FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: AlanCasida on July 22, 2019, 08:46:32 PM
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I am planning on going to another test&tune session this Friday and I would like some total timing suggestions. Right now I am running 16 int with 37 total. I see on some posts here that some of you guys are running a lot more total timing. My buddy who races a lot of 460 stuff thinks I am running way too much total and suggested 18 int with 30 deg total advance. I am listing my specs below and am planning on running pump gas. Any help & suggestions would be greatly appreciated. This will probably be my last T&T session before Drag Week.
1965 Mustang
427/452 FE 4.25 bore 3.98 stroke
about 11:1 static compression
Comp 288R solid roller cam
.645 lift, 292 dur, 110 lobe sep, 106 c/l
TFS heads
TFS Track heat Cleveland intake on FE power intake adapter
950 Quickfuel carb
MSD ignition
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Alan:
I am all in at 38 degrees. It seems most of the FEs like a lot of timing. The dyno guys thought it was too much too, but most of their work is GM stuff. This seems to be a common story for most FE vehicles.
-Keith
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depending on how many passes you get to make , I would check the timing and make a pass , see what it runs , increase timing by 1 to 2 degrees , and see if it runs quicker , make more passes and keep increasing timing by 1 degree at a time until you slow down , go back down by 2 degrees for a little insurance form detonation . make sure you have a good timing light . may be old school , but that is the way I do it . 1 degree will make a difference .
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Back in the Day, the story on FE performance engines was to be sure the advance mechanism under the plate in the diz was set on the 10 degree end (so as to have 20 engine degrees) and then try to run as much as 18 initial for a total of 38. You could be sure of having no ping or run-on problems with Sunoco 260.
Recognize, of course, that the above is a generality and see how much initial it takes to do your best. It makes a massive difference at low RPMs to use as much as you can.
KS
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With tfs heads and piston waving at very top max advance 33-35 degrees.
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I’d try 32-34 total with those heads and compression.
I agree, 37 is prob on the high side.
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I haven't used a set of TFS heads yet, got a 461 getting started here with them now, won't have any real info until November or so when we put it on the pump
However, with your compression, assuming it's not running lean, and assuming a decent quench, I'd say that small chamber only wants 34 or so.
Hopefully Brent will see this, he has done a few now........ON EDIT: Looks like he beat me to the enter button LOL
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OE iron heads usually ( back in my youth) liked 36 to 38 degrees. Modern aluminum heads with heart shaped chambers usually like 6 to 10 degrees less.
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X4 , those modern combustion chamber doesn't need as much timing as the old style chamber
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Take Gdaddy01’s advise.
Start an 33 degrees and keep adding until your ET increases, then back off a degree or two. Don’t get hung up on any specific number of degrees, focus on the ET.
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X4 , those modern combustion chamber doesn't need as much timing as the old style chamber
As above. My iron head 351C runs locked 38, the 302 locked 34. The AFD aluminum heads on the dragster 393C like 28.
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What dictates the change on the Aluminum heads? Chamber shape or head temperatures?
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Chamber design, sparkplug location. The more modern design promotes faster flame travel, and requires less timing. Joe-JDC
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I hope they don't require a re-curve. I went with the Edelbrocks with a bit of porting and 2.19-1.75 exhaust. The compression is now at about 9.9 instead of 11:1.
-Keith
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I hope they don't require a re-curve. I went with the Edelbrocks with a bit of porting and 2.19-1.75 exhaust. The compression is now at about 9.9 instead of 11:1.
-Keith
Edelbrocks are not Trick Flow, they like timing, the chamber is pretty old school In fact, lower compression may actually like 1-2 degrees more, easily done by adding initial
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Thanks a lot for all the input, guys. I really appreciate it. Goodness knows I need all the help I can get!!
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I'm in Indy this weekend on the second time out with the new 482 TFS engine. Haven't done as much testing as I want yet but I can say this engine shows signs of dropping off as the timing approaches 30 degrees BTDC...best pass at Norwalk was at 25 advance and I was intentionally trying to slow it down.... :o
Really challenging my thinking here...the 428 with Edelbrock heads and10:1 comp wanted 38 adv.
