12 degrees initial on 2001 5.0 Explorer 5.0, carbureted/HEI on 87 octane?? Maybe too much??

[corerftech]

Hey folks,

The questions I have is anyone else running better than 10BTDC on a stock explorer (98-01), carbureted, distributor..... I have tried for the moon at 16, now to 12 and heading back to 10 for a final test drive.

See below:

I have wrapped up, 99.6%, my 01 Explorer conversion from EFI to Edelbrock Carb with HEI.
Initially I got greedy at the timing light, capped vac advance, initial at 16 degrees and 36 in by 3500 (stock HEI springs/weights). Add the vac and total went to about 46! I pulled about 10 degrees of VAC out (at idle) which tamed it but still it will give 40-41 total at 3500.
It was snappy in the driveway, awesome.
Put a load on it and it is unhappy of course. I anticipated it but was hioping for a miracle.
87 octane only, I will not run anything better. It is a grocery getter....... built for highest reliability.


So I pulled it back to 12 initial, with vac its at 22 or so and all in at 3500 is still about 41
Pinged a ton less but really not happy under load at WOT. Like hit it and lift just as fast in dreadful fear.
I am going to pull initial back to 10 where Ford set it. With EFI that engine ran on baby oil mixed with urine and did not ping, although not as snappy as it is right now! I love carburetors--- throttle response is awesome.

I may be able to get back a couple of degrees both in VAC and initial once I have the Wideband installed. I had one hit at 12 degrees, just one. I had a bog, like a lean bog, and then the ping. I believe that I am weak on enrichment.
But as well I think the transmission shifted somewhere in there due to far from optimal shift curves. I need to ELIMINATE timing for a week until I can get the Wideband and some measurements. It will be hard to tune the transmission with funky ignition and funkier fuel.

This is a stock 1905 Carb, Mech choke, tuned to 22.5 in HG vac for idle (max lean/max rpm/max vac). I have performed zero tuning as until I get a reasonably safe timing set, it is too difficult to deal with fuel.
As well last night was the first test drive on a Microsquirt TCU. Trans controller programming and function trumps fuel and ignition ever so slightly for priority.

So all that is backstory for the vehicle. The question remains, is it likely that 10BTDC is all I will get out of the Exp engine on 87 or is there someone who can testify to a bit more (given fuel is perfect!).

This is not a request for a fix, just for feedback on experiences.

Thanks for the read and sharing your experiences.

 

[bobbywalter]

stock cam and rockers and springs?

 

[bobbywalter]

4r70w run by a ms tcu? and the converter is not prematurely locking?

i would....from your description say your throttle response is less then awesome. i do not like edelbrock carbs over holley off road...but for street use they work pretty damn good all around....generally on these weak ass wheezer 150-240 hp 302's they really are pretty good out of the box. i would think an old school he cam springs and rockers would go a long ways towards living with a carb.

but depending on what springs you are using in the distributor and other scheduled vacuum leaks ect like egr and pcv there can be issues.


there are usually two vacuum ports...one side is emission's and the other non emmissions. the egr setup and porting of certain intakes ect can be an issue as well...

start there and with as low as fuel as possible and step up.....8 to 10 with stock gt40 heads is a good place to start.

 

[corerftech]

Thanks Bobby.

Engine is bone stock, Edelbrock performer 289 manifold. Jegs junk China HEI (works as it shoudl so far).
I am now at 10 preparing for a test drive.
You mention 8 and I am willing to go there if needed in the interim.

The system is tight, zero defect, leaks, etc. HEI on manifold vac, ported capped. All is in order, as it should be. The ping reminds me of what I got back in 1990 when my Mustang GT was advanced a couple of degrees past the 10 from OE. Had to run premium to facilitate 12 degrees.
I may be lean at the hit and thats the issue as well. Ill konw as soon as I retard back far enough to not detonate and get to discern carb behavior.

Ill try 8 next. Matter of fact, I think Ill start at 8! If its lean it will tell me at that point quickly.

 

[bobbywalter]

and for sure that dizzy does not want ported vacuum?

it wants manifold like the modulator for a auto trans?

8-12 is standard for these critters. the truck cam can lug too compared to the ho or an e type.

