with a close ratio trans. Figure the 3.55's and close ratio is about the same first gear ratio as a wide ratio trans with 3.08's.


That’s why I was wondering about the tune up,get b out of there before he has to get a 2nd mortgage to get this thing running


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## bwayney (Apr 27, 2019)

I'm definitely not very experienced with carburetor-ed engines, but here's what I believe the shop said they did:
-New Taylor plug wires
-New cap and rotor
-New points and condenser (But they went with some sort of electronic system which will allow me to never have to worry about replacing the cap and rotor???)
and a few other things that I can't remember. They were estimating around $500 for these items which included labor.

With a new carburetor (close to $600), and install, they were guestimating around $1300 for everything out the door. 

I don't have the original carb that came with the car, I was just told it was a holly double pumper, but they were saying that it wasn't actually a double pumper due to it having vacuum secondaries or whatever. Clearly I don't know much about these lol.

If a 650 CFM is a "mother in law" carb, what would be the best performance carb for a mostly stock 400, with only edelbrock heads. (I might want to to do exhaust in the future). My mechanic raved about Q-Jet carbs, but said they don't make them new anymore, and I obviously don't have the original.


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## O52 (Jan 27, 2019)

Millions of Q-Jets were made. And there are basically only two sizes. 750 and 850 CFM and two versions, Chevrolet /Cadillac (side fuel inlet) and Pontiac/Buick/Oldsmobile (front fuel inlet). They were used on 230 cubic inch six cylinders through 500 cubic inch Cadillacs so are very versatile. Over the years Q-jets were continually improved and adapted to operate with on board computers. With all that being said they are still out in the market place as used units. But...
Do not buy from a parts store, or Rock Auto or catalog stores. They will sell you a generic Q-Jet that went through the rebuilders assembly line. There are individual rebuilders out across the country that will custom build to your engine specifications. Here are a few. 

ourservices.html








Mountain Man Fuel Systems


Carburetors, Rebuilding Service, Parts, Kits, Electric Choke Thermostat, and more & Fuel Injection Shop Hackett Arkansas



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Cliff Ruggles is considered one of the best Q-Jet people in the business. He no longer builds them but has a website, parts store and forum just for the Q-Jet. He will gladly give you advice as to what you need as will the other builders.



Cliffs High Performance Quadrajets – Quadrajet Rebuild Kits, Cabruretor Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning


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## pontrc (Mar 18, 2020)

I’m sorry bwayney I know you probably don’t have the knowledge on these cars and I certainly don’t want this shop to take advantage of you.Do you any club or car cruise in buddies to help you out on the goat? I Agee totally with 052 and lemans guy on the carb issue I would try to locate a Q jet if you could. But get a “car guy “ to look and help you out. We here at the forum are happy to give you suggestions but I think this shop is not getting you know where but filling there cash register


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## Montreux (Mar 8, 2009)

Yep, need to find a club! Check GTOAA for a local chapter, or start talking to guys at car shows with similar vintage cars. You'll quickly find out who the local ripoff artists are, and (hopefully) who the local heroes are. And there's usually at least one "motorhead" in the club who will show up on a Saturday and hold your hand while you fix it yourself. 

Sadly, a lot of "mechanics" and "garages" are as lost as you are when it comes to working on cars with points and carburetors. Even more lost when it comes to modified cars.

How was the car running before you started working on it? If you still had points ignition and it was a little rough, it was probably time for a full tuneup. If the points were marginal, and the plugs were gapped at .045, probably just didn't have enough grunt to fire the plugs. I like Pertronix ignition conversions. Pontiac Jim will argue. 

Points ignitions require a ballast resistor or resistance wire to the coil to drop the voltage from 12v down to about 8v. There are three different Pertronix ignition conversions (plus full distributors). The original Pertronix is just an electronic switch that replaces your points and will run okay on the (stock) resistance wire. Pertronix II and III are happier with a full 12 volts, which requires some wiring changes. And of course we don't know for sure what brand conversion they used.

If you didn't have a fuel problem before, you shouldn't have one now. A light tweak of idle speed and mixture is usually part of a tuneup. Ignition timing also affects idle, and should be set before final carb adjustments. 

Another big advantage of finding the "motorhead" in a club is that you can get advice from someone who's not trying to sell you something. Any bonehead can bolt on a carburetor. Even a newly rebuilt carb will require tweaking in for best performance. And it takes a minor genius to reject a carb to match a modified engine and actually have it run better. And there are Holley guys and Quadrajet guys who may be proficient with one or the other, or both. If the mechanic you've found is preaching Quadrajet, he may know what he is doing.

Your car came with a Quadrajet. If its relatively stock, it would probably be relatively happy with a parts-house rebuilt carburetor. Pontiac spent a lot of time getting it right.

Or you could spend an extra $500 (or more) and get a correct restored carb from one of the specialty houses. Better? Probably. Worth it? Maybe.


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## Montreux (Mar 8, 2009)

Montreux said:


> Yep, need to find a club! Check GTOAA for a local chapter, or start talking to guys at car shows with similar vintage cars. You'll quickly find out who the local ripoff artists are, and (hopefully) who the local heroes are. And there's usually at least one "motorhead" in the club who will show up on a Saturday and hold your hand while you fix it yourself.
> 
> Sadly, a lot of "mechanics" and "garages" are as lost as you are when it comes to working on cars with points and carburetors. Even more lost when it comes to modified cars.
> 
> ...


Apparently, REJET is not a word! This damn computer has "corrected" it twice!


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## lust4speed (Jul 5, 2019)

Toss in a hyphen and call it re-jet and the computer should be happy. If plug wires were disturbed at the cap all it takes is to be one terminal off and many times the engine won't even burp - just cranks over. Remember also that Pontiac distributor rotates counter-clockwise so firing order will be backwards around the clock with 1-8-4-3-6-5-7-2


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## bwayney (Apr 27, 2019)

Just an update for everyone:
After getting the Holley 0-4777C 650 carburetor on, the car ran great. They put it on the dyno, and they were able to get 229 WHP, and 315 lb-ft of torque. This is after they messed with the timing a little bit, and these are the best numbers they were able to get.

However, like a bad dream, on the last dyno pull, the water pump blew, and one of the rear brake lines that was rusted broke. So it looks like I'm going to be putting more money into this.

One question I have is, would it be cheaper to buy all new brake lines and put them in, or just replacing the one rear broken one? My worry is that if that one was rusted, the others are as well.


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## Mine'sa66 (Oct 30, 2019)

bwayney said:


> Just an update for everyone:
> After getting the Holley 0-4777C 650 carburetor on, the car ran great. They put it on the dyno, and they were able to get 229 WHP, and 315 lb-ft of torque. This is after they messed with the timing a little bit, and these are the best numbers they were able to get.
> 
> However, like a bad dream, on the last dyno pull, the water pump blew, and one of the rear brake lines that was rusted broke. So it looks like I'm going to be putting more money into this.
> ...


Is it cheaper to do all the lines at once? Depends. Are you doing it yourself? If so then no, not really. If you're paying a shop to do it, then yes, a little. You are correct that the others MAY be weak, but not necessarily. Best bet is to get a look at them and then decide. Odds are you'll end up replacing both axle lines up to the junction black at the same time. The main line may/may not be as bad. Take a good look at any of the flex hoses while you're there. They're likely to be dry and cracked if not replaced in the last few decades.


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