Thread: 302 Stroker??

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I do remember a number of cars running this setup successfully in SCCA racing, we played with them on a Shelby for half a season, then went big block and A Production instead the next year.... I do remember playing with jetting, linkage, and secondary springs along with a long stroke on the gas pedal to make the power transition more even and less likely to blow the tires off the car coming out of a turn, or just going up through the gears..... Could really adjust that "transition rate" (as our driver called it) on acceleration. As mentioned, the next season was a 428 CJ....no such thing as sneaking up on the power with that monster in the car!!!!!!!!! First race of the season at College Station with the big block, Ben spun the car 3 times....all 3 on turn exit!!!!

them longer gas pedals have been one of the best race invintions ever!!!!!!!!!!!!!!

I saw an advertisment from Shelby American which had all his manifolds spread out around a young lady in a cowboy hat. In the description for this manifold, "they" claim it to be satisfactory for street operation. By the way it behaves right now, I have to agree. The car actually runs smoother right now, even the sound is smoother / calmer than with the dual plane!

Now I just have to wait for the snow / ice and the salted roads to go away.

I believe a lot of that comes from the more equalized flow characteristics of the manifold....

BYW===When the roads get fit for playing again, I'd suggest a good vacuum gauge installed when you start playing with the secondary springs.... Holley makes a really neat quick change kit for the secondary springs. Getting the secondary springs set to work progressively and at or near the rate of the progressive linkage will make the setup smoother, improve driveablity, and improve efficiency!

PS--You're really making my feeble old memory work here Mike!!! We also played with the advance rate on the mechanical advance side of the distributor----got any friends with an old Sunnen Distributor machine in their shop??????

One vacuum gauge is installed permanently in the dash, and I wish I knew who had a distributor machine.
Right now I've got the advance stretched out to 40' at 2200 rpm... but I was reading one of RSpears posts and he mentioned that he was cautioned that the pistons wouldn't tolerate that.. I think I may back off just a bit, get the advance back to 35 / 36.

Originally Posted by 34_40

One vacuum gauge is installed permanently in the dash, and I wish I knew who had a distributor machine.
Right now I've got the advance stretched out to 40' at 2200 rpm... but I was reading one of RSpears posts and he mentioned that he was cautioned that the pistons wouldn't tolerate that.. I think I may back off just a bit, get the advance back to 35 / 36.

Like Dave says, it's easy when you're playing with a Spark Map, just boxes on a chart! My limit came from the fact that I have KB Hypereutectic pistons, and KB puts a 36 degree limit on timing for those pistons. Other pistons don't carry that limit, and even with that limit mine pushes up to 40 degrees at and above 3000rpm when MAP is 10"HG or less. Basically, this is an economy setting because the only way the engine can ever see that part of the curve is throttle closed coasting down a hill with high rpm. That feature came from the guy at Edelbrock, and he said that they often crank up to 44 to 46 degrees in that zone because it's almost never seen and there's virtually no load on the pistons at that part of the map. I chose to limit mine to 36 degrees under load (MAP 12 and above), ramping up to a peak of 40 on the lines for Zero and 10"HG above 2500rpm. If you're in that zone and blip the throttle, total timing drops immediately to a peak of 36 - boxes on a chart, telling the ECU what to do.

The little engines can take 40----just not for long!!! I've ran 38 and 40 on lightweight drag cars, but there's a lot of difference between a few passes on race gas with a 5 speed and a driver, backing it off to 36 is good....

Best thing about the old distributor machines, could play with the rate at which the advance came in rather then just what the total was. Could do the same thing with a really quality timing light with a dial and digital scale on it (I've got a Snap-on light that will do it) and checking the advance every couple hundred RPM and see when and how much advance is coming in..Very tedious, maintenance intensive, and probably not necessary at all on a street engine.....

With the new Coyote engine it's "easily(?)" done just by mapping the advance curve and the fuel curve to match, then another couple grand worth of data acquisition pieces to verify it when it goes down the track!!!!! Everything is easier if you can just sit back and throw money at it, huh?

Yeah, tossing money can make some of it easy.. I have the snap on dial back light and use a external vacuum gauge and tach and it takes a long time to gather data, make an adjustment, retest, repeat....

You know what I'll be doing this weekend!

