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My friend restores Mustangs and always dynos the motors and his last Boss 302 made 330HP through the stock exhaust. This motor was built to 100% stock 70 boss specs. He also did a 69 boss 429 and it made 440 hp. 428CJ made 377.
 

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The cleveland head thing is all over the place. OUR experiences with running them heads for years and setting national record sometimes seems to contradict the trends, so be it.

Steve, we did a mild 356/357 cleveland headed deal years ago, solid cam, cleaned up heads and I forget exactly the single plane intake, with 750 carb. 3000 lbs streetcar with a stick would run 10.70's without issues. Respectable street manners and could easily drive on the street. OEM block heads and nodular crank deal must have made 550+hp.

Cleveland heads respond GREAT to compression, cam and intakes. BEST engines I have ever seens for those 3 minor things make huge gains. another 356 with nod, crank, alum rods 12.5 compr, solid roller, PORTED 4v heads and Weiand tunnelram with 2 750's is an easy 720+Hp deal. Redid that 356 with 13-1 piston, C302B heads, bit bigger solid roller and home made sheetmetal intake, made 789Hp @ 8600 on Oddy's dyno. These motors were trouble free and just flat out WORKED.

I don't think anything out of ANY manufacturer make the power like a cleveland headed Ford. My shop did what I would say is the most impressive Cheveland headed mild motor. OEM 4v head and block, cast single, 9.03 @ 3000lbs N/A. Must be right in the 800Hp range. But could just be the Canadian air here in Ontario?????

It does surprise me that this Boss 302 making the power as low in the RPM range though!!!!
 

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Looks exactly like one of my 10:1 357 sbc’s with way less head & a stock 600 dp.

Seems you could make more steam than that with those magical heads.
Oh you could and i have. By a long ways. But owner requested want he wanted.Just showing you that you dont need a chevy peanut port to make low end tq.
 

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The cleveland head thing is all over the place. OUR experiences with running them heads for years and setting national record sometimes seems to contradict the trends, so be it.

Steve, we did a mild 356/357 cleveland headed deal years ago, solid cam, cleaned up heads and I forget exactly the single plane intake, with 750 carb. 3000 lbs streetcar with a stick would run 10.70's without issues. Respectable street manners and could easily drive on the street. OEM block heads and nodular crank deal must have made 550+hp.

Cleveland heads respond GREAT to compression, cam and intakes. BEST engines I have ever seens for those 3 minor things make huge gains. another 356 with nod, crank, alum rods 12.5 compr, solid roller, PORTED 4v heads and Weiand tunnelram with 2 750's is an easy 720+Hp deal. Redid that 356 with 13-1 piston, C302B heads, bit bigger solid roller and home made sheetmetal intake, made 789Hp @ 8600 on Oddy's dyno. These motors were trouble free and just flat out WORKED.

I don't think anything out of ANY manufacturer make the power like a cleveland headed Ford. My shop did what I would say is the most impressive Cheveland headed mild motor. OEM 4v head and block, cast single, 9.03 @ 3000lbs N/A. Must be right in the 800Hp range. But could just be the Canadian air here in Ontario?????

It does surprise me that this Boss 302 making the power as low in the RPM range though!!!!
Lol believe every word. We have seen similar results.
 

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Every one of these Boss 302 "ports are too big" rants inspires me to repeat this.

The single thing that wakes up the Boss 302 is the advance curve Ford published in the off-road tuning literature, the "Muscle Parts" books. They specified the spring part numbers and fortunately they were the same springs as in '65 and '66 300 HP 390 engines, so 50 years ago they were easy to get out of a distributor bone pile. I did this several times and guarantee it is the single thing that eliminates the Boss 302 "ports are too big" BS.

The carb jetting is in those books too. I recall it was up 2 # in the primary and some stagger in the secondary jets.

Advance curve Cliff notes are thus: 16 degrees initial until 1200 then up to 30 degrees at 2000 RPM then a slope to 40 degrees at 8000. This makes the Boss 302 have torque like it has another 100 cubic inches. I kid you not.

The all in at 2500 BS has too much timing for best torque in the lower RPM range when it is timed for best power at high RPM, too much advance kills the torque, ergo "the ports are so big it has no bottom end" BS.

I tuned probably a half-dozen of the stock production cars when they were near new and they all woke up bigly from just doing the distributor.

The simple key to success was in the Ford tuning advice and knowing how to use a distributor machine to calibrate an advance curve. Combine that with literacy sufficient to understand instructions and believe Ford knew how to tune their own engine, It was too easy.
I set all my distributors to be full in by 2000-2500. On bbf and small. Reguardless of configuration!!
 