 

[corerftech]

Yeah so Bobby, that has been a source of contention. Every HEI/GM engineer/superman says Ported is for 1980s EPA cars with specific conditions. Those engineers, and every other GM aficiaonado of high value says manifold. Edelbrock says manifold. Everyone says manifold.

My nut crusher is at 10BTDC initial, the HEI came out of the box adding 20 degrees of vac! So 30 degrees at 22.5inHG vac, idle. Then add 20 of mech advance, holy hell im in the 50's. That cant be right??

So I research and sure enough at idle and off idle, usually 26-30 or more is available with initial and vac. Then add mechanical at say 2500 and it deep in the 40's. The argument from engineers is LEAN MIX is slow and needs that 40 for a time.

Ported wouldnt allow that idle advance of 26 to 30 to be avail until you crack the barrel. And then vac disappears.

So no, it should not be on ported from every reliable source I have found.

I tried 8, boy was it rough. Just laid over fan failed. I bumped back to 10 and it was better. I think I heard the slightest tinkle at specifc low speed modest load o primaries only. It is so obvious thogh it is lean/lean/lean. At 8 I matted it in 2nd and it sounded like a 1976 cop car crapping itself. It has enrichment issues for sure, Ill pull a plug tomorrow night and confirm that it is NOT rich and probably snow white. Ill prpbably find some spaltter too. I know the air door is not opening fast enough either and will need tuning. It is an AVR2. I think it will need to go to the bottom cam hole for the accel pump.

Real lean would make it ping driving at 20mph in the neighborhood for sure. I have yet to see a puff come from the exhaust pipe under any circumstances. Id be real happy if I did.

Next Saturday now that it drives, I am having the platinum removed so that my o2 sensors can live free. Too hard from me to cut and weld on my back, a lift is needed. By Sunday Ill have an idea of ratios.
Friday my HEI calibration kit will arrive and ill spring it for all in at 2500. It comes in so late, its almost 4000 before it is really all in right now.

Thank you sir. Ill report back. Appreciate you Bobby!

 

[bobbywalter]

Yeah so Bobby, that has been a source of contention. Every HEI/GM engineer/superman says Ported is for 1980s EPA cars with specific conditions. Those engineers, and every other GM aficiaonado of high value says manifold. Edelbrock says manifold. Everyone says manifold.

My nut crusher is at 10BTDC initial, the HEI came out of the box adding 20 degrees of vac! So 30 degrees at 22.5inHG vac, idle. Then add 20 of mech advance, holy hell im in the 50's. That cant be right??

So I research and sure enough at idle and off idle, usually 26-30 or more is available with initial and vac. Then add mechanical at say 2500 and it deep in the 40's. The argument from engineers is LEAN MIX is slow and needs that 40 for a time.

Ported wouldnt allow that idle advance of 26 to 30 to be avail until you crack the barrel. And then vac disappears.

So no, it should not be on ported from every reliable source I have found.

I tried 8, boy was it rough. Just laid over fan failed. I bumped back to 10 and it was better. I think I heard the slightest tinkle at specifc low speed modest load o primaries only. It is so obvious thogh it is lean/lean/lean. At 8 I matted it in 2nd and it sounded like a 1976 cop car crapping itself. It has enrichment issues for sure, Ill pull a plug tomorrow night and confirm that it is NOT rich and probably snow white.

i assume you have a gun that goes at least 0-50 deg manually?


generally 8 to 10 with iron heads and mild setup is the base at idle...we agree here?.

at idle. if you plug in the vac line and it advances 20 deg at idle....then that thing wants ported.

so....regardless lets see where the mechanical is...

pop the vac line and plug the vac port

make sure your balancer is on point...run engine at 3600 rpm and set to 36-38 for total.... i usually do 36-36...

then see where it is. from there set your curve.

 

[corerftech]

I’ll go backwards on the list.

crank was timed by piston stop. Crank TDC and marks are dead accurate.

