stock 350 Chevy engines at 6, 000 RPM

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tbolt25

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Someone we know that runs a wrecker service said that if a stock 350 Chevy engine cannot rev 6, 000 RPM, it is no good.
 
What a silly statement!

The small block Chevy V-8 is one of the most common engines ever produced in the history of cars, and was made in many variations from starting in 1955. The 350 cu. in. size came out in '67 but was a rare option until '69, when it replaced the 327 as the most common small block. This means it was made in versions ranging from economy engines with low compression and 2 barrel carbs to high compression, solid lifter Corvette engines. In the '80s it got electronic fuel injection (as distinct from the old Rochester mechanical injection offered from '57-'65), but still came in lots of flavors.

By nature it's not a revver, being a large displacement overhead valve engine with wedge head combustion chambers. However, the chambers are pretty good for a wedge head, and it was always oversquare (i.e., bore diameter larger than the stroke). Built right, small blocks can turn over 7000 rpm and plenty of the high performance factory versions will go well over 6000 rpm. My sister's old '66 Corvette, with a 327 that is virtually identical to a 350, would happily turn 6000 rpm and put out lots of power so long as you felt like putting up with 11 mpg. On the other hand, while the low performance engines might be coaxed to 6000 rpm they will be long past their power peak and doing nothing more than making noise.

Before asking such an engine to turn high revs, first ask whether Chevy built that engine to go in a pickup, a Corvette, or a Cadillac (and yes, Caddy used them too).

Some of the more interesting places a small block can be found include the Opel Diplomat, Gordon-Keeble GT, and Iso Rivolta/Grifo/Fidia. The first was Opel's top of the line sedan in the late '60s and early '70s, normally called the Admiral and equipped with an Opel six. For the few people willing to put up with terrible mileage, Opel would drop in the Chevy V-8 and voila!, an instant autobahn stormer. This was when Mercedes made very few V-8s, and aside from those the Diplomat was the fastest sedan made in Germany. The Gordon-Keeble GT was made in England in the early '60s, with a body design by Georgetto Guigiaro while he was at Bertone. Beautiful, fast, and elegant, only around 100 were made. Renzo Rivolta at Iso in Italy clearly like the idea, as he commissioned Bertone to design a similar car for him, and produced them from '64 through the early '70s. The last few had Ford 351s, but most have small blocks (I have seen a couple of Grifos with big block 427s or 454s!). The Rivolta is an elegant four seat GT, the Fidia (or S4) a beautiful four door sedan, and the Grifo (now by far the most sought after) is a very sexy two seat GT.

The photo below is of a Grifo, taken at a French and Italian car show I run with some friends. This Grifo definately has a small block, although I'm not sure if it is a 327 or 350. Given that Iso always ordered Corvette spec engines from Chevy, I'm quite sure it could turn 6000 rpm with no problems whatsoever. It probably has the very nice little Muncie four-speed gearbox, although a few were made with ZF five speeds and also some two speed Powerglide automatics for the terminally lazy. Wonderful cars for people who like Italian exotica but are phobic about maintaining an old Italian exotic engine with lots of camshafts and carburettors.

8-9-2008-11-44-31--hydralique.jpg
 
The thing I most notice about a Chevy small block are the stock stamped cam rockers. It's an ingenious design - very cheap to mass produce and reasonably well designed for the application. I gather that higher performance engines dispense with the cheap stock stamped rockers and go for more expensive cast and/or machined rockers, often with roller followers.

The other thing I notice about the small block is how common they are. Being a mopar guy, I got kind of envious of how easy it is to find parts/mods for the small block - particularly the 350, which must be a favorite of hot-rodders. The best Mopar competition for the 350 of the time is perhaps the Chrysler 340 wedge head. Another oversquare motor, a bit overbuilt, that can be pushed to very high revs and hp when modified correctly. But it's nowhere near as common or easy to find parts for as the Chevy 350.
 
small-block Chevy's are excellent engines.....

The small block is a most excellent engine, and was chosen as one of Ward's 10 best engines of the past century (along with the Model T engine, Volkswagen air-cooled engine, Ford flat-head V-8 engine, and several more and including the GM 3.8 V-6 used in many of the front-wheel drive GM cars today).

The guy telling you this just doesn't know to much, be wary of his advice that seems questionable to you.
 
Chevy wobble rockers . . .

