Locking out MSD Distributor on 496

RBlaha

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My dad's car was running very rich and wouldn't idle right. I ended up rebuilding the carb 850cfm Demon and retuned the carb with 81 jet primary and 93 secondary with a 6.5 power valve and also messed with the timing. My dad has a digital 7 box which can retard the timing at start up. I ended up putting the black round shim in the MSD distributor and timing is at 28 degrees at idle and 36 advanced. The car is pulling 10-12 inches of vacuum now and idles and drives like a dream. My buddy said we should just lock out the distributor at 36 and low end would benefit from it and also be more responsive. The motor is a muscle motors 496 with a 11 to 1 compression, stage 6 aluminum heads with a M1 intake and 850 demon. the cam my dad bought years ago and he cant find the cam card but but its a decent bigger cam in it and it seems to like the timing. Before the MSD had the blue shim for the advance and the car was 18 degrees at idle and 36 advanced, and it really didn't like that to much as the car wanted to die and both primary and secondarys were open just to get the car it idle pulling 8-9 inches of vacuum. My dad is also running a RJ18YC Champion plug which I think that might be to hot of a plug. What do you guys think of locking out the timing on the distributor and would it be worth the hassle? Also the car has no vacuum brakes. Thanks, Rick.
 

topside

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RJ18YC ? That's way hot. A 14 would be plenty hot.
Locked out the distributor on my SB Duster drag car, but needed an ign kill switch most of the time.
I'd spin it over for a couple secs, a pump on the pedal, flick the switch, and it's happy time.
On a street car that could be a pain. That car was only raced.
My other Duster - fairly rowdy Indy-head 512" RB - liked 18-20 initial; no starting problems, lit off almost immediately.
 

1 Wild R/T

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Good buddy had a RBRE 440 running an Ultradyne 271@.050 .620 lift SFT, he ran it on the street for years.. Incredibly docile, he'd go on 300 mile drives with us regularly.... Considering the power it made & how nasty it sounded I was always blown away... Ray Barton sent the engine out complete with the carb & distributor.. Timing was locked, it had a timer in the starting circuit so it would disable the ignition for about a half second when the starter was engaged so the starter would have the engine spinning before the ignition came on preventing kickback... The digital seven is a better option... Do it & don't look back...
 

Geoff 2

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Rick, Couple of points.
- with 11:1 compression, plugs are too hot, you might want one step colder in spark plugs; a NGK 6 heat range, not the Champion junk.
- yep, not surprised it runs nice with 28* initial timing. That is a very smart move, & it might well idle even better with more. Try it: if idle rpm increases with more timing, that is what it wants.
- nothing wrong with locking out the dist, but it means the engine has to crank with 28* initial. You will need a high HP starter for that such as the MSD Dyna 3.2 hp.
- the hard cranking is the reason for the retard feature, to make it easier to crank.
 

66Satellite47

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That plug is WAY hotter than I ever ran. I'd look into an NGK compares to the 10 or lower Champion range.
 

RBlaha

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Thanks for the replies. I'll buy some NGK plugs to a colder plug and we will try locking out the distributor and see what happens.
 

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