273 commando Build

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I was disassembling the piston rings today .. I had 3 pistons that had frozen rings on them. took 3 hours to clean all the ring lands .
My cam arrived today !
 
what will be the torque spec on the cylinder head bolts for the commando engine ? would it be any different being mine will have 10.5:1 compression vs. a low compression 273? I see a chart here showing 340 with higher torque specs.
Small Block Chrysler 273, 318, 340, 360 “A” Engine

Fastener Type Torque Spec
Main cap bolts 5 ft.-lbs
Connecting rod bolts (plain) 45 ft.-lbs.
Cylinder head bolts 273-318 85 ft.-lbs.*
Cylinder head bolts 340-360 95 ft.-lbs.*
Rocker shaft bracket bolts 17 ft.-lbs.
Intake manifold bolts 35 ft.-lbs.
Oil pump cover bolt 95 in.-lbs.
Oil pump attaching bolt 35 ft.-lbs.
Oil pan bolts 15 ft.-lbs.
Cam locking bolt 35 ft.-lbs.
Cam thrust plate bolts 210 in.-lbs.
Harmonic damper bolt 135 ft.-lbs.
Flywheel/flexplate bolts 55 ft.-lbs.
Flywheel housing to engine block bolts 50 ft.-lbs.
Flexplate to torque converter bolts 270 in.-lbs.
Clutch housing bolts 30 ft.-lbs.
Front cover bolts 30 ft.-lbs.
Water pump bolts 30 ft.-lbs.
* Follow factory torque sequence
 
stroker402 said:
what will be the torque spec on the cylinder head bolts for the commando engine ? would it be any different being mine will have 10.5:1 compression vs. a low compression 273? I see a chart here showing 340 with higher torque specs.
Small Block Chrysler 273, 318, 340, 360 “A” Engine

Fastener Type Torque Spec
Main cap bolts 5 ft.-lbs
Connecting rod bolts (plain) 45 ft.-lbs.
Cylinder head bolts 273-318 85 ft.-lbs.*
Cylinder head bolts 340-360 95 ft.-lbs.*
Rocker shaft bracket bolts 17 ft.-lbs.
Intake manifold bolts 35 ft.-lbs.
Oil pump cover bolt 95 in.-lbs.
Oil pump attaching bolt 35 ft.-lbs.
Oil pan bolts 15 ft.-lbs.
Cam locking bolt 35 ft.-lbs.
Cam thrust plate bolts 210 in.-lbs.
Harmonic damper bolt 135 ft.-lbs.
Flywheel/flexplate bolts 55 ft.-lbs.
Flywheel housing to engine block bolts 50 ft.-lbs.
Flexplate to torque converter bolts 270 in.-lbs.
Clutch housing bolts 30 ft.-lbs.
Front cover bolts 30 ft.-lbs.
Water pump bolts 30 ft.-lbs.
* Follow factory torque sequence
Click to expand...
head bolts 85 lbs. If you use AAR, you can go 15% more.
 
stroker402 said:
with a 340 being 10.5:1 also , why not go 95ft/lbs on the commando ? why is there a difference ?
Click to expand...
273/318's factory torque spec is 85 lbs. 340/360 is 95 lbs. I don't think the head bolts have anything to do with it, nor compression as 360's have next to no compression.
I'm sure you can torque yours to 95 lbs. But if your heads/block are flush, 85 lbs is sufficient.
 
working on installing the new piston rings today , cleaned all the grooves real well and had one piston that the bottom ring would not spin freely in it's groove . tried others fine rings, and same thing ? what is going on with that ? all others pistons were fine . it's like the grove is just isn't wide enough. anyone ever have that happen to you ? going to get the jewelers file out .
 
pishta said:
now if the member here that has 2 D-Darts can put to rest this 1.87 valve issue, Ill sleep better tonight. Curiously, the 1.87 figure is the valve center to center of all LA heads.....and its also a dyslexic 1.78. I wonder if something got screwed up in translation?
Click to expand...

Must be talking about me. I took the heads off of the first D/Dart that I owned and didn't measure the valves. I'm pretty sure that they were 1.78's and 1.50's. The block is not chamfer for valve clearance. This is what the piston in the D/Dart engine looks like. It had 128,000 miles on the car when I got it. About 75,000 of those miles were in California with the 4.86 gears in it. The engine also has the barbell style lifters in it.

D-Dart Piston076.jpg
 
ddartdude said:
Must be talking about me. I took the heads off of the first D/Dart that I owned and didn't measure the valves. I'm pretty sure that they were 1.78's and 1.50's. The block is not chamfer for valve clearance. This is what the piston in the D/Dart engine looks like. It had 128,000 miles on the car when I got it. About 75,000 of those miles were in California with the 4.86 gears in it. The engine also has the barbell style lifters in it.

