D Appeldorn

I want to understand the whole timing thing

I have a 455 in my delta 88 with a Hei with vacuum advance.

It runs nice, a bit low about 6 degr.

What do i need to know to set my timing.
Do i need te set the vacuum and the centrifugal advance?
Do they have both?

I do have a degree tab on my balancer so i could set the timing at 35degree at 3000rpm?

And do you guy's mean with total timing, centrifugal advance and the vacuum both?

And are the totall advance degrees like 35 degree to 3000 rpm the same as all the olds 455 engines?


Trie to understand how i can set my engine timing for best performance

oldcutlass

Your full mechanical timing of 35 deg btdc is set with the vacuum advance disconnected. Then when you reconnect your vacuum advance it should add somewhere from 12 - 15 degrees more for a total of 50 deg btdc, which should equate to around 12-14 deg base timing. If you get any pinging then back your timing off a bit.

Btw you may get up to 5 deg more if you play with it.

D Appeldorn

At 3000rpm?

And is it differend with low and high comp engines.

svnt442

Do it this way. Disconnect the vacuum from the distributor and plug the line. set the RPM to 1100 and then set the timing to 20° BTDC. After you set the timing you will have to re-adjust the RPM to confirm it's correct because it will go up from 6° to 20°. After you do that you can adjust it from there. Being that you have a 69 (?) engine you may need to back it down a few degrees for the engine to be happy. Another option is to get an advance curve kit (Moroso and Mr. Gasket both make them) and bring the mechanical advance to where the points distributor was so you can set the timing as if it still had points.

D Appeldorn

This is the reason i lost it

I see so manny differend way off setting the timing.


I bolted a 76 longblock with my 69 350 parts to bolt on back in my 69 delta.
Didn't check the HEI pressure load or such thing.

I did having a singel exhaust at the time, timed my olds to 8 degree and it runs fine stationary. as it did with 10 degree.

But after driving a short distance the engine is sudden running bad
Like fare to rich on feul, and i backed off the timing to 6 degree.

Stationairy and the first few meters it does drive with 8 and 10 degree timing.
After that it does not run happy.

My Hei is an aftermarked type made to replace the later types engines with HEI. coil is in the hei like later types.

And i have a timing mark on my balancer.

So i need to know what i need to do to set my centrifugal timing corect at a certain rpm.
simply the basics, like 30degree at 3000rpm.
If i read the older post everyone having differend timing settings,

TripDeuces

I'll try and give you the simple version of timing:

You have three types, initial, distributor and total timing. Initial is what you see with a timing light on the harmonic dampner at idle, You said you have 6 degrees. Your distributor has a factory set timing amount built into it. It can't be changed easily but can be done but that's another topic I won't go into. For our example let's assume you have 24 degrees built into the distributor. Initial + distributor = total. In this example your total timing would be 30 degrees. Most engines run best somewhere between 34-38 degrees of total timing. So you have three choices, increase initial, increase distributor or both to try to get to the ideal.

Total timing is usually all in by 3500 rpm on a stock unit (sometimes higher) so if you have a harmonic dampner that is degreed far enough you can read it with a timing light at that rpm. Most aren't so in these cases you'll need to add a timing tape to your dampner or have a dial back to zero timing light. This must be done with the vacuum advance disconnected from the distributor. Any time you check timing you need to remove that vacuum line unless you are checking vacuum advance.

Vacuum advance is a separate type of timing that is designed to help fuel economy and engine efficiency when the engine is under low load conditions such as idle and cruising. Under WOT engine vacuum drops to near zero and the vacuum advance is removed from the equation. If left in the engine would detonate severely and cause damage.

Hope this helps your understanding of timing better.

TripDeuces

I went back and reread this and I have to ask, did your car originally come with a HEI or points? If it had points and you replaced it with an HEI aftermarket like you said you have to make sure you have 12v going to that HEI for it to run properly. What year is your car?

MDchanic

It sounds to me like he's got a '76 350 in a '69 Delta.
That means low compression, smog heads, and smog cam, so timing recommendations will be different, and optimal timing will be different from the original specs.

I'll just contribute these articles to read, for background, to make it easier to explain things as we go along:

Wikipedia

Ch--y High Performance, February, 2009

John Hinckley, C*rv*tte Enthusiast Magazine (a good article)

C*rv*tte Forum (HEI Recurve)

Crane Distributor Recurve Kit Instructions

- Eric

TripDeuces

If that's the case are you using the heavy insulated wire as power to the HEI? If so you're not getting a full 12v which will complicate this whole thing.

