Need a liittle help from the higher ups

Jridge1

Well Known Member
I have a 64 340 hp 409 that is falling on its face after 3000 rpm. It idles very nice maybe a little rich. The engine has about 60000 miles on it so with recent events I started to replace some things the last wires were done in 1971 so i replaced cap rotor wires spark plugs and checked dwell which is at 29. The timing is at 6 degrees before tdc at 550 rpm with vaccum advance disconexted and total advanvane of 36 at 4000 rpm. It has the original 4 jet which was just rebuilt as well as the original fuel pump that was rebuilt. What am I missing
 

rstreet

Well Known Member
Supporting Member 17
If you know someone who still has an operating Sun Distributor machine that would eliminate or point to the distributor. I believe a degreee tape on the balancer would somewhat accomplish the same effect with a timing light. There are many things I could think of that would cause that but elimination of all items one by one is time consuming but necessary. For now I would recommend focusing on distributor first then the carb. Be nice if you had an exhaust gas analyzer.
Robert
 

Jridge1

Well Known Member
It has the original exhaust manifolds no damper that I'm aware of. It has great take off power it is only when it hits 3000 rpm it is like some one shut the ignition off.
 

Junky

Well Known Member
Do a leak down test, to check the overall condition of the engine so you have a starting point. I also am thinking that it might be in the distributor, but it also can be that the lifters are tired. Lots of things that can cause you problems after 60K, and in the end, it might be one of those engines that requires an autopsy to figure out the problem. By then you are already half way there to doing a complete rebuild.
 

Jridge1

Well Known Member
I do have an exhaust gas analyzer. How would that help? Don't know anyone with distributor machine. Guess I could throw an electronic distributor in and see what difference it makes
 

blkblk63ss

Well Seasoned Member
Supporting Member 5
When it stalls does it die completely ? Can you restart without a long crank ? Or does it just unable to get above rpm and keep running?
 

Jridge1

Well Known Member
If I hit the gas it will peel the tires until it hits 3000 rpm then it is like the engine is turned off then it bogs and hovers around 3000. It never dies and when I let off it will return and hold a normal idle.
 

oldskydog

Well Known Member
Supporting Member 10
Could be wrong but I would think you would want all your advance in by about 3200.
 

Jridge1

Well Known Member
Would it make the engine fall flat if the advance is at 4000. I thought the older advance was set up that way.
 

blkblk63ss

Well Seasoned Member
Supporting Member 5
Sounds like exhaust restriction .I have seen double wall pipe collapsed coming off oof manifold area. Or it could be a collapsed muffler.you can also check restriction with a vacuum guage just setting and accelerating engine and not driving.
 

Don Jacks

Well Seasoned Member
Supporting Member 3
Would it make the engine fall flat if the advance is at 4000. I thought the older advance was set up that way.
No it wouldn't,and you're right about the stock advance being in the 4,000 range.If the problem is that the engine cuts off cleanly[like you cut off the ignition],then I suspect the dist,or something in the ignition circuit. If it surges and bucks[like it's running out of fuel,and while you're driving and/or trying to accelerate] ,then it's more likely a fuel supply issue.A vacuum test will point out a possible exhaust blockages as Don mentioned
 
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Jridge1

Well Known Member
It does cut off cleanly no back fire or pops. It just bogs down almost like a 3000 rpm rev limiter if such a thing exists
 

Don Jacks

Well Seasoned Member
Supporting Member 3
Can you duplicate the condition by just reving the engine to the problem rpm area? If so,put your dwell meter onit and watch it's reaction.If it gets irattic,then disconnect the vacuum advance and repeat the test. If it stablizes,then look at the ground wire that runs from the advance plate to one of the screws that hold the vacuum advance.Also,if your points set is one of those "uniset" units,DUMP IT!It sounds like you may be having a situation where that dist.is loosing it's ground.
 

blkblk63ss

Well Seasoned Member
Supporting Member 5
The engine is like a air pump. Air goes in ,air has to get out. If exhaust cannot dump it out air intake cannot increase.Use the vacuum guage to test or drop exhaust pipes .
 
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