401 sbc ready for the Dyno

[Tom68]

Agree Tom but the rotor never changes relative to cap post. Timing is changed digitally. I just have to re-check set up procedure.

You see, the rotor is only correct for the advance that you set it at, when the timing changes from there the rotor is still mechanically at the original set point. i.e. set it at 30 degrees mechanically and electronically move the timing 20 degrees and it's 20 degrees from the post. It'll jump the gap easily but it can also decide to jump the bigger gap to the possibly easier to fire plug. Mechanical advance doesn't have that problem but Vacuum does.

[HQM383]

Agree Tom but the rotor never changes relative to cap post. Timing is changed digitally. I just have to re-check set up procedure.

You see, the rotor is only correct for the advance that you set it at, when the timing changes from there the rotor is still mechanically at the original set point. i.e. set it at 30 degrees mechanically and electronically move the timing 20 degrees and it's 20 degrees from the post. It'll jump the gap easily but it can also decide to jump the bigger gap to the possibly easier to fire plug. Mechanical advance doesn't have that problem but Vacuum does.

I know what you mean now. Still, I’ll re-check the set up procedure and how the rotor aligns with the cap. The 10* initial set up may have the rotor starting offset on the clockwise side of the post. There are marks on the distributor body to line the rotor up to that represents 10* adv starting point. So I’ll line the balancer up on 10* btdc comp stroke and take the cap off and see if the black etch mark on distributor body is aligned with the rotor. We’ll see.

[Tom68]

Sometimes I would draw a white line on the rotor and drill a hole between coil post and number one then point the timing light down there, that was for reluctor triggers when you never really know, some would turn out to have the reluctor leads crossed.

[HQM383]

I'm convinced now the 10° set up puts the rotor to the clockwise side of the cap post. In the previous pic one of the alignment marks is over the O and N on the Progression sticker. Cap post is anti clockwise to that black mark in below pic. Correct 10° set up should be good phasing as circuitry is telling it to fire 10° BTDC as the rotor is almost past the post. My yellow line is a bit wonky but you see what I mean.

[HQM383]

New best today of 571hp @ 6250rpm and 538ft/lb @ 5000rpm.

Swapped to an ICE ignition set up (except for coil as I have an MSD blue HVC that was found to be crapped out so an old MSD Blaster 3 canister coil was used. Need to get an ICE coil now). Carb was 975cfm (gold sleeve) Race Demon, air cleaner on. Tried the 1050cfm annular last thing today but nothing in it between carbs. Dyno runs overlayed each other almost perfectly. 1050cfm was a bit rich but there wouldn't be 10 or even 5hp in leaning it out. The guys are away until next Monday. By then I should have longer studs to try 2" spacer. Trial some different carb calibrations too. Not so much looking for horsepower but afr curve.

[Tom68]

Looking back, I didn't think that progression system had any ignition amplification.

Did you check how big a gap it would jump ?

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Screenshot 2024-03-13 175516.jpg

[HQM383]

Looking back, I didn't think that progression system had any ignition amplification.

Did you check how big a gap it would jump?

Last week we went from .040” plug gap to .030” and top end miss became better but not eliminated. Didn’t go looking for it’s upper limits though. If it has amplification it wasn’t enough. No such issues with ICE set up. Remember this engine has close to 11.6:1 comp. The Progression distributor would likely work like a charm on something with less comp.

It is disappointing not to be using the Progression timing table features but the decision was a new MSD cdi box to connect to it or ICE distributor and box for almost same cost (got ICE at dyno shop cost price). When I hooked up the old Digital6 I wired it incorrectly and fried something.

Something that raised the eyebrows was how much 2* of timing gained. Started with 20* timing at idle and selected the +10* all in by 3800rpm curve on the box. Went 548hp. Went up 2* to +12* all in by 3800rpm. Jumped to 562hp. Went +14*, made 571hp.

[HQM383]

I've seen where Big Joe and others have always had power losses with the extreme lid but also saw where power masters I think found that also and taped up the round filter and pulled only thru the lid and power picked right back up to match dyno's airflow hat alone. They theorized both this and the turbine sent the air straight down the carbs throat eliminating air buffeting when entering from both sides and top of carb. All I can say is your already on the dyno try it and let us know please?

