The Plymouth Weslake DOHC Motor from the 60's

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TrailBeast

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1969 Plymouth Weslake DOHC V8

It’s unknown whether this project was purely for racing, or Plymouth had the intent to offer the motor in a street car at some point. Keep in mind that the entire Chrysler group witnessed the excitement and positive impact on the brand when the previously race-only 426 Hemi was offered in production cars.

Following the 1968 season, Richard Petty announced he was leaving Chrysler and going to Ford for the 1969 NASCAR season. The money allocated for Petty was used to develop the Plymouth Indy DOHC V8. Design work began in February 1969 and running engines were provide to Andy Granatelli’s STP race team less than 90 days later.

The designer of the special cylinder heads was Harry Weslake, a British engineer best known for his expertise in gas flow through internal combustion engines. If you recognize the name, it may either be for his V12 engine in Dan Gurney’s 1967 Belgian GP winning Eagle, or the Gurney-Weslake cylinder heads used on GT40 Fords.

The engine lacked top-end horsepower necessary to compete at the high speed oval tracks, it had plenty of bottom-end torque which made it quite competitive on the short oval. In fact, Art Pollard drove the Plymouth-Westlake engine to victory at the 200-mile Indy car race at Dover, Delaware on August 24, 1969. This would turn out to be the only victory for Plymouth in the history of Indy Car racing.

Weslake.jpg
 
One of the first how-to engine books I bought in my mid teens mentioned that effort. Had a few pictures or cut-away drawings of the heads and injection too. Pretty cool shizzzit.
 
I have a set of heads that as I understand were from Tom Hutchinson from the early development of the indy motor before the weslake, and sents they didn't use them they made stock, superstock cheater heads for the 1969 season. They are a set of X heads 11-68 date code and were built in 2-69, they have 5/16" hemi style tulip valves, guides are drilled 5/16" not bushed .100" longer 2.02 1.60, BB battleship springs, hemi retainers and locks, hemi style 3/8" push rods,
pedistals milled down and drilled offset for the longer valves, and the T/A rockers shown in the picture. Here is a artical from Motortrend 7-69.

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I have a set of heads that as I understand were from Tom Hutchinson from the early development of the indy motor before the weslake, and sents they didn't use them they made stock, superstock cheater heads for the 1969 season. They are a set of X heads 11-68 date code and were built in 2-69, they have 5/16" hemi style tulip valves, guides are drilled 5/16" not bushed .100" longer 2.02 1.60, BB battleship springs, hemi retainers and locks, hemi style 3/8" push rods,
pedistals milled down and drilled offset for the longer valves, and the T/A rockers shown in the picture. Here is a artical from Motortrend 7-69.

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Awesome info u provided
Its refreshing to see vintage articles featuring the LA platform.
 
IIRC that motor failed at Indy because they filled it with cold oil filming an STP commercial! Was supposed to be hot oil so it was thinner, and the cold oil overtaxed the oil pump causing a failure. Read that somewhere.
 
I wonder how it would have gone if they had tried again in the 1970s using the W-2 setup...
 
1969 Plymouth Weslake DOHC V8

It’s unknown whether this project was purely for racing, or Plymouth had the intent to offer the motor in a street car at some point. Keep in mind that the entire Chrysler group witnessed the excitement and positive impact on the brand when the previously race-only 426 Hemi was offered in production cars.

Following the 1968 season, Richard Petty announced he was leaving Chrysler and going to Ford for the 1969 NASCAR season. The money allocated for Petty was used to develop the Plymouth Indy DOHC V8. Design work began in February 1969 and running engines were provide to Andy Granatelli’s STP race team less than 90 days later.

The designer of the special cylinder heads was Harry Weslake, a British engineer best known for his expertise in gas flow through internal combustion engines. If you recognize the name, it may either be for his V12 engine in Dan Gurney’s 1967 Belgian GP winning Eagle, or the Gurney-Weslake cylinder heads used on GT40 Fords.

