Trying to start rebuilt engine, spitting through carb

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hotrod swinger

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1966 Plymouth Valiant 225

Rebuilt engine
Confirmed TDC by watching valves
Plugs in correct firing order
Distributor set 10 BTDC
Petronix kit instead of points

I can start and run the engine with the choke on and high idle.

Once I reduce idle and/or open the choke the engine dies, usually with a spit out of the carb, sometimes flames.

The engine will not idle below 1500 rpm.

This is my first time starting a rebuilt engine by myself so I’m possibly missing something obvious.
 
I would be willing to bet that the ignition timing is retarded. I know that it seems that you did your homework on the timing, but it sure seems as the timing is off. Just try advancing the distributor a bit and see what it does. From there the only other thing I can think of is that you have a vacuum leak somewhere. Check all your vacuum hoses. Does not seem to be fuel related, but you never know. Could the idle mixture screws be completely closed?
 
I would be willing to bet that the ignition timing is retarded. I know that it seems that you did your homework on the timing, but it sure seems as the timing is off. Just try advancing the distributor a bit and see what it does. From there the only other thing I can think of is that you have a vacuum leak somewhere. Check all your vacuum hoses. Does not seem to be fuel related, but you never know. Could the idle mixture screws be completely closed?

Vacuum lines on carb are all plugged, I haven’t hooked up vacuum advance or power brakes yet.

Idle mixture screws are 1.5 turns out.

I wanted to try advancing my timing more but I am up against the slot on the distributor so I’ll need to adjust the bolt under the distributor, I haven’t tried that yet.
 
Backfire through the carb is usually retarded timing as stated above. 65'
 
Vacuum lines on carb are all plugged, I haven’t hooked up vacuum advance or power brakes yet.

Idle mixture screws are 1.5 turns out.

I wanted to try advancing my timing more but I am up against the slot on the distributor so I’ll need to adjust the bolt under the distributor, I haven’t tried that yet.
Best thing to do is pull the distributor and back the rotor up a tooth. Sounds like it's in one tooth retarded.
 
^^THIS^^ AND IF YOU DON'T CHECK THE TIMING WITH A LIGHT you are wasting your time.

You likely have breaker points ignition. THERE IS NO REASON you cannot STATIC TIME the engine and have it within just a very small error of correct timing

(Static timing is how VW Beatles were set "in the day.")

Set up the dist as you did, then adjust the engine so the timing marks are NOT on TDC but rather "on the timing marks" where you want timing, be it 5 BTC or wherever.

Now, rotate the distributor body "retard" until the points are closed. Use a light meter or other means to indicated ELECTRICAL points break. "With practice," you can even use the coil wire and a gap or neon lamp and see when the spark happens

Now slowly advance the distributor body until the points just open. This should be quite close, within a couple degrees WHEN DONE correctly
 
If it runs & idles at high idle speed, it is unlikely to be timing. Although the timing could be 'out' slightly.

I would be looking for vacuum leaks [ is the PCV connected? ] &/or dirt/blockage in carb idle cct.
 
If it runs & idles at high idle speed, it is unlikely to be timing. Although the timing could be 'out' slightly.

I would be looking for vacuum leaks [ is the PCV connected? ] &/or dirt/blockage in carb idle cct.
I disagree. If it's retarded one tooth, it will have to be idled way up to even run.
 
Vacuum lines on carb are all plugged, I haven’t hooked up vacuum advance or power brakes yet.

Idle mixture screws are 1.5 turns out.

I wanted to try advancing my timing more but I am up against the slot on the distributor so I’ll need to adjust the bolt under the distributor, I haven’t tried that yet.

Are there any vacuum ports on the manifold you may have overlooked?
 
I removed the distributor. The other bolt was also in the fully advanced position. I made an adjustment and also inserted the distributor one tooth advanced. Now my engine is idling nicely with 6 degrees timing at 750 rpm in neutral and 650 in gear.

Having two adjustment bolts complicated things for me.
 
I admit I dislike the slant distributor setup................
 
I removed the distributor. The other bolt was also in the fully advanced position. I made an adjustment and also inserted the distributor one tooth advanced. Now my engine is idling nicely with 6 degrees timing at 750 rpm in neutral and 650 in gear.

Having two adjustment bolts complicated things for me.
You can change that and find the clamp that they used on the later slants into the 80s. It allows basically infinite adjustment similar to a small block. They are kinda hard to find, though.
 
Basically where I have it now is the lower bolt is completely retarded, the upper bolt is completely advanced and my initial timing is 6. I’ll have to pull it again to make an adjustment underneath because I think it wants more initial.

The two bolt set up is a PITA
 
Basically where I have it now is the lower bolt is completely retarded, the upper bolt is completely advanced and my initial timing is 6. I’ll have to pull it again to make an adjustment underneath because I think it wants more initial.

The two bolt set up is a PITA
It's actually quite easy with a 7/16 distributor wrench.
 
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I ended up removing the distributor and advancing the other bolt. My initial is 18 and my total is 30, I guess that means a performance curve. It’s really purring now. Fires right up just by turn key. Thanks for the help guys.

I think this slant six is going to be a lot of fun. Hopefully on the road later this month.

Did I mention a mandrel bent 2.5 exhaust with magnaflow?
 
View attachment 1715965260 View attachment 1715965261 I ended up removing the distributor and advancing the other bolt. My initial is 18 and my total is 30, I guess that means a performance curve. It’s really purring now. Fires right up just by turn key. Thanks for the help guys.

I think this slant six is going to be a lot of fun. Hopefully on the road later this month.

Did I mention a mandrel bent 2.5 exhaust with magnaflow?
Nice piece! You did very well indeed.
 
View attachment 1715965260 View attachment 1715965261 I ended up removing the distributor and advancing the other bolt. My initial is 18 and my total is 30, I guess that means a performance curve. It’s really purring now. Fires right up just by turn key. Thanks for the help guys.

I think this slant six is going to be a lot of fun. Hopefully on the road later this month.

Did I mention a mandrel bent 2.5 exhaust with magnaflow?
Looks like a beauty! What color code is that green?
 
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