I think the ball and wobble rocker design was pioneered on the small block Chevy in '55, when pretty much everyone else was using more expensive and less durable rocker shafts. Later on the concept was picked up by others, but at least some of the Ford 351s didn't have any adjustment in the rocker stands like Chevy. Ford correctly figured that the hydraulic lifters would account for production tolerances, but that didn't always work well at high revs. So, a buddy of mine who grew up street racing Chevys but loved DeTomaso Panteras would get a machine shop to adapt the 351 Cleveland heads to adjustable Chevy rocker stands. It worked great and he'd regularly run hydraulic 351s close to 7000, and a solid lifter 351 to 7400 - beyond that it would bend pushrods. I can't recall if those engines were using stamped or cast rockers, but I can verify that a 351 Cleveland that'll pull 7400 with four Weber 48 IDA carbs is just scary fast, especially when it's sitting two feet behind your head in a Pantera. Ford really got the heads right on the Cleveland - it breathes better than most Chevy or Chrysler small blocks, but they never were as strong on the block as Chevy or Chrysler. Of course, there are Mopar guys who contend that both Ford and Chevy cribbed quite a lot from Plymouth's mid '50s polyspherical heads, with the outcome being Chevy's "porcupine" heads on the second big block, and then Ford's 429-460 and Cleveland.

Suds, being a Mopar guy take a look beyond the Iso in my photo and check out the blue car with the big whitewalls. That's a Chrysler-Ghia from the mid '50s. Very rare, and what a sight it is with the hood opened to reveal a big, beautiful DeSoto Firedome V-8 with twin carburettors.
 
There's a Dual-Ghia at the local auto museum (at Blackhawk) that I see from time to time. Even saw a Chrysler Turbine at a concours about 10 years ago. They fired it up and it sounded much like a very expensive vacuum cleaner ;-)
 
I am SO envious that you heard a Chrysler turbine run! I've seen at least one of the survivors but only as a static exhibit. Supposedly there are no parts left for them and all the experts on the turbine retired years ago, so if it ever breaks it'll be a real problem. The same goes for the Rover turbines. I believe the Rover-BRM race car is still operable but the car's current keepers are mostly afraid to do anything with it.

Dual-Ghias are so cool. My favorite is the later Ghia L6.4 - I had a Corgi model as a child and always loved it. There's a black one around here that's been lowered a bit and has the rectangular Cibie headlamps - it looks just wicked! Most likely it was one of the Hollywood star cars modified in period by George Barris, as he did this to a few, with Sinatra's being the first.

The last Chrysler-Ghia collaboration was the Ghia 450SS, using the Barracuda suspension and 273 V-8. I was shocked to see one quite by accident a few months ago parked behind a building in Hollywood. Nice shape, but obviously not in regular use. I assumed it must have been owned by the building's owner or occupant, but if it were mine it would be safely at my house, not behind my business!
 
Yeah, I kept on looking for the extension cord for the turbine. And of course what was in the engine bay didn't look like any car motor I'd ever seen before.

Call me old fashioned, but my favorite car at the local museum is the '33 Pierce Arrow Silver Arrow. It may be the original streamlined car - beating the Chrysler Airflow by one year. At one time I delved into the museum library archives - there were five Silver Arrows, originally. One was lost. Another one was found chopped so that it could be used to deliver firewood (!). The other three survived more or less intact. I've seen one other, at auction, and the one at Blackhawk is in much better condition. I think one of the Silver Arrows saw duty as a gangster's transportation - complete with phone books stuffed into the door cavities to act as bullet-proofing.

One of the Silver Arrows was owned by a wealth car dealer. There was a comment in the archives from his wife. She didn't like the car because she felt it was too warm inside. I guess Pierce-Arrow hadn't yet gotten its hands on a usable car A/C system. It could also be that Pierce-Arrow hadn't yet figured out how to vent engine heat from the closed engine bay effectively, and perhaps hadn't figured out the best way to vent the streamlined passenger space.
 
Turbine car

A fellow down in TerrHaute Indiana has the only running privately owned Chrysler Turbine car. I have some video I shot of it with a dig still camera in 1996. No sound. He'd had help from a helicopter engine rebuider who reworked the broken recouperator disks for it with used allisons, and a engine case from Jay Leno. The fuel control, of course, was a South Bend Bendix.

It sounded just like an electrolux vacuum.

Btw, I don't drive my wife's 1987 shadow much over 2500 rpm = 35hp. Most city and highway driving is under that. So talk of 6000-7000 rpm begs the real issue for most, efficiency at "normal" rpm is sacrificed to attain breathing above 3000 rpm. Really. HP statistics, but harmful or at least irrelevant to most. And rear end ratios also are kept 3.5, 3.8 when 2.7 could be used to reduce engine friction and pumping losses (shift down to get rpms up, duh.).... oh don't get me started.
 
Revs can be your friend . . .

I drive a 90 hp diesel VW everyday and find that I often shift at 4000 or more rpm when getting on the freeway. It's not that I want to, but rather that the ramp at my entrance is both uphill and metered most of the day. At rush hour traffic is going 10-30 mph so it's not an issue, but from 10 am to 3 pm the meters are still working and there is very little room once the light turns green to accelerate uphill and onto a road where there are five crowded lanes of traffic doing 65-80 mph. This is a pretty common situation for people who drive on freeways, and the only alternative to using higher revs would be a much larger and less efficient engine.