For the last run with the 975cfm today I went from .033” mab to .031” to fatten the top end a little. Left the air cleaner off. Difference in hp was about margin of error. Could have been fuel, could have been air cleaner but only 2hp in it. Left the air cleaner off for the 1050cfm and as mentioned before the overlay of the two carbs were near identical.

Air cleaner is 11” diameter and 3” element with X-stream top.

[HQM383]

Also noticed an interesting trend with AFR output between banks. The even numbered bank (2-8) at low revs was around .5 lambda richer than the odd number bank. As it approached peak tq it evened out and by peak tq even (.86 lambda) and after that they swapped and the odd numbered bank became the richer bank similar discrepancy to lower in the rev range. Is this expected with an sbc?

[skinny z]

Looking back, I didn't think that progression system had any ignition amplification.

Did you check how big a gap it would jump?

Last week we went from .040” plug gap to .030” and top end miss became better but not eliminated. Didn’t go looking for it’s upper limits though. If it has amplification it wasn’t enough. No such issues with ICE set up. Remember this engine has close to 11.6:1 comp. The Progression distributor would likely work like a charm on something with less comp.

It is disappointing not to be using the Progression timing table features but the decision was a new MSD cdi box to connect to it or ICE distributor and box for almost same cost (got ICE at dyno shop cost price). When I hooked up the old Digital6 I wired it incorrectly and fried something.

Something that raised the eyebrows was how much 2* of timing gained. Started with 20* timing at idle and selected the +10* all in by 3800rpm curve on the box. Went 548hp. Went up 2* to +12* all in by 3800rpm. Jumped to 562hp. Went +14*, made 571hp.

Do you think the Progressive distributor would have done the job with a new ignition box?

Interesting on the timing cause and effect.
How do the chambers compare to something compact like a Vortec or something like Darts or AFRs? (I'm unfamiliar with Twisted Wedge heads).

[HQM383]

Looking back, I didn't think that progression system had any ignition amplification.

Did you check how big a gap it would jump?

Last week we went from .040” plug gap to .030” and top end miss became better but not eliminated. Didn’t go looking for it’s upper limits though. If it has amplification it wasn’t enough. No such issues with ICE set up. Remember this engine has close to 11.6:1 comp. The Progression distributor would likely work like a charm on something with less comp.

It is disappointing not to be using the Progression timing table features but the decision was a new MSD cdi box to connect to it or ICE distributor and box for almost same cost (got ICE at dyno shop cost price). When I hooked up the old Digital6 I wired it incorrectly and fried something.

Something that raised the eyebrows was how much 2* of timing gained. Started with 20* timing at idle and selected the +10* all in by 3800rpm curve on the box. Went 548hp. Went up 2* to +12* all in by 3800rpm. Jumped to 562hp. Went +14*, made 571hp.

Do you think the Progressive distributor would have done the job with a new ignition box?

Interesting on the timing cause and effect.
How do the chambers compare to something compact like a Vortec or something like Darts or AFRs? (I'm unfamiliar with Twisted Wedge heads).

Yes, I’m sure it would have done the job. But weighing everything up I decided the ICE was going to give the best spark where it is needed in this combination. And they are relatively local so if there is ever any issues they are less than an hour from me.

I’m not all that familiar with Vortec heads. Because of the 13* intake valve the intake side of the chamber is shallower than the 23* exhaust side.

[408 Nova]

Those are some darn good numbers my friend. Thanks for keeping us updated.

[HQM383]

Those are some darn good numbers my friend. Thanks for keeping us updated.

No probs, thanks for the positive comments.

A bit more to go with carb tuning and spacers this coming Monday and Tuesday so a bit more could be squeezed out. Otherwise it’s exceeded my goals and expectations already!

[HQM383]

For those that are wondering where the engine is going when it gets off the dyno

[treyrags]

Something to check on the Progression misfire if you haven't already. The switched power to the distributor must be a full 12V. When I first ran mine it had a very slight misfire at higher rpm. My switched power was below 12V. I changed the wiring to correct it. The miss went away and has run flawless since. I do not use my ignition box, just an E-core type coil. Have run it to 7200 many times with no problem.