1970 455 engine and California emissions

[wildcatsrule]

Does anyone know what additional emissions equipment was added to the 455-4 engine in 1970 on cars that were sold in Southern California? This engine was rated at 370 horsepower (for an Electra 225). What effect did California emissions have on the horsepower of this engine? Thanks David

[NTX5467]

Typically, CA spec engines would have had leaner carb jetting characteristics, distributors with an altered advance curve (less advance at lower rpms than Federal spec vehicles), initial timing would be closer to TDC than a Federal spec vehicle, and they probably most certainly had the Air Injection Reactor system (i.e., air pump). Heated air to the air cleaner was on all cars and light trucks by that time so that would be constant. EGR came into the mix a few years later.

In some cases, most of the calibration changes only affected idle, low speed, and midrange rpm cruise situations with WOT typically being the same or a little richer to compensate a little for the leaner primary calibrations. The rated horsepower and torque figures are at WOT and not part throttle. Some initial throttle reponse off idle and a little more lethargic reaction to throttle input during the altered operational phases might be evident too. As the spark advance was "slower" than optimum, fuel economy could suffer a little too.

Ultimate cruise fuel economy might not suffer as much as everyday fuel economy as the lesser throttle response usually results in deeper throttle movements which could put the carb into the power mixture more, further decreasing fuel economy.

The 8.5 to 1 compression ratio came online with the 1971 engines and hardened valve seats happened along about April,1971.

During those earlier times, the strategy was to alter existing calibrations as that was cheaper than adding equipment and running the production cost upward and later redesigns specifically for emissions reduction were not yet funded.

Hope this helps,

NTX5467

[Guest]

CA cars were the only ones to have Charcoal Canisters in 1970. I believe everyone else got them in 71. In 72 Buick and Mopar invented their own style of EGR systems. The Mopar system was unreliable and they adopted the Buick style system along with the rest of the automotive industry in 1973.

My '70 El Camino had a Transmission Controled Spark solenoid on it. It did something to the timing based on load, I'm not sure what, and I never hooked it up.

Air Injection on 68-72 GM cars was usually found only on Stick Shift cars.

[NTX5467]

I'd forgotten about the Transmission Controlled Spark. It was connected to an automatic trans high gear pressure switch that ran a vacuum chopper/bleed solenoid in the vacuum advance line between the carb and the distributor. It allowed normal vacuum to the distributor only after the trans had shifted into high gear, keeping the vacuum bled off during operation in the lower gears. A "less advanced spark" led to higher combustion chamber temps and more fully cooked the unburn hydrocarbons before they went into the exhaust manifold.

On some 1970 higher model series 455s with TCS, there was an override for the vacuum advance to help keep the engine from overheating during prolonged idle time with "less advanced" vacuum advance. When the coolant got to about 220 degrees, it would put straight manifold vacuum to the vacuum advance to increase engine speed (plus fan and water pump speeds) to cool things back down.

The EGR that Chrysler used initially was like a controlled vacuum bleed, except it did it with small "floor jets" in the intake manifold that fed off of the heat crossover passage. A pretty neat concept that cost little to implement and obviously worked pretty well for what it was.

The floor jets let exhaust gases be drawn into the intake manifold from the heat crossover passage that went laterally under the manifold plenum area. The jet sizing would be critical as if too much came in during higher vacuum situations at idle, idle quality would suffer, but once higher rpm levels for cruise conditions were reached, the engine tolerated the extra inert gasses better. In prior times, when or if a manifold might crack to do the same thing the Chrysler floor jets did, it would be replaced, but the Chrysler situation was carefully calibrated to do what they wanted. Later, they did go to the more normal and controllable vacuum controlled EGR valve.

During those higher vacuum operational modes, there would be very little back pressure in the exhaust so the jet sizing "worked". Just as with regular EGR valves, the EGR would go away at WOT with the lessened manifold vacuum.

I found an SAE Transastion along about '73 or '74. It was done by an unnamed GM division on the effects of EGR on engine performance. The two engine sizes were 350 and 455. From the way it read, I suspected it would be Olds that did it, but it could have been Buick. Many graphs, dyno runs, and data. They determined that a maximum of 15% EGR should be used for best results. Also, any power loss that occurred from the introduction of the inert exhaust gasses to decrease the heat of combustion (and oxides of nitrogen production) could be regained with advanced spark timing. After all, it takes more lead to fire off a diluted charge than a clean charge. This is why that some engines clattered when their EGR valves became non-functional.

NTX5467

[Smartin]

I have a 71 LeSabre that was built (finished) in April of 1971. Would the 350 be included when they started using hardened valve seats? Also, I want to rebuild the engine...Does anyone have a good idea of what it will cost to do this?

Thanks,

Adam

[Smartin]

The main reason I want to rebuild is to fix the low compression in one of the cylinders. I have an exhaust valve that leaks and I lose compression at low idle. I was told I could just do a valve job, but I might as well just rebuild the motor, as it would benefit me $$$ wise and time wise later on.

Adam

[NTX5467]

As I recall, the April date was for all passenger vehicle engines for the North American market. It involved induction hardening the valve seats. Such induction hardened seats will have a blueish tint in the immediate seat area from the heat. It only goes about .003" deep so one good seat "facing" could go through it.

