In a word, yes. That's what I'd want to do.

What? Why would you want to lower the compression? Where do these rebuilders think the engine's 385 hp comes from? Squirrel cages? Add in the 4-bbl carb and the dual exhaust and all the rest, and it's all of these aspects of the design working together that result in the rated horsepower. You start fiddling around with something as basic as the compression ratio, and you might as well throw that engine away after all and find something else.

If you want the car to BE a Toronado, you want the engine that goes with it in its original form. If you want a car that just LOOKS like a Toronado and nothing else, then, fine, find a 4-banger from a '62 Falcon or something, put that in, and be done with it.

 

Hi OLDSter Ralph, so I have soaked that cylinder in MMO for a few days multiple times (I've learned to do that for longer.) Also GM top end cleaner once for 3 hours as its recommended no longer than that. Ive put air in there with piston at TDC and I can clearly hear it rushing out of the exhaust. There is a missfire and at higher rpm it gets real bad. I took it to a great mechanic, he said because of the obvious blowby it's rings. He said on the leakdown it wouldn't hold any air at all. I double checked his compression test numbers and got the exact same on each cylinder except on #7 I got much lower. The intake manifold gasket is leaking oil all along the front and rear china walls which can be contributing to the miss. The piston head is covered in carbon. There is very light scuffing in the cylinder walls. That sparkplug has carbon buildup. Ourkid says his 66 toro gets a psi of between 185 190. That's my same engine there was only one available. Would there be any other ways to diagnose other than pulling the valve cover and then the head?

 

No, that is incorrect. The 425 was only available from 1965-67. The 455 was available from 1968 on and used the same camshaft bank angle (39 deg.) and lifter size (0.842) as ALL the Olds gas engines, regardless of what model it was in.

 

Ah ok sorry. What I was thinking about this was if for some reason if I decided on a 455 out of a 68 or 69 then would it be a direct fit?

 

My question is WHY #7 cylinder is so much lower than the rest of the cylinders ? How many miles does the car have ?

I kinda know a little about the 1966 Oldsmobile Toronado.

 

Any 455 would be a bolt in; all of the big blocks are physically the same as far as interchangeability. The differences are internal; the lifter dia. and cam bank angle. I have a complete 425 that is out of a '67 Toro, if that's what you want; however, the issue is compression ratio vs today's fuel. I believe that there's a good chance that you have broken the ring lands on the piston of the offending cylinder. I've seen it numerous times on engines that I tore down at my shop. I even did it myself to an early 455 that I had in my street car years ago. Cast pistons can't take the detonation and ring flutter from low octane fuel. Once you get your engine straightened out I would recommend that you buy some VP or CAM II race gas and blending one gallon to a tank of premium unleaded. I did that on my bracket car with a mild 455 high compression street engine and raced it for years without any issues.

 

Ahhh beautiful! Love the tires. Love that you kept the rims the way they are. Drums stop this car just fine! Color looks origional too. Sorry it has 92000. I got it at 89000, drove it just about every day. I think majorly its running so poorly because the exhaust valve is damaged. I have a friend with an emaculate '69 442 with a mildly built 455 in it. He's suggesting we take off the heads. How many psi does your compression read? Do you have any problems running 93 octane?

 

Ok, I was putting VP octane booster with lead additive but one can to a full tank. Guess that wasn't quite the ticket. Does the 67 have C heads, I've heard they have the best flow. Mine are B heads. Or if I had mine polished would it really matter between the two?

 

I wouldn't pull the heads until you determine whether or not the ring soaking helps the blowby. If the rings don't free up if they are stuck you'll be pulling the heads again to do a ring job. I'd be patient, continue with a ring soak keeping the pistons covered in a solvent for a week OR pull it completely apart.

Has the compression gauge been proven to be good/compared to another gauge? Did you and the mechanic use the same gauge?


I'd also check for timing chain s t r e t c h.

 

I may be wrong on this -- never owned a Toro -- but I'm under the impression that Toronado engines, 425 or the later 455, required a special oil pan with a relocated sump because of FWD clearance issues?

 

Well I can verify that a 66 does have a different oil pan. For one there is a distinct inverted hump in it to allow for the axle clearance. The oil filter is at about a 45 degree angle i think to clear the frame as the engine is offset and doesn't even mount to the side rails of the frame. It has one mounting plate bolted to the front crossframe and then mounts to the engine behind the harmonic balancer. Is has more open space under the 6ft long hood than any car I've seen. I've come across information that the block deck is at a steeper angle. I do have to use almost a quart of marvel in order to cover the rings and the piston has to be all the way down so I can only soak one at a time which needless to say makes that process way more tedious. It's the flexplate torque, convertor, and then I have a sprocket connected to a chain drive to the backwards gearbox which runs along the drivers side just under the exhaust manifold directly to the diff which has planetary gears in it if I'm not mistaken. I dont know yet if the diff takes trans fluid or gear oil bit I've been trying to find out the answer. The book actually says "special lubricant" which is not helpful.

 

Yes ill soak the rings before anything else. He used his and I used my own so there's one checked to the other. I also checked compression multiple times always the same psi on each. The engine mounting plate is infront of the timing chain cover.

 

That is my Toronado DeLux, It has been repainted GM paint code K, Oldsmobile color "Ocean Mist". It has 99,900 miles and the engine has never been touched. I found no reason to do a compression test because it runs so good. I run 93 "Non Oxygenated" fuel. It gets about 12-13 mpg.

The transmission has been overhauled and a Tran-Go shift kit installed. The transmission had slippage issues when I bought it.
.
Tires are Milestar MST P235/75/R15 White Wall tires (6 months old). They are 40,000 mile tire. White wall tires in that size are scarce. I got them through Discount Tires.

