EightballZ

hey guys..

did a compression test today...dry ....

#1-150
#2-140
#3-150
#4-140
#5-160
#6-140
#7-158
#8-150

odometer says 45.000km (28K mls)...but maybe thats 145.000km (90K mls)? from the compression results i wouldnt say its a high mileage car...

what do you think?

also i pulled the spark plugs...only #1 is a little too black...maybe mixture is a little rich there? normal condition?

let me know..
thanks kay

MDchanic

Those plugs look great. Is the darker one wet and oily, or just sooty?

The compression numbers look fine, largest gap is 140 to 160, which isn't too bad, but I would expect a 10.5:1 Toro to be in the 160s to maybe 180s, so I will ask, was the engine warmed up, and was the throttle completely open the whole time you were cranking?
Also, is there any chance that this was a lower-compression car, since it was made for the foreign market? How does it tolerate the highest-octane gasoline you can get over there (which I believe is something like 96 or 98, using European octane numbers)?

- Eric

EightballZ

#1 spark is just sooty...

the engine was cold and i forgot to open the throttle...so it was completely closed...maybe i do that test again after changing the oil...(i can do a wet test as well then..with the old oil)

i couldnt find a reliable source concerning export engines...i know that there were low comp. engines for foreign markets...but it also says that every W34 is high comp.

car has a km/h speedometer as well...never found a source for that "option" in the shop manuals or fac. assembly manual

i took a short look through the spark plug hole..i could see a small dish in the pistons..but honestly..i never saw a hi- or low comp. piston in real life

i usually put 95 octane (EU) fuel in it ...which is like US AON 91 as far as i know...never tried a higher octane...timing the engine with factory specs made around 8° BTDC initial timing...i advanced it to 15° BTDC...never had detonation or ping issues

cutlassefi

Just because you can't hear it doesn't mean it's not detonating.
Remember European fuel is rated differently than here. 98 there is about 93 here, be careful.

MDchanic

Yeah, the European numbers should be the same as the old US numbers that were used when our cars were made, so if your car needed 100 octane (Premium) or 102 octane (Super Premium) originally, our European members would have to find 100 or 102 in the EU, which they won't be able to do. (Americans would need the current US 96 or 98 octane, which they won't find either).

A Toro, if it's the normal compression, was definitely a Premium motor, the 10.5:1 motors were Super Premium, so I would NOT run it on anything less.
I've had a 455 piston essentially shatter from years of detonation (before I bought the car), and I'd rather not have that happen again.

As for the compression test, with the throttle closed, it's completely invalid, so you need to do it again.
Remember that with the throttle closed, the pistons are essentially trying to suck air from a vacuum condition, and won't get enough for a valid test.

- Eric

EightballZ

can you tell from these pictures if these are low-comp pistons?

MDchanic

Wow. Very difficult.

They look a bit deeper than the high-compression pistons to me, but it could just be the light.
They are NOT the later deep-dish pistons, though.

Would it be possible for you to measure the distance from the spark plug seat to the high and low portions of the piston crown and subtract to find its depth?
We could tell you for sure if we had that measurement.

- Eric

72 w29 all green

That drop to the dish looks greater than 1/8" to me. Of course i don't know what you have definitively, but it looks like what i saw in mine a few years ago when peering down a spark plug hole with a flashlight and a homemade measuring device, and yes they were (and still are) the low compression pistons. Also compression test readings averaged 150 with a fairly mild cam. Before that i had hi compression Silvolites with stock cam and compression was between 180 and 190.

Ozzie

As mentioned, you should probably rerun the compression test to get more accurate numbers. However, even as done, it satisfies the criteria for "normal" in the 1970 Olds chassis service manual. See page 6C-5 for the procedure and result interpretations.
Also, as mentioned, measuring the depth of the dish would help in the compression ratio determination. It's hard to tell from the photos with certainty. Oldsmobile used a notch (round or V) in the top of the pistons to also identify low or high compression, but you would probably need an inspection camera to see it. There are some comparative views of the different pistons on page 6B-20 of the service manual.
Don't assume there is a problem with the internals of the engine due to the dark spark plug, especially if it is not oily. Your compression on #1 seems good. There could also be a problem with the ignition. Check the plug in a tester which applies compression or exchange it with another cylinder's plug. Be sure there is adequate voltage being applied to the plug. A bad wire or cap can reduce the voltage.

