MP 528 cam vacuum

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Yes, I've been always running 35 or 36 total. I don't know if I can describe it right in english, but I feel a lack of power over 5500 and at 6000 it sounds like backfiring or something, but not from the carb.
 
Are you talking cruise or just wot?

Say the pv is right and it's happening at cruise too
and well...since you're already 2 jets fatter than stock 67's...I'd say back the timing down to 32* total and then weld up the slots on the advance to limit the mechanical advance down to only 8* or 10*..so that you can have the 22-24* initial but not have it advance more than 32* total.
 
Sounds like it's lean and likely needs a larger Idle Feed Restrictor.
 
I think I have maybe less than 10* of advance now. It was really close to the total at idle, I think about 26-28. I'll back up to 32 and see what happens. But I still think its a bit lean because it runs better in the moments the booster is spittin gas (when I push the throttle).
 
ok...but what rpm does the distributor full advance in relation to your goosing the throttle...and what power valve are you running will help the xcelleration/wot ..you may have a flat spot when tipping it into wot if its not opening,

Not saying you dont need more jet but at the same time..
If you need to jet more than 4 sizes over stock spec jetting, get a bigger carburetor.
 
I'm confused. what is the timing with the engine idling?
 
At this moment I don't know what's the initial timing. I suppose its about 26-28*, with 36* total.

I'm running the stock 6.5 PV, 69-75 jetting and a slightly larger booster on the primaries.

With more alcohol than the "usual" in the gas, I think I need to run richer than you guys.
 
If it will start with 26* I say leave it, but look at testing with less total, like if dont surge at 32*...it most likely is not necessarily the jetting...the same air/fuel..just different spark timing..

but how about looking at the plugs color?

you need a vac gauge so you can stick a pv in there thats about 2'' below what you have/read at idle.fwiw...but thats not the cruise surge culprit..
 
Ok, my plugs were always brown or dark brown. But it surges, what is strange. What I was thinking before today: the PV is too large, so it opens at idle and make the plugs brown. So I would put a smaller PV and larger jets and see what happen, but MAYBE I'm wrong!
 
Marcelo Dart BR said:
Ok, my plugs were always brown or dark brown. But it surges, what is strange. What I was thinking before today: the PV is too large, so it opens at idle and make the plugs brown. So I would put a smaller PV and larger jets and see what happen, but MAYBE I'm wrong!
Click to expand...

the larger the number on the pv, the sooner it will open...but the pv will only effect the main circuit...not the idle circuit, the reason for this is there is no signal to pull fuel through an open pv IF the blades are positioned correctly/.020 or so thousandths of the slot exposed, as in only signalling the idle circuit..

so if the pv is responsible for you overly rich ''idle''...its because you are idleing off the main circuit to begin with.

though if you have the initial set as high as you claim, you shouldnt have any problem with the pv effecting your idle.
 
I just ordered the vacuum gauge.
The idle mixture screws are about 1,5 turns, maybe a little more.
As now I'm running a "new" idle, I'll have to check the plugs again, NOW I don't know how are they looking like.

So, tomorrow I'll try less total timing. If it doesn't help, I'll try the larger jets. If it doesn't help, I'll cry like a baby.
 
Marcelo Dart BR said:
I just ordered the vacuum gauge.
The idle mixture screws are about 1,5 turns, maybe a little more.
As now I'm running a "new" idle, I'll have to check the plugs again, NOW I don't know how are they looking like.

So, tomorrow I'll try less total timing. If it doesn't help, I'll try the larger jets. If it doesn't help, I'll cry like a baby.
Click to expand...

Get a new plug, at least one...cause once they go brown...they dont really clean up and allow you get a real look into the mixture.
 
I backed it a bit today, don't know exactly how much because I didn't checked with the timing light yet, but a couple of degrees.

I tried to run it but there's a lot of traffic at this time. I could only push it to 6000 one time, and it showed no signs of surge. Apparently this issue is solved!

So, it was pinging, just at high rpm?
 
What exactly is the timing curve set up like? What initial (a real number, not "I don't know"), what total? At what rpm are you checking it? What distributor are you running? Electronic ignition or? If electronic, what module is running it?
 
You really need to put a light on it. Detonation can occur without you ever hearing it.
 
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