Thread: New 496 wont run??

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36Sedan, that was quite a pile of work to put together. Good job on that! Everyone here knows you to be a straight shooter and not someone who would go off on a tangent of some sort... ( unlike .... ME!)
The only thing that I wanted to add to the OP, if and when you get it running again. Install your vacuum gauge while tuning for your idle, NEVER let vacuum go below the setting of your power valve plus a half inch. So if your PV is a 6.5 then don't go below 7 inches of vacuum. The cam may need 12 or 1300 rpm's to maintain that much vacuum. But that's the price of horsepower sometimes. We didn't select the components or know what they installed so can't help you beyond what we've already discussed.

That's why earlier I suggested you remove the power valve and plug it - if things got better, then you can search for a lower numbered valve. Or like me, just leave it out. I don't spin my motor fast enough , long enough, to get lean enough to hurt it. It's a street car. And I freely admit, I don't know you, your engine builder or your personal situation... but the guy who built this needs to be contacted and see if he can help you sort this out. If he's turned his back on you... perhaps others need to be warned of the situation?

Turn out the lights, the party's over.

A great summary, 36 Sedan! You're a gentleman.

i dont understand . it was run on a dyno but now wont run ? look to what you changed after getting it home .

I appreciate all the replies and help, this isn't a sick joke I promise you, I have had this car for 20 years and finally have had a chance in my life to restore and build it up the way I want. I did not build my power train I bought a fully dressed long block that had been dyno'd. At that time I did not have the vehicle it was at the shop that was doing some of the work for me and they installed it so I am not sure what happened between all that to when I got it. I am trying to learn as I go I am use to newer vehicles where I can monitor O2 sensors and fuel trims. I am unable to do this on this vehicle and yes maybe I am in over my head but I still trying to learn so I can be able to work on the vehicle myself when I need to.

I live in South Florida, just every one calls it Miami but I am not in Miami, the closest shop with dyno that has a good reputation for me is over 30 miles away and to tow it there and have them work on it and tow it back, I unfortunately don't have those funds at the moment so I am trying to learn and work on the things I can at the moment. I understand I can damage something, and that's why I am here asking for help so I can learn and possibly not have to spend the money to have someone possibly take 30 mins to correct a simple issue (if that's the case).

Once again I thank you for all your feed back, I understand its very hard to attempt to diagnose someone else's issues without seeing or knowing all the information, just don't knock me for not knowing something that maybe you deal with on a regular basis or have a lot of experience with and seems easy to you. I am learning new things every time I work on the car. I haven't had a chance to work on it lately so that is why I have not posted in a little while. I have not given up on it and will go over everything you all have listed and get back to you all. Thank you.

OK, assuming all is good with the motor. This may simply be a big cammed motor and carburetor not set up for it. So lets try something very simple first and get the motor idling so we can go from there.

This is an article I wrote for my car club that may get you going in the right direction;

Perhaps this will help? https://www.youtube.com/watch?v=hhrlN59BA_s

I don't agree with his "final solution" with bumping the motor over to get the dizzy to drop in. But that isn't where we are right now. At least review it and maybe it'll help.

Denny you can't make it any simpler than that. Been doing it that way for over 50 years

Originally Posted by DennyW

Same here. Learned that early, hated the fire in the carb, or belching thing going on.

Yup - works good. Note to self, do not get between the screwdriver and any point of ground on the car - ask me how I know this... Yikes - it'll give you a good wake up jolt. Not to get too far off, but years ago, I thought I'd help a friend time his Triumph motorcycle - I mean how hard could it be to hook up my chrome plated Sears timing light to the #1 and give it a go. Well those old bikes were positive ground and when I squeezed the trigger I felt the furry of the coil down to my toes.

Originally Posted by glennsexton

I felt the furry of the coil down to my toes.

LOL!!! Been there done that!

Ok so I did go and get a spark tester and with it installed and just turning the distributor I had it light up. I got in contact with the engine company to find out my plug gaps and timing again. They told me the plug gaps should be .35, the new ones I got were not that gap they were much smaller. So I gapped them all to .35. They also told me the timing should be 12 initial and 36 total.

