273 commando heads vs. standard

[toolmanmike]

Motors Auto Repair Manual for 1973 also list valve spring pressures for 1967 273 as

273 2 bar carb 145 lb @ 1.312 in

273 4 bar carb 177 lb @ 1.312 in

68 up 273 and 318 2 bar carb appear to use the 67 4 bar carb valve spring.

And I have copies from a Chilton or Motors Manual that lists parts. "slant 6 and 273 part number 1739534" Also includes 1968 318. I couldn't get my Factory parts book to work. Old program and newer operating system I imagine.

 

[Syleng1]

Wow! Not to ruffle feathers but more info is listed here on those heads than the original engineers had on them.

This is turning into a “what horsepower can a turbo /6 put out?”
Lol! All good energy....

 

[clifcuda65]

That may be true but that isn't a factory parts book and may not reflect actual production.
There are an endless availability of aftermarket springs, Mopar Performance or other.

Show me Chrysler literature from 64-67 showing this information.


Alan

1967 Plymouth Service Manual. ( Chrysler Literature )

 

[Cuda Al]

1967 Plymouth Service Manual. ( Chrysler Literature )
View attachment 1715202861 View attachment 1715202862

View attachment 1715202873

Yup, after 66fs mentioned the Motors Manual I checked my 67 Factory Service Manual and saw that.

Alan

 

[toolmanmike]

Wow! Not to ruffle feathers but more info is listed here on those heads than the original engineers had on them.

This is turning into a “what horsepower can a turbo /6 put out?”
Lol! All good energy....

??? Huh? ???

 

[pishta]

The replacement seats are 1.563 OD but your cutting iron to sink these in. My 64 valves were spot on: 1.78 and 1.50 at the valve edge so the ID of the seats is smaller. still dont know where that 1.563 valve comes from but its very coincidental that the seat OD is that size. More BS? (Ha ha, good 'ol Rockauto for a reference? )

 

[MOPAROFFICIAL]

I have the 920 heads, cut down stainless 1.88's to 1.84, 1.60 stainless exhaust. bowls blended, radiused, smoothed exhaust, rounded around the guides. They flow 166.9 cfm at .450 of lift with 116% port velocity. Plenty for the 273 combo I'll be running.

What depression? That was not a successful venture if its @28".
Should be 200s by then.

 

[kgip2k]

What depression? That was not a successful venture if its @28".
Should be 200s by then.

The GREAT Depression... Lol

 

[BillGrissom]

I have read that the only difference between a 2 bbl & 4 bbl (HiPo) engine in 1965 is the pistons, camshaft, valve springs, and valve covers. The blocks and heads are identical. I have the 1965 Dart shop manual and it shows the 4 bbl engines with higher spring installed loads than the 2 bbl engines (as post 53 shows for 1967).

 

[66fs]

I have read that the only difference between a 2 bbl & 4 bbl (HiPo) engine in 1965 is the pistons, camshaft, valve springs, and valve covers. The blocks and heads are identical. I have the 1965 Dart shop manual and it shows the 4 bbl engines with higher spring installed loads than the 2 bbl engines (as post 53 shows for 1967).

Distributor was a Prestolite dual point, faster curve, and ball bearing vacuum advance like early 340's also.

 

[perfacar]

his heads were tested at 25" . more realistic . superflow 600, factory set at 25".