chryslerfat
Well-Known Member
This thread started before most members did.
273 commando heads vs. standard
- Thread starter smokn440
- Start date
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pishta
I know I'm right....
2 bucks says it a transposed misprint. 1.78-1.87...? Find a part number for a 1.87 intake in 1967 or a D/Dart spec sheet that calls out the larger D/Dart valve, that is kinda major for a stock class. Misprints happen, especially in Mopar lore.
ddartdude
Well-Known Member
Since Chrysler built 50 cars to compete in D/Stock, all engines would have to be the same. Since the car's were being built and sold around the country, even California, the engines would all have to be w/C.A.P. The C.A.P. engines could have had larger 1.87 valves to meet California emission standards if they had them back then. Standard replacement valves went up to +0.030 or 1.081.
pishta
I know I'm right....
Yes, they all had to be the same and no, the C.A.P did not have larger valves. The D/Dart build up pamphlet did say you could use larger valves but when you got 'em, they were 1.78.
http://www.seriousviewers.com/d-dart/Technical Service Bulletin.pdf
http://www.seriousviewers.com/d-dart/Technical Service Bulletin.pdf
Thanks for clearing that up.
One is a 1966 model year head ( 2536178 ) and the other ( 2658920 ) is a 1967 model year head; they both cc out the same, 57 to 64.5, valve size is the same at 1.75 intake, 1.5 exhaust, there is no real difference. Reference "How to Hot Rod Small Block Mopar Engines" by Larry Shepard
ddartdude
Well-Known Member
1.1.78 or 1.87. Whatever! Enjoyed going back and forth with you on this pishta. I use to get into it with Paul Ceasrine on D/Dart stuff.
Just think, I have the original docs that appear in your last post. Got them with the latest D/Dart. I misread the o/s valve size in the 1966 parts book. It was +0.030 dia stem.
Got a call into Galen to see if he transposed the 1.78 and 1.87 in his casting book. I'll update you when I find out.
Just think, I have the original docs that appear in your last post. Got them with the latest D/Dart. I misread the o/s valve size in the 1966 parts book. It was +0.030 dia stem.
Got a call into Galen to see if he transposed the 1.78 and 1.87 in his casting book. I'll update you when I find out.
pishta
I know I'm right....
Its all good, we could have been talking this stuff over a beer and a game of pool! Check out top of page 12..the exhaust valve size in your old material, then well start up a new conversation...1.563"?
moper
Well-Known Member
I was going to say I'm by no means and expert on 273s but I know of no "big valve" versions.
Cuda Al
Well-Known Member
Bottom line in a given year both the Commando and the standard 273 used the same heads.
Alan
Alan
Agreed!
What version of book do you have? May be it has been corrected in the newer books.
The only difference is valve springs.
Cuda Al
Well-Known Member
ddartdude
Well-Known Member
TMM -- I have the 6th printing of the part &casting number book dated Jan, 1996.
pishta -- 1.563 is a winner. I could buy my old/first D/Dart engine back for 5k and measure the valves but I'm going to pass on that. I'm curious about the so-called free flowing intake. Pretty sure the 4 throttle bore holes were left as machined for the CAP engine because of the casting number and NHRA. The Carb Flange (2863052) had the larger 1 11/16 holes in it for the Holley carb.
Cuda Al -- the D/Dart valve spring number is 2843922 and they cost $1.66 each.
pishta -- 1.563 is a winner. I could buy my old/first D/Dart engine back for 5k and measure the valves but I'm going to pass on that. I'm curious about the so-called free flowing intake. Pretty sure the 4 throttle bore holes were left as machined for the CAP engine because of the casting number and NHRA. The Carb Flange (2863052) had the larger 1 11/16 holes in it for the Holley carb.
Cuda Al -- the D/Dart valve spring number is 2843922 and they cost $1.66 each.
Cuda Al
Well-Known Member
I thought I remember reading they used some slightly larger 392 Hemi valves.
I have a 1991 book. Those numbers aren't in there but my 2013 book has them in. It lists the #920 head with CAP and the #951 head for the D Dart as having a 1.87 intake valve. It is interesting though that in 67 the #920 head has the 1.78 valve. I have a pair of #920 heads I will look at later to see if I can figure out what I have. The casting number and production date should tell.
Like finding a needle in a haystack but I will look for this info as well.
Thanks for the discussion. Interesting stuff.
My #920's are 1.78 dia. intakes.
From the Blueprint specs in the Chrysler Racing Manual, Valve Springs
Load Closed Height Closed Load Open Height Open
273-2 bbl 74 1.62 150 1.31
273-4 bbl 103 1.62 184 1.31
Cuda Al
Well-Known Member
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
I really don't care to prove anything to anybody. I've had 4 or 5 of these engines and cars since 1970. The springs on 4 barrel 273's are painted a different color and have different loads. Not everything is in the parts books either. I personally always run 340 red springs on all my small blocks.
Because we are talking about 273 heads, I snapped some photos of one of the 920's I have. I have never noticed the bosses cast into the head below and onside the exhaust ports. Also it looks like the Julian date code is Feb 7 1970. Strange!
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.
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.
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