FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: CV355 on October 25, 2021, 12:57:59 PM
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I'm seeing about 6" of vac at idle and a max of 10" on rpm decel after a throttle blip. Is that about normal?
Engine Specs:
484ci, 9.6:1 CR, Trick Flow Heads
Initial timing = 15 degrees, advance to 30 WOT (through Dual-sync and Holley Sniper)
The cam specs are:
287/299 - 110LSA
Dur @ 0.050": Int 233 / Exh 245
Lift = Int 0.595" / Exh 0.595"
Lots of overlap...
The engine idles nicely, so we doubt there is a vacuum leak anywhere. Initial timing might not be perfect, and there is some notable low-end hesitation until the engine is up to temp (give it a blip of the throttle and it misfires). I'm adding an electric pump for the brake booster, and I am working out details for adding a GZ vac pump. The tuner noted that the engine was weeping a tiny bit of oil out the FMS after 10-20 minutes of running on the dyno, low varying throttle. I haven't seen a single drip anywhere myself, but it is something I am watching for. Then again, the car hasn't left my driveway as I'm working out other issues first.
Any advice or things I should watch out for?
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What displacement, what static compression, and what base timing? Nobody knows the answer to your question without filling in some blanks.
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What displacement, what static compression, and what base timing? Nobody knows the answer to your question without filling in some blanks.
Good call, sorry I missed that. Updated my post. I am waiting on the tuner for the initial timing, but the rest was available.
Also, this is N/A for now. I have an F1 Procharger on the engine, but we don't have a belt or intake on it yet. We fired the car up N/A so it's just breathing through a flat canister filter for now. End goal is 4-5psi max, in case that has any bearing on the vac issue or solutions
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So the engine is running with no supercharger plumbing or drawing air through a compressor wheel? I would say you have something going on there. That vacuum signal is way low for those engine specs. I would first suspect that with your other issues, you have a problem in the tune up.
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So the engine is running with no supercharger plumbing or drawing air through a compressor wheel? I would say you have something going on there. That vacuum signal is way low for those engine specs. I would first suspect that with your other issues, you have a problem in the tune up.
Correct, the blower is just bolted up and that's it. No intake piping. The Sniper unit is breathing from a canister filter for the time being.
I also updated the post with the timing, tuner just got back to me. He thinks the Sniper tune reset for some reason, so I'm going to re-run it tonight.
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"...advance to 30 WOT" I think you mean total advance. It seems you are getting an LS tune. The guys like Barry and Brent will probably chime in, but you are six to eight degrees short of where you can run a modern FE head, like a TrickFlow. Your initial seems pretty close. Your fuel maps are probably fubar.
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I agree with Gerry regarding total advance. The old factory solid lifter approach was to have the diz in the slot marked 10 degrees, which is, of course, actually 20 ignition degrees. Putting in an additional 18 initial, for a total of 38 always worked well so long as you made sure to keep your tank full of Sunoco 260. More modern combustion chambers in aluminum heads might well see your ultimate at 35 or thereabouts total, but you'd need to sneak up on it from where you are at present. Very likely 30 isn't enough. Working with a set of Dove F5 heads with Jim's own chamber design, at 11.5 measured compression and a Comp cam with 242-248 at .050 and lift around .650, we found 34 to work very well during Dyno evaluation.
KS
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A couple of things. 72 degrees overlap isn't bad, it should be showing you closer to 10-12, especially if you feed it some timing
The total timing won't change vacuum, but regardless, the Trick Flows I have used ranged from 32-35 degrees advance, yours is a bit lower compression (until the blower is connected) so I'd stop at 35-36 but bentter do check on dyno for peak power, no benefit going higher with the good chamber
Be sure your initial is right, check the balancer, set the Sniper, then see if the commanded timing reads the same as the balancer.
To adjust the timing correction once you check it, use the inductive delay section under"system parameters" "Engine parameters" and "ignition" The delay up or down will move the mark to make sure what the commanded timing matches what you read. Holley's system usually requires you to upload after every change, easy, but be sure you are doing it
Additionally, depending on your distributor, reference angle has to be right too. That's applicable for Dualsyncs and set during distributor install (but again, balancer must be checked)
After all that, the root cause I think is I'd likely be at 15 crank and something like 18-20 idle. If using the Sniper to control, the 2D table for timing is a pain at initial setup. Set it up 18/40/35 across the board using the "simple" field, and 15 for crank under "cranking parameters" then if you need to tweak areas, you can go to 2D table
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"...advance to 30 WOT" I think you mean total advance. It seems you are getting an LS tune. The guys like Barry and Brent will probably chime in, but you are six to eight degrees short of where you can run a modern FE head, like a TrickFlow. Your initial seems pretty close. Your fuel maps are probably fubar.
So if it was higher compression, 29-30° total would probably be where I would head. I have some 12-13:1 engines running TFS heads that like to run there.
