Pfiffle

Where exactly is my dist. hold down bolt in my 1970 Olds 98 to adjust the timing? I'm feeling around back there and I feel 2 bolts through all the gunk. Where should it be? It's a 455. Thanks.

hamm36

There should be only one bolt in the middle of a big washer that is cupped. I believe what you are feeling is the cup part of the hold down set up. Let say the back if the motor is 12 o'clock, then the bolt head will be between 1 and 2. I use a regular distributer wrench to get to it. Shoot some break cleaner back there if you want to see it better and a light.

Pfiffle

Thanks hamm36. How much should I be turning the Dis. I know it depends on how far out the timing is but it seems like I just barely move it and the timing mark moves alot. This is the first time I'm attempting this and just need a little guidance. I also have a Pertronix and Flamthrower coil on it if that makes any difference. Thanks.
Tom

hamm36

Note: 9/16 bolt head for future reference. One day you might think about HEI. I got mine off a Cheby truck in the bone yard 15 years ago and I have not had any trouble out if it. I even ran the wires that came with it up in tell this new rebuild, back in May 08'.
Timing: I set mine by ear, if it starts with out any hesitation I think it is dead on. I mean "click = varoom". To get it close, have the distributor a little loose, but tight (not sloppy) and start it. Up the throttle with left hand and use a shop towel with the right on top of the cap (right advance, left retard). Turn it until it sounds smooth. Back off throttle, and see how it runs. Do it at idle, and see what is best for you. Start it a couple times. You will know when it is right. You'll be burning rubber by the end of the day.
Tighten down bolt either runninng, or not as long as it does not move from where have it.

Allan R

I put HEI on my 72 Cutlass. Runs great and it's reliable as you could ask for. BUT, my stock air cleaner wouldn't fit without modification. The clearance between the rear of the can and the HEI distributor is about 1/8 - 1/4 inch to close. I modified my air can because I couldn't find a stock one with the indent and the proper side for the breather vent connection. My car is a 350. Just curious, does the 455 have more clearance?

Oldsguy

Set your timing according to the spec sheet or the sticker on the radiator shroud, vacuum advance dis-connected and vacuum source plugged to prevent a leak. hamm36, you should get yourself a timing light, invaluable.....

hamm36

Dan, all do respect. When there is a little bit of a cam, and a few other mods. Would the spec sheets still be effective and better then a clean starting motor? Even then his question was not answered by anyone else? I only gave pointers on how to adjust timing. I never had a light and probable never will. thanks
Pfiffle, use the light to put it at 0, and let us )me) know how it runs/starts.
Allen, I have a 70 350 with HEI, and original air cleaner it fits fine.

Oldsmaniac

Maybe I am missing something but why would a person set timing at zero when specs that I am aware of never call for zero timing. A fast starting engine does not mean the timing is correct and you could be loosing performance because of it. Timing by ear is a pure guess. A Cheby distributer will not fit an Olds engine for HEI.

Olds64

Timing is set with a timing light. If you don't have one you can rent one at your local auto parts store.

hamm36

Tom, sorry to have high-jacked you thread with my shade tree techniques. But looks like no one is trying to answer your question either.
Let me know when you find the specs?
And what the timing is set at with the light?
zero was a just a joke. it is only a starting point. Thanks for straiting me out. I am on a learning curve with only this website for guidance.
It must have been a Olds puck-up, because that is sure what it (HEI) came out of.

88 coupe

8° BTDC @ 850 RPM.

Norm

Oldsguy

I think it would be good to start pfifle off on the right foot. The 455 in my project doesn't have a stock cam, intake or carburetor but I still start at about 10 degrees advance. I think any Oldsmobile engine will at least "like" that initial setting. I didn't mean to insult you, I still think you would benefit from owning a timing light though, you might have to tune up a stock engine some day.

88 coupe

Its a no brainer.

Ideal total setting can be found with the help of a dynamometer, or by making numerous drag strip passes while comparing (altitude corrected) trap speeds. A timing light is needed to document the changes made during either process.

Then, once you have the "magic" number, you can check or set it accurately, whenever you feel like it.

You can also see, for yourself, how misleading the "azz dyno" can be.

Norm

Pfiffle

It's 8 degrees like Norm said but I just want to know If I should be more aggressive with turning it. (The distributor). I'm barely moving it now and I seem to be missing the mark. If I start cranking it a bit more, like 1/4 to 1/2 inch do you think it would come back in the "range" of the mark? I've got a light also. Would it be that much out? I literally bought this car from a 91 year old granny that used it for shopping and bingo. I'm still trying to stop my Dieseling problem when it gets warm. Maybe cooler plugs would help? Could the chain have stretched? It's got 75,000 original miles. I'm just trying to cure this annoying problem (Dieseling) systematically and I thought I'd start with the timing. Thanks for all the input.
Tom

hamm36

cheap or old gas could be part of the problem, and new plugs can not hurt.

Oldsmaniac

I would guess your run-on problem is most likely due to carbon buildup on the pistons and combustion chambers. It can act like a glow plug and cause a run-on condition. There are ways of clearing this out such as water injection, glugging carb cleaner down the intake, and hard driving with a lot of long full throttle bursts.

Danny Wiseley

You refer to the problem as 'dieseling,' and you are going to start with the timing? When we say "timing" we are usually referring to the timing of the spark. (Most generally say "Cam timing" when referring to cam timing.) But what some people don't stop and think about is that there is no spark with the ignition turned off. Most of the folks who think they cured "dieseling" by retarding the spark timing actually solved the problem with the reduced idle speed brought about by the retarded timing.
Does it "diesel" when you turn off the ignition with the car idling in gear?
Also, remember we had lots better gasoline when that car was designed, and it required premium fuel, even then.
Put in some good gas, and slow down the idle speed, and think your problem will go away. Good luck!

Pfiffle

I will try reducing the idle speed by adjusting the dashpot, Danny. It has 93 Octane in it now, maybe not enough? Oldsmaniac, I tried to clear that carbon deposit theory first with Sea Foam treatment and it didn't help. I might need a rebuilt carb.? And hamm36, I'm sure it had bad gas because of who I bought it from but I siphoned whatever she had in there out and put good stuff in. Thanks.
Tom

csstrux

I may be full of it please correct me if I am wrong, but I thought a lean run could cause run on or dieseling. I seem to remember being told that a long time ago.

hamm36

Is this with, or without the vacuum advance attached ???

I brook down and borrowed one (a light), and I set it without vacuum advance attached and carb vacuum capped. When I put the advance back on it went to 1100 rpm's. So, I set it with advance attached. Or as close as I could before the light burned up. Now it looks like I will have to buy one to replace the one I borrowed.

88 coupe

Without.

Because it's exactly what it is supposed to do, that verified that it's working properly.

Norm

Oldsguy

Then, if that idle is too high according to the tune up specs (I really don't know for your car), then you adjust it with the idle speed setting on the carb, not by retarding your timing back more, which is in essence what you did when you re-attached the vacuum advance and re-set the timing.

88 coupe

That's twice, in two days, I forgot to read a post before I replied.

Silly me.

To clarify: 8° BTDC @ 850 RPM with no vacuum advance, then return the idle to 600 (in Drive) and reattach the hose.

At 600, there should be no vacuum to the can. At 850, there should be enough advance to raise the (unloaded) idle to 1100 RPM.

Thanks for waking me up.

Norm