Thread: New 496 wont run??

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i would stick another power valve in it . even though they clam the problem is fixed you can still blow one with a back fire . 99% of the holley problems turn out to be a power valve .

Hey guys so I took my carb out and checked the power valve it’s a 6.5 and it’s not blown i tested it with my vacuum gauge. I also removed my intake manifold and changed the gaskets and resealed it. Put new plugs in and changed the oil and filter and started it up and same results.

I think I’m still possibly off timing, I removed my valve cover and set number one cylinder on compression stroke and tdc with my balancer set at around 13 and the distributor rotor was pointing past number one closer toward the center of the engine, but I set the cap on and put number one plug wire on where the rotor was. Like I said before it starts but I can’t get it to idle to set my initial timing. According to the engine builder initial timing is 13 total 36.

Try setting your total timing first, usually all the advance should be in by about 2200 RPM. Try holding the RPM steady at about 2500 RPM, set the total timing, then see if it will idle down to check the initial timing. Oh yeah, without going back and reading all the posts, are you using vacuum advance or just mechanical advance in the distributor?

Originally Posted by Dave Severson

Try setting your total timing first, usually all the advance should be in by about 2200 RPM. Try holding the RPM steady at about 2500 RPM, set the total timing, then see if it will idle down to check the initial timing. Oh yeah, without going back and reading all the posts, are you using vacuum advance or just mechanical advance in the distributor?

I’m trying to reset my carb after messing with all the adjustments. I am running only mechanical advance. The engine builder told me not to run vacuum advance on the motor so I have that blocked off on both the carb and the distributor. I pulled the distributor and rechecked all the timing, set rotor exactly on number one and 0 tdc and now it won’t start. So I have to figure out what happened now. It cranks strong but now no start.

There is a possibility that you are 180º out in timing

I like to verify dizzy by putting the engine on the timing mark, and rock the dizzy back and forth with ignition on, looking for spark: with a plug laying on the block.

I've stayed out of this discussion, but noted that in your original post you mentioned not being able to move your distributor to point to your #1 cylinder on the cap with the balancer at zero. In post #39 you again mention being out of position with the rotor. It sounds to me like you're one tooth off on the distributor to cam gear, which is making your distributor position cockeyed to the engine and limiting your travel for adjustment.

You've said that you lack experience with "old school carbs & distributors", yet you're continuing to risk damage to an engine that I expect set you back close to $10K. I agree 100% with 36 sedan. You need to trailer your car to a good mechanics shop that has a good tuner, and let them sort out your problem before you end up damaging your engine and costing yourself a bunch of money. Good luck getting this beast running right, so you can enjoy some cruising!

Hey, This just in: have you confirmed zero on the harmonic balancer? You can reach in to the plug hole on #1 with a screwdriver and feel for TDC while you move the crank by hand.

Put it on a trailer and take it to the shop! Just trying to help, ignore if you want.

I think the OP is playing a sick joke on us. No one would be this ------..........

Whats the plate under the carb? Are you running points or electronic dist? What size jets are in the carb? what power valves are in Primary and seconary?
have you checked the springs/weights/ distributor advance shaft for freedom of movement?

Unfortunately I don't have the means to have it towed nor have I found anyone close to me that works on these types of engines/vehicles. I am trying the best I can to figure this out it doesn't make sense, that I can be on TDC (I have bore scoped the number 1 cylinder and have confirmed TDC on compression stroke) set the dizzy rotor at number one and set the cap on ensuring the number one spark plug wire is set to that point. I even took my carb back off and reset everything and still no start. I wants to start and no matter what adjustment I do to the dizzy nothing changes much.

With cap off visually confirm rotation of rotor, then confirm the wires are on cap in correct rotation and sequence

Curious how you could scope the #1 cylinder at TDC. Piston is at the top of cylinder and both valves closed, zero space for a camera. And unless you've also got the valve cover off to witness both valves are closed fully, you could be 180 deg out.

QOUTE;
Hey guys, I need some help or guidance, I have a newly pro built 496 for my 1969 camaro, it was originally dyno’d by the company it was built by so it has been run.

1.) Pro built and ran on the dyno

it got shipped to us and We installed it into my camaro, its mated to a 700r4. When I first got it running it would run but not very well. It had about 6 inch of vacuum at idle.

2.) Vacuum is too low

And didn’t like off idle much and would be around 700rpms and the exhaust would burn your eyes.

3.) Running way too rich and probably not enough timing

It has a quick fuel 830 carb with electric choke on it and a msd hei ignition with mech advance. I first tried to tweak the carb setting the floats and then the mixture screws but no change.

4.) Low vacuum and rich idle usually points to high fuel pressure, high float setting and or power valve staying open

I changed out the fuel with fresh 93 and started messing with the distributor.

5.) Octane will not correct for carburetor adjustments/settings

I found that the cap was damaged so I replaced the cap and rotor, set the engine on tdc, at 0 on the crank verified it was on the compression stroke but I can’t get the distributor to point exactly to #1 cylinder, I can get close but not exact when at zero on the crank.

6.) If you are truly on compression stroke this should be close enough to start and adjust from there

i have verified plug wires are in correct location with running order but now after all that it starts and now dies right away. I’ve pulled all plugs they were wet with fuel mostly likely, I cleaned them took the carb off and reset everything I could see but still nothing.