D Appeldorn

No my car original came with a low comp 350 and points

But it hase now a 455 with performer and performer carb, with dual big car manifolds.
It also have a aftermarked HEI that looks like the factory one ( coil within hei)

So 76' 455 with aftermarked hei in my 1969 delta 88

I did use the timing teeth/tab from the 69' 350 and bolted it on the 76' 455.
And the piston dishes are the same as the 69' lowcomp 9.0 compr.


gonna check the timing this week.

It runs fine, could smoke tires if i want to.
But i never understand the whole picture of timing.

Thanks,

442scotty

If you get tired of playing around with it, contact the folks at DUI...they can recurve you unit using the vehicles and you engine specs or they will build you a new unit..

For me it was money well spent after all the frustrations

D Appeldorn

I will if it does'nt do what i want

But want to understand the basics of timing.
And everyone had differend degree angle's and revs listed in other mails.

And i wanted to know if there were a standard to aim for like 30degree at 3000rpm.
so i could check if i were close to that setting.

And like normal timing, disconecting the vacuum advance.
I did not know this.

just did set it to 10 and 8 degree with my scope.
It dit run realy good stationairy but after a few meters driving it started to run eratic.
Turned it to 6 degree and it worked.

Stupid thing is even a lowcomp with 4bll schould be at 8 degree timing.(export).

So i wanted to know if my timingsettings is how it suposed to be, and how to check and adjust.