The best way to achieve a gasoline engine that operates efficiently at both low and high speeds is to use a modern variable valve timing system, like the Honda V-Tec. Other companies have it as well, though Honda and BMW are probably the best. The problem with building only low speed engines is that they end up being huge to make enough power without revving high. American companies fell into that trap in the '70s, when Ford, GM, and Chrysler all had 6-7.5 liter engines that barely made 200 hp at about 4500 rpm and wouldn't breathe at higher rpm. These 700 lb. behemoths then required enormous engine compartments and heavy front suspensions, resulting in oversized cars that got 12 mpg in the city. With high gearing and a big torquey engine you can sometimes do OK on the highway, but it doesn't work too well in the city.
 
It's been my impression that the problem with the big V8's of the 70's had more to do with poor handling of emission controls. These wound up sapping horsepower while still giving lousy mileage. Case in point: my '78 Dodge pickup with a 360 V8. According to the specs I've seen it makes all of about 180 hp, which is abysmal for a motor that size. Modern versions of the 360 (5.9 liter Magnum) make about 50% more horsepower with about the same mileage if not better. Fuel injection and proper emission controls made all the difference. I understand the same motor prior to the 70's also made respectable HP and performance without having its exhaust strangled.
 
You're right, Suds . . .

To breathe well at high rpm an engine needs hotter valve timing, which generally leads to more overlap - that's the time during which both the intake and exhaust valves are open. Under some conditions, this can be helpful for emissions, but it causes major problems at low rpm. As you correctly note, good fuel injection makes a huge, huge difference in mileage, power, and emissions.

GM and Chrysler both experimented with fuel injection in the '50s. Chrysler offered a primitive Bendix electronic system in about '58, but only built 10 or so Chrysler 300s with the system before dropping the option. The cars were recalled and fitted with carburettors and Chrysler ceased all development. Both Chevy and Pontiac offered the Rochester mechanical injection in '57, but by '58 it became a Corvette only option which lasted until '65. For the next several years nobody in Detroit was interested in injection - all they wanted was big V-8s and single four barrel carbs. In Europe, Bosch succesfully made both diesel and gasoline mechanical injection systems but they knew the future was in electronics and spent most of the '60s developing D-Jetronic. By 1970 Mercedes, VW, Volvo, Saab, and Citroen all offered models with D-Jetronic.

When emissions controls became much stricter in the early '70s, Detroit was stuck with no currect injection knowledge at all, and had to use much less efficient carburettors to control emissions. The easiet way to do this was to start with a low-compression engine with super conservative valve timing with very little overlap. This resulted in an engine that wouldn't breathe at high rpm and so didn't have much power, but was smooth and torquey at low rpm, if inefficent. To compensate for the lack of power they simply made the engines larger. Remember in '65 a 283 Nova was considered a hot compact, but by '75 a strangled 350 was common in one. Chrysler was dumping 360s into Aspens and Volares, while the old Darts and Valiants mostly had 273s.

Had the '73 energy crises not occured, Detroit would probably have been happy to continue making huge and inefficient engines, but just like today they got caught in a bind due to fuel prices. They ended out frantically playing catch up to develop engines that could breathe well and meet emissions standards, but it wasn't until the '80s that they really caught up to the rest of the world.
 
Volvo injection.

Today, there are many older Volvos from the 70s and 80s running D-Jetronic fuel injection systems (I think that's what the really old ones run). The K-Jetronic system came later and was used in the mid 70s to mid 80s on some models. My '87 has LH-Jetronic. All these systems are by Bosch. Volvo has sold fuel injected cars exclusively in the US since 1973, although it was available on some models as early as 1970.

In comparing my 21-year-old Volvo with many domestic cars of the time, mine runs quite well. (How many Chevy Celebrities do you see nowdays anyway?) I can let my Volvo sit for months and when I come home, it always fires right up on the first crank.

All that being said, I like the 350 and think it has earned a very good reputation for durability and versatility. Just imagine how it would do with variable valve timing and shutting down cylinders like Chrysler is doing.

I think I need to take the 240 out for a spin,
Dave
 
Don't forget - that the rocker set-up that introduced on the small block Chevy in 1955 ALSO made a debut on the Pontiac engine as well that year. Rumors have been afloat for years that it was the Pontiac engineers that came up with the idea first then was 'borrowed' by the bow-tie guys.

Interesting topic - again, no reason to rev any stock block that fast. Three things not happening at that speed: flow, flow, and flow.

Ben
 
Point about RPM

GM found, back in '60s (see custom cruiser) that @ 70 mph a 3000 rpm reving v8 uses as much energy just turning around as pushing the car. The point is that "high gear" on the highway should drop RPMs down to the mud, and the valve timing should be optimized for this 99% of use RPM. To get more power, to raise RPMS, one downshifts.

The absolute worst thing run 3000 rpm down the highway with a oversized engine, worst at least for economy
 

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