273 Head Swap...Help

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pastortom1

pastortom1

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OK..............here's da' scoop............

I have a nice 1967 273 numbers matching in a survivor Barracuda. I absolutely HATE and ABHOR the stinking rockers........I am SICK and TIRED of the blessed little boogers, and I want them GONE, GONE, GONE.

At the same time, my valve seals are old and tired too.......the "morning puffs", don't ya' know..........

I'm wondering if I can swap out the whole head for a suitable 318 set-up perhaps...........BUT then, I'd be up against a cam swap too, would I not? (to match the non-adjustable rockers, I mean........I'd have to install a hydraulic cam and a new set of lifters to use with the heads, right?)

......and would the exhaust manifolds mate up properly, or would I need to buy the manifolds along with the replacement heads?

I want to keep the 273 in the car, solve the adjustable rocker problem, and keep it looking stock. This is my dilemma.

WHAT TO DO?? I really need to decide NOW, and round up my parts.....I'm going to NY shortly to work on this car and drive it back to Florida. Any help or suggestions will be appreciated......I'll be looking for parts too if the swap is the best way to go......need shipping to NY 13339. I'm looking for the EASIEST way out of those stinking rockers.

What say ye ?:read2::read2::read2::read2::read2:
 
Huh, I wish I could help. Why dont you like the rocker set up???? Because they are adjustable??? I always thought everyone liked those. I even have saved a set of them for many years thinking they were good ones to have around.
 
Well Pastortom1, here's what I did on my wifes 66. I retained the original 66 heads and changed to the 340 magnum camshaft with hydraulic lifters. I then got a complete rocker assembly from a 318 engine I had sitting around and just swapped them to my 273 commando heads. Viola, hydraulic lifters and non-adjustable rockers. I think I also bought the 340 valve springs for the extra strength. Of course you could buy all of the items needed from Mancini or just about anywhere, but if you can find somebody with a 318 engine nearby, the rocker assemblies are very seldom ever worn out, and if you can't get the whole set up for free, it should be next to nothing!!! You could also just swap some 318 heads on there too, and your exhaust manifolds will bolt right up, just another option. If you lived closer to me, you would be coming over and picking up this extra 318 I have and taking it home. Swing on by on your way to NY, I'm only about 6 hours away!!!LOL!!! Good luck with your project, and if you need some valvetrain stuff, P.M. me and I'll round you up some!! Geof
 
'302' casting heads Tom. Small valves, (1.78, same as the 273) closed chambers, swirl-port design, hardened valve seats. Any 318 car/truck/van from the mid '80s has 'em. I bought a pair of theses heads complete with valvetrain gear (non-adjustable rockers and shafts included) for $40 just last year. Not sure about accessories though, might want to check those locations.

Just as an aside, NHRA says these castings are legal replacements for 273 engines in Stock Eliminator so someone out there deems these a worthwhile upgrade.
 
I'll back 'rmchgr'- the 302 castings are the best flowing production heads for a 273/318. Did a set w/ an Edelbrock cam kit (close to stock 340 spec's), an M1 dual plane intake, and a 600 CFM Edelbrock carb with a friend for a runner 318 in his '68 270 Dart. Only the cam kit and the carb were new, the heads were just freshened up, and that little sedan is a great street performer. Better mileage than before, too!
 
OK.......... Let's say I get a set of the 302 casting heads complete.....I still have to change out the cam and lifters to support the new rockers.

What do you guys recommend for a stock 273 2BBL set-up ?
 
Is that Comp 268 a little snottier than the original? I've used Comp before and had no complaints.

It's surprising just how much stomp that little 273 has.......a little tweak wouldn't hurt, as long as I can keep my 2BBL.
 
pastortom1 said:
Is that Comp 268 a little snottier than the original? I've used Comp before and had no complaints.

It's surprising just how much stomp that little 273 has.......a little tweak wouldn't hurt, as long as I can keep my 2BBL.
Click to expand...

I think so, it would provide more lift at the valve for sure. Not sure on the duration spec, but what's the orig. cam lift for a 273 2bbl, like .410" or something? Probably like a 220º duration maybe? Even if you went a step down with the 262 you'd probably be better off than the original.

The first cam listed in the Comp catalog is for a 318 2bbl replacement, #252H; dual 252 duration, 206 in. @.050", 206 ex. @ .050", .425" lift, 110º LSA. There's your basic cam. The 268 is 268/280, 224/230, .477