The drum brakes work just fine, the car will cruise at 75 MPH on the freeway. It doesn't over heat when cruising very slowly at just above an idle. In fact it has never got hot.

Now, don't pull the heads yet. Determine that air is going from the combustion chamber at TDC on the compression stroke, on #7 out through the exhaust pipe.

 

Yes sir thats exactly what I was thinking when he said that. Ive never heard of anyone doing it. I'm just looking for pointers really. See what my options are and the reality of getting parts.

 

Yes sir I will do that tomorrow. How do I know for sure that the piston really is at top dead center. I've looked at it many times and can never tell for sure. My transmission actually is extremely smooth so no worries there. I'll check those tires out too thank you.

 

If your aiming for TDC to check for air leaking out the exhaust be sure it is at TDC on the compression stroke not TDC on the exhaust stroke. TDC compression can be confirmed by pulling the #7 spark plug and feeling the compression as the piston rises. If the test is done on the exhaust stroke at TDC and the timing chain is stretched enough a valve may just be opening giving misleading test results.

Another way around this would be to pull rocker arms off #7 and put air in the cylinder without being concerned about piston position. You're just trying to see if the exhaust valve seals, if it was a true leak down test then you'd want the piston at TDC.

 

Ok thank you for clarifying. I'll be at this tomorrow and will update.

 

That is correct; Toros have different oil pans and oil filter adaptors. They also have unique intake and exhaust manifolds. All of these "accessories" can be swapped over to a replacement engine from a different model.

 

First of all, if the heads are removed, your chances of finding factory head gaskets (~0.017") are slim to none. A common replacement is the Fel-Pro Permatorque, which is ~0.042", which by itself will drop the compression down to a more fuel friendly ~9.8:1. The felt difference in power is negligible. Unless you're racing this vehicle in competition, lowering the compression a modest amount will make it more enjoyable and easier on parts.

 

To emphasize, you need a good mechanic. Not a modern, mass quantity of sales, throw parts at it mechanic, but someone who knows this stuff and will fix only what is broken with a minimum of new parts. Most mechanics will not be interested in working on the car, or saving the engine.

 

Ok thats very helpful info that never even occurred to me. That might be what the builder meant although he didn't say how so I assumed it would have had something to do with the piston size, thank you.
Also if cast pistons can't deal with ring flutter would there be any issues with forged pistons and chromolly rings? I've heard that they're harder to break in

 

Also if cast pistons can't deal with ring flutter would there be any issues with forged pistons and chromolly rings. I've heard that they're harder to break in.

 

Yep I did find one not to far away like that. All kinds of classics there from all across the country. Even had an early 1900s Olds in a back corner of a barn. I would say whatever came after the curved dash

 

Mahle offers a 1mm ring pack forged 10cc piston in a .030" oversize, no issues at all with ring break in. I don't know if Kleenflo Combustion Chamber cleaner is available in the states, I gained as much as 30 psi soaking cylinders with it. It does sound like a valve job will also be needed on #3. A very nice car.

 

Thank you olds 307 and 403. The car has been a dream of mine for years. I figured this would be a good idea as well.

Lucky for me, everything specific to the toronado is in the second volume.

 

Hi OLDSter Ralph, so I have confirmed that the air still does come out of the exhaust with the piston at TDC on compression stroke.

 

Hey guys, so I have decided to take the heads off to get them done. The chassis service manual shows different specs for 425 heads. I belive my engine has the 39 degree lifter bank angle. They are B heads. As far as removal and instalation, is everything procedurally and spec wise the same as the other 425's? Is there anything I would need to tell the machine shop that would be specific to Toro heads? Also on both driver and passenger side closest to the rear, I found these pieces of rubber in the oil ports. Has anyone seen this before and could maybe tell me what they think these pieces are from? Greatly appreciated thank you.

 

Most likely they are pieces of old valve seals.

 

As far as I know there is nothing different about the heads other than valve sizes.
That won’t make any difference on machine work / rebuilding.

 

Thanks Sugar Bear, I was hoping someone would say just that.

 

Thanks Fun71, I think there's a decent possibility that I'll need one exhaust valve but can't be sure until I take the heads off.

 

When I took the valve covers off my '66 Toro to replace the valve cover gaskets I found a few pieces just like that. The consensus on here was valve seals.

 

Thanks ourkid2000, that's what I was hoping they were.

 

Has anyone had problems with their engine properly oiling? What improvements can be made?

 

On a stock rebuild for an engine that has lasted over 50 years I wouldn't change anything unless I noticed a piece of casting remnant that needed to be removed because it was restricting a return opening. Confirm that the oil returns in the head are clear, do the valve job and reinstall the heads.

 

FWIW, it has been my experience that if you correct an issue with the top end sealing of an engine with a lot of miles on it, you will encounter problems regarding the rings. You already have a noted concern with possible stuck rings, among other problems. I would consult someone in your area that has experience with older vehicles and ask them to evaluate your engine, before you open up a can of worms. Again, just my $ .02.

 

OK, noted

 

Yes sir and I respect your example and opinion. So I've been going to the car shows for a few months now to get in with that community. The experience varies but some of these guys are very knowledgeable. It's one of them that has offered the physical help. All I can say to that is that his Olds has to be at least worth 70Gs on the very low end and he's had his heads off 3 times. He suggested it may be just the valve guide seals initially. Now obviously I don't have hardened valve seats and I'm running 93 pump gas so there is that. I can't see the harm in polishing. I understand and agree with what you're saying about the rest of the engine, but I'm planning on having the rest done after the winter or if the economy picks up before then and I get some good jobs.

 

I have two questions. Why has he had to remove the heads three times? Secondly, and maybe more importantly, what model year is his car and what engine does he have.

 

I'll ask him. 69 442 with a 455 but he said originally had a 400