The reverse is true for vac line.
Vacuum line capped at carb, set base to 10, reattach vac line to vac advance, timing now 21. Initially that can was set adding upwards of 20 to base timing and I dialed it back (can adjuster screw with Allen wrench). I pulled 9 degrees of vac advance to lower total. Under no load that engine was quite happy with 36 degrees at idle- LOL. (Base plus vac advance)

After setting base, engine run to 3500 rpm and mechanical verified. I don’t get full mech till near 4000, distributor is sprung wrong from factory and will correct when kit comes.

 

[19Walt93]

The vacuum advance should be getting ported vacuum, not manifold vacuum unless your goal is extreme spark knock and sluggish part throttle acceleration. I prefer to limit the centrifugal advance to 18 degrees or so to permit running more initial advance. I would first verify that the centrifugal advance works smoothly and progressively, then think about changing springs. I originally had a Pertronix Billet Flamethrower(Chinese built) distributor on my 351 and replaced it with a Napa Duraspark unit- that is also Chinese- but it works. I'll attch the story about the Pertronix in a second post.
I'm also not an Edelbrock carb fan but it may work OK for what you described. The soggy response and lack of power probably won't matter.

 

[19Walt93]

I've installed Pertronix units in a couple points distributors and been happy with them so I decided to buy a Pertronix distributor for my 351 Ranger. It's shiny billet which doesn't appeal to me but it has bearings instead of bushings on the shaft and was very simple to wire. The problem is the centrifugal advance mechanism. It looks like a GM unit and the springs and weights are under the cap and easier to access than a Ford distributor. But they don't work. Centrifugal advance should come in smoothly and in a linear manner as the RPM's increase and drop back to base timing instantly when the engine returns to idle. My distributor doesn't advance at all until it's been held at about 2000 RPM for at least 8 seconds and doesn't return to base timing until it idles for 14 seconds. If I put in lighter springs it will advance at 1500-also after 8 seconds- and will only drop back when the engine is shut off. I called Pertronix in the summer and described what it was doing, at first I was told it can't do that, then he suggested I see if Summit would exchange it and call him for a replacement if they wouldn't. Summit replaced it without question even though I bought it 14 month prior. The replacement works exactly the same so I called Pertronix again and arranged to send it for testing after I parked the truck in November. It cost $35 to send it and I just got it back with a note :tested good , no details, no comment about the advance, no date or ID of the person who "tested" it. I assume they plugged it in, spun it up and it threw sparks, and put it back in the box.
If I had a good 351 distributor with a roller cam compatible gear I might put a Pertronix unit in it because the Ford advance mechanism works. I don't so I'm looking.
This distributor is a shiny turd and would be perfect on a Chevy small block with billet pulleys and an Edelbrock carb. The folks at car shows who are impressed by bling would love it.

 

[corerftech]

Walt I will try ported. As easy as moving a hose.
There are as many ported vs manifold perspectives as there are grains of sand at the beach.
I guess try them both and test.
All you indicate does make sense, then the GM engineer white papers makes sense too. I hate GM (flame me) so I would be quite happy if ported is the answer.

 

[bobbywalter]

Walt I will try ported. As easy as moving a hose.
There are as many ported vs manifold perspectives as there are grains of sand at the beach.
I guess try them both and test.
All you indicate does make sense, then the GM engineer white papers makes sense too. I hate GM (flame me) so I would be quite happy if ported is the answer.

....read what you posted and i highlighted.

it wants ported and you will be able to utilize your cans curve better based on what you reported.

you are destroying that engine with that timing.



when setting the mechanical curve it should really be all in by 3-3200...36/36 is just my starting point.

i dont care about vacuum port theory.

just what the fawk you have going on.

your.....YOUR stated observations dictate ported vacuum. read them.

the generality of 8-12 on base idle timing is exactly that. with a decent cam 14 might be perfect....maybe not. you just have to play with it.

the big thing is limit it mechanically to 38 total max until you know what your afr is and plugs indicate. might want 40.....might be done at 32..... just have to do the work.

edelbrock out of the box with these slugs generally work ok....FARRRRR from ideal...but work decent enough most will just move along.

if you had a big power engine or were autocrossing i would try to talk you out of it... but they have great support and offer charts ect....so working within their limitations is real easy to do for the average guy.

