Now the carb is broke.

What am I doing wrong? I took a perfectly good carb and blew it up.The dist is good. It is in the right tooth. It may be a little advanced or retard but I am not sure. No vacuum leaks. The adjustment screws are 1.5 turns out from closed. The idle screw is 1.5 turns. I have not touched anything else on the carb.

Now what should I do? I am very frustrated with this part of the project. I have come so far. To make matters worse I was really hoping to drive it this weekend. Now it will take me most of the summer before I can come up with the money to buy another carb. I do have a two barrel I can put on there. Maybe I will do that. Still I am very very disappointed with my actions. I am my biggest problem.

Any ideas are greatly appreciated. Just don't know what to do.

Thanks for listening to me ramble. The weekend is going to suck.

Richard.

------------------
rmousir
'66 Mustang Coupe
Ford Blue & white stripes
'95 302 auto
Mustang ~ 04-05

I will wait along with you for the real mechanics to show up and teach both of us what is wrong.

A backfire can also be a mixture problem or a timing problem. Very few things that go wrong with an engine have only one thing that can cause it.

quote:

---

Originally posted by Aussie XAXB:
What carb was it?

---

It WAS a 4100 with a fresh clean and rebuild.
I supplied it, and I've built dozens of them. Not saying it was perfect, but I really don't see what would have been wrong with it.
I would suspect the ignition spark occured while an intake valve was still open, allowing the flame to travel up thru the intake.

Most likely it's a vacuum leak, by the sounds of it a big one. Check the base gasket, perhaps it got ripped, or if you changed it, make sure it is completely sealing the base of the carb. Some manifolds have machined areas that don't leave much material left for sealing.

Check also for vacuum lines you left off, too.

Resist the urge to go 'adjusting' the carb or timing, that's the areas you can be sure the problem isn't, since you didn't make any changes to them before the problem started. Have patience and retrace your steps and you'll find the problem.

http://www.mustangsandmore.com/ubb/Forum1/HTML/017024.html

------------------
oddly obsessed with big scoops on little Mustangs

quote:

---

Originally posted by rmousir:
.The dist is good. It is in the right tooth. It may be a little advanced or retard but I am not sure.

---

Richard,
Don't give up and don't be too disheartened. This is all part of the fun and challenge of working on an old car. You've conquered many other areas of the car and this is just another challenge to overcome.
You have mail.

quote:

---

Originally posted by Fastymz:
Steve, he had this problem before he worked on the carb.

http://www.mustangsandmore.com/ubb/Forum1/HTML/017024.html

---

Thanks Scoop, I didn't see that.

Wish I could be there to help you out.

The bang you describe above sounds like a lean backfire.

quote:

---

Originally posted by SteveLaRiviere:
Wish I could be there to help you out.

The bang you describe above sounds like a lean backfire.

---

When that was fixed I had it running again. Surging as it was before. Thinking it was the timing as many have pointed out I re-stabbed the dist by doing the thumb over the #1 plug hole. Then I also rechecked the wires to make sure they are correct. Then got the car running again.

The only real adjusting I have done is to the idle screw and the dist. Turning it to the left or right a small amount at a time to get the motor to smooth out when it was warm. I had all of the vacuum lines removed from my vacuum tree and had the tree plugged when I did this. When it was running and while I was thumbing the gas to keep it running I had wd-40 sprayed around the vacuum tree, the base of the intake, the base of the spacer, the base of the carb. Never heard or saw a difference of the way the car ran.

Then when the car was warm it back fired (1st time) up through the carb. Then, after I changed my pants, I went back to the task at hand. Just to get the carb to idle nicely. That never happened. A lot of run time (at least a hour or so) and then the back fire (2nd time).

I then changed my pants and decided to put it out on the forum here and see what was what. That is when the power valve came up. So I went out and got one. It was easy enough to swap out and I had no problems with it. Then today BANG!. This one was big and again, I changed my pants.

So I posted this thread and went out to eat and hang out with the family. I have just put on the old 2 barrel that I had on the old motor. I have a 2to4 adapter sitting here so I thought I would try it. Problem is I don't know if it will still work or not. I will start the car up tomorrow morning and see what happens. If it happens again I know that it is a timing issue or something other than the carb. If it does not happen and the motor runs fine I know it is the carb.

I feel much better after going out and walking away from the car. I am sorry if I sounded like a big baby when I posted this. I should have taken a break before posting. LOL.

I will let you know what happens tomorrow and go from there. Hopefully the 2 barrel carb will work and the motor will start and I will know which direction to go in.

quote:

---

Originally posted by rmousir:
I feel much better after going out and walking away from the car. I am sorry if I sounded like a big baby when I posted this. I should have taken a break before posting.