MDchanic

In the front-facing edge, actually.

- Eric

EightballZ

so..i don't know how accurate my measure-method was..but the dishes are around 4mm deep..which is like 0.15748 inches (or 5/32?)

this is what olds FAQ states:

CID CR dia. depth vol(cc) vol(ci)

455 10.25 2.85 .150 15.7 15.0

455 9.0 3.010 .350 40.8 37.0

MDchanic

Yup, those are the 10.25:1 pistons.

Use the highest octane fuel you can get.

- Eric

EightballZ

made my day...good news

EightballZ

so these are the new numbers...compression test at operating temp. with WOT

#1-160
#2-160
#3-150
#4-148
#5-150
#6-150
#7-160
#8-150

after changing that sooty spark plug i took a 50mls trip...i didnt got sooty again.

unfortunately i lost 2 cylinders on that trip due to bad spark plug wires.

any idea why the car has problems with hot starts? starter seems to turn over pretty slow when engine is at operating temp...ppl say timing could be too far advanced(?)

you can hear a knock-sound when it finally starts after some hard and slow turns..

gonna get myself a stopping tool to find true TDC in a week...since the eninge is timed to factory specs but timing seems to be off

MDchanic

Looks like good compression.

The slow starting could be caused by advanced timing, but could also be caused by having the wrong starter motor.

The high compression 455s used their own high torque starter, different from the one on low compression 455s / high compression 350s and from the one for low compression 350s, but all look essentially the same from the outside.

You might not notice the difference in cranking when cold, if you didn't know what it was supposed to sound like, but it would crank too slowly when hot.

You can't tell whether you have the right starter without disassembling it and looking at it VERY carefully. The Chassis Service Manual shows how each type is wired internally.

A hot high compression engine may knock once or twice when it first starts, so I wouldn't worry about that, it it doesn't do it any other time.

- Eric

jpc647

I didn't know the throttle had to be open when cranking for a compression test. Interesting. I guess I'll have to re-do mine.

TripDeuces

My 70 Toronado had a hot crank problem but it turned out to be nothing more than bad electrical connections. Grounds and hot. Cleaned them and gtg

EightballZ

after the compression test the car had problems firing all cylinders..

replaced the spark plugs, spark plug wires and distributor cap...car was cold and idle was fine after that...but after 15min of driving, the car had some off-idle stumble and accelerated like it was missing 1 or 2 cylinders..at part throttle and WOT

checked the timing today and took a look over the carb and float level..all good...accelerator pump works fine too..

is it possible to damage the ignition coil during a compression test?

Junkman

In theory, you should ground the high tension wire of the ignition coil when doing a compression test, however, no one ever seems to do this. If I had to guess, if the coil is old, and / or original, it might have an internal breakdown of the windings, and give you a weak spark. I have found lots of anomalies in ignition coils, from dead ones that look like they are new, to a very old one that had rusted out at the bottom, and still worked like it was new. When in doubt, change it with another known good one, and see if the problem goes away. If it does, then it was the coil, and if it doesn't, then start looking elsewhere. The ignition system is only as good as its weakest component. For this reason, I have found that it is faster, easier, and better, to just replace everything if it is original or very old. The reproduction ignition wires are very good quality, and I try to find NOS distributor caps and rotors whenever possible. When it comes to ignition points, and condensers, I only use NOS Delco or high quality units that were produced when quality meant something. I have had nothing but problems with the quality of the ignition parts that are being produced today. The rubbing block on the points is prone to early wear, and the contact surface of the points are not of sufficient quality to stand up to the arcing of the points making and breaking.

MDchanic

Never heard of it happening, but your problem does sound like a bad coil or condenser.

Easy enough to change, and those parts are very available, as they were used in pretty much every GM car for about 20 years.

Someone you know has to have an old American coil - even one from F-rd or Chrysler should work, as long as it used a ballast resistor and points.
Borrow one for an hour to test it.