The engine lacked top-end horsepower necessary to compete at the high speed oval tracks, it had plenty of bottom-end torque which made it quite competitive on the short oval. In fact, Art Pollard drove the Plymouth-Westlake engine to victory at the 200-mile Indy car race at Dover, Delaware on August 24, 1969. This would turn out to be the only victory for Plymouth in the history of Indy Car racing.

View attachment 1715006937

I always thought that the Gurney-Weslake heads developed for Chrysler small block engines, were to meet USAC rules for stock block, push rod engines at a 318 cube displacement limit. Never herd of any cammer set ups other than some ( maybe like the ball stud Hemi ) engineering excersizes.
 
I've read many articles on this engine and most call it a DOHC when in fact it's a push rod motor !
 
I always thought that the Gurney-Weslake heads developed for Chrysler small block engines, were to meet USAC rules for stock block, push rod engines at a 318 cube displacement limit. Never herd of any cammer set ups other than some ( maybe like the ball stud Hemi ) engineering excersizes.

Whoops.:D
I didn't say this.

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They must be hiding the DOHC head because this Westlake head is a push rod head, that is the rocker shaft in the picture.

westlake1.jpg
 
Another big clue is that there is no cam drive (chains or belts) which would require a totally different design for the whole front of the engine.
 
Hi Brian,
Loving the pre Weslake X heads you have there!
I have a few Mopar Weslake heads here too, a pair of 340 J heads and a complete 440ci engine with W2 style ported heads.
The Big Block W2's are not modified standard castings but unique heads cast from scratch!
Seems that Harry must have been involved with Mother Mopar in 68-69 to develop Chrysler engines?
When they shut down in Rye, some of the engines were sent back to the USA and some stayed here.
I know of a 426 hemi and my own 440 nascar engine that have been 'unknown' for many years.
It was only recently that the 340 'Weslake ported' Small block heads have come to light.
Best wishes from England, John

440 ovalports.jpg


Ovalport 440 heads and rockers.jpg
 
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No Carillo rods in my 440ci Nascar engine , just shortened 426 hemi rods?
The hemi rod in the foreground is a stock length 6.860 and the Weslake rods are of course, 6.760 440 length!
No obvious signs of reworking just hemi rods at the 440 sizing...:thumbsup:
No forged pistons either just plain old 70 Sixpack ones, off the shelf.
But the engine was reworked for a street car back in the 80's so the original pistons may have been changed?

426 hemi rod with Weslake-440 HEMI-Rod+piston.jpg
 
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Heads are very similar to the ones in the Mopar Performance book by Larry Schrieb, page 92 and 93 with conventional chambers and extra COOLING waterways too. (like late Motorhomes)
2.250 intakes and 1.81 exhausts.

Lovely 'D' port exhausts!
All the rage now lol.:thankyou:

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Nice!
I have that old DC book as well ... in the same condition ...lol
 
Have you ever run those heads ?
How did they perform ? Any flow data ?
 
I remembered those style of heads, but didn't know they had tried them with a conventional chamber as well. So I had to dig out the book and refresh my memory. The small block section of that book was VERY helpful and educational in my earlier racing years. Note that they said the "Big Block W-2" heads simply didn't work!
 

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The Speedway Museum in Lincoln NE has 2 of those Westlake Plymouth engines. A lot of other neat engines also
To the OP, thanks for posting that information!
I think there are more than 2 there, I thought I counted 3.
And in their motor shop I took pictures of the injected motor just like the one pictured in the article on the dyno. I had posted it a couple of years ago, and no one knew what it was.
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I have a set of heads that as I understand were from Tom Hutchinson from the early development of the indy motor before the weslake, and sents they didn't use them they made stock, superstock cheater heads for the 1969 season. They are a set of X heads 11-68 date code and were built in 2-69, they have 5/16" hemi style tulip valves, guides are drilled 5/16" not bushed .100" longer 2.02 1.60, BB battleship springs, hemi retainers and locks, hemi style 3/8" push rods,
pedistals milled down and drilled offset for the longer valves, and the T/A rockers shown in the picture. Here is a artical from Motortrend 7-69.

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Give me some of that 9500 RPM valve train goodness
would love to be able to wind up my engine to 9500 rpm must sound insane
 
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