---

If it backfires only when you open the throttle, check the accelerator pump. With the engine OFF, open the throttle and see if there are two streams of gas directed at the primaries.

Every time I've had issues with backfiring its been timing related, not the carb. Sounds like there's been issues from the begining with getting this new engine going. I hate to suggest this as it means tearing her open again, but is there a chance that the cam gear/chain was installed one notch off.

The cam gear chain was never removed. This is a motor from a wrecked '95 mustang gt. I never removed the timing chain and/or gears. I only added the eccentric. The motor was run tested before I bought it and I bought it from a reputable yard here in my local area.

I also agree on the part about the carb being top notch coming from Scott. I am sure that this is somthing on my part. Being new with lots to learn I am finding that I am the problem most of the time.

Originally posted by sigtauenus:
For you experienced guys, how would you eliminate timnig error in the distributor from the cam/crank degreeing.

I got the 2 barrel carb out. I will start the car up tomorrow and get it warm and see what happens. Will add a update tomorrow.

quote:

---

Originally posted by SteveLaRiviere:
The bang you describe above sounds like a lean backfire.

---

What is a lean back fire?

quote:

---

Originally posted by rmousir:

What is a lean back fire?

Richard.

---

Is this to say that the timing has never been set with a timing light, only by ear? Just looking to clarify that.

I would have to agree, sounds like Scott has built enough carbs to have a handle on what he is doing.

I bet you can't stall your engine by blocking the choke with your hand.

I got the car started with my 2 barrel carb.

NO SURGING at all!

Starts up just fine and is smooth but I can not get the car to run at idle with out stalling. I am starting to think more vacuum leak. Oh, also i got my nice new timing light. Bought a good one from Sears. Still, can't use it until the car idles right?

quote:

---

Originally posted by SteveLaRiviere:
I bet you can't stall your engine by blocking the choke with your hand.

---

Do you mean to cover the top of the carb with my hand to cut back the air? If so I will give that a try and see what happens. i will then follow up with everyone here. Should be tonight. Really want to get this fixed. I know I can do it.

Also wanted to say thanks to everyone who has been jumping in and helping me out. I really appreciate.

Richard.

quote:

---

Originally posted by Aussie XAXB:
The Holley 1850 has a reputation for back firing at low RPM when you rev it.

A backfire can also be a mixture problem.

---

Had the same problem with my old 600cfm Holley. It was running rich & backfired & bogged down when I stepped on it. I replaced the carb with a new one & that fixed it.
Haven't torn the old one apart yet to see what was causing it. Metering blocks maybe, or something internal???

"Turning it to the left or right a small amount at a time to get the motor to smooth out when it was warm."

Very true about the idle adjustment screw too. A little bit goes a long way.

quote:

---

Originally posted by Blacksmith:
Had the same problem with my old 600cfm Holley. It was running rich & backfired & bogged down when I stepped on it. I replaced the carb with a new one & that fixed it.
Haven't torn the old one apart yet to see what was causing it. Metering blocks maybe, or something internal???

---

That may be true for a Holley, but this is an Autolite 4100 and they don't have metering blocks.

Richard -
First step is to get it running right with your old two-barrel on there. Fix the intake gasket leak if there is one, get your timing set at 10 degrees without the fast idle engaged and engine warmed up and vacuum advance disconnected and plugged.

THEN try swapping back the four barrel and maybe we can pinpoint what you need to do to the 4100 to smooth it out. Might be something as simple as a little bit of dirt got thru the filter (remember when you first tried to start it and the bowls flooded?).

quote:

---

Originally posted by rmousir:
Then when the car was warm it back fired (1st time) up through the carb. Then, after I changed my pants, I went back to the task at hand.
A lot of run time (at least a hour or so) and then the back fire (2nd time). I then changed my pants and decided to put it out on the forum here and see what was what.

Then today BANG!. This one was big and again, I changed my pants.

I feel much better after going out and walking away from the car. I am sorry if I sounded like a big baby when I posted this. I should have taken a break before posting. LOL.

Richard.

---

Sounds like your making progress, but this post made me think there may be a product that could help you spend more time in the garage
http://www.depend.com/

quote:

---

Originally posted by Jake11:

Shure sounds like a vacumn leak. Could be
your intake gasket leaking underneath where
you won't be able to find the leak with
WD40. Do you have one of those propane torch
things for soldering? Propane works good for
finding vac. leaks, and it don't make a mess
like squirting WD40 all over. If you pull
the pcv valve out of the valve cover and
squirt some propane in the `hole, it might
show if you got a vac. leak. Good luck

KeithP

---

------------------
William
The easiest way to find something lost, is to buy a replacement.

Get the car running and put my hand over the butter fly and see if it stalls.