- Eric

oldcutlass

It could also be that you got some grease on the points contacts.

EightballZ

so here is how the car acts right now...it's a PITA to check the timing since the car won't fire all cylinders right..but it seems to be ok...used the cylinder-stopper method to find true TDC....dwell angle is ok too

car has some off-idle stumble when you rev it from slow idle (around 700 RPM)

i raised the idle RPM to 1.100 ...in the video you can also see how the RPM is going up and down...i disconnected the vac adv in this video..

i replaced spark plugs, wires, ignition coil, dist. cap, points.....compression is ok too (see test results above)...adjusted float bowl level...carb is a rebuilt one ..i added new gaskets and acc. pump....fuel tank is filled with fresh high octane fuel....replaced fuel pump

oh yeah..i shut the car down and it was dieseling a bit...is that normal when you shut it down from high RPM ?

i have absolutely now idea what the problem is...at the end you can see in the background how the engine shakes cause its not firing all cylinders

about the float level...factory specs lead to flooding the carb/engine...did the adjustment 4 times (!!) till the gas stopped flooding the intake

Ozzie

I would not think that the dieseling is "normal", and may be a clue to the problem. Sometime the dieseling can be caused by something (carbon?) glowing in one or more of the combustion chambers, producing ignition at an inappropriate time.
Also, do not assume that a component is doing its job correctly just because it is new. Try to verify the component's performance.
And when changing ignition wires, sometimes the routing of the wires can be significant. Give close attention to wires going to adjacent cylinders which fire next to each other as #5 & #7.
You have done a lot, but have not yet arrived at the solution. I know it can be frustrating. The good part is that the compression indicates that there is no big problem with the internals. Be persistent. With the help of the forum members, it can be resolved.

EightballZ

i guess its because i'm off the idle circuit (?)...raised the idle to 1.100 RPM with the slow idle screw..which opens up the primaries...

oldcutlass

It will diesel with the idle that high. What's your dwell and timing set to? Is the advance working properly, both mechanical and vacuum?

EightballZ

dwell is set to 30° ...timing 12° BTDC @ 1.100 RPM (factory specs)

vacuum advance was disconnected....mechanical moves freely

Old Olds Fan

You physically checked TDC #1 cylinder, dampers are known to slip. If the engine was cold in the video, I think your over timed, just my thought.

MDchanic

The engine can't be cold in the video because it dieseled one time as he was cranking it.

Sounds like a vacuum leak to me. Obviously hard to tell from several thousand miles away, but still easier than back when he would have had to write a letter to get that idle over to this side of the pond.

- Eric

oldcutlass

Drop your curb idle down to 750 and see if it stops dieseling.

EightballZ

yes..engine was @ operating temp...

today i started the engine after i plugged all vac ports (brake booster, A/C stuff, vac adv, etc.) ...she stumbled around 1.000 RPM like i set her yesterday...still not firing all cylinders...

when i covered the airhorn with my hand a bit, RPM rises..i sprayed brake cleaner around the carb and the intake...could'nt find any leak

after she warmed up she idled smooth @ 1.100 RPM...i took the chance and adjusted the timing again...then i turned down the idle speed to 750 RPM (still smooth) and ajdusted mixture screws...she pulled like 15" vac @ idle

everything seemed ok so i took her for a short ride...again..she accelerated like theres not enough fuel or no sparks at certain cylinders...well at least the dieseling is gone..

here are another two videos from today @ idle....gonna look at the spark plugs again tomorrow...too hot today..time for a cold german "pils" ..the only thing that helps when you got pissed

@Old Olds Fan: i used the cylinder-stopper method to find true TDC

idle after cruising around:


...you can hear a "pop pop pop" sound out of the exhaust @ idle..maybe these are the cylinders that are not firing(??):

MDchanic

You look like the right guy for that car!

I know that you plugged all of the vacuum lines, but I have to say that is still sounds like a vacuum leak.

Also, on that car, your vacuum should be closer to 18 or 19 inches, I believe.

Understanding that you have checked it already, I would suggest that maybe you have a vacuum leak somewhere else, like possibly between the intake manifold and a head, or maybe even a crack or other flaw in a manifold, or a missing screw that goes into an intake tract.