7.) There is no such thing as cleaned fouled / wet /fuel soaked spark plugs, they will not fire reliably. Replace them

I have tried to adjust the timing by turning the distributor both ways and still no change. I am running a mechanical fuel pump.

8.) See #3 & 4

I am waiting for my fitting to come in so I can install a gauge and see my pressure. My carb has sight glasses so I can see the float levels and they are set to just below half way.

9.) See #3 & 4

Right now I have the card choke set to be closed when starting. I have tried to adjust the idle throttle screw from full closed to slightly open with no change. My issue is I am not sure if it’s a timing issue or fuel issue.

10.) See #3 & 4

I talked to the engine builder and they told me that I should have around 14 inches of vacuum at idle.

11.) See #2, 3 & 4

Not sure if it’s running to rich and flooding the cylinders, when I bore scope number one I have a little fluid built up in the corner of the cylinder wall on top of the piston but I don’t know if that’s oil or fuel. I am assuming it’s fuel because the plug is wet and smells like fuel not oil.

12.) It’s RUNNING TOO RICH, See #3 & 4

I set the idle mix screws to 1-1/4 turn out from stop which is even leaner then what it comes from the factory. I was told that the engine parred with this trans should run rich but I have a feeling it’s too rich but I don’t know how to find that out or what to look for.

13.) See #1, 2, 3, 4, 5, 6 & 7

I have it running but like I stated I have to have the idle really high, over 1200rpms to keep it running. Fuel pressure is about 7psi at the carb. I have shut the idle screws and the vehicle does die after a min, it will run with the screws about 1/2 turn out but beyond that it struggles and smells really rich.

14.) See #3 & 4, lower fuel pressure 7 is too high

I reset the choke and fast idle and still no change.

15.) Of course not, it’s not the problem

When I read vacuum from the carb full manifold vacuum port it’s around 13-15 psi at 1400rpms.

16.) Vacuum will be higher at 1400rpm, BUT it is not 13-15 at idle, see #2

But when I close the throttle to bring the idle back down the vacuum drops and the vehicle will eventually die.

17.) See #2

I sprayed down the whole intake and carb with carb spray and no leaks were detected. Not sure how it’s running so rich with only 1/2 turn out on the mixture screws u less I have a power valve issue.

18.) See #3 & 4, also check throttle blade transition slot exposure

I even checked the breathers on the valve covers to see if they were pulling vacuum under load and they were not so I don’t think the intake manifold is leaking either.

19.) Usually a vacuum leak runs lean, not rich. But you could plug both (all) breathers (tape or otherwise) connect vacuum gauge to dipstick tube to be sure

Hey guys so I took my carb out and checked the power valve it’s a 6.5 and it’s not blown i tested it with my vacuum gauge.

20.) 6.5 power valve will open at 6 hg, see #2

I also removed my intake manifold and changed the gaskets and resealed it. Put new plugs in and changed the oil and filter and started it up and same results.

21.) Of course it doesn’t run any different, you have not solved the WAY OVERLY RICH and/or timing issues

I think I’m still possibly off timing, I removed my valve cover and set number one cylinder on compression stroke and tdc with my balancer set at around 13 and the distributor rotor was pointing past number one closer toward the center of the engine, but I set the cap on and put number one plug wire on where the rotor was. Like I said before it starts but I can’t get it to idle to set my initial timing. According to the engine builder initial timing is 13 total 36.

22.) Are you setting/turning the distributor the same direction as distributor’s rotor rotation, if so you are RETARDING ignition not advancing (chevy’s rotor usually turn clockwise), advance distributor counter clockwise

I’m trying to reset my carb after messing with all the adjustments. I am running only mechanical advance.

23.) See #3 & 4, also check throttle blade transition slot exposure

The engine builder told me not to run vacuum advance on the motor so I have that blocked off on both the carb and the distributor.

24.) Vacuum advance will not effect starting the motor, vacuum advance has nothing to do with high performance, vacuum advance is a fuel economizer

I pulled the distributor and rechecked all the timing, set rotor exactly on number one and 0 tdc and now it won’t start. So I have to figure out what happened now. It cranks strong but now no start.

25.) Check spark see #7

Unfortunately I don't have the means to have it towed nor have I found anyone close to me that works on these types of engines/vehicles.

26.) You've spent a considerable amount of money on a pro-built motor to NOT have the means to fix it. And, I can not believe you can not find someone in MIAMI to help you.
I believe you are either WAY over your head or playing a sick joke on us, if this is a joke end it now.
If you are serious, YOU CAN’T AFFORD to continue like this without risking sever motor damage, GET SOMEONE LOCAL TO HELP YOU OR TOW IT TO A SHOP THAT CAN FIX IT!

I am trying the best I can to figure this out it doesn't make sense, that I can be on TDC (I have bore scoped the number 1 cylinder and have confirmed TDC on compression stroke) set the dizzy rotor at number one and set the cap on ensuring the number one spark plug wire is set to that point. I even took my carb back off and reset everything and still no start. I wants to start and no matter what adjustment I do to the dizzy nothing changes much.

27.) See #26

Please, I’m not trying to be disrespectful, cruel or anything else, however your thread leads me to believe you don’t have the knowledge or experience to fix it yourself without an experienced person there on site to help you.
PLEASE minimize your expenses and get someone or a shop to help you before it’s too late……