Help with a recent 8ba rebuild

D

Dirtslinger

Member
Ive got my recently rebuilt 8ba on the run stand with a new Merc crank, .30 over and a mild Schneider cam (260f) with the original single carb setup. I've gotten it started and in fact was on my way to completing the cam break in when a lower radiator hose popped off after a few minutes. But I have noticed that it will only start with the distributor turned all the way to the left and runs erratic, missing and at times popping. I have confirmed that Im not 180 out as I have the rotor on the #1 cylinder on the compression stroke. Any ideas? Btw the engine sounds great and has around 55-60psi of oil pressure upon start up.
 
What distributor are you using ? Ithink You can lift the distributor a little with the cap off and rotate one tooth . Sorry no coffee yet . More after I wake up .
 
You need take the cap off, unbolt the distributor and move the rotor one or two teeth, clockwise. Then do your static timing.
I hope you have a timing light!
 
You can do what was mentioned up above - to be sure your timing is correctly set . . . or you can explore other distributor options. Even with the initial timing set correctly, you'll still have an advance curve to deal with - and you won't really be able to tune it to match your modified engine.

If it was mine, I'd probably ditch the stock distributor and find a Mallory mechanical advance distributor and have it rebuilt or converted for a flathead advance curve. You can also have SBC distributors modified to work on a flathead.

There are a few guys that can help you with this - Charlie NY is one of them. The stock distributor understands the vacuum signal of a stock engine - it has no mechanical advance. When the vacuum signal is changed from stock, then the advance curve changes with it.

While some guys can get them to work on non-stock engines . . . to me, I'd much rather go with a completely different setup.
 
Just curious, when you guys are recommending to move the rotor one or two teeth, can you explain more what you mean? All of the flathead distributors I've dealt with just have a flat spot for the rotor to slide down against.

I think what you saying is to pull the distributor out so it's not against the cam gear and rotate the rotor while still attached to the shaft?

I'm assuming that's what you mean by one or two teeth and trying to visualize it.
 
Tim, moving the distributor one tooth at a time refers to the little gear at the bottom of the distributor meshing with the cam gear so that the timing is correct. To do this, you literally loosen the distributor hold down bolt, gently lift the distributor up and turn the rotor by hand until you feel the distributor drop down and mesh with the next tooth on the cam gear.
 
19Fordy said:
Tim, moving the distributor one tooth at a time refers to the little gear at the bottom of the distributor meshing with the cam gear so that the timing is correct. To do this, you literally loosen the distributor hold down bolt, gently lift the distributor up and turn the rotor by hand until you feel the distributor drop down and mesh with the next tooth on the cam gear.
Click to expand...

Got it, Jim. Thank you and that's what I thought. Maybe you can tell from my post, I don't fool around with the side mount distributors much if at all. LOL!
 
I try to assume nothing but #1 on a flathead is the front US passenger side cylinder. People who are used to modern engines often get that wrong. Also, as far as I know, a flathead is the only v8 engine where #1 is not the cylinder farthest forward.
As others have stated, moving the distributor gear a tooth at a time or ditching the Loadmatic for something better like B&S suggested will probably fix the problem. The stock distributor uses vacuum from both the carb and intake which is a problem with a non stock cam.
 
The cam is the culprit, the load a matic distributor is following it. Now you cam go back to a stock cam or a distributor that follows the engine.
Gramps
 
I do have the stock distributor and the engine ran fine before rebuild although it was very tired. So I can't run the stock dizzy with a cam? I didn't know that. Is it worth it to move it a tooth or two?
 
I assumed when you said you couldn't turn the distributor any further to the left, that the vacuum can on the distributor was hitting the cylinder head.
The only reason for jumping the teeth is that the body of the distributor needs to be rotated!
What did the timing light tell you?
No way you had the timing 180 degrees out when you actually had the motor running.
 
The loadmatic distributor is purely vacuum operated. Since your cam is changed , it changes the vacuum signal plus the mechanical valve timing . All of those alter the needed ignition timing you need . There are some good replacement distributors available, but you need to look for them now . The modified sbc ( small block chevy ) and older mallory, plus some like the newer electronic offerings from dealers like Speedway.
 
With the wrong cam, the distributor is getting the wrong advice from the can you put in. simple??
Gramps
 
I would suggest contacting: Charlie Swendler who does a great job with the GMC distributor conversions which should assist with your situation. I have a 8BA with a Max 1 cam running one of his set ups. Runs just fine. I'm using 6 V.
Phil NZ
 
The distributor doesn't care about voltage, nor does the condenser. The coil is the governing factor and should be for the correct voltage.
 
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