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69's had a skirt cracking issue exacerbated by unhooking the rev limiter.
It would seem that simple, but as usual the real "rest of the story" is in the details, the real reasons for the "ports too big, no torque" and "broke piston skirts" has more causes in effect than just unhooking the rev limiter.

If you glance over my post about the advance curve here DZ302 VS Boss 302 on the dyno and glean from it the important detail is the Ford 'off-road' specification for WOT timing is an advance curve with a smooth slope from 30 at 2000 to 40 at 8000.

These engines ran really good between 6000 and 7000+ when the timing was 38-40 deg. The rev limiter was 6150. Every sporting Boss 302 owner/tuner I ever met unpluged the limiter and installed super light advance springs, sometimes total at less than 2000. 40 deg at 2000 made them detonate with any heavy throttle below 3500-4000 RPM and the situation became much worse when the gasoline octane went in the shitter in 1971-72. Lugging the engine with a too-quick advance curve is what broke Boss 302 piston skirts.

Detonation damage wasn't just a problem for Boss 302s, all of the late 60s high compression engines of every make suffered the same, broken skirts and slopped out timing chains, slipped harmonic balencer rings, beat up valve seats and guides, slopped out ring lands, all from detonation.

Another problem for the Boss was the original dual point distributor has a ball bearing breaker plate that would get sloppy in just a few hundred miles when people installed the Accel points with the extra heavy breaker arm and 48 oz. spring tension. The heavy spring and arm mass would kill the ball bearing in not much time at all, so then the timing was erratic because of slop in the distributor.

Accel's marketing plan was cunning, sell the stiff points to kill the stock distributors, then because they seemed to work OK when first installed, more Accel is better, so buy the Accel dual point distributor with the (you guessed it) all-in at 2500 advance. The Accel distributors had bad spark scatter right out of the box and a lot worse after about a week. They killed their own distributors with the same extra-heavy points springs.

The fix was to use the original distributor with a regular Ford single point plate and a set of Mallory points that have a light breaker arm with only 26 oz. spring tension. With select-fit bushing and shaft clearance and other details in snugging up clearance of the breaker plate pivot for the vacuum advance, a Ford distributor could fire accurately to over 8000 RPM with little or no dwell loss.
 

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I set all my distributors to be full in by 2000-2500. On bbf and small. Reguardless of configuration!!
Don't keep your head in the sand, that just isn't how to get best power. Do you realize the timing is retarding after its all in because the electronics have slew rate? A high RPM advance curve compensates for the electronic retard.

With almost no exceptions, all engines benefit from increasing advance as RPM increases above the torque peak. This is extremely so with fast burn combustion chamber heads. Just how much to advance is the key. Some engines it is a lot more than you might think. If you don't try, you never know.

I've done a couple of 392 Windsors with the heart shape chamber aluminum heads that wanted 20 deg at 2000 with a slope to only 30 deg at 8000 for best torque/power over the entire range.

It used to be some dyno time was necessary to plot an advance requirement. Nowadays you can use an accelerometer app in a smart phone and test acceleration in 1000 RPM ranges with different timing settings to figure it out without a dyno, if you want to spend the time.

To make distributors do this accurately and reliably is the problem. It wasn't too difficult with the old 60s-70s era OEM distributors but most of the new junk (made in China) is almost worthless because the advance parts are so soft engine harmonics, mostly oil pump chatter, beat the advance parts up so bad they won't survive extended use.
 

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I got a set of heads that flow 380 cfm on my street car. Has a 224/230 @ .050 cam in it. Makes decent power to 6500.
 

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I have a few of those books. I thought I had some of that stuff scanned, but it looks like my photobucket account dumped a bunch of pictures .... dammit.
Do you have the '69-'70 Muscle Parts book that has the recipe for the 428 Super Cobra Jet that shows the advance curve for (I think?) the .600 lift cam. If you do, could you put it up here? Time and lending, I am missing that book.

That curve is so unusual that for a long time I thought it was a misprint until the same info turned up in another Ford source, and mostly, I began to understand more about why some engines might have unusual timing requirements.

In the case of the 428 SCJ it needs more high RPM advance because it is carb restricted with the 735 Holley they used to meet emissions.
 

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Don't keep your head in the sand, that just isn't how to get best power. Do you realize the timing is retarding after its all in because the electronics have slew rate? A high RPM advance curve compensates for the electronic retard.

With almost no exceptions, all engines benefit from increasing advance as RPM increases above the torque peak. This is extremely so with fast burn combustion chamber heads. Just how much to advance is the key. Some engines it is a lot more than you might think. If you don't try, you never know.

