I'll try this forum..273 monster build up.

[cudaspaz]

ok. I've got a 67 barracuda and am thinking about building the 273 motor as radical as possible yet streetable. I don't want a crate motor cause I heard lotsa bad about them.
Is it worth building a 273?
If so what goodies should I pack into it with a 3500.oo budget?.

[bwlizard]

It is hard to build something " As radical as possible " and yet be streetable. With your budget I would find a rebuildable 360 and go to town ! Just my opinion.

[1972roadrunner]

umm, i don't think this will stay within the budget but i would....
*bore it
*hone it
*good pistons
good rods
*steel crank
*good-size cam (i would perfer solid, or anti-pump hyd. lifters)
1.6 rockers (i would perfer adjustable roller rockers)
longer valves and springs
stainless steel valves
*good heads
generous porting
3-angle valve job
*good intake (i would suggest single plane)
*4bbl carb
*good rings
*good bearings
*high volume/psi oil pump
*double roller timing chain
balance and blue-print everything....

the things with the "*" by it MIGHT be within the budget, but i'm not familiar with the prices of parts for that size motor...

[pishta]

He has aready got a steel crank. As for the pistons and boring it, I would try and build a D-Dart code motor. 275 horse and fairly streetable. Look up D-Dart on a search and use those components. Itll be very hard to get the 273 pop ups though, as they have been out of "print" for many years. If you want to go the modern route, ask 66273 for the "book" on his drag motor. He is smokin the big boys with his mill. Remember, a hot cam for a 340/360 will be huge for a 273,conversly a hot cam for a 273 (D-code) may look mild for a 340/360. just match your components and get a tall rear as the little mill will need to rev to produce the power. May want to lose the factory seats as they weigh a ton and put your car on a diet, every 100 lbs is like getting XX more horsepower.

[rumblefish360]

Pista has good thoughts on theat D-Dart. That was MoPars first 1hp per cube engine I think.
No matter. 275 HP from a 273 makes that a hot little engine.
It should be in a "light as posible" car. The engine lacks torque to move a heavy ride.

The D-Dart cam with a 284 duration cam, mech. rockers and factory tubular exhaust. (Headers)

Todays cams are bigger than yesteryears cams. You'll need a lot less cam to do the same. A small mech. cam will do the trick.MoPar has a 276 duration mech. cam that'll out perform the old one used in the D-Dart build up.
If you use the 1.88 intake valve, you'll need to notch the block. Info on this can be found in the MoPar engines book.
BECAREFULL HERE!

[pishta]

I think the 1.88 intake is close on the 273, the 2.02 is the notcher. A set of '302' heads would work well on that mill. I have a few build ups on a AF/X contender in a mag somewhere. He ran 4 webers though so you are not going to duplicate that particular one!

[rumblefish360]

To all interested in valve clearance's in the small block.
(Just so you know)

In the MoPar "small block "A" engines" book, on page 51 under, "Updating standrd engines to high performance"

340-360 heads with the smaller intake valves (1.88) are the best choice. However, since the 273 bore is smaller than the 340-360, the valves will overlap the 273's bore.
(Remember, it's the 1.88 valve we are talking about here.)
To fix this, the block will have to be notched. This notch should be adequate to provide .060 valve to block clearance. It's approximate dimensions are 1 1/4 long, 1/4 deep (down the cylinder) , .070 maximumradially outward from the centerline of the cylinder, This notch should be flared into the cylinder wall smoothly; however, care must be taken to see that the notch does not extend into the ring travel area.

From page 83.

"Notching the cylinder bore for valve clearance"

Except the 273 bore, valve clearance notchs are not required for the "A" engine. However to increase flow in 273 engines, a small notch by the intake valve helps. The recomended shape of the combustion chamber at the block surface is shown in fIGURE 2-12, make sure the notch does not go down into the area of piston ring travel.

All this from MOM MoPar.

It does not make mention of the 2.02 valve. But, I did some math.
3.63 - 2.02 - 1.60 = .01 and
3.63 - 2.02 - 1.50 = .11 and
3.63 - 1.88 - 1.50 = .25

Not alot of room in there huh. Remember, you need some room inbetween the valves as well as the cylinder walls.
Thank God it's a wedge and not a brand "X". Otherwise there would be less room.

[pishta]

OK ill go with that. Figures dont lie.

[Doug Wilson]

Ma MOPAR always speaks the truth - as she sees it. Small bore engines are inherently better suited to high compression ratios. I'd start with the Ed. heads and adjust the build to a 13:1 comp. ratio. The "D" Darts had 13.5 and the hot street 273s had 12.5. The aluminum heads will make 13:1 work, and your breathing will be real good.

Also, a solid lifter cam of medium specs will perform well - as has previously been stated - for a build like this. You should talk to several cam manufacturers to see who seems to know what they're talking about when dealing with small displacement V-8s.

You should be building your engine for a redline of 8500+.

I don't know if that can be done on your budget - on the mild 340 we built for HELLFISH, the machine work was $3,000 - that doesn't count parts.

For $3500 you can build a stout 360 that will outperform any $3500 273.

[leon441]

I am not that familiar with the 273 and they were the first engines I ever attempted to rebuild. I have a set of zero deck pistons that are flat top made custon from Ross. I bored the block .030" and turned the crank .010". So far I have only spent $660 and that includes the rings and wrist pins. The head work is were I have stopped. This is why those who advise me on what valve will fit with different over bore figures don't seem to understand that the centerline of the valves and the centerline of the piston are not the same. Offset dowels could change the clearance some and the amount of overbore also. But this is probably not going to make that much difference. The valve head diameter is not important if you don't cut the throat behind it. I think I am going to turn down a 1.88 until I have something that will work. But I will for sure stretch that throat and the bowls to get all I can get. The exhaust will not be very important sense typically mopars flow well on the exhaust side. Besides my W8 Prostock truck heads only have 1.55 exhaust valves. I did however find an Offy intake for the little beast. This thing will be in the works for a long time. It is playing second fiddle to the Super Street Barracuda I race.

[pishta]

Leon, I get what you are talking about when you say the CL of the valves is not the same as the CL of the piston. if you were to take a line straight across the centers of the valves, it would not be the diameter of the bore, it would be slightly less because the valves sit a little offcenter of the bore. As for offset dowels, Hamburger makes them , but I never heard of using them to move the valves to a bigger part of the cylinder. I guess I never thought of them doing that ! I thought Mopar heads were below average on the exhaust side?

[Doug Wilson]

Me, too.

[leon441]

I have only one set of production heads ported and had no trouble getting 65% out of the exhaust compared to the intake. Now the W2 and Arrington, I had no trouble getting 70%. I now run a W8 prostock truck head with nitrous and it only has a 1.55 Valve as compared to it's 2.25 Intake and I have changed cams three times trying to get the exaust out of the combustion chamber. I have no idea on 273 heads and probably will only know hear say because I will not be spending that kind of time or money on them. But I like the food for thought on the little 273. It is relaxing to think about after dealing with the gremlins on a 457" Small block that is hit off the line with 350hp fogger and then with another 100 on a plate .3 seconds out and still doesn't go fast enough.