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Jack_Vines

Old hemi experts?

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Greetings, All Dodge hemi experts:

If memory serves, the evergreen Mopar 318" V8 evolved from either the Dodge or the DeSoto hemi/polyspheric engines. Which was it and what was the first and last year for the in-line valve 318" V8?

Actually, a bit of research answered my own question. See if I have my facts straight. It began with the 1953 Dodge hemi and in 1955 was converted to the A-engine polyspheric head, grew to 318" and was converted to in-line valves with the LA-engine version for the 1965 273" Barracuda engine, grew to 318, 340 and 360, still used in Jeep and Dodge trucks today. A fifty-year run is not bad for any engine.

thnx, jv.

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Benefits of AACA Membership.

Bet you didn't know that the hemi concept came from the WWII Rolls Royce V-12 'Merlin' engine used in the Spitfire,Hurricane,Lancaster bomber and the Mustang? I've often wondered if that's where Chrysler got the idea from because they did use the name 'Spitfire' on their engines in the early 50s but not on the hemis. Hmmmmmmmm? <img src="http://forums.aaca.org/images/graemlins/laugh.gif" alt="" />

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Actually, the hemi combustion chamber and dual rocker shafts goes back to the dawn of the internal combustion engine. Literally dozens of European engines used it through the teens, twenties and thirties before the Merlin.

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The American-built Welch had a hemi head engine in 1908.

Chrysler used a British Riley 4-cylinder engine with hemi heads in the later 1940's for testing, It used short pushrods with the camshafts placed high in the block - actually just below the head.

And getting to the original question, the A block was a completely different engine from Dodge, DeSoto or Chrysler engines. Although the Dodge and Chrysler engines came as either a poly or hemi, the DeSoto came only as a hemi and the A only as a poly. The A block has bigger bore centres than the other three which is one reason why Dodge hemi heads will not fit an A block.

The largest Dodge V8 was 325-cid, and that was with a raised engine block (higher deck height). The A block came only in one height.

The A block was introduced in 1956 in 277 and 303 sizes. The 301, 313, and 318 arrived for 1958, the 301 lasting one year, the 313 until 1964, and the 318 until 1967 (1966 in the U.S.).

It is incorrectly referred to as a wide block but the block is vritually identical in exerior dimensions to the LA block. THe wider A poly heads with the splayed valves give the impression the engine is wider.

The LA block with its wedge head and valves in a row looks, as a result, narrower than the A.

Present day V8 engines share nothing with the LA family.

Bill

Vancouver, BC

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"This is the first time that I knew that the Dodge Poly was a higher block, probably to lower the compression ratio, (a guess.)."

What they did was make the block taller so they could run a longer stroke crankshaft. This was done when they enlarged the engine to 325 cu in. The 325 was made in 1957 or possibly 1956 and 57, I can't be sure without checking but it was only made one or 2 years.

Likewise the 1957-58 392 Chrysler hemi was a raised block version of the 331/354 engine they had used since 1951.

Hemi and polysphere engines used the same block.

By the way they did the same "raised block" trick on the B and RB engines introduced in 1958. They made a 350, 361 and 383 B engine. Then they made a raised block "RB" engine in 383 and 413 flavors.

Later they made a 400 low block and a 426 and 440 raised block.

Some years back I tried to sort out the welter of engines and transmissions Chrysler used back in the 50s. After several years of work I had the whole thing down on a big chart but I'm not sure I ever did get every detail straight. You can go nuts trying to figure it out.

The 40s were a lot simpler, and between 1958 and 1961 they rationalised the line but for the period 1951 to 1960 who knows what they were thinking.

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mlander</div><div class="ubbcode-body"> Quote:

This is the first time that I knew that the Dodge Poly was a higher block, probably to lower the compression ratio, (a guess.).

I have of late been studying the Dodge Poly and especially the Plymouth Poly and trying to find out a lot about this item is about like trying to find the proverbial needle in a haystack! Or possible worse. Just try to find any real and accurate information about the 1959 325 cubic inch Dodge, this is about like having a Root Canal operation! Is it a Dual Quad Carburetor or a Single Quad and just what about the Camshaft, Pistons and the Compression Ratio, etc?

