FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Red Lehr on May 10, 2018, 09:51:45 PM
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I put a new set of BBM heads on my 428 and the dist. needs to be recurved. I put the lightest springs in the MSD and checked the timing. Initial timing is 11 and all in at 31 at 2900 rpms. We advanced the timing to 12 and the engine wouldn't start... >:(..turned it back to 10 degrees and it starts fine.
My compression was 10.5:1 before the new heads...
Is it possible my damper has slipped ?? ???
Just scratching my head why I can't get the initial timing higher.... :-\
Thanks,
Red
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I can't see why two degrees difference of timing would make the engine start or not start. I don't have any idea what it is, but I think it is something else.
Have you tried the timing at 10 and 12 more than once to verify that is the problem?
paulie
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Does it crank the same at both timing settings, or is it more sluggish to crank at 12 degrees? If it cranks the same, put a timing light on it and see if the light flashes when you crank it at 12 degrees.
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Did you degree your cam?
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Does it crank the same at both timing settings, or is it more sluggish to crank at 12 degrees? If it cranks the same, put a timing light on it and see if the light flashes when you crank it at 12 degrees.
When I tried to start up at 12 degrees , the engine hardly turned at all, about a quarter revolution and just stopped... I'm going to double check the timing at 12 degrees again to see if does the same thing...Stay tuned..
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Scott, I did not put the short block together.......I was wondering the same thing myself. ....
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Scott, I did not put the short block together.......I was wondering the same thing myself. ....
Valve events not being right can make an engine really sensitive to ignition timing.
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Camshaft or "Distributor" timing, which is generally what is specified in "the book", is half of crankshaft timing.
This little detail can lead to some confusion.
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Dumb question,,,is it possible to degree the cam with the engine in the car ? I have the tools to do the job, but I didn't know if anyone has done this before...I actually took all the plugs out last night and put a stop plug in the 1st cylinder and I must not have had the stop in far enough because I never did get the piston to hit the stop....Newbie.....
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You can definitely degree the cam with the engine in the car. That's how I did my last cam. You just have to get the front dress and intake off the engine. and find a stable way to mount your dial indicator gauge on a lifter. A fair amount of work, but very doable.
JMO,
paulie
edit: I'll post a picture tonight if I can find it.
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put the heavyest springs you have back on and reset , if you have the lightest on, its all in under 1500 so your numbers are off
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Rotor phasing out of whack? Trigger is firing at 10*, but the rotor is not putting the fire in the right place.
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Dumb question,,,is it possible to degree the cam with the engine in the car ? I have the tools to do the job, but I didn't know if anyone has done this before...I actually took all the plugs out last night and put a stop plug in the 1st cylinder and I must not have had the stop in far enough because I never did get the piston to hit the stop....Newbie.....
Yes. Biggest thing is finding true TDC but sounds like you're all over that. Then all you have to do is pull the rockers on #1 and you can use the end of the pushrod to measure lifter rise...if you can find a way to stabilize it. I've made some pretty long extensions for my dial indicator in the past. You sound like someone who gets the details...you just have to be patient. Mounting the degree wheel and pointer...well, you just have to mount them. Thousand different ways to do that. If you;re within a degree either way (advanced is preferred) then IMO you're golden. Even a couple degrees advanced is OK. More than that and I'd start thinking about correcting it. I won't tolerate retarded cam timing but that's just me.
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I also took a picture of the plugs. some of them look like there a little on the lean side and I'm not sure what will make a plug turn orange but you can see in the picture also on plug number 3. The first picture on top is 5 through 8 the picture below that are plugs 1 through 4
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put the heavyest springs you have back on and reset , if you have the lightest on, its all in under 1500 so your numbers are off
i had the litest springs in my 428 and my initial would bounce up and down making it hard to set.i have mine set on 15 initial and 33 total and it starts instantly
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I took Faron's advice and put the original heavy springs back on ,and set the timing back to 13 initial. Starts great and idles at 800 rpms.
The original problem I was having after the install of the new heads was on start up the engine would be warming up (around 1500 rpms) and then just start to die. This will continue until something changes. I use electronic choke...