It may help to take a number of pictures of the engine, especially the intake manifold, from different angles, and post them here, and maybe one of us will notice something that is not right.

I do not feel that you have cylinders not firing, though that is possible.
This can be checked by removing, and then reattaching, one spark plug wire at a time as the engine idles - if the speed drops, the spark plug was working, but if it doesn't change, then it was not.

This is very frustrating, as I feel like I could figure this out if I just laid hands on the engine.

- Eric

EightballZ

here are some engine pics..i retorqued the intake bolts (were not really tight around the 1st cylinder)

i've put some sealer on the threads of every vacuum fitting...then she ran pretty rich till she warmed up and till i adjusted the mixture screws again....there was also some sort of condensated water on the carb

idle was ok around 15" Hg ...i sprayed some more brakecleaner around the carb and the RPM rose again...the hand-over-carb test had not that much impact like it had before i used that sealer around the vac fittings...so it definitely closed some vac leaks

i finally gave up..also my holidays are over....ordered new gaskets for the qjet and some other stuff...removed the radiator to get this thing rebuild..

suspected the qjet to have minor vac leaks...maybe its warped too...we'll see

i'll let you know when i'm done

maybe there are some MAW's ...a lot of space down there w/o the radiator ...enough to do the timing chain etc.

EightballZ

some more

MDchanic

I took a close look at those pictures. I don't see anything obviously wrong with them.

I see no open vacuum connections, and everything important looks like it's connected as it should be.

I still suspect a vacuum leak, and the fact that your symptoms improved after you sealed some leaks seems to support my theory.
Your idle vacuum of 15" is too low for a stock Olds - it should be closer to 18".

How is your PCV valve? Does it rattle like it's supposed to when you shake it?
Is it very old?

I would recommend trying to find leaks again with a different substance - like maybe propane.
Hold an unlighted propane torch around all of the seams and connections.
If it seems to raise the RPMs at first, try it again with the gas turned down a bit lower, so that it doesn't go all over the place.
After you do the outside, plug the PCV hose and puff a little gas into the oil filler - if the intake manifold has a leak on the inside, it will pull in the gas and the RPMs will increase.
Obviously, be careful when blowing flammable gasses around a running engine.

If you are taking things apart, disassemble the carburetor and check the sealing surfaces with a straightedge - if any are warped, you could be pulling in air.

Please keep us posted on how you are doing.

Good luck.

- Eric

Old Olds Fan

when doing all of these tests have you disconnected and plugged the power brake booster vacuum line,I believe it is possible to have a vacuum leak created by a bad diaphragm in that booster unit if 18mg. of vacuum is 'normal' then I think your looking for a fairly gross leak, if it was a missing bolt that ran down through the roof of an intake runner then you would be running a very lean cylinder and should show up as a very white plug on the effected cylinder, just my thoughts

EightballZ

little update....pulled the engine last weekend...gonna pull the intake, heads and oil pan next weekend...found a little timing chain slack

we'll see

MDchanic

Wow. That engine looks pretty clean.

Good luck and please keep us posted.

- Eric

ps: I recommend cutting that Fram filter open and comparing it to another brand, such as WIX or NAPA - you'll be surprised, and will probably change brands.

pogo69

i realize thisis late because you pulled the engine...but are the ignition wires crossed or damaged when you pulled them off for the compression test...check them with a meter...just a thought

EightballZ

damn...i ordered 3 of those filters....gonna check this

engine is clean cause i cleaned it 2 years ago..the valve cover gaskets were leaking so it had a lot of oil crud on it...besides that..its a low mile engine

radiator support looked great too...i've heard a lot of horror stories about that thing...but a little cleaning here and a some POR15 there..and its done.

@pogo69: i replaced the ignition wires after the compression test..just to make sure they are ok

MDchanic

Yes, I had seen some extensive reviews of oil filters on line, but hadn't paid much attention, until one day when I finally got up the motivation to actually cut open a couple of used filters myself. I was shocked by the poor workmanship and quality of the Fram filter's construction.

I'll never buy one again.

- Eric