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351MooseStang wrote:
I have a 10.2 to1 351W w/ Erson HFII cam installed 4 degrees advanced, and have to run a medium and a light spring or I get spark knock at around 1800-2000 RPM at sea level, air temp above 70. It's brief if I am accelerating but I can bring it in and hold it there if I'm light on the throttle and under load in third gear, which is bad news if you aren't paying attention to it. Going with one medium delayed the advance enough to eliminate it, even at an air temp of 95. That's with 91 octane non-ethanol racing gas (as it says on my receipt to make me feel better about the price...lol).
Higher compression, tight LSA = heavier springs
Higher compression, wide LSA w/ advance = lighter springs
Lower compression, just about any cam = light springs
and so on and so on. Toss in the other variables and you can see that it's not so cut and dried for advance. Most of my work is in marine systems and you have to be very careful with modified timing curves on high performance marine engines and the constant loads they are under, so I'm a bit more tuned in to it than most mechanics are (no pun intended,,,lol). Bad timing in those situations costs big $$$ and will kill your reputation in a small shop, so you test, test, test...
Then you hand them the bill, the best part of the job!
THAT is the kind of discussion we need on this subject!!
UR right 351 Moose.one size don't fit everbody!
The Sig Erson cam.....what is the LSA and the duration on that puppy!!? All these factors come into play when "modifying" factory stuff to try and gain more performance.
6sally6
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Well .. as far as my distributor is concerned , stabbed it , got the engine running , total timing is set at 38, and my initial fell right at 17.. so 10L successful for sure
Haven’t hooked up vaccum advance yet.. (the vaccum advance arm hole had to made bigger as it wouldn’t have fit or would have caused a bind (just drilled it 5/32”, it’s a little bigger than the post now , but not much. It’ll be ok.
Now let’s talk about the engine
Engine fired right up! No backfires .. but I had this tapping noise coming out of it .. (I have heard lifter clock before , it wasn’t that) .. it was a tap.. I though timing was too much so I retarded it a bit , it didn’t go away. So I let the engine idle till it got about 180, then started setting timing . Revving it I didn’t hear any knocks or pings .. got the total timing set to 38.. checked initial timing .. revved yo a few times all good!
But ... the engine sounds a bit different .. not the same exhaust tune for one
Also I went inside to check the temp and just sitting there it was Dang near 220!!
I have NEVER had the car ideling in the garage go to 220 . I’ve had the car run in the garage for I kid you now an hour before just doing some test , and it never went past 190! That concerned me a lot and I shut it off
AC was off ..
No weird vibration in the engine .. it ran smooth but like o said it sounded different .
What do I do now ? :/
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It probably would not have long as it did with no oil pressure but on Fords there is a chance that when you pull the distributor the oil pump shaft will lift out of the pump and go to the bottom of the pan. If you re-stabbed the distributor and it went right in without hitting the shaft it might have a problem. If you saw normal oil pressure (gauge or light), then you are probably OK but some tapping/knocking and a spike in temps would be a symptom. I hope that's not it.
Since we can all offer advice on timing from afar, 37 or 38 degrees total mechanical may be a bit much on a cast iron head engine. You can't identify knock or ping under no load in the garage. The only way to know is to drive it under varying conditions. I would probably take it down to 34 or 35 and work my way up rather than starting to high. All engines are different and you may be OK with 37 or 38 but too me it seems a bit high.
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I thought I had oil pressure but I’ll fire up the car one more time and check
I had that noise even with total advance of 30.. I advanced it and locked in the distributor and checked temp within 5 minutes or less .. anyway. I’ll let you know what I find about the oil pressure .
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Ok I definitely have oil pressure! (I have a mechanical gauge that went to 60 at startup choked rpm)
Last edited by Gaba (8/09/2019 1:05 PM)
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Good news. Sounds like you need to drive it rather than idle in the garage!
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Over heating was not cured by ignition mod........Try a higher number (higher than the 13) and see if that make a dif.
Verify your thermostat is opening and water is 'rolling' in the radiator.
Remove cap BEFORE it gets real hot and watch the water. When thermstat open YOU WILL SEE the difference. If it just sits there.........it ain't opening.