As far as I can find out it was just a bored out 318 and nothing else. The only information I found was at Wikipeddia. They probably were just as frustrated as I.

Yours M.L. Anderson

</div></div>

The Dodge Hemi/Poly came in low block with a 3.256" stroke -

241-cid - 3.44" bore - 1953-1955 (Also 1955 Plymouth poly)

260-cid - 3.56" bore - (Used by Plymouth in 1955 - poly)

270-cid - 3.625" bore - 1955-1956 (Also 1956 Plymouth)

The raised block version used a 3.80" stroke -

315-cid - 3.625" bore - 1956

325-cid - 3.69" bore - 1957-1958

The 1959 326 was an A block poly engine. It shared the 3.31" stroke with the 318 but the bore was increased to 3.95" from 3.91". Compression ratio was 9.2:1. Horsepower was 255 @ 4400 rpm while torque was 360 @ 2400 rpm. It was used only in the Coronet V8 series (MD2-L).

The A block used two stroke dimensions - 3.13" and 3.31".

The 3.13" stroke came in 2 sizes -

3.75" bore - 276.1 (or 277) - 1956-1957

3.91" = 301-cid - 1957

The 3.31" stroke -

3.81" - 302.5-cid (303) - 1956-1957

3.87" - 313-cid - 1957-1964

3.91" - 318-cid - 1958-1967

3.95" - 326-cid - 1959

The DeSoto V8 (hemi only) with 3.344" stroke -

3.625" bore - 276.1-cid - 1952-1954

3.720" bore - 291-cid - 1955

The raised block with 3.80" stroke -

3.72" bore - 330-cid - 1956

3.78" bore - 341.4-cid - 1956-1957

3.80" bore - 345-cid - 1957

(The poly 325 used in the 1957 DeSoto Firesweep was the Dodge engine. The Canadian-built 1954 Firedome used Chrysler's 354 poly.)

And for the Chrysler hemi, 3.625" stroke -

3.81" bore - 331-cid - 1951-1956

3.625" bore - 301-cid - 1955

3.94" bore - 354-cid - 1956-1958

The raised block Chrysler hemi used a 3.90" stroke -

4.00" bore - 392-cid - 1957-1958

The 301 was a poly while the 392 came only as a hemi. The 331 and 354 had hemi and poly versions.

Bill

Vancouver, BC

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the 1951-'58 Chrysler Hemi engine was, with the exception of the head design and configuration is a direct copy of the 1949-up Cadillac OHV V-8. The bore,stroke, compression and HP are the same, as are many of the external dimensions.

One chrysler engineer said that they went to a Highland Park funeral home that had just received a new Cadillac herse. Paid the driver to let them "play with it for a while". The Hemi head was an obvious way (albeit expensive) to aviod any legal entanglements over a pirated design.

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To clear up a lot of confusion about these engines I suggest the people go to the address below to clear the air on these engines! Also it is easy to get confused as several engine have very simliar displacement but different Bores and Strokes.

http://en.wikipedia.org/wiki/Chrysler_A_engine

and

http://www.allpar.com/mopar/list.html

Edit; I am now in a very high mode of operation to just clear up the Ply./Dodge Polys only! 08-30-2007

Yours, M.L. Anderson

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If this is true why did Cunningham go to the bother of swapping Caddy pistons and rods into their racing Hemis?

At the time they said the Caddy pistons and rods were lighter and gave a higher compression ratio for more hp.

Also the Chrysler was rated at 180 HP vs 160 for the Caddy. Chrysler engineers have stated since that their engine put out 190 HP but since they already had the most powerfull engine in the industry they chose to understate it and not scare off the more conservative customers.

No one ever accused GM of understating their horsepower.

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Hi Bill-W just to add another dimension to the 313, we used this engine down here for the locally produced Chrysler Royal 1957 - 1959; 1960 saw the introduction of the 318. What info, if any, can you shed on this family group ?

My 313 engine number starts with LV, another titbit is that the original hand book, supplied with the car, specified engine capacity as 303ci and then a correction to 313ci was pasted over the top of it.

Many thanks - Chris H

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The 303 and 313 were Canadian made versions of the basic 318 model engine block.