View attachment 1715164327
Click to expand...
appears it has the large bore gaskets installed or the imprint of them .
 
ok............ Things are going together smoothly .
crank is in , pistons are in . moving right along .
Now we are hit with nasty weather for the next 4 days . things are at a stand still now. Burrrrrrrrrrrrrrr.
 
toolmanmike said:
The Galen parts book lists the
#315 head as a 64-65 head with 1.78/ 1.50 valves and a closed chamber #080 head as a 64-65 head with 1.78/ 1.50 valves and a closed chamber
#178 head as a 1966 head with 1.78/ 1.50 valves and a closed chamber (early)
#234 head as a 1966 head with 1.78/ 1.50 valves and a closed chamber (late)
#920 head as a 1966 head with 1.87/ 1.50 valves and a closed chamber (273-4 with CAP)
#951 head as a 1966 head with 1.87/ 1.50 valves and a closed chamber (D Dart)
#920 head as a 66-67 273 and 67 318 with 1.78/ 1.50 valves and a closed chamber
In 1968 the 273/318 heads went to a open chamber with the same 1.78/ 1.50 valves

I have a set of #920's but without matching the part number I don't know what they came off of. I doubt if they are the 1.87 intake valve heads.
Click to expand...

I know the D/Darts used the 920 castings. These are the ones from my first car. I did take pictures of the casting numbers before I sold it. But, I didn't measure the valves. I'll try to pull the valve cover off the race car tomorrow and see what heads are on it. These are dated 03076.

P1010791.JPG


P1010792.JPG
 
oem small bore 3.63" bore .021 head gaskets will be here tomorrow . Should be a "TRUE" 10.5:1 compression 273 commando engine .
 
stroker402 said:
oem small bore 3.63" bore .021 head gaskets will be here tomorrow . Should be a "TRUE" 10.5:1 compression 273 commando engine .
Click to expand...
You should have the shop measure it. You may be surprised what you find.
 
tmm.
I received the 273 commando head gaskets today #2463 338 , far and behold they are not what people say they aim to be. p/n 2463 338" Is NOT a steel head gasket , it's composite . the bore is not 3.63 it is 4.0 and the thickness is not .021 it's .041. I think there never was a steel head gasket produced for the 273 . first of all >>>>>>>>>>>> #2463 338 is a composite gasket not steel Here is a quote >
General Information
Near impossible to find a set of Original {.020"} Thin-Steel Head Gaskets {#2463 338} for the 273 4-Barrel.
they used on the 2bbl as well. That's what they used back then.
I DON'T THINK SO !
 
So, if these are the head gaskets they were on the 65 273 from factory the compression ratio should still be quite high.
here is another question >>
which would be better to use to acheve max compression on the commando ? The above oem gasket or the mr gasket 1121G bore 4.141 and .028 thick ?
sacrifice bore size or thickness or would they be pretty much equal ??
 
barracudadave67 said:
View attachment 1715161039 View attachment 1715161040
Heres pics of how the gaskets fit. You can see they are not round, as the cylinders. Their is roughly a 1/8th in gap all the way around, except for the extreme top of cylinder, and the gap is wider at the center of the cylinder. I measured them with a vernier, and as close as I could get. Vetically they measure 3.963 in, and horizontally they are 3.763 in, that is at the wide point.
One pic is with out gasket, the other is with gasket.
Dave
Click to expand...

Would you have pictures of the gaskets against the head so we can see how they line up with the combustion chambers????
 
stroker402 said:
tmm.
I received the 273 commando head gaskets today #2463 338 , far and behold they are not what people say they aim to be. p/n 2463 338" Is NOT a steel head gasket , it's composite . the bore is not 3.63 it is 4.0 and the thickness is not .021 it's .041. I think there never was a steel head gasket produced for the 273 . first of all >>>>>>>>>>>> #2463 338 is a composite gasket not steel Here is a quote >
General Information
Near impossible to find a set of Original {.020"} Thin-Steel Head Gaskets {#2463 338} for the 273 4-Barrel.
they used on the 2bbl as well. That's what they used back then.
I DON'T THINK SO !
Click to expand...

stroker402 said:
So, if these are the head gaskets they were on the 65 273 from factory the compression ratio should still be quite high.
here is another question >>
which would be better to use to acheve max compression on the commando ? The above oem gasket or the mr gasket 1121G bore 4.141 and .028 thick ?
sacrifice bore size or thickness or would they be pretty much equal ??
Click to expand...

They could have revised the specs/drawings over the years....
 
4spdragtop said:
Looks like the old school logo too.
I have a couple of new sb head gaskets I may be posting for sale shortly if interested.
Click to expand...
I seen some sb mopar new gaskets on ebay with about the same measurements as the ones I just purchased. I have 2 pairs of head gaskets now . just have to see which ones I will use ...... the oem or mr gasket 1121g 's. bore size vs thickness is the question.
 
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