6sal6
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6sally6 wrote:
Over heating was not cured by ignition mod........Try a higher number (higher than the 13) and see if that make a dif.
Verify your thermostat is opening and water is 'rolling' in the radiator.
Remove cap BEFORE it gets real hot and watch the water. When thermstat open YOU WILL SEE the difference. If it just sits there.........it ain't opening.
6sal6
I know that’s true that this wasn’t gonna fix overheating .. let’s c .. I’ll get her on the road with about 34 degrees total and no vaccum and see how it does.. I’ll change the cap to 16lb and also check for water pump and tstat operation.
But as far as this ignition mod goes , I am certain that the distributor is bringing in advance quick and the max it’s adding is 21degrees. So all the work is for sure successful !
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351MooseStang wrote:
I have a 10.2 to1 351W w/ Erson HFII cam installed 4 degrees advanced, and have to run a medium and a light spring or I get spark knock at around 1800-2000 RPM at sea level, air temp above 70. It's brief if I am accelerating but I can bring it in and hold it there if I'm light on the throttle and under load in third gear, which is bad news if you aren't paying attention to it. Going with one medium delayed the advance enough to eliminate it, even at an air temp of 95. That's with 91 octane non-ethanol racing gas (as it says on my receipt to make me feel better about the price...lol).
Higher compression, tight LSA = heavier springs
Higher compression, wide LSA w/ advance = lighter springs
Lower compression, just about any cam = light springs
and so on and so on. Toss in the other variables and you can see that it's not so cut and dried for advance. Most of my work is in marine systems and you have to be very careful with modified timing curves on high performance marine engines and the constant loads they are under, so I'm a bit more tuned in to it than most mechanics are (no pun intended,,,lol). Bad timing in those situations costs big $$$ and will kill your reputation in a small shop, so you test, test, test...
Then you hand them the bill, the best part of the job!
Good info Moose, thank you. What are the numbers you consider for tight and loose LSA? And what LSA does your motor have, I couldn't locate your cam specs?
Last edited by rpm (8/12/2019 1:14 PM)
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As with anything related to timing, are you sure that TDC on your balancer is really TDC? Ford used at least 3 different locations for reading TDC, and they correspond to three different balancers and three different timing pointers. This is why when I build an engine I always check TDC with a deck bridge and set it using an adjustable timing pointer, or remark the balancer as needed. With the engine built and in the car you can check it with a piston stop.
Its extremely unlikely that you have knocking at idle unless something is WAY off. A typical low compression engine with a stock cam could have 60+ degree of timing at idle and still run fine and not knock. I've had that experience before due to a balancer/pointer mismatch. Engine ran fine going down the road too, just lacked power.
As far as total timing goes you'll have to sort that out, but I've never had an issue running 38+ degrees on a low compression, stock cammed, iron headed engine close to sea level.
The overheating could absolutely be caused by timing though. I had the headers on my IROC glowing red one time due to the timing be so far off and causing an incredibly lean mixture at idle (WAY too much advance). This leads me back to the point about TDC on balancer vs. actual TDC in the engine.
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Noise he heard COULD be the fuel pump arm . Whenever we do "something" new to the engine we hear EVERYTHING and wonder...'oh geez, is it a rod knock'in etc. At least I do.
6s6
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6sally6 wrote:
Noise he heard COULD be the fuel pump arm . Whenever we do "something" new to the engine we hear EVERYTHING and wonder...'oh geez, is it a rod knock'in etc. At least I do.
6s6
One way or another the noise will go away when you hit the nitrous button, right?
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Hornman wrote: Today ( Sunday ) in DFW would be a good day for testing cooling systems: 104 on the thermometer (in the shade). I won’t be doing anything outside until the sun goes over the yardarm. "
Yes I'll say Did brave the heat and took my girl for a hot test ride ...
after adjusting carb -
18 # rad cap -
set initial timing at 18 * .. was getting Mechanical Advance 25* @ 1500 rpm / 30* @ 2500 rpm / 38* @ 3500 rpm
Took it out about 11: am for about a hour drive without hooking Vacuum Add ....