geckonz08

Centrifugal advance assy. on the HEI is pretty darned good. The stock weights and advance plate are perfectly acceptable for all but the highest HP/RPM engines. Centrifugal advance is used to advance engine ignition timing relative to an engine’s RPM. With more RPMs, more advance is needed- UP TO A POINT (more on that later). ALL stock HEIs that were installed in V8s are designed to have a total centrifugal advance of 20 degrees, +-1 degree due to production line tolerances. This is as measured at the crankshaft (10 at the cam).
The HEI’s centrifugal advance is susceptible to old age, though. Typically the centrifugal advance weights wear their pivot holes into an "oval" or eat a trench into their pivot pins OR BOTH. This is bad and no attempt to change the advance curve should be made on a distributor that suffers from these problems- fix it first or get another HEI to start improvements on (I can buy them for $20 a piece in decent shape at local junkyards- just make sure you are getting the right one for your engine- they were used on ALL makes of GM V8s and all look very similar). Also, the centrifugal advance plate (that pivots around the main distributor shaft as the centrifual advance moves it), near the top of the distributor shaft sometimes gets gummed up and sorta "sticky," slowing the advance curve and generally preventing the centrifugal advance assembly from working correctly. If your centrifugal advance doesn't "snap" back when you twist the rotor with your hand and let it go then you have this problem. You need to pull the distributor shaft apart and clean everything out, especially up top, before you proceed with upgrades.
The stock HEI also uses a vacuum advance canister to further advance engine timing. Vacuum advance’s purpose is to compensate for and engine’s LOAD. Manifold vacuum is an excellent indicator of an engine’s load. A lightly loaded engine can tolerate more spark advance than a heavily loaded one for better fuel economy, emissions, and to keep the tip of the plug hot enough to keep it from fouling with combustion contaminants. The centrifugal and vacuum advance work together, but independent of each other, each adding its appropriate amount of timing advance, to supply the correct TOTAL spark advance to the engine under all RPM/engine load conditions.
Tuning for performance (changing the advance curve):
1. Centrifugal: Stock the advance mechanism is pretty good but the stock springs are usually way too strong, causing the advance curve to come in too slowly, if it ever gets fully advanced at all. All you need are the right springs and the right initial advance setting. Most Small Block Chevys like about 32-38 degrees total advance at WOT. Since we know already that the HEI has 20 built into the stock mechanism the first thing we need to do is set the initial advance correctly- that means you need an intial advance between 12 and 18 degrees (you might want to retard it 2-4 degrees for daily street use just to build in a little safety margin).
Now all we need to do is make sure the centrifugal advance comes in at the right RATE- relative to engine RPM. You want it "all in" by about 2800-3200 RPMs for a typical street performance motor. (Additional advance above this RPM point is neither needed or wanted- increased turbulence in the combustion chamber offsets the need for further ignition advance beyond this RPM level) You do this by changing the centrifugal advance springs to lighter ones. IF you use the Crane advance kit like I do you are looking to install one Blue (heavy) spring and one Silver one (medium). These springs are located directly under the rotor and are easy to remove/replace by hand or with needle-nose pliers. These springs will give you an advance curve that starts at about 800 RPM and ends at 2800. If you don't have the Crane kit then install whatever springs you have and check the advance curve with a dial-back timing light (or use a “timing tape” wrapped around your harmonic balancer) and a tachometer, swapping springs until you get it close to these specs. It doesn't matter if the springs are not "matched" side to side- you can install one heavy one and one light one and it will work fine. Please note that getting the advance in sooner does NOT build peak HP, but it does build quite a bit of bottom end torque. This mod will have you grinning ear-to-ear with the nice seat-of-your-pants improvement!
2. Vacuum advance: Stock cans typically provide 22-24 degrees of advance. This is WAY WAY WAY too much if you have recurved the centrifugal and initial advance as described above. You will get "3 rocks in a coffee can" kinda detonation.
Can you just leave it unplugged? Yes. Your highway mileage will be off by about 5MPG and your plugs will load up with crud within just a few thousand miles. For a race car or a weekend street/strip can this is probably no big deal. For a daily-driver street car, forget it.
Vacuum advance for the street: You want about 12 (crankshaft) degrees total vacuum advance if you run WITHOUT a functional EGR system, 16 degrees if you run WITH a functional EGR system. Regardless, you want it to come in between about 5 and 15 inches of manifold vacuum. I have found the most expedient solution to be the Crane advance kit once more. Install their can with about 9 turns (tighter than the loosest setting) on the adjustable advance can spring. IMPORTANT!- Also, use the little "lockout" cam that comes with the Crane vacuum advance to lock out AS MUCH ADVANCE AS POSSIBLE. This will still leave you with about 12 degrees of available vacuum advance. If you set it with 2 notches LESS lockout than the maximum you will end up with about 16 degrees available vacuum advance- perfect for those of you running a functional EGR system valve.
So your “typical” advance curve will look something like this:
14 degrees initial advance + 20 degrees centrifugal + 16 degrees vacuum adv. = 50 degrees total
If you are in the 45-55 degrees range for total advance you’re in the ballpark. Each engine is a little different and what works for your engine might be a little different than what works for someone else’s.
That's about it for distributor setup. You're ready to rock and roll. Now all you have to do is install it correctly and plug everything in correctly. Here's a few tips:
Number 1 plug wire should be at the front of the distributor just to the driver’s side of centerline. The vacuum advance can should be pointing roughly at the passenger side front tire. If that's not your #1 plug wire, or your vacuum can is pointed in a weird direction then you have the distributor installed off by a few teeth. It won't hurt performance if timing is still set correctly but plug wire routing gets a bit messy.
The vacuum advance can should be plugged into a "ported" vacuum source on the carb. This is a vacuum port on the carb that provides NO vacuum at curb idle. When the throttle is opened past idle the vacuum kicks in and starts your advance curve for cruising/part throttle.
WATCH YOUR IDLE RPMS WHILE YOU SET INITIAL ADVANCE TIMING!!! You note that the centrifugal advance curve that I recommended above starts at about 800 RPMs. If you try to set your initial timing with the engine idling ABOVE this RPM point you will NEVER get a true initial advance reading since the centrifugal with be partially advanced at that point! Set it with the idle temporarily slowed WAY down if you have to but DO IT RIGHT!
A final word about that HEI "module:" Lotsa mystery around this little "thingamajig." This is just the little electronic brain located on the floor of the distributor housing with 4 wires going into it (2 per side). All it does is read the magnetic pickup signal from the magnetic pickup assy. around the distributor shaft and then using this reference signal, tell the coil when to fire and with how much "dwell". I always recommend a good stock GM module, not a parts-store cheapie. No reason to go crazy and get one of those $70 “super-high output modules here”- I have tried them and they do nothing for performance. But get a genuine GM one. Stock GM modules incorporate what they call a "variable dwell" circuit that reduces dwell at lower RPMs to keep the coil from over-saturating. This is good for sharp performance and long coil life. Some parts-store modules don't have this circuitry in them.

courtesy gen111
mike

TripDeuces

I might have missed it but is 12v going to the HEI?

Timing is not an exact science. What works on one car may not on another. There is a lot of trial and error. Basically you want to have as much timing as you can as early as you can without the engine detonating or losing power. I've seen 2 degrees difference gain 40hp in some cases. This kind of stuff is hard to gauge by the seat of your pants.

You have to remember that you changed out a points distributor for a HEI. It's sounds like your car ran better because the vacuum advance is different between the two. No one is going to be able to give you the exact numbers as to what is going to work. We'll get you in the ballpark and from there it's trial and error.

You have everything you need to find out what timing you have now. You have an initial of 6 degrees. Rev the engine to 3500-4000 (wherever timing advance stops) and record that number. Subtract 6 from that and that is your distributor degrees. It can be changed but on a stock HEI it will require work. You can change the rate of advance easily with springs. I'd try to have all my advance in between 2500-3500. How quickly that happens will depend on what your engine can handle, once again trial and error.