I've done a couple of 392 Windsors with the heart shape chamber aluminum heads that wanted 20 deg at 2000 with a slope to only 30 deg at 8000 for best torque/power over the entire range.

It used to be some dyno time was necessary to plot an advance requirement. Nowadays you can use an accelerometer app in a smart phone and test acceleration in 1000 RPM ranges with different timing settings to figure it out without a dyno, if you want to spend the time.

To make distributors do this accurately and reliably is the problem. It wasn't too difficult with the old 60s-70s era OEM distributors but most of the new junk (made in China) is almost worthless because the advance parts are so soft engine harmonics, mostly oil pump chatter, beat the advance parts up so bad they won't survive extended use.
Have you actually looked at the phase delay with a signal generator sweep and a 2 channel DSO?

8000 rpm is only 133 hz, and my gut feel its nowhere near the limit of saturation of the secondary or the upper end of primary frenquency response of an electronic ignition.
 

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Don't keep your head in the sand, that just isn't how to get best power. Do you realize the timing is retarding after its all in because the electronics have slew rate? A high RPM advance curve compensates for the electronic retard.

With almost no exceptions, all engines benefit from increasing advance as RPM increases above the torque peak. This is extremely so with fast burn combustion chamber heads. Just how much to advance is the key. Some engines it is a lot more than you might think. If you don't try, you never know.

I've done a couple of 392 Windsors with the heart shape chamber aluminum heads that wanted 20 deg at 2000 with a slope to only 30 deg at 8000 for best torque/power over the entire range.

It used to be some dyno time was necessary to plot an advance requirement. Nowadays you can use an accelerometer app in a smart phone and test acceleration in 1000 RPM ranges with different timing settings to figure it out without a dyno, if you want to spend the time.

To make distributors do this accurately and reliably is the problem. It wasn't too difficult with the old 60s-70s era OEM distributors but most of the new junk (made in China) is almost worthless because the advance parts are so soft engine harmonics, mostly oil pump chatter, beat the advance parts up so bad they won't survive extended use.
Well i have to say i did not know that. We have always ramped the advance in hard and even my dyno guy likes to do the same. But now that you mention the retard factor we did notice that on our last couple sessions and couldn’t understand why it was backing off. I believe you on the harmonics from pump drive as i see timing jump until rpm pegs the advance hard against stop at higher speeds. I also noticed when i use my 5inch offset distributor with belt drive none of that exists. The belt seems to absorb it. Thanks for info. Very interesting.
 

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Have you actually looked at the phase delay with a signal generator sweep and a 2 channel DSO?

8000 rpm is only 133 hz, and my gut feel its nowhere near the limit of saturation of the secondary or the upper end of primary frenquency response of an electronic ignition.
Yes. You can see it easily with a 2-channel 100 MHz scope. Some of the recent years manufacture HEI modules are crazy slow. Ironically, points have the least slew rate because there is only one switch. The slew rate is in the R/C rise time and switching speed of the solid state components in the amplifier circuits, plus the coil has rise time. It may seem insignificant until you think about 8000 RPM is 48,000 degrees per second.
 

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While we are on this ignition topic i was under the impression that some engines pick up hp on upper rpms by retarding timing a few degrees?i know this is especially the case in two stroke snowmobile engines. Does this apply to car/race engines?
 

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Well i have to say i did not know that. We have always ramped the advance in hard and even my dyno guy likes to do the same. But now that you mention the retard factor we did notice that on our last couple sessions and couldn’t understand why it was backing off. I believe you on the harmonics from pump drive as i see timing jump until rpm pegs the advance hard against stop at higher speeds. I also noticed when i use my 5inch offset distributor with belt drive none of that exists. The belt seems to absorb it. Thanks for info. Very interesting.
When the advance mechanism is not bottomed out against a hard stop, in other words somewhere in the middle of the range of advance, the transfer of radial motion from the main shaft to the trigger reluctor is through the weights and springs, which in essence act as a pendulous torsional absorber, and so steady the rotational velocity of the trigger reluctor. Similar or same effect as the added mass and belt in your belt drive, as you notice.

One of the advantages of the big HEI coil-in-cap distributor is the advance mechanism when properly configured does not have a hard mechanical stop, the advance stops increasing because of the geometry of the weight and cam when properly coordinated with the spring tension, and additionally the large heavy rotor acts as a flywheel, smoothing the rotational velocity.

This link should open at the pendulous absorber description.

 

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It would seem that simple, but as usual the real "rest of the story" is in the details, the real reasons for the "ports too big, no torque" and "broke piston skirts" has more causes in effect than just unhooking the rev limiter.