I should be able to close the butter fly and the car should stall right?

I will then check the intake seal again to see if I can find it. If not then pull the intake and super seal it.

Then put it back to gether and hopefully it will idle. Then set my timing at 10 btdc. If is smooths out with the 2barrel on then I will put the 4 barrel back on and see how it goes.

how does that sound?

I will have some time this weekend to go over it. If I have to pull the intake is there a sure way to seal it?

------------------
William
The easiest way to find something lost, is to buy a replacement.

Also, you bought a vacuum gauge right? Hook that gauge up to the manifold vacuum tree and see what it is reading. This will let you know for sure if you have a leak. Sometimes the intake gaskets will leak from the inside of the motor, so the old carb cleaner trick won't work.

One final thought is the gas/filter. Do you have fresh gas in the tank and do you have a good filter after the pump? I had problems in the past with the cheap clear fuel filters that autozone sells. The filter is a plastic mesh and doesn't filter anything. I kept getting rust and gunk in my carb and it was blocking the passages in the carb, creating a lean condition and the car wouldn't idle under 1300rpms. Even though you put another carb on there, it could have gotten plugged up like the last one immediately.

One other thought, have you messed with the rockers or valvetrain at all? Just curious if the rockers were properly adjusted, as this can mess up the timing of the valvetrain causing backfires.

quote:

---

Originally posted by buening:
do you have a good filter after the pump? I had problems in the past with the cheap clear fuel filters that autozone sells. The filter is a plastic mesh and doesn't filter anything.

---

------------------
William
The easiest way to find something lost, is to buy a replacement.

quote:

---

Originally posted by rmousir:
I should be able to close the butter fly and the car should stall right?

---

quote:

---

Originally posted by SteveLaRiviere:
Yes, it should either stall or stumble like crazy. If it smoothens up, you've found a vacuum leak.

---

However I was reading my Tom Monroe book on the intake install to see if I missed anything. He mentions that I should have washers on the intake. I don't. I used the bolts from my '95 intake. If I do the test of putting my hand over the carb and if the car smooths out I have a vacuum leak. Would it be a good idea to put washers on the intake bolts?

I will be doing the test tonight for sure. Cole said he would help. What a nice kid. :-)

quote:

---

Originally posted by 68mustang351w:
What kind of intake do you have ? If its cast iron dont worry too much about it but if it is aluminum it would be recommended... David F.

---

Alum Offenhauser 360. I will put the washers on one at a time and see how she runs. Do you think it will make a big difference? How thick a washer should I go?

Richard.

I got to do some testing on the car tonight. Here is what I have found. My intake was loose.... I tighten it up to about 30 pds according to my torque wrench. Then started the car and it made a difference. But it still ran really high on the rpms and then stalled. Started it again and then by thumbing the carb I took and closed the butter fly with my hand. WOW!

It changed the rpms a lot. I had to reduce the idle screw on the carb and the motor ran much better. If I let the butter fly open the rpms got really high and then the car stalled. Also with the butter fly close there was no surging. Remember that I have my 2 barrel on there now with a 2to4 spacer/adapter. I don't like it and I think it may be part of the vacuum leak.

So this means I have a vacuum leak right?

So what to do now?

I assume that I have to drain the coolant. remove the carb, spacer, pcv hose, the upper rad hose, etc, and pull the intake. Get a new set of seals and reinstall it after a good cleaning. Then put it all back on. Is there a fool proof way to do that seal so it does not leak? Again, I am assuming that the intake seal is the problem here. Special seal part number or something?

Then when I reinstall it should I torque it to the 30pds again? When I installed the intake I am almost sure I torque it really tight. I remember using my Tom Monroe book and I think it said somewhere around 80pds. Is that too tight? I am pretty sure that is what I did. How did it get so loose? Should I go tighter than the 30 pds? Also I did not put on the washers.

Then I will get the 4 barrel carb back on there and get new seals for it also.

Still need lots of help on this one, I really want to drive the car this summer.

quote:

---

Originally posted by rmousir:

When I installed the intake I am almost sure I torque it really tight. I remember using my Tom Monroe book and I think it said somewhere around 80pds. Is that too tight?

Richard.

---

If you did 80pds I think that is way to tight and that is probably your problem. Here is a link that will help you.

http://dfwmotorsport.com/Fairlane/Manifolds.htm

quote:

---

Originally posted by johnmustang:
If you did 80pds I think that is way to tight and that is probably your problem. Here is a link that will help you.

http://dfwmotorsport.com/Fairlane/Manifolds.htm

---

Thanks. It was loose when I got to it tonight. I dug through my book and I have a copy of that page in my book and now that I have seen it I think I may have done it that way. That would explain why the bolts were so loose. If it were 80 pds I don't think they would have gotten this losoe. It is about 30 pds now.

quote:

---

Originally posted by rmousir:
Thanks. It was loose when I got to it tonight. I dug through my book and I have a copy of that page in my book and now that I have seen it I think I may have done it that way. That would explain why the bolts were so loose. If it were 80 pds I don't think they would have gotten this losoe. It is about 30 pds now.