Usually, the reason a valve "burns" is from guide wear. When the guide to valve stem clearance becomes excessive, it can result in the valve not seating squarely in the seat. This can degrade the seat itself also start some erosion of the valve edge. End result is that a flat spot on the outer circumference of the valve head begins until compression is further lost past the valve head/cylinder head interface.

In previous times, it was common practice to knurl the valve guides internally. This basically puts grooves inside the existing guide to result in raised areas to make up for the wear. They can last for a good while, but a temporary fix at best.

When you get the cylinder head off, it will be evident from the way the crowns of the pistons are "cleaned" or have deposits on them how much oil is coming up past the rings and getting into the combustion chamber.

In prior times, it was common to pull the heads and just fix what needed to be fixed on the cylinders that needed repairs and resinstall everything. Theory was that if you "renewed" all of the valve seats it would show up the lesser capabilities of the compression rings (due to their wear). It is possible to have good compression yet had oil consumption due to poor oil ring performance.

The other situation is that when the heads were torqued onto the motor when it was originally built, the head bolts exerted a particular "distortion" into the cylinder wall areas. A distortion that the rings have come to wear into over the miles. When the cylinder heads are removed and then retorqued, this distortion pattern can change and compromise the rings' performance until they once again might become acclimated to their new "circle" in the cylinder wall. Oil consumption can increase until they get re-worn-in.

Some of these things are "worst case scenario" situations. The deal with fixing only what needs to be fixed and putting things back together was the main way things were done in the '70s (an later) and prior with good results.

Of course, the "high dollar" was to do things is to remove the motor, find a quality machine shop, and have them do an OEM-spec or better rebuild. That would include boring the block (probably about a .030" cut to clean it up) with deck plates to simulate the heads being bolted down, line honing the main web saddles to make sure the crank is in the block "true" and will spin easily, decking the block to make sure the heads are sitting squarely on the bore as they need to be, polishing and checking the index on the crankshaft, resizing and honing the rods, checking things for cracks or defects or high wear situations--and all of that is before you even look at the cylinder heads.

As for the cylinder heads, putting a new set of chrome stem valves into correctly-sized valve guides with new bronze helicoil inserts, with high quality valve stem seals (but NOT valve stem seals that will not let enough oil get into the guide for necessary long term lubrication), and a quality valve job that does not "sink" the valves into the cylinder head.

Of course, the heads will neeed to be surfaced to correct any surface warpage which might have existed when they left the factory or have accumulated over time. Not to mention being checked for cracks also.

Don't forget to inspect the oil pump mechanism (if it's mounted in another engine part casting) for rotor and casting wear. If it's a self-contained unit, preplacement probably is the best option.

When all of that is done and the long block reassembled, the engine is ready for reinstallation.

Now, for the sticky part, there are always plenty of "good" engine builders but few of these have a full complilment of machines to do all of these machining operations themselves. Many times, though, they have access to these people. Quality machine work is the backbone of any engine build procedure and poor quality machine work can ruin an otherwise and previously good engine core--regardless of how "good" this shop allegedly is.

Always use and specify gaskets, rings, etc. which are AT LEAST OEM-spec quality so that you don't end up with what I call a "30,000 mile rebuild". What that means is that those less expensive gaskets and rings and such will work fine for 30,000 miles before the oil consumption and such start instead of the basically 100,000+ mile durability from the at least OEM-spec parts.

In the small block Chevy engine book that Grumpy Jenkins wrote in the '80s, he stated that they used used engine cores to build their race engines. Even if they had to buy new ones, they put them in a protected place outside for them to cure further. End result, when you remachine a used engine block, the machining does not "move" as it will with a "green" casting. So, if you take a used engine in good condition and then optimize the machine work on it (with high quality machines and an operator that knows how to use them correctly), it should last longer than the original buildup did.

Depending on what your financial and logistical issues might be, the least deal with just fixing what needs to be fixed (but in a high quality manner) and let the other stuff sort itself out might be the best way to do things. If there are no issues with oil pressure or lower engine sounds, then it's still probably good enough to be usable for some time yet. Other than that, you can play it by ear on the rest of the things I've mentioned and see how it goes. Plus, it's probably a lot easier to find a garage that can get a good valve and guide job performed (probably less than $1000.00 depending on what all is done and how extensively, plus labor rates) than a complete engine rebuild (where the rebuild itself could run probably $2000.00 or a little more--without any remove and installation labor).

I hope this might help explain some of the various orientations and options you might have to consider.

Enjoy!

NTX5467

[Smartin]

Thanks for all the info! I'm still not sure what I want to do with the car in terms of dumping unneccesary $$$ into it. I am going to Staunton, IL to look at a 71 Centurion convertible in a few days. I have a feeling I'll be driving home in it. My LeSabre is starting to wear on my patience somewhat.

The body was pretty pummeled by hail a couple years ago, and I havent had the $$ or time to fix it. I don't think it's worth it either. So I'm going to go look at this centurion to see if it's worth the $6000 price tag. It looks real nice on the internet, but I want to get a closer look.

Wish me luck!

Adam