By now I hope you've realized there are no hard and fast rules. You have to find what works for you

D Appeldorn

thanks.

I do now now how the timing works,
Gonna take a look at it this week and see at what range the full advance is getting in. (without vacuum)

MDchanic

Way up above, I inserted the wrong link for the CraneCams recurve kit instructions (it was for a... a... a... F*RD ).

I fixed the link.

- Eric

D Appeldorn

Thanks, that will be a great help with it.

I saw that i have a wysco distributor with adjusable vacuum advance.
Did'nt looked at it at al when i mounted it on the 455.

And have to seek where i put down the allen wrench i got with it.
Did'nt understand it and never got a decent manual with it.

Stupid is, i saw that it have a adjustable vacuum advance on the box.
A good thing i store all the boxes of the parts i ordered.


Second, on the front of the label it say's oldsmobile 350-455 50000v
And on the backside 1981-80 267,305 and 1979-77 305-350

D Appeldorn

do the crane hei set fit all the hei?

Your right, timing is way off and even with all in i don't come near 45-55 total.

And it looks like the stock springs are to stiff.

MDchanic

Yes, the Crane kit should fit all HEI distributors.

If the stock springs are too stiff, it will take a L-O-N-G time to get to full advance, and full advance will be at a very high RPM.
If they are too weak it will get to full advance very quickly, at a low RPM.

- Eric

oldcutlass

The adjustment in the advance can is not to limit the amount of vacuum advance, but at how much vacuum it takes to get there!

Rickman48

Just to add - once you get your timing all set-up, take the plug you used to plug the vacuum advance off, and use that port for a vacuum guage.
Set your idle adjusting screws at the highest vacuum you can get, re-set your idle speed, [it should go higher] and re-check your timing again.
It all goes hand-in-hand!

D Appeldorn

? you mean the 2 screws in the middle of the carb.

Becouse i have only one idle adjusting screw on my performer carb.

A Update to my timing thing,

I Did set my timing on 14 degree, and with the initial it is going to 34.
Not at 2800rpm as desired but much later so the springs are to stiff.

And my vacuum advance did not come in at all????

So i called my lokal usstuffsuplier and he's gonna look at it.
Otherwise i had to buy me the crane stuff and sent it to the netherlands.

Are all the vacuum advance units that are adjusteble with a allen wrench?
becouse the allen wrench i had did fit but not alter the timing at all.
And must it read 45 degree at wot?

D Appeldorn

O it does run much nicer and it does run with lesser engine temp.
Maybe a bit to low on engine temp, gonna check if i did not pull any wires

Rickman48

Look again - I've never seen a 2 or 4 bbl carb with only 1 idle adjusting screw!!
Yes, the 2 towards the middle, facing the front of the car!
You must be thinking of the idle speed adjusting screw, on the drivers side.

MDchanic

NO! Only the fancy high-performance adjustable ones are adjustable.
Regular vacuum advance units are set for specific parameters and can not be changed.

??

At Wide Open Throttle, your vacuum will be zero, and your timing will depend on where you have set your initial timing adjustment, and on how much advance your centrifugal advance unit adds, based on your engine speed - at lower engine speeds, the centrifugal advance will advance the timing less, at higher speeds, it will advance it more.

- Eric

D Appeldorn

On the cardboard box from the hei, i read thet it hase a adjustable vacuum advance.

Not that my hei is a fancy one, never heard of the trademark wysco.
And when i put a allenwrench in it i can turn it like it have a screw inside.
But nothing change.

So how exactly do i read the vacuum advance? I set the timing on 14 degree so plus 20 is 34.
And when i put on the vacuum advance it stay's ad 34 and does not change, reading the timing on the balancer.

I turned also the screw of the vacuum advance 4 rotations clockwise and anticlockwise and did not see any changes on the balancer timing.

oldcutlass

I know this maybe a dumb question?? Did you reconnect the vacuum? With your vacuum adv + initial timing + mechanical you should be close to 50 @ around 2800 - 3400 rpm.

455man

Vacuum advance will be low to zero at an idle. It's meant for highway cruising speeds. So slowly raise the idle and at about 2000 rpms you will notice the timing advancing then move the rpms on up and it goes back down and is only relying on centrifugal advance. To check the vacuum advance: This might sound gross but suck on the vacuum advance hose at idle and it should idle up due to increased timing.

D Appeldorn

already did that

Could it be that i can not read the vacuum well becouse the initial is comming in late? du the stiffer springs?