---

You may have compressed the gasket, it could have slipped or you could also have a crack on the intake.

Are you having any overheating problems? After you have run the car for a little while, remove the rad cap (very carefully) and see if you can smell any exhaust fumes coming from the rad, if you can then you definitely have a problem with the intake.

I will do that and then post my results. Hopefully they are better.

Thanks.

on edit: remember to use the correct tightening sequence and a torque wrench when you are ready to install it. When you are done, run the engine until its fully warm turn it off and retorque the intake. You might have to do that a couple of times. Keep us posted.

quote:

---

Originally posted by johnmustang:
Any luck yet? What is the verdict?

---

I am picking up the new gaskets tonight from the local autozone. Felpro. Also need some break cleaner so I can finish the clean up. Should have it back together by this weekend.

When I took off the intake I could see that the seals did not 'seal' so I am feeling very confident that I found my problem. I will post all of the mistakes i made with this project when I get the car running. I was thinking about it yesterday and I can't believe that i have not sold the car yet. You guys really keep me going on this.

thanks.

quote:

---

Originally posted by rmousir:
I was thinking about it yesterday and I can't believe that i have not sold the car yet. You guys really keep me going on this.

thanks.

Richard.

---

If we all sold our cars after making a few mistakes then none of us would own a classic mustang. We have all "done that been there" don`t feel bad it is just part of the learning curve.

I can guarantee that we all still make a bunch of mistakes (at least I do) but that is part of the fun (I think)

quote:

---

Originally posted by rmousir:
When I took off the intake I could see that the seals did not 'seal' so I am feeling very confident that I found my problem.

---

A telltale sign of a leaking intake gasket is oil in the intake ports of the heads.

As someone mentioned be sure to follow proper torque sequence. Also I noticed after partially tightening the screws and them torquing them to specs that they all needed "clicking off" with the torque wrench a second or third time as the intake snugs down between the heads and the gaskets compress. Don't forget the washers too.

quote:

---

Originally posted by FSTBK65:
Permaseal not printoseal

---

quote:

---

Originally posted by 68 S-code GT:
Well I think someone made a gasket some point in time and they called it that. Maybe it was Fel-Pro and maybe it wasn’t. It could have been phased out also for a better design and name.

---

Could you be thinking of Permagasket (the silicone sealant)? Another thing to point out is to be sure that your torque wrench is calibrated. I used one of the click torque wrenches and tested it with the bar type and found it to be WAAYYY off. I use an in-lb beam type torque wrench on my intake bolts, since the torque requirement is pretty small. Be sure to multiply by 12 to convert ft-lb into in-lb.

https://www.jegs.com/webapp/wcs/stores/servlet/CategoryDi splay?lang=-1&catalogId=10002&storeId=10001&categoryId=16061

[img]https://www.jegs.com/images/photos/300/375/375-1250.jpg[/img]

https://www.jegs.com/images/photos/300/375/375-1250.jpg

[This message has been edited by 68 S-code GT (edited 06-09-2006).]

I swapped out the intake seals and redid them. Put it all back together and got a chance to fire her up last night. Still had the same vacume leak that I had before but no surging or back firing. So I was a little frustrated.

So I called my wifes uncle. He is a old car guy. He comes buy and asks me a string of questions and then sees that I have 2 barrel carb on the 4 barrel intake with the adapter. He told me the adapters are big leakers. Told me that I most likely had a vacuum leak on the intake seals when I had the 4 barrel on there but had no idea why it was surging and back firing. After I put on the 2bl with the adapter the surging was gone but I still had the vacuum leak with was most likly the adapter/spacer that I was using.

He pulled out a Holley carb that he brought, poped it on. Started the car up. Ran with no problems. Adjusted the idel screw a little. Told me to get a new carb and that I could borrow his until I did.

Took the car out this morning and droveit about 10 miles or so, filled it up with gas. I have to tighten the one muffler clamp but other than that the car ran very well. Ideled nice, was powerful, responded nice. It has never driven this well for me since I have had it. You were right, I could feel the difference in the motor. Did a little burn out and was very happy with it.

Thanks for the help everyone. Especially ScottH. He was a huge part of me getting through this.

------------------
oddly obsessed with big scoops on little Mustangs

Glad to hear you got it going!! I bet that is a great feeling, I finally got my EFI conversion completed (few small things left).