This was the letter that forever changed hot rodding.  The most popular hot rodding engine ever would never have come around if it weren’t for this memorandum from Zora Arkus-Duntov.  He was the father of the Chevrolet Corvette and infamous Chevrolet small-block V-8.  His 1953 memorandum to Maurice Olley, Chevrolet’s Director of Research and Development changed hot rodding forever.

Duntov was new to Chevrolet, but he wasn’t new to hot rodding.  Before coming to Chevrolet, he’d developed an overhead-valve conversion kit for the also-infamous Ford flathead V-8.  His conversion kit was called the “Ardun.”  Today, it is one of the most coveted hot rodding parts ever made.  The Ardun was a cylinder head that moved the valves about a half inch above the cylinder.  It’s hard to explain.  Here’s an outside photo, and then an cutaway.

Back to the subject.  His 1953 three-page letter, simply known today as the “Duntov Letter,” he leveraged the power of hot rodding (it was referenced nine different times in the letter) in the hopes that he could do for Chevy what the flatheads and lakebeds did for Ford.

The Duntov Letter turned 61 a few days ago.

To: Mr. Maurice Olley
From: Mr. Z. Arkus-Duntov
Subject: Thoughts Pertaining to Youth, Hot Rodders, and Chevrolet
Date: December 16, 1953

The hot rod movement and interest in things connected with hop-up and speed is still growing. As an indication: the publications devoted to hot rodding and hop-upping, of which some half-dozen have a very large circulation and are distributed nationally, did not exist some 6 years ago. From cover to cover, they are full of Fords. This is not surprising then that the majority of hot-rodders are eating, sleeping, and dreaming modified Fords. They know Ford parts from stem to stern better than the Ford people themselves.



A young man buying a magazine for the first time immediately becomes introduced to Ford. It is reasonable to assume that when hot-rodders or hot-rod influenced persons buy transportation, they buy Fords. As they progress in age and income, they graduate from jalopies to second hand Fords, then to new Fords.



Should we consider that it would be desirable to make these youths Chevrolet-minded? I think that we are in a position to carry out a successful attempt. However, there are many factors against us:



1. Loyalty and experience with Ford.


2. Hop-up industry is geared to Ford.

3. Law of numbers thousands are and will be working on Fords for active competition.

4. Appearance of Ford’s overhead V-8, now one year ahead of us.



When a superior line of G.M. V-8s appeared, there where remarkably few attempts to develop these and none too successful. Also, the appearance of the V-8 Chrysler was met with reluctance even though the success of Ardun-Fords conditioned them to the acceptance of Firepower.

This year is the first one in which isolated Chrysler developments met with success. The Bonneville records are divided between Ardun-Fords and Chryslers.

In the non acceptance of G.M. V-8’s and very slow beginning of Chrysler, cost must have played a part.

Like all people, hot-rodders are attracted by novelty. However, bitter experience taught them that new development is costly and long and therefore are extremely conservative. From my observation, it takes an advanced hot-rodder some three years to stumble toward the successful development of a new design. Overhead Fords will be in this state in 1956-1957.



The slide rule potential of our RPO V-8 engine is extremely high but to let things run their natural course will put us one year behind and then not too many will pick Chevrolet for development.

It seems that unless by some action the odds and the time factor are not overcome, Ford will continue to dominate the thinking of this group. One factor which can largely overcome this handicap would be the availability of ready engineered parts for higher output.

If the use of the Chevrolet engine would be made easy and the very first attempts would be crowned with success, the appeal of the new will take hold and not have the stigma of expensiveness like the Cadillac or Chrysler, a swing to Chevrolet may be anticipated. This means the development of a range of special parts – camshafts, valves, springs, manifolds, pistons and such which will be made available to the public.

The association of Chevrolet with hot rods, speeds and such is probably inadmissible. But possibly the existence of the Corvette provides the loop hole. If the special parts are carried as RPO items for the Corvette, they undoubtedly will be recognized by the hot rodders as the very parts they were looking for to hop up the Chevy.

If it is desirable or not to associate the Corvette with the speed, I am not qualified to say, but I do know that the in 1954, sports car enthusiasts will get hold of Corvettes and whether we like it or not, will race it. Most frequent statement from this group is “we will put a Cadillac in it”. They are going to, and I think this is not good! Most likely they will meet with Allard trouble that is breaking sooner or later, mostly sooner, everything between the flywheel and road wheels.

In 1955, with V-8 engine, if I needed to they will be still outclassed. The market-wise negligible number of cars purchased for competition attracts public attention and publicity out of proportion to their number. Since we cannot prevent the people from racing Corvettes maybe it is better to help them to do a good job at it.

To make good in this field, the RPO parts must pertain not only to the engine but to the chassis components as well. Engineering-wise, Development of these RPO items, as far as the chassis concerned, does not fall out of line with some of the planned activity of our group. Use of light alloys, and brake development composite drums, disc and such are already on the agenda of the Research and Development group already.

As I stated above, V-8 RPO engine has a high power potential it is hard to beat inches, but having only 80% of cubic inches it has 96% of square inches of Pittston area of the Cadillac. In my estimation, the power output comparable to the Cadillac can be obtained not exceeding 270 ft.lb. of torque at any point. (323 ft.lb. of Cadillac)*. The task of making powertrain reliable is therefore easier. 

 These thoughts are offered for what they are worth: one man’s thinking aloud on the subject. 



