I have a 408W with AFR 205 heads, an FTI cam, Vic Jr intake, custom carb, etc. Someone recommended that I run my distributor (MSD) with the timing locked out as it would improve performance even though the car is primarily street driven. Anyone run their distributor with the timing locked out and how has the performance been.
408w Timing
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dennis112
15 Year Member
I too have heard the same and have considered trying it.
My concerns are that I have 11.1:1 compression (205psi static compression) and needed to purchase an aftermarket starter to turn the motor over reliably when it is warm with 14 degrees initial timing. The plugs show light borderline specks, but that is after racing hard down the track. I built it for pump gas 93 octane as I don't want to use race gas.
Adding a start retard module should help in most cases. My MSD ignition system offers a 20 degree retard setup which could put me back to 12-14 degrees area during cranking with the 33 degree total timing that I run.
I run mine locked out, 30 on pump and 34 on race gas. Mine is 12.7:1 ( I also run water/meth, but that doesn't come on until about 3K). Mine was actually way harder to start when I put a retard program into the MSD box (I think I pulled 20 degrees out), and I have heard this from numerous others. I had originally bought the programmable box just for that purpose (I've since upgraded to a different programmable box and now have timing set at 34 and the box pulls it to 30 for the street). I do run a power master starter. The motor does turn slightly slower when hot. Though I generally start the car with two hands, push the starter button to get the motor spinning then throw on the ignition and that fixes the problem. My car has yet to see the track (to busy with work), but is a race oriented motor. Seems most SBFs like between 30 and 34 degrees.
65ShelbyClone
Founding Member
I'm puzzled as to how an engine that has varying timing requirements in operation could see a performance improvement with locked timing.
My vote is to keep some sort of an advance curve.
My vote is to keep some sort of an advance curve.
Not sure of the science, I would have to think about it. I think it is going to have to do with the ideal timing for the maximum performance of the engine. Many people do it on race oriented motors. My idle and throttle response is great.
Here is a speedtalk post http://speedtalk.com/forum/viewtopic.php?f=1&t=21986 ; a couple post speak of the why, and also has opposing opinions. again, I haven't really try to think it out but it works on my car and numerous other people I know.
To the OP, since you have an FTI cam ask Ed.
Here is a speedtalk post http://speedtalk.com/forum/viewtopic.php?f=1&t=21986 ; a couple post speak of the why, and also has opposing opinions. again, I haven't really try to think it out but it works on my car and numerous other people I know.
To the OP, since you have an FTI cam ask Ed.
blown65
Founding Member
65ShelbyClone
Founding Member
And then you have a long-winded guy trying to convince everyone that locked-out timing pulls air in through the exhaust and makes the engine run better regardless of exhaust length and, additionally, that experience of result trumps understanding of reason.
The timing requirement of an engine is dependent on many factors, but it is never the same for all combinations of load and engine speed. Locked timing will sacrifice something somewhere in the curve.
yeah, I saw that too. I don't disagree that there are sacrifices, but there are gains to be had too. I am not sure that you can get the curve right either, the number of variables is pretty high. I would think factory engines take into account as many as they can and do a pretty good job of getting the curve right. You can go test for best timing on a dyno, or at the track when the motor is no longer factory. I guess it depends what you are trying to do. The OP was asking about performance benefits, just informing him of what I've done and numerous others with race oriented motors (and not the guy who feeds his motor through the exhaust). Sorry I don't have any back to back testing, and my car is far from typical.
woodsnake
15 Year Member
I have always been, and remain a believer that a street driven car needs the vacuum advance for better part throttle conditions. Locked out timing on a race car that is at WOT all the time makes perfect sense.
Thank you for the information. I only have about 200 miles on the motor but I believe I have a timing issue as the motor "breaks up" at certain RPMs and seems down on power. I'm going to get it dyno tuned so we'll see where I end up, locked out timing or not.
Also, no vacuum advance on the distributor so that's not an option. Anyway, the FTI cam I have installed doesn't really allow the engine to pull much vacuum.
Also, no vacuum advance on the distributor so that's not an option. Anyway, the FTI cam I have installed doesn't really allow the engine to pull much vacuum.
some engines are designed to have the mechanical advance locked out, and just use either a load based advance system, aka vacuum advance, or are race only engines that see a very narrow rpm band and thus dont need mechanical advance so it becomes just one more thing that can break and cause issues. a friend of mine used to have a 79 cadillac with the 425 engine, and it used a locked out mechanical advance, and just had the vacuum only advance. it was done for emissions and fuel economy. and given that cadillac owners at the time didnt really care about performance, it worked just fine for them.
BuckeyeDemon
Member
ive always had good luck running timing locked out. i go with what makes them fastest at the track. everyone wants a different amount of total, but they always seem to run better locked out. its a tuning tool. some may respond different depending on the combination.
blown65
Founding Member
Our Shelby is not a race car and drives great with locked timing. Same with our Pantera. Then again its not a stockish motor so I guess you wouldn't notice the little bit you may give up.
My 65 is efi so the timing is all over the place and is a street car/race deal. Opposite of your statement. LOL
break up could be with your ignition box, my box went out (and I used this as an excuse to upgrade). You can get them rebuilt.
DYNO RESULTS...We dyno'ed my car today. Its a 408W with AFR 205 heads and FTI HR cam through a C6 Trans. First pull was 391RWHP. We then setup the MSD distributor to run the timing "locked out" with total advance around 31 degrees, no start retard. Cranked right up, no issues and pulled 411 RWHP corrected, 406 Torque. Peak torque at 4500 RPMs and peak HP about 5900 RPMS. So, I picked up about 20 HP by moving to locked out timing. Street manners is good. Better throttle response too.
BuckeyeDemon
Member
can you provide the two dyno sheets for those runs?
was the total timing the same for both runs?
did you do multiple runs with each configuration to ensure there was no anomaly?
was the car colder (i.e. rear end temps, transmission temps, etc) on the non-locked out runs?
how much did the environmental conditions change between the two tests highlighted (yes, i know the correction factors are supposed to account for these changes)? did they continually update the environmental conditions for each test?
you explicitly wrote 411 RWHP corrected for the locked out case and you didn't mention the 391RWHP being corrected. Is there a reason you highlighted that or were both runs corrected?
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