 

[bobbywalter]

I've installed Pertronix units in a couple points distributors and been happy with them so I decided to buy a Pertronix distributor for my 351 Ranger. It's shiny billet which doesn't appeal to me but it has bearings instead of bushings on the shaft and was very simple to wire. The problem is the centrifugal advance mechanism. It looks like a GM unit and the springs and weights are under the cap and easier to access than a Ford distributor. But they don't work. Centrifugal advance should come in smoothly and in a linear manner as the RPM's increase and drop back to base timing instantly when the engine returns to idle. My distributor doesn't advance at all until it's been held at about 2000 RPM for at least 8 seconds and doesn't return to base timing until it idles for 14 seconds. If I put in lighter springs it will advance at 1500-also after 8 seconds- and will only drop back when the engine is shut off. I called Pertronix in the summer and described what it was doing, at first I was told it can't do that, then he suggested I see if Summit would exchange it and call him for a replacement if they wouldn't. Summit replaced it without question even though I bought it 14 month prior. The replacement works exactly the same so I called Pertronix again and arranged to send it for testing after I parked the truck in November. It cost $35 to send it and I just got it back with a note :tested good , no details, no comment about the advance, no date or ID of the person who "tested" it. I assume they plugged it in, spun it up and it threw sparks, and put it back in the box.
If I had a good 351 distributor with a roller cam compatible gear I might put a Pertronix unit in it because the Ford advance mechanism works. I don't so I'm looking.
This distributor is a shiny turd and would be perfect on a Chevy small block with billet pulleys and an Edelbrock carb. The folks at car shows who are impressed by bling would love it.

i have used clp lube on the pivot points and deepened the grooves for the springs and seen where the springs bellied up on the weights causing the delay you speak to. and the limiters binding as well. the clp actually helped but eventually it would start to get sticky. but not as bad as what you are having.

though i would be out at 36 or so total as well for what i am working with.

 

[corerftech]

So here is a question that arose a few months back at project start and I was contemplating/researching distributors and advance system for the car.

The GM engineer who designed the HEI and another of course……
Give a dissertation on theory for manifold vac correctness.
Always on a GM engine I might add.

A GM
Small block times at like 2 btdc initial. Add a vac can for added and your at 15-20.

A sbf times at 10 btdc. Way more initial on all engines.

So as I am reading all of the gibberish from sage wise humans in the ignition world- and their constituents who swear by the switch from ported to manifold—- they all are running a GM.

I asked myself early on- does this only pertain to GM? Can’t be that selective right?

But———

Curious as I have not had success in finding Ford specific reading on vac sources- was ford ever full manifold, always full manifold, never full manifold- re:302/351w family?

Just curious. I reread the timing 101 paper by the GM engineer and it all leads to a GM late event rotating assembly and never a ford with more advanced assembly timing.

just curious. I would love to find a ford specific paper that argues one vs the other and why- with duraspark, etc …but the whole darned works runs on Friggen sbc.

Appreciate the replies. I’ll test and report.

 

[bobbywalter]

none of that shit matters unless you are using specific parts in a specific application.

old nailheads.....455 buicks.....500 cadillacs......425 wildcats....345 international harvesters....410 428 429 390 fords.....i love them all and work on them all.


the run of the mill truck 460 has a ton of power built into it if you know how to curve the dizzy and put a good carb on it and put the cam where it should be....

timing and fuel are the key to power. and just relative to actual output.

the precision and resolution of fuel and ignition points relative to the valve events to actual compression and combustion.


in your case.....adding manifold vacuum to the can bumped timing..... this suggests to me to not use manifold vacuum.
it told you to knock it the fawk off....or it was going to murder your engine.

certain buick and cadis and other rigs have devices that actually use both ported and manifold vacuum under certain conditions and the dizzy is setup to work that way.

in your case it wants nothing but base at idle. because it pops 22 degrees at manifold it is clear go port. more importantly for now limit total to 36. for this mild combo that is the general deal. then tune from there.

there are dizzy setups that work with manifold vacuum. because its holding the min with vac.


both setups go to near zero vacuum wot. any engine will tolerate too much timing at idle no load.....you want it to advance off of idle....not at idle. does not matter.....gm ford mopar toyota...