However, with 9.5:1 that number will most likely need to go up some. I'd try some 33-34-35° pulls on the dyno or read plugs to see where it wants to be.
I'm an 18-20° initial kinda guy.
Definitely something going on though, 6" of vac is way low for that combo.
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When I get a whacky number like that, I verify the vacuum gauge and timing light are good…especially since the engine is running okay.
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Thanks for the responses, guys! This helps a lot. Sounds like an initial timing issue at the very minimum based on the responses. I could live with 10-12" at idle, might not need the belt vac unit if that is achievable.
have the diz in the slot marked 10 degrees, which is, of course, actually 20 ignition degrees.
Can you elaborate on that?
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Can you elaborate on that?
Inside the Ford distributor, below the points plate, there is the centrifugal advance mechanism. This consists of a plate with two slots opposite each other, the springs, and the distributor rotor shaft that is controlled by the advance mechanism. Those opposing slots are where a tab fits in, but only into one of the slots. The slots are stamped with the number of distributor degrees, which are half crankshaft degrees. Every Ford distributor is different to account for the many configurations required. In this instance, he's referring to the one slot being stamped "10", which is 10 distributor degrees, or 20 crankshaft degrees. And it is crankshaft degrees from which you use the timing light and read the distributor centrifugal advance. You can see how the centrifugal advance works by removing the distributor cap and turning the rotor. It does move a bit and in this case, up to 10 degrees out of the circle.
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Can you elaborate on that?
Inside the Ford distributor, below the points plate, there is the centrifugal advance mechanism. This consists of a plate with two slots opposite each other, the springs, and the distributor rotor shaft that is controlled by the advance mechanism. Those opposing slots are where a tab fits in, but only into one of the slots. The slots are stamped with the number of distributor degrees, which are half crankshaft degrees. Every Ford distributor is different to account for the many configurations required. In this instance, he's referring to the one slot being stamped "10", which is 10 distributor degrees, or 20 crankshaft degrees. And it is crankshaft degrees from which you use the timing light and read the distributor centrifugal advance. You can see how the centrifugal advance works by removing the distributor cap and turning the rotor. It does move a bit and in this case, up to 10 degrees out of the circle.
Ah, gotcha.
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What are you using for a distributor?
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Can you elaborate on that?
Inside the Ford distributor, below the points plate, there is the centrifugal advance mechanism. This consists of a plate with two slots opposite each other, the springs, and the distributor rotor shaft that is controlled by the advance mechanism. Those opposing slots are where a tab fits in, but only into one of the slots. The slots are stamped with the number of distributor degrees, which are half crankshaft degrees. Every Ford distributor is different to account for the many configurations required. In this instance, he's referring to the one slot being stamped "10", which is 10 distributor degrees, or 20 crankshaft degrees. And it is crankshaft degrees from which you use the timing light and read the distributor centrifugal advance. You can see how the centrifugal advance works by removing the distributor cap and turning the rotor. It does move a bit and in this case, up to 10 degrees out of the circle.
Thanx Gerry---
Very well explained. (I come from a time when we mostly used factory parts and people were aware of the inner 'guts' of factory distributors.) I did put an all-Mallory ignition on my first car---a '53 Merc Flathead :))
KS
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Somehow my post didn't post :)
CV - The slot discussion doesn't apply to your Dualsync
Reset the cam and crank sensor at the value the instructions tell you, usually 50 degrees BTDC
Verify the programming "reference angle" in the distributor section matches that number
Set timing to 15 crank, 18 initial, 40 cruise, 35 total for nat aspirated
Fire it, let it idle, read timing with a light, if not 18 adjust inductive delay until it reads 18
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Somehow my post didn't post :)
CV - The slot discussion doesn't apply to your Dualsync
Reset the cam and crank sensor at the value the instructions tell you, usually 50 degrees BTDC
Verify the programming "reference angle" in the distributor section matches that number
Set timing to 15 crank, 18 initial, 40 cruise, 35 total for nat aspirated
Fire it, let it idle, read timing with a light, if not 18 adjust inductive delay until it reads 18
Dumb question here, but if the static timing was already set/sync'd with the Holley DualSync, if I alter timing by rotating the distributor base, do I have to update it somewhere in the Sniper ECM?
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Good question
1. When you sync the dual sync (Put the engine at 50 BTDC and turn the distributor until both lights turn on and one barely shuts off) you are giving it a reference point to control timing from. If it's right, it's right, but personally I would go back and make sure given what you are seeing. There are two components of checking it....setting the distributor per the instructions and second is making sure the reference angle in the program matches the instructions. For example if 50 degrees is the reference angle, you set up the distributor, and then when you power up the program you make sure the same value, 50, is in the reference angle field.