RAD temp 185 * on hwy @ 1500 rpm - 70 mph
temp on Hwy @ 2500 rpm - 70 mph rose to 200*
?? should I curve Dist to total Mechanical Advance of 20 * to come in at 2500 rpm ???
then hook up Vacuum ( and how much ? )
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Hornman I am hoping for the same.. May not help too much with the heating.. but it will a bit .. As far as you arent knocking. The distributor recurve will help a lot with throttle response.
I will post what my timing graph looks like after this recurve with and without vaccum soon. (may be today) lets c
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Go Baby Go!!!!
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" Gaba "
VKT- Vernon wrote that not Hornman !!!
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Vkt-66 wrote:
Hornman wrote: Today ( Sunday ) in DFW would be a good day for testing cooling systems: 104 on the thermometer (in the shade). I won’t be doing anything outside until the sun goes over the yardarm. "
Yes I'll say Did brave the heat and took my girl for a hot test ride ...
after adjusting carb -
18 # rad cap -
set initial timing at 18 * .. was getting Mechanical Advance 25* @ 1500 rpm / 30* @ 2500 rpm / 38* @ 3500 rpm
Took it out about 11: am for about a hour drive without hooking Vacuum Add ....
RAD temp 185 * on hwy @ 1500 rpm - 70 mph
temp on Hwy @ 2500 rpm - 70 mph rose to 200*
?? should I curve Dist to total Mechanical Advance of 20 * to come in at 2500 rpm ???
then hook up Vacuum ( and how much ? )
20 degrees of total advance is nowhere near enough. The least amount of advance I've ever had in any automotive V8 engine I've built or tuned was 32 degrees. I run 38 in my 289.
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Tko
My total timing was 38* @ 35oo rpms no vacuum advance hooked up.... My question is how much do I change this before I add vacuum advance and how much vacuum advance would I put in it
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I wouldn't change it. GT40 heads shouldn't need a ton of spark lead. Vacuum advance has to be tuned by driving and adjusting. Static numbers on a stationary engine aren't going to get you anywhere because that's not what vacuum advance is for. An old rule of thumb is set the can to add another 10 degrees at 2,000 RPM, but that's an extremely oversimplified way of looking at it. I'd add vacuum advance until it pings then knock it back until it stops, reducing it by about 1 degree for a safety margin.
Just remember clockwise is LESS advance, counterclockwise is more.
I'd also try to get the mechanical advance in sooner with lighter springs. You want it all in by 3,000 or even a bit less.
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OK Gaba!!!!!! We've waited ALL WEEKEND for you report.........You took it down the road yet? Is it better......worse.......about the same?
Enquiring minds want to know.
6sal6
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6sally6 wrote:
OK Gaba!!!!!! We've waited ALL WEEKEND for you report.........You took it down the road yet? Is it better......worse.......about the same?
Enquiring minds want to know.![]()
6sal6
Maybe he was thrown from the car with the g-forces - post recurve
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Sorry... haven’t gotten a chance to even do a static timing light test with wife yet ..
Took apart the front grill to try to install the trans cooler and now that means no hood latch, and no driving :/ yet..
Haha! I am sorry! Last week was working from home so got time here and there to tinker , this week I am in the office more lol
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Does anyone have any updates on this modification?
I will have my results next week.
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Stevo wrote:
Does anyone have any updates on this modification?
I will have my results next week.
I have had zero time, or I would have done the test with someone in the car and posted the new numbers..
Also issue is , I started the trans cooler install , so the hood can’t close so I can’t drive it till that’s done.. lol
But I am building the lines for it now, as soon as that’s done (I hope this week) I’ll even post my driving results
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I did this light spring mod on my 69 351w stoked to 393ci, 10.2cr, AFR 185 heads, Comp XE 268 flat tappet, 680 cfm Quick Fuel carb. I used the lightest springs in the Mr Gasket 929g kit. My dizzy already had a sleeve over the 13L post from a prior owner.
After several emails, texts, and calls with Sally, this thing is running better than ever. I did have to play with the adjustable vacuum screw on the distributor to eliminate pinging and stumble.
W/O vacuum to the dizzy, I get 26° at ~2,900 rpm.
Thanks again Mike!
Last edited by rpm (8/18/2019 1:19 PM)
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