The story goes that this engine was introduced at 276 cu in for the 1955 Plymouth. At the same time, Canada got a new engine plant to produce this engine.

As no Dodge V8s were made in Canada, they made a larger 303 cu in version of the Plymouth engine for Canadian Dodges.

No 303 was used in American made Dodges, they had their own exclusive engine

When the Plymouth people were looking for a more powerful engine for the 1956 Plymouth Fury they grabbed the Canadian 303. As it was a modified Plymouth engine it fit right in the Plymouth chassis.

I can't put my finger on any documentation at this time but from memory the 313 was used in Canada up to 1963 or so.

I believe the English Bristol sports cars used the 313 as well.

For tax reasons American cars and parts for export to Commonwealth countries were sourced from Canada whenever possible. No import duties were payable on goods going from one Commonwealth country to another.

Your 303 and 313 engines were probably imported from Canada for this reason.

Other than the odd bore and stroke dimensions they are very like the Polysphere 318 engine used by Plymouth and Dodge up to 1966.

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rusty_OToole</div><div class="ubbcode-body">The 303 and 313 were Canadian made versions of the basic 318 model engine block.

The story goes that this engine was introduced at 276 cu in for the 1955 Plymouth. At the same time, Canada got a new engine plant to produce this engine.

As no Dodge V8s were made in Canada, they made a larger 303 cu in version of the Plymouth engine for Canadian Dodges.

No 303 was used in American made Dodges, they had their own exclusive engine

When the Plymouth people were looking for a more powerful engine for the 1956 Plymouth Fury they grabbed the Canadian 303. As it was a modified Plymouth engine it fit right in the Plymouth chassis.

I can't put my finger on any documentation at this time but from memory the 313 was used in Canada up to 1963 or so.

I believe the English Bristol sports cars used the 313 as well.

For tax reasons American cars and parts for export to Commonwealth countries were sourced from Canada whenever possible. No import duties were payable on goods going from one Commonwealth country to another.

Your 303 and 313 engines were probably imported from Canada for this reason.

Other than the odd bore and stroke dimensions they are very like the Polysphere 318 engine used by Plymouth and Dodge up to 1966. </div></div>

The 303 was based on the A block and was introduced for 1956. The A block, in 1956 and 1957, was the Plymouth engine. The 1955 Plymouth V8 engines were Dodge blocks with poly heads.

Chrysler of Canada imported V8 engine blocks from 1952 through 1955 and gave them unique engine numbers with a "C" at the end. For the 1956 model year, Chrysler of Canada opened up a new V8 engine plant and began building A block engines - 277 for the Plymouth (same as in the US) and small Dodge, 303 for the Dodge Custom Royal and Chrysler Windsor.

They continued to import blocks for the DeSoto and Chrysler New Yorker. Chrysler Canada began building B block engines for the 1959 model year.

The 313 was introduced for 1957 and used through 1964.

The Commonwealth countries had low import duties (I would not say none) for goods from other commonwalth countries. Except Britain. They did not follow the agreement after the WW II.

Thus Chrysler Australia imported A block V8 engines from Canada, with the flathead sixes coming from either Canada (Windsor - 251-cid) or Britain (Kew - 230 or 251).

The "LV" means it is a 1958 (L) V8 engine as used in the Plymouth and small Dodge. And it would be a 313 as the 303 was built only in 1956 (J) and 1957 (K).

The poly 318 was used through 1966 in the U.S. and 1967 in Canada.

Bill

Vancouver, BC

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Thanks Bill I have been trying to find the sales order for my car (without success) which I am sure stated it as 1957 delivery,therefore a 1958 engine would make this record somewhat dubious. However as the introduction of a V8 powered Royal was a rushed decision I would not put too much faith in the integrity of these records.

Thanks

Chris H

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Bill -W,

Now that I have straightened myself out using your voluminous @ very informative passages, now for another very real question!

There are a lot of places on the Internet about the sparkplugs used in the Poly engine from 1956 to about 1966. There is as you know a lot of wrong information about sparkplugs on the various places about this item.

Were the Sparkplugs 14mm straight thru from 1956 to the end, approx 1966?

Were the reaches all the same at 3/8” or ¾”?

Were they all gasket seats or were some Tapered seats?

M.L. Anderson

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