shoe box Jack
Senior Member
I installed points in the 49 at 15 thow. the dwell meter reads 31, witch way should I go on the point gap/?? Jack
point gap = dwell
- Thread starter shoe box Jack
- Start date
rotorwrench
Well-known member
I set them at .016". The gap will decrease over time due to wear on the follower block but they will last longer if a smidge of cam lube is used and the condenser is a good one.
shoe box Jack
Senior Member
Thanks for the info guys, I'm going to reset the points at 17 and go from there. Thanks again. Jack.
tubman
Well-known member
I set the points on a Mallory dual point to the gap specified in the instructions. The car would hardly run. I check with the dwell meter and it was way off. I then set them according to the dwell specs in the instructions. It ran perfectly. I have to believe there was a misprint in the instructions.
3twinridges
Well-known member
Let’s say you test with a dwell meter and get an angle of 26 vs spec of 28. Is that 2 degrees worth adjusting out or is it close enough not to notice?
JB
JB
cadillac512
Well-known member
I'd leave it at 26. As the rubbing block wears the gap will close a thou or two and you'll be at 28 after a few thousand miles, and you won't notice any difference in the way it runs with that amount of change.
Crankster
Well-known member
If you get in the shop manual it explains this. (I know, I know, crazy talk)
Setting the dwell with a feeler gauge is generally speaking just to get the points close enough so that the engine will start and run, and then the dwell can be adjusted to spec using the dwell meter.
Theoretically with a brand new set of points installed (and serviceable distributor) setting the point gap with a feeler gauge to spec would (or should) result in the correct dwell time.
What happens though, the point surfaces become uneven with wear over time and get deposits etc, and just setting the gap with a feeler gauge or whatever will not result in accurate dwell. How much does it matter? Well the dwell is fixed even when within spec, (though RPM is not) so the dwell angle is an engineering compromise. For best smooth engine power and performance the dwell should be set accurately, just like any other spec. If you're just bombing around the Farm it probably doesn't matter too much if you're at 26° versus 28°.
Set the dwell with an accurate meter to 28° (Or whatever specification is listed for what you are working on) without regard to the resulting physical point gap. What you'll find too, if the distributor itself is clapped out and worn, you'll never get the same dwell reading twice in a row.
Setting the dwell with a feeler gauge is generally speaking just to get the points close enough so that the engine will start and run, and then the dwell can be adjusted to spec using the dwell meter.
Theoretically with a brand new set of points installed (and serviceable distributor) setting the point gap with a feeler gauge to spec would (or should) result in the correct dwell time.
What happens though, the point surfaces become uneven with wear over time and get deposits etc, and just setting the gap with a feeler gauge or whatever will not result in accurate dwell. How much does it matter? Well the dwell is fixed even when within spec, (though RPM is not) so the dwell angle is an engineering compromise. For best smooth engine power and performance the dwell should be set accurately, just like any other spec. If you're just bombing around the Farm it probably doesn't matter too much if you're at 26° versus 28°.
Set the dwell with an accurate meter to 28° (Or whatever specification is listed for what you are working on) without regard to the resulting physical point gap. What you'll find too, if the distributor itself is clapped out and worn, you'll never get the same dwell reading twice in a row.
3twinridges
Well-known member
Always learning from you guys, appreciate the insight, and putting up with me hijacking the thread. I measured this evening and have a dwell angle of 27.
JB
JB
V8 Bob
Well-known member
Just some additional info on '49-up single point Ford V8 dwell. Ford used point dwell contact percent of 58-63 from '49 until '55-'56, based on shop manuals on hand. To convert percent to degrees, simply multiply percent numbers by 45, the total allowed degrees per cylinder (360/8=45). So, 58% would be 26.1, and 63% is 28.35. The mean average is 27.2, or 27, what I refer to as a "target" dwell.
The 27 degrees dwell spec applies to other Ford V8 engines as well, including the Y, FE, MEL, Super Duty, Windsor, Cleveland, and 385.
I thought about starting a new thread but hope this info fits into this discussion.
The 27 degrees dwell spec applies to other Ford V8 engines as well, including the Y, FE, MEL, Super Duty, Windsor, Cleveland, and 385.
I thought about starting a new thread but hope this info fits into this discussion.
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Crankster
Well-known member
Woah woah Woah!! I was told there'd be no Math
I wondered about that, why or how the shop manual for my Y-Block sez "26 to 28.5" deg. Clears that up I guess.
How many of you'ns running contact points have a spring scale? It's true, that's part of a good Tune-Up.
The specification is approx. 1 lb of tension. That's why you'll notice there are two nuts securing the spring, the innermost nut is a jam nut, loosened so the spring can be moved around to apply greater (or lesser) tension on the point contacts. Normally "point bounce" can be an issue at higher RPM. One of the tricks drag racers would do is crank up the tension crazy high, and/or jam a piece of vacuum hose in the spring to keep the tension high. The point block would rapidly wear in just a few miles I guess (haven't tried it) but points were inexpensive, it was a way of maintaining full ignition potential at stupid high RPMs.
On Ford V8 contact points, you'll notice a notch in the baseplate and distributor breaker plate. What is that for? It has a purpose. The idea with that, is to use a flat blade screwdriver as an adjustment tool, the point screw already having been tightened juuuust enough to hold the point adjustment setting, yet still be movable on the fly to and fro. Using a dwell meter and preferably a remote starter (SWMBO is not necessarily a good choice) the correct dwell angle can be achieved without needing to even start the engine, just crank it over for a few seconds.
GM obviously hit one out of the park on their distributors with that little window access on the cap and Allen hex key as dwell adjustment tool.
I wondered about that, why or how the shop manual for my Y-Block sez "26 to 28.5" deg. Clears that up I guess.
How many of you'ns running contact points have a spring scale? It's true, that's part of a good Tune-Up.
The specification is approx. 1 lb of tension. That's why you'll notice there are two nuts securing the spring, the innermost nut is a jam nut, loosened so the spring can be moved around to apply greater (or lesser) tension on the point contacts. Normally "point bounce" can be an issue at higher RPM. One of the tricks drag racers would do is crank up the tension crazy high, and/or jam a piece of vacuum hose in the spring to keep the tension high. The point block would rapidly wear in just a few miles I guess (haven't tried it) but points were inexpensive, it was a way of maintaining full ignition potential at stupid high RPMs.
On Ford V8 contact points, you'll notice a notch in the baseplate and distributor breaker plate. What is that for? It has a purpose. The idea with that, is to use a flat blade screwdriver as an adjustment tool, the point screw already having been tightened juuuust enough to hold the point adjustment setting, yet still be movable on the fly to and fro. Using a dwell meter and preferably a remote starter (SWMBO is not necessarily a good choice) the correct dwell angle can be achieved without needing to even start the engine, just crank it over for a few seconds.
GM obviously hit one out of the park on their distributors with that little window access on the cap and Allen hex key as dwell adjustment tool.
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