2. You should never turn, or need to turn, the distributor after that, but you may need to adjust inside the program to make timing perfect. Let's say your initial is set at 18 in the handheld, but you see 15 in the balancer with a timing light, the Inductive delay is like a thermostat that will correct it, it changes the delay in the computer to make the commanded timing match the actual timing, you don't turn the distributor. I am not sure if the handheld will let you adjust inductive delay, but it is easily done on a laptop. Also, you may not even need to do it, but it is worth checking with a light. I did not need to do it on mine or the last one on the dyno, but since you are fighting potential timing issues it's a great idea to check it
After that, you are done forever with basic setup, you will just change timing values in the computer... initial, cruise and WOT. I think it is FAR better to do timing changes on a laptop, but it takes a couple steps after you program the ECM to save to the SD card. Easy after you do it once or twice.
Do you have the program on a laptop or doing it all by handheld? The reason I ask is the Wizard is not as good as the free Sniper program. However, if you have the ability to pull your global file off your SD card, I could manipulate it for you too and email it back
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Good question
1. When you sync the dual sync (Put the engine at 50 BTDC and turn the distributor until both lights turn on and one barely shuts off) you are giving it a reference point to control timing from. If it's right, it's right, but personally I would go back and make sure given what you are seeing. There are two components of checking it....setting the distributor per the instructions and second is making sure the reference angle in the program matches the instructions. For example if 50 degrees is the reference angle, you set up the distributor, and then when you power up the program you make sure the same value, 50, is in the reference angle field.
2. You should never turn, or need to turn, the distributor after that, but you may need to adjust inside the program to make timing perfect. Let's say your initial is set at 18 in the handheld, but you see 15 in the balancer with a timing light, the Inductive delay is like a thermostat that will correct it, it changes the delay in the computer to make the commanded timing match the actual timing, you don't turn the distributor. I am not sure if the handheld will let you adjust inductive delay, but it is easily done on a laptop. Also, you may not even need to do it, but it is worth checking with a light. I did not need to do it on mine or the last one on the dyno, but since you are fighting potential timing issues it's a great idea to check it
After that, you are done forever with basic setup, you will just change timing values in the computer... initial, cruise and WOT. I think it is FAR better to do timing changes on a laptop, but it takes a couple steps after you program the ECM to save to the SD card. Easy after you do it once or twice.
Do you have the program on a laptop or doing it all by handheld? The reason I ask is the Wizard is not as good as the free Sniper program. However, if you have the ability to pull your global file off your SD card, I could manipulate it for you too and email it back
Sorry for the late reply, I didn't get a chance to actually work on the car until the weekend.
The reference angle on the DualSync is 50, which I verified. I had to reset the static timing to 15 initial. The engine fired right up and idled far nicer, but the vac dropped from 6" to 2". No joke, the needle was resting on the tick mark around 0 just at idle. We're still convinced that there is not a vacuum leak. I did not get a chance to verify the timing with my timing light- that's a task for tonight and will adjust inductive delay as needed to sync the set and actuals.
I do have the ability to change initial, cruise, and WOT timing in the handheld. The cruise and WOT figures looked fine.
Based on what I'm reading online, it sounds like I have a big discrepancy between actual and set timing. It's acting like the timing is severely retarded when the Sniper thinks it is at 15 degrees advance. If I should be seeing 10"-12" of vac at idle with this cam, I'm wondering just how far off the timing could be (assuming no leaks).
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I recommend you download their Sniper program and get the laptop connector. Otherwise, you could send me your file from the SDE card and I could try building you another to try
In the end though, you need to look at initial on the handheld (commanded) and what the timing light sees. If they are different, we can fix in the program
Your initial should not be 15, initial should be 18 or 20, there is another field for crank timing. I can set that if you send me your file. My427stang AT yahoo . com
It'll take me 10 minutes to try something for you o upload and we will name it something else. You just need a computer that can read the card...worst case, an adapter is dirt cheap from Walmart (SD card to USB)
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I recommend you download their Sniper program and get the laptop connector. Otherwise, you could send me your file from the SDE card and I could try building you another to try
In the end though, you need to look at initial on the handheld (commanded) and what the timing light sees. If they are different, we can fix in the program
Your initial should not be 15, initial should be 18 or 20, there is another field for crank timing. I can set that if you send me your file. My427stang AT yahoo . com
It'll take me 10 minutes to try something for you o upload and we will name it something else. You just need a computer that can read the card...worst case, an adapter is dirt cheap from Walmart (SD card to USB)
I'll give that a shot with my laptop tonight. If I can't figure it out, I'll send the file over to you. Really, really appreciate your advice on this.
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Happy to help, it keeps me thinking between engines too.
One thing I noticed is when you get on the laptop program.
When you use the wizard, the timing comes in too fast and not enough. Real odd too, like 30 degrees all in by 2100
The way around can be done 2 ways
1 - Start with one of their packaged global files for a big block they tend to be slower curves
2 - Under timing, set your initial, cruise and WOT under "simple", then open the 2D table option and copy and paste cells to slow the curve down.
3 - Of course there is still the starting timing to set, that's a completely different field, and you want that nice and low to let it crank easy, 13-15 should work