If you glance over my post about the advance curve here DZ302 VS Boss 302 on the dyno and glean from it the important detail is the Ford 'off-road' specification for WOT timing is an advance curve with a smooth slope from 30 at 2000 to 40 at 8000.

These engines ran really good between 6000 and 7000+ when the timing was 38-40 deg. The rev limiter was 6150. Every sporting Boss 302 owner/tuner I ever met unpluged the limiter and installed super light advance springs, sometimes total at less than 2000. 40 deg at 2000 made them detonate with any heavy throttle below 3500-4000 RPM and the situation became much worse when the gasoline octane went in the shitter in 1971-72. Lugging the engine with a too-quick advance curve is what broke Boss 302 piston skirts.

Detonation damage wasn't just a problem for Boss 302s, all of the late 60s high compression engines of every make suffered the same, broken skirts and slopped out timing chains, slipped harmonic balencer rings, beat up valve seats and guides, slopped out ring lands, all from detonation.

Another problem for the Boss was the original dual point distributor has a ball bearing breaker plate that would get sloppy in just a few hundred miles when people installed the Accel points with the extra heavy breaker arm and 48 oz. spring tension. The heavy spring and arm mass would kill the ball bearing in not much time at all, so then the timing was erratic because of slop in the distributor.

Accel's marketing plan was cunning, sell the stiff points to kill the stock distributors, then because they seemed to work OK when first installed, more Accel is better, so buy the Accel dual point distributor with the (you guessed it) all-in at 2500 advance. The Accel distributors had bad spark scatter right out of the box and a lot worse after about a week. They killed their own distributors with the same extra-heavy points springs.

The fix was to use the original distributor with a regular Ford single point plate and a set of Mallory points that have a light breaker arm with only 26 oz. spring tension. With select-fit bushing and shaft clearance and other details in snugging up clearance of the breaker plate pivot for the vacuum advance, a Ford distributor could fire accurately to over 8000 RPM with little or no dwell loss.
This post and many others in this thread are excellent! Thanks for the information and a glance into your experience and hard work. Fascinating.
 

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Yes. You can see it easily with a 2-channel 100 MHz scope. Some of the recent years manufacture HEI modules are crazy slow. Ironically, points have the least slew rate because there is only one switch. The slew rate is in the R/C rise time and switching speed of the solid state components in the amplifier circuits, plus the coil has rise time. It may seem insignificant until you think about 8000 RPM is 48,000 degrees per second.
I've got plenty of them and the last time I looked, was at a 7AL3 15 years ago don't recall any issues. I would figure the offset would be constant at such a low frequency range. 48,000 degrees a second seems like a red herring as your your firing event period is about 2msec. FYI, Δ1 degree would be 20µsec offset at 8K rpm (1/90 of the spark to spark period)

I would have expected the manufacturer's stuff to be more stable. Thank goodness its repeatable, but I would hate using a timing light at 8K rpm.
 

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While we are on this ignition topic i was under the impression that some engines pick up hp on upper rpms by retarding timing a few degrees?i know this is especially the case in two stroke snowmobile engines. Does this apply to car/race engines?
Besides the obvious RPM range factor, the timing requirement of any engine is mostly dependent on VE effect on cylinder pressure. In the case of the two stroke engine wherein VE is heavily influenced by the intake and exhaust tuning, the cylinder pressure increase at high RPM is due to "coming on the pipe" and would not need as much advance as less pressure at low RPM when the VE is much less. Similar to part-throttle and WOT in a NA four stroke. Essentially, highest cylinder pressure needs least spark advance. NA engines peak torque RPM is also peak cylinder pressure, and because cylinder pressure falls off above peak torque, most engines benefit from chasing the declining pressure with more timing.

The other factor is heat, charge temperature. Higher temperature reduces timing required. A drag race engine starting a pass with cold water and oil heats up during the pass so usually needs progressively less timing the further it goes down the track, which is why the MSD grid provides for different retard curves with each shift.

The situation with circle and road race and highway cars is different because the water and oil temperatures are saturated at a high operating temperature (compared to a drag engine).
 

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Do you have the '69-'70 Muscle Parts book that has the recipe for the 428 Super Cobra Jet that shows the advance curve for (I think?) the .600 lift cam. If you do, could you put it up here? Time and lending, I am missing that book.

That curve is so unusual that for a long time I thought it was a misprint until the same info turned up in another Ford source, and mostly, I began to understand more about why some engines might have unusual timing requirements.

In the case of the 428 SCJ it needs more high RPM advance because it is carb restricted with the 735 Holley they used to meet emissions.
Is this it?

 
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