I gonna change that soon so it does come in at 2800 rpm.

And with wot i can not read the vacuum? only part throttle at +/- 2800-3500 rpm?

D Appeldorn

today is the second time my hei is failing.

it does not give the 12 volts, and after some wibbeling at the conection it starts.

I bought an for me unknown trademark wysco hei.
And have a apointment next saterday to recallibrate the hei.
But if it starts failing like it now does, i was thinking to put a new distributor.

What ype do you guys recomend, stay with this one or go with a differend one.

And with one, there are many differend like mallory and msd etc.

what do you guys recomending

olds 307 and 403

The factory HEI's are the best recurved to what you want. I understand you have to order everything being over seas. I heard good things about the Summit HEI, Pertronix, Accel and MSD units. That cheap Chinese unit you have are known to do that. Wobble or crap out. If you have the points distributor, put in an ignitor 2 or 3 in it with a good coil.

442_Mustang

Sounds like you need to replace the wire from the electrical block on the firewall to the distributor. HEI needs a full 12 volts to run properly and the wire that feeds the coil on a points distributor is a resistor wire. Cut that wire at the electrical block and replace it with a good wire that's not resistor.

D Appeldorn

thanks olds 307,

My aftermarked HEI run good for over 1 year.
and yes it hase a 12 volt full sourse without the resistor.

and my problem is sitting in the conection 12v bat/ tach.

When i wibbel the 12 volt wire at the distributor cap it starts right up.

So i know where the malfunction is,

but right now i want a good distributor that is best for my engine that i know.
not a strange unknown one.

svnt442

Either you have a bad connection at that point, or you have a bad connection with that wire inside the cap to the coil. Try another coil and see if that cures the problem.

TripDeuces

MSD makes decent 'Ready to Run' model for Oldsmobiles. Has a vacuum canister and can even use a stocks points cap so it looks like factory if you're into that. It's also has a totally adjustable advance mechanism that's fairly easy to use. Probably around $300.

D Appeldorn

ok thanks, tripdeuces.

saw it in the summit magazine, that was also the reason to ask what distributors are the best for my olds.

Don't have a racer, but my big flagschip could be a streetperformer with the 455 in it.
And want a combination of good performance and feuleconemy and easy to set it right.

Today i'v looked to my 12 volt source, it is the first +/- 6 inches of the resistance wire.
But it does not have the resistance part on it anymore.

Reads solid 12 volts after i put the ignition key on and running.

And are all those distributors the same? like 12volts- tach-ground plug?
I know some can be combinated with ignition kit's.

Gonna rely on your advice, and gonna ask how much they costs over here.
as it goes about distributors i'm still new,

TripDeuces

12v while running is the important thing. Many will read 12v while cranking and then switch to the lower voltage once running, just keep that in mind.

Not all are the same, some points conversion kits required resistance to them some don't. I think most full distributors require the full 12v though.

You can actually use your resistance wire to activate a relay that will supply a true 12v at all times. Very simple really. Hella made a relay I've used in the past for this and I'm sure Hella is readily available in the Netherlands.

I have the MSD ready to run unit and it's simple and straight forward, just three wires to hook up. Don't get all confused about the vacuum advance just now. Get your total timing set and then just hook up the vacuum canister. Remember total timing equals initial timing + distributor timing = total timing EX. 12 + 24 = 36 degrees total. The MSD instructions are very self explanatory and easy to follow. You can even see them online at MSD.

We all try to help here and I know it must be frustrating with all the opinions expressed by everyone and especially being in the Netherlands and having English as a second language. This forum is probably the most informative and helpful of all the Oldsmobile ones I participate in so you'll have good luck with it here.

George

D Appeldorn

i know, that is why i signed in in first place.

people with knowlegde of chevy etc are not hard to find over here.

but my big olds is in parts and knowledge a differend story

D Appeldorn

Tripdeuces,


I ordered the MSD 8529 ready to run pro billit distributor.

Do i need to remount a coil?
If so, i do not have the my resistance wire in one piece anymore.
About 9 inches before i cut and splieced it in HEI and starter.

original the resistance wire and the starter were atached to the coil + and after removing the original coil i soldered the 2 together and feed the 12 volt to HEI and starter.

So how does it wire? as stock or like hei

TripDeuces

It does use a separate coil if that's your question?
It needs a dedicated 12v source so in that regard it's like an HEI. Your resistor wire is not needed unless you want to use it to power a relay.
All of this will become apparent once you get the distributor and see the instructions or you can go online and see them at MSD.

http://msdignition.com/instructions/...pdf?terms=8529