Another thing I noticed is the damn carbon contact in the MSD cap is burned off again. I swear you should change the cap on these MSD dist. when you change the oil !
I've been thinking of a new distributor , what would be a good choice ?? MSD Digital E-Curve ??
Something Larry talked about was rotor phasing and I noticed when I lifted the rotor that the lugs on the reluctor are never lined up with the magnetic pick up as it shows in the picture.
Correct reluctor position is the first pic,
my reluctor is the second pic....
BTW, thanks for all your kind help fellas....
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The carbon tip on the MSD cap will survive if you bend the rotor tang up. For some reason, if you install the rotor out of the package it does not make contact to the carbon tip on the distributor cap. Then the spark has to jump that gap, and it wears away the carbon electrode in the center of the cap. Bend the tang on the rotor up so that it will make contact to the carbon tip and the problem should disappear.
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
Me too. Am I in trouble now.
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
Locked out timing is often OK at WOT. How much timing are you applying at steady state, light throttle cruise and crowd accelerations? With locked out timing the answer is either too much or not enough. Vacuum advance adds a whole "nother" layer of tuning optimization to the equation. Thats where rotor phasing can get really spiffy - you work with a sweep rather than a fixed position. OEMs had this figured out a few decades ago...
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
Locked out timing is often OK at WOT. How much timing are you applying at steady state, light throttle cruise and crowd accelerations? With locked out timing the answer is either too much or not enough. Vacuum advance adds a whole "nother" layer of tuning optimization to the equation. Thats where rotor phasing can get really spiffy - you work with a sweep rather than a fixed position. OEMs had this figured out a few decades ago...
You're right Barry...none of the engines I build ever end up in customers cars or are ever driven on the street. I don't know what I was thinking.
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Well said Barry. Yes, one does leave mileage and more on the table otherwise. Funny, but there are zero drawbacks IMO to running a vacuum advance on all but the very hottest engines.
I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
Locked out timing is often OK at WOT. How much timing are you applying at steady state, light throttle cruise and crowd accelerations? With locked out timing the answer is either too much or not enough. Vacuum advance adds a whole "nother" layer of tuning optimization to the equation. Thats where rotor phasing can get really spiffy - you work with a sweep rather than a fixed position. OEMs had this figured out a few decades ago...
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Late to the game, but glad to hear Red figured it out with Faron's advice. I have also seen a quick curve bounce right at idle, however your "all in at 2900" makes me wonder if you had once spring tab bent, or a wrong spring that left slack in the spring then let it initially jump and then slow the curve down. Because 2900 is not a very fast curve.
That being said, to jump in the curve conversation, in the EFI world, ignition tuning is often as effective in drivability as fuel management. I almost said MORE effective, but you can do some fancy stuff with injector timing and change street behavior. Having ignition control by RPM, temp, load, and wide range of other inputs, can be dramatic when on the street, but almost have zero effect when you have your foot mashed to the cowl. Although a street distributor will not have nearly the control, you do have RPM and load inputs through both advance mechanisms. Mileage is of course one benefit, but part throttle tuning is what makes you happy to take that ride in your hot rod with a coffee between your legs and/or roll on and light them up without being fussy.
I agree with Barry's comment about rocker geometry. You can go 200K miles with good build and stock or marginal rocker geometry, certainly doesn't mean ignore it. Although this thread made me think a little about a locked out timing combined with ported manifold vacuum, another way to skin the cat, or a combo, sort of like an early Pontiac approach (very little mechanical and Q-jet ported vacuum to make up the difference (Behaves differently than a Holley ported source). I don't think I like locked distributor with vacuum, but never tried it and I know I dislike the Pontiac approach as I just had to undo a mild 67 GTO and follow a traditional timing curve approach.
I can't argue with anyone's success, but I would ask what the intended benefit of taking the curve away would be on a street strip car? Seems to me if you are trying to get ahead of a slow burn, whether lean, chamber or cam induced, at varying loads or RPM you are going to have too much advance.
Red - As far as the rotor/button, Jay likely gave you the right answer. I had a string of BBC/SBCs that a hot rod club in Vegas had the same issues. They ran Mallory stuff, but we had a run of a few that the rotor tang didn't contact the cap well. Bent it up by hand to make the cap push it down, and they lived happy lives. Almost too easy to fix, hope that is your issue. However, I would add that plugs gaps too large, "power towers" and other things that introduce resistance will also contribute.