So with all the plugs out I put a little bit of oil down all the cylinders in case of wash down, I then pulled bank 1's valve cover off and watched the intake valve one cylinder one open and close and then set the crank pully on 0 degree's. Looked at my rotor and it was pretty much pointing to number one cylinder. I marked the housing for the rotor location and put the cap on and put number one at the mark on the dist. I cranked the motor over a few times to let the oil in the cylinders move around, put all the plugs back in, and exchanged the oil.

I pulled the carb off and went through it I set both primary and secondary throttle plates so you can just barely start to see the idle circuit groove. I exchanged the power valve from a 6.5 to a 3.5 even though everything I read told me that that will not effect idle. I set the idle mixture screws to only 1/2 turn out from stop to start. I re-installed everything and I am going to flush the fuel system and ensure I have fresh fuel in it and attempt to start it this weekend. If you guys can think of anything I might have missed please let me know.

Originally Posted by Camaro350

I exchanged the power valve from a 6.5 to a 3.5 even though everything I read told me that that will not effect idle.

This is true normally, because the power enrichment circuit operates via venturi vacuum (fuel is introduced above throttle blades through the boosters). However there are a couple of exceptions;

1). If the power valves diaphragm is damaged, it can leak and pull fuel in through the vacuum passages.
2). The idle stop on the carb is set too high combined with low vacuum, the low vacuum opens the the valve with the throttle blades opened enough to introduce the fuel through the boosters. Usually this condition also activates the transition circuit adding even more fuel.

Skipping past this, if the throttle relationship and low vacuum are a contributing problem changing to a lower value PV will not help it (may make it worse). While tuning the PV circuit is essential and contributes greatly to performance, I would not lower the value until I had it running correctly.

Unfortunately, guessing at this is not the answer.

I'm going to ask a few questions that may have been asked already but I did not see when scanning back through your thread (apologies if it has been asked), so at the risk of redundancy;

1). Is this a NEW or used carburetor?
2). While it is running at its lowest idle speed, have you looked down into the boosters to affirm NO fuel is coming out of them.

At idle you should NOT see any fuel coming through the boosters. If you are unsure what the boosters are, just ask we'll explain, no need to be embarrassed.

At IDLE, you should NOT see any fuel entering the motor, as the idle circuit's entrance is below the throttle blades (transition circuit as well for that matter). So, if you see fuel entering the motor at idle, you have another problem.

If this is a used or rebuilt (even from the manufacturer) there could be an error in assembly causing fuel to enter the motor from a source it should not be coming from. Often, it is a simple as a misaligned or incorrect metering block or gasket.

If this is a new carb, and you see fuel entering through the boosters at idle. Contact the manufacturer for directions on what they want to do to correct it for you.

Good luck!

First and foremost get and use a vacuum gauge when doing any tuning! You may be wasting time and effort guessing at what's happening. I think you said you had a timing light. Is that correct?

Ok I know this is way basic, but consult a Haynes , Ciltons, or similar manual and confirm that you are looking at #1 cylinder, as different manufacturers put them on different sides.

Oh, and that would be .035 on the gap.

.35 would be about 3/8"

Yes everything is new on this engine, it is a complete build. I just got a new distributor because I noticed that the cap was damaged due to shipping possibly so I replaced the whole thing with a DUI HEI.

Yes I’m sorry I did mean .035 on the plug gap.

So I put fresh gas primed the bowls to halfway in the sight glass and tried starting it. It wants to start but won’t. When I open the throttle plates it starts but then quickly dies and coughs through the carb. I rechecked the timing, the pictures shows you the location of everything after I bump the motor until after number on cylinder intake valve closes. I set number on plug wire on the location of the rotor and go around from there in firing order. 89B8C5AA-F9EE-47B2-B23E-AFC1F33E24C8.jpegDA60A041-76E7-4959-B791-4700C584120C.jpeg4E3077A2-7A8A-40ED-8945-BEB16144BD5D.jpeg