Z. Arkus-Duntov
December 16, 1953

* The comparison pertains to a special type of Cadillac

As we all now know, the Duntov Letter changed hot rodding forever.  The legendary Chevy “Mouse Motor” small-block V-8 was born in 1955.  It made more than double the power of the Ford flathead V-8.  It took a couple of years to catch on, but when it did, oh my.  It stayed in production for an astonishing 45 years, before being replaced by the small-block-based LS-series engines.  It is still one of the best engines ever.  It sounds good, weighs as much as a V-6, and has found it’s way into just about every car imaginable.  Hot rodders love it.  It’s small enough to fit into a 1932 Ford engine bay.

Today it’s been replaced with the LS-series engines.  The only big-block LS motors are the LS7 (found in the C6 Corvette ZO6 and 2014 Camaro Z/28) and LS2/LQ4 (found in the C6 Corvette and GMC Sierra HD/Chevy Silverado HD).

Here is a list of the Chevy small-block motors and what cars they were used in.  I have also included what years that engine was made:

Chevrolet Small Block V-8:

  • 262 C.I. V-8 (1975-1976).  Used in Chevrolet Monza, Nova, Pontiac Ventura.
  • 265  C.I. V-8 (1955-1957).  Used in Chevrolet Bel Air, 3100-series pickups, Suburban, Corvette.
  • 283 C.I. V-8 (1957-1967).  Used in Chevrolet Bel Air, 3100-, 3600-, and 3800-series pickups, Corvette, Impala, Checker Taxi (1965-1966).
  • 307 C.I. V-8 (1968-1973).  Used in GM A-Body cars.
  • 302 C.I. V-8 (1967-1969).  Used in Chevrolet Camaro Z/28.
  • 327 C.I. V-8 (1962-1970).  Used in GM A-Body cars, Chevrolet Impala.
  • 350 C.I. V-8 (1967-2000).  Used in Chevrolet Camaro, Corvette, Chevelle, Pickup Trucks, El Camino, Nova, Pontiac Firebird, Pontiac Ventura, Chevrolet Blazer, GMC Pickups and Jimmy, Chevrolet/GMC Suburban, Cadillac Brougham, Buick Roadmaster, GMC Vandura, Chevrolet Caprice 9C1, Oldsmobile Custom Cruiser, AM General HUMMER H1, Cadillac Escalade, GMC Yukon, Chevrolet Tahoe.
  • 400 C.I. V-8 (1970-1980).  Used in GM A-Body and B-Body, GMC/Chevrolet Suburban, GMC Jimmy/Chevrolet Blazer.
  • 305 C.I. V-8 (1976-1992).  Used in Chevrolet Camaro, Chevrolet Caprice/Caprice Impala, Chevrolet Corvette (1980 CA only), Chevrolet Monte Carlo, Chevrolet Malibu, Chevrolet Monza, Chevrolet Nova, Chevrolet/GMC Trucks/Vans, Buick Regal, Buick Skylark, Cadillac Brougham, Checker Marathon, Oldsmobile Custom Cruiser, Oldsmobile Omega, Oldsmobile Cutlass, Pontiac Catalina, Pontiac Bonneville, Pontiac Firebird, Pontiac Grand Prix, Pontiac Grand Le Mans, Pontiac Parisienne, Pontiac Parisienne Safari, Pontiac Sunbird.
  • 267 C.I. V-8 (1979-1982).  Used in GM F-Body, GM G-Body, GM B-Body, Checker Marathon.

Which of these engines saw the most work?  Well, the 350 has found it’s way into just about every car made.  People have built Smart Car drag cars with them.  The 350 is a reliable engine that can have just about anything slapped onto it and be fine.  It can be built into a holy drag strip terror by simply stroking it and shoving a big cam in.

The 305 is the engine everybody complains about.  It took a 283 block, but had the crankshaft and internals of the 327.  This means that you can pick up a lot of horsepower by simply adding forged 327 internals.  It’s also extremely reliable.

The 400 was the biggest Chevy small-block to come from the factory.  All Chevy did was bore and stroke the 350.  This means that it is more powerful than a 350 with a cam, but only weighs about 20 pounds more.  Oh, and it’s externally the same size.  That helps a lot with hot rodders who want the power and reliability that they know a Chevy small-block V-8 will provide, but need the compact dimensions of a smaller engine.

The 283 is a great engine.  It doesn’t rev high, but it revved higher and better than the 265 that preceded it.  Interestingly, when you put fuel injection on top of it instead of a carburetor, it revs 1,000 RPM higher.  It also makes 283 horsepower.  Back in 1957, anybody who had a 1957 Chevrolet Bel Air with the fuel-injected 283, not only did you have a beautiful car, but you had a car that could keep up with sports cars ten years down the road.  Today, it is one of the most coveted cars ever.  I will own one before I die.

Chevrolet still lets Mercury Marine make the 305, 350, and 327 for marine applications.  They are popular in offshore powerboats.  Drag boats use heavily massaged Chevy big-blocks.  Offshore powerboat engine builders take a Mercury Marine 350, pull it apart, add a couple of turbochargers, and forged internals, and shove it into a really cool boat.

You can check out Mercury Marine at https://www.mercurymarine.com/en/us/

Chevrolet Performance still makes small blocks that they sell to the public.  You can check out their website at http://www.chevrolet.com/performance/overview.html

On another note, I will be taking a few weeks off for the holidays.  Look for a new post sometime in mid-January.  Happy holidays to my faithful readers – you are amazing!

 

5 thoughts on “The Duntov Letter

    1. That’s a hard one. It really depends on their age and how involved in hot rodding they are. I’m going to hedge a bet that somewhere between 50-80% of hot rod owners know about the letter. Out of that number, I’m going to say that almost all of them know what it’s about.

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