Pistons are dumb----------------


The issues of timing------------people talk about degrees of timing before top dead cender---it actually comes down to Time ( you know, one of them absolutely constant values, like gravity????) If spark could be set by time in milli seconds, you could run many more degrees of timing ----


Reason we are limited on the street to more restricted numbers with the lower quality fuel is it burns much faster (ever noticed how often you got to stop for gas?) and with the timing numbers we run for midrange(to me that's low range--) there is more time for the fuel to burn and reach that pressure point at say 2000 rpm than at 8000 rpm----------The reason we can/need to run more advance for wot operations is to enable the flame front to reach that sweet spot for the flame/pressure front, piston/rod/crank angles, etc which ironilly is past top center on the way down------------

Originally Posted by jerry clayton

Pistons are dumb----------------


The issues of timing------------people talk about degrees of timing before top dead cender---it actually comes down to Time ( you know, one of them absolutely constant values, like gravity????) If spark could be set by time in milli seconds, you could run many more degrees of timing ----


Reason we are limited on the street to more restricted numbers with the lower quality fuel is it burns much faster (ever noticed how often you got to stop for gas?) and with the timing numbers we run for midrange(to me that's low range--) there is more time for the fuel to burn and reach that pressure point at say 2000 rpm than at 8000 rpm----------The reason we can/need to run more advance for wot operations is to enable the flame front to reach that sweet spot for the flame/pressure front, piston/rod/crank angles, etc which ironilly is past top center on the way down------------

And that's what we call the "OTHER 359" degrees!
Also, gas with a lower octane number doesn't mean it's of a lower "quality", but it does burn quicker for a shorter power cycle. And many vehicles actually achieve a better mpg on a lesser octane rated fuel!

Originally Posted by 34_40

...Also, gas with a lower octane number doesn't mean it's of a lower "quality", but it does burn quicker for a shorter power cycle. And many vehicles actually achieve a better mpg on a lesser octane rated fuel!

I agree 100%. I took a class in college, Internal Combustion Engines, and one of the things we learned was that at a given timing setting you get the most power and highest efficiency with the lowest octane fuel that your engine tolerates without any pre-ignition "ping", and to clarify, "ping" precedes "knock" which is detonation. Back in the day when we had only two grades, "regular" and "ethyl", guys would pull in and say they were going to fill up with ethyl for more power, and actually the reverse was true.

Originally Posted by rspears

I agree 100%. I took a class in college, Internal Combustion Engines, and one of the things we learned was that at a given timing setting you get the most power and highest efficiency with the lowest octane fuel that your engine tolerates without any pre-ignition "ping", and to clarify, "ping" precedes "knock" which is detonation. Back in the day when we had only two grades, "regular" and "ethyl", guys would pull in and say they were going to fill up with ethyl for more power, and actually the reverse was true.

You and I took the same class!

1500 rpm=25rps=12 1/2 ignition sparks per second= 0.08 second per spark




3000 rpm=50 rps=25 ignition sparks per second = 0.04 second per spark


6000 rpm =100rps=50 ignition sparks per second=0.02 second per spark


think about where your piston is at in the cycle dealing with TIME ( a constant in physics ) in relation to your degrees of timing according to crank rotation------------


Keep that too much advance at the lower rpm levels for the sake of cruising economy is probably more destructive when you moderately accel (no downshift) to pass or climb a hill than if you downshift and rev it up---cutting the time wave before top for that dreadful knock-----------


And if I opened a box of pistons that said limit timing-----------------

Originally Posted by jerry clayton

.....And if I opened a box of pistons that said limit timing-----------------

For some, Jerry, it's a matter of being prudent in understanding any limitations that may exist for the components that were selected when the engine was assembled by someone else, and not being asked/aware of those limits at the time selections were being made. Knowing the limitation that Keith Black, who's products I consider to be of very good quality, put on these particular pistons it's simply a matter of prudence to set limits accordingly. The option would be to tear the engine down and change out pistons which would, in my book, put my sanity in question. I could limit my total timing to 30 degrees and likely not notice the difference given the power to weight ratio we have in these cars. I'm perfectly happy with the KB Hypereutectics that were selected, and care not a whit that they have a timing limit.

Roger-----I did it more as a joke than anything-------------


However, since you mentioned Keith Black, I guess you don't remember/know that he passed away years before his name was sold by family members to this piston company-----------I knew Keith personally, and he, like many others, knew no limits----