Is it right to think this combination my legitimately run best around in the mid 20's for total timing?
Its 12.15:1 comp, .040" quench, TFS heads.
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May wanna check your balancer marks and verify TDC.
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Edelbrock's on my stroker but just went from 18 to 20 initial and as Cammer FE said, makes a ton of difference down low in idle and pull (smoothness and launch at least). Had been hesitant to go over 18 and allow in gear rpm's up over say 850 but decided to try it as I had a free evening, 20 initial, ~37 total, 900 rpm's in gear, tweaked A/F and very solid off the line and throughout. All in timing is set a little slower than some others I suspect due to very heavy car.
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May wanna check your balancer marks and verify TDC.
I did just that during assembly. I have a new ATI balancer and set my timing pointer perfect to TDC. Have checked timing with two different lights, both agreed.
At 31 total adv it started to develop a slight miss down track
At 23 total, a hiccup coming off the starting line.
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My Edelbrocks liked around 37 degrees best on the dyno. Surely the Trick Flow heads will need less. That doesn't tell you an exact number, but it tells you that you will almost certainly want less than 37 degrees.
I think the octane of the fuel, and of course the compression ratio, makes a difference, too. I have been told I am wrong about that before. Could be. Also cam timing...…
…..and vehicle weight and gearing, and air temperature. …..and altitude.... and stall speed...… and...…. LOL!
JMO,
paulie
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It's all about flame travel, all ignition advance does is allow the air/fuel mixture to do a complete burn when it's the proper time when you are at a given RPM
- Big chamber, takes longer, more advance
- Sloppy chamber, not churned well - more advance
- Mixture lean - more advance
- Less or mismatching squish pad churning things - more advance
- Big dome, usually more advance, but sometimes just crappy burn
- Lots of overlap - poorly burning mixture, wants more advance until things get efficient with overlap
Keep in mind, this is what then engine would want for making power, not what it can handle
- Big chamber, loose quench, lean mixture WANTS advance, but may not be able to handle it. That's why we try to keep things tight.
Should have some good data in November, doing a 10.25:1, Trick Flow headed 461, .041 quench, with 64 degrees overlap, estimate is a peak around 6200 RPM. Nice clean chamber and piston, should end up around 16 in vacuum at idle. Shouldn't need a lot of advance.
TFS heads certainly need less than an Edelbrock unless someone tried hard to make it less efficient LOL if for no other reason, the chamber is 5-6 cc smaller and replaced with quench pad.
Brent has built a few of these now, if build is anything like his, just listen to him on where to start for total. I intend to start this one at 32 on the dyno and experiment from there
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Keep in mind, this is what then engine would want for making power, not what it can handle
You are absolutely correct. I was looking at it from the other side. What it can handle. And even in a sub-optimal situation you might be able to get the same total timing, with a different curve. I know you know this. Just working my jaw. :)
paulie
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Brent has built a few of these now, if build is anything like his, just listen to him on where to start for total. I intend to start this one at 32 on the dyno and experiment from there
This is true, too. If Brent knows where the typical build works best within 2 degrees or so, you are already 99% there.
JMO,
paulie
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Mine have generally wanted 32-34 degrees.
Sometimes you see a head make bigger power with less timing on the dyno but it’s lazier in the car.
Any type of miss or cut out would not be timing relayed. Maybe fuel, etc.
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maybe check rotor phasing?
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No expert, but at 3,500 feet my 445 with BBM heads liked 18 initial and 34 total, moved to sea level and it likes 24 initial and 34 total. I did check my timing marks with a piston stop so I know my TDC mark is about 2 degrees out and those numbers take the error into consideration. Had to change the stop position on the distributor to bring total down, but it wasn't complaining about total at nearly 40. Having said that we only saw 40 while testing without load and once we were sure it wanted 24 initial we pulled the distributor and changed the stop position.
I don't know if it is normal for an engine to like more advance when it is getting more oxygen, but mine seemed to. Of course, I could have been too timid with the advance at 3,500 feet, but it seemed to labour more at sea level than at altitude with 18 degrees of advance. Was much easier to dial in the carb with the initial at 24.
I'm not running vacuum advance at present.