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You're right Barry...none of the engines I build ever end up in customers cars or are ever driven on the street. I don't know what I was thinking.
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Not what I wrote. At all.
Just because they drive OK does not mean that they are optimized. Kinda like the millions of engines running down the road without a quarter inch thick spacer under the rocker stands.
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Gotta chime in here on timing. If you're locked out, you are leaving a ton of part-throttle driveability and fuel economy on the table with a street car.
It's all about maximum cylinder pressure and when it occurs. At light loads, the flame front travels less energetically so you need to get it started earlier. Otherwise you're still burning during the expansion stroke - wasted work. The engine feels mushier and fuel economy takes a big hit.
If it wasn't important, the OEM's wouldn't spend money on developing spark timing maps. Believe me, they hate to spend money on powertrain stuff. They'd rather put it into things you check off on the options sheet...
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The bounce at idle is "for real" - you can sometimes see it at idle timing because the springs don't hold the mechanism in position. One of my friends who is really into such things (distributor machine, and more electronic widgets than darn near anyone on this planet...) also says that the same deal can happen at high RPM when the deal bounces off the stops. He wants to have the heavier springs and tweaks weight to allow a tiny amount of advance to continue throughout the entire power band so that the weights never bang of the limits. Says that you have hysteresis in the electronics causing a delay so that an extra degree or two in the mechanical side won't hurt you.
Doing it all from ported works but not that well. Brings back memories of the Holley "Load-a-matic" distributors found on some six bangers back in the 1960s. The combination of mechanical for RPM variance coupled with vacuum for load variance gives plenty of "knobs and levers" to optimize timing within the limits of a mechanical system. Cool EFI and electronic management allows us to do oddball stuff like reversed curves to compensate for cylinder pressure changes as intakes and exhausts come into tune - or around torque peak.
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Well said Barry. Yes, one does leave mileage and more on the table otherwise. Funny, but there are zero drawbacks IMO to running a vacuum advance on all but the very hottest engines.
I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
Locked out timing is often OK at WOT. How much timing are you applying at steady state, light throttle cruise and crowd accelerations? With locked out timing the answer is either too much or not enough. Vacuum advance adds a whole "nother" layer of tuning optimization to the equation. Thats where rotor phasing can get really spiffy - you work with a sweep rather than a fixed position. OEMs had this figured out a few decades ago...
I'm not talking about a vaccum advance, after the fact...I'm talking about a curve in the distributor. I don;t disagree that for a street deal at part throttle, additional ignition timing can sure help efficiency. I've never found a benefit to a curve in the distributor other than for starting. In my experience, if you need to retard the engine to start it, there are other issues.
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The bounce at idle is "for real" - you can sometimes see it at idle timing because the springs don't hold the mechanism in position. One of my friends who is really into such things (distributor machine, and more electronic widgets than darn near anyone on this planet...) also says that the same deal can happen at high RPM when the deal bounces off the stops. He wants to have the heavier springs and tweaks weight to allow a tiny amount of advance to continue throughout the entire power band so that the weights never bang of the limits. Says that you have hysteresis in the electronics causing a delay so that an extra degree or two in the mechanical side won't hurt you.
Doing it all from ported works but not that well. Brings back memories of the Holley "Load-a-matic" distributors found on some six bangers back in the 1960s. The combination of mechanical for RPM variance coupled with vacuum for load variance gives plenty of "knobs and levers" to optimize timing within the limits of a mechanical system. Cool EFI and electronic management allows us to do oddball stuff like reversed curves to compensate for cylinder pressure changes as intakes and exhausts come into tune - or around torque peak.
Amen brother...I still think that a curve that came in at 2900 though, to bounce at idle, must have too little static spring load. 2900 rpm curve holds them pretty tight, and if they were moving around at idle, the springs could be too long for the application or the tabs were bent in prior life
I'm not talking about a vaccum advance, after the fact...I'm talking about a curve in the distributor. I don;t disagree that for a street deal at part throttle, additional ignition timing can sure help efficiency. I've never found a benefit to a curve in the distributor other than for starting. In my experience, if you need to retard the engine to start it, there are other issues.
To me it isn't a starting issue. In the pump gas world, too early too soon can ping. There are band-aids but the engine doesn't need it to fire that early. The Poncho I talked about is a 10:1, 280/280 224/230 iron headed stocker with headers and a relatively quick curve. 16 initial, 20 in the distributor, and it comes in about 2500. That was the way the car showed up. It has ported vacuum advance. It'd rattle part throttle in 4th pulling a hill at 2200 or so. If locked at 36, it'd rattle worse at that RPM. As it is, I slightly slowed the rate ad it's pretty happy now
If it was a 4.11 car, with a loose converter, sure, you could do with less curve, but to get them cleaned up and happy all over town, I'd rather let the distributor help
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
Ever built an engine for a towing application? Not a sled pull, but something that's hooked to a 12000 lb trailer that's being lugged down at 1800 rpm.
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Ah, thx for clarifying that Scott. I had thought that vac. advance was off the table from your previous post. And yes, the curve is king so to speak....if one gets it right, the benefits are large indeed.
link=topic=5968.msg65004#msg65004 date=1526232794]
Well said Barry. Yes, one does leave mileage and more on the table otherwise. Funny, but there are zero drawbacks IMO to running a vacuum advance on all but the very hottest engines.
I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
Locked out timing is often OK at WOT. How much timing are you applying at steady state, light throttle cruise and crowd accelerations? With locked out timing the answer is either too much or not enough. Vacuum advance adds a whole "nother" layer of tuning optimization to the equation. Thats where rotor phasing can get really spiffy - you work with a sweep rather than a fixed position. OEMs had this figured out a few decades ago...
I'm not talking about a vaccum advance, after the fact...I'm talking about a curve in the distributor. I don;t disagree that for a street deal at part throttle, additional ignition timing can sure help efficiency. I've never found a benefit to a curve in the distributor other than for starting. In my experience, if you need to retard the engine to start it, there are other issues.
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I'm going to throw this out for reference, not necessarily as a suggestion, but I lock out the distributor on every engine I build and never have timing related starting issues. They all start with a hit of the key and the pump gas street motors run just fine under all conditions.
That's at least as wrong as incorrect valvetrain geometry. Probably worse.
I've heard that before. Never experienced it, but heard it.
Ever built an engine for a towing application? Not a sled pull, but something that's hooked to a 12000 lb trailer that's being lugged down at 1800 rpm.
No I haven't and that's probably where my lack of experience in that sort of area is showing itself.
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The bounce at idle is "for real" - you can sometimes see it at idle timing because the springs don't hold the mechanism in position. One of my friends who is really into such things (distributor machine, and more electronic widgets than darn near anyone on this planet...) also says that the same deal can happen at high RPM when the deal bounces off the stops. He wants to have the heavier springs and tweaks weight to allow a tiny amount of advance to continue throughout the entire power band so that the weights never bang of the limits.
Funny you mention that.... a lot of the old timer tuners I've chatted with have mentioned that they prefer a comparable setup with heavy springs, where the engine never truly hits max advance. It's a lot harder to set perfectly on the vehicle that way, would be nice to have access to a distributor machine for that sort of thing.
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Just sitting back taking it all in or should I say taking it all in good time , not a fan of locked timing, great for dyno pulls but the advantages of a correct / proper curve always drive better and get more mpg than Locked IMHO of course 8)
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'Back When', the basic set-up for a performance Ford was to use the 10-degree slot in the diz (which gives you twenty degrees of advance in the mechanism) and then turn the diz body to get 18 degrees of initial, for 38 total. With modern combustion chambers you might not need that much total, but lots of initial will make the engine VERY responsive at low RPMs.
KS
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Just sitting back taking it all in or should I say taking it all in good time , not a fan of locked timing, great for dyno pulls but the advantages of a correct / proper curve always drive better and get more mpg than Locked IMHO of course 8)
That completely depends on the engine and combination. WAY too many variables to make a general statement like that.
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really ? 1000+ recurved Dists say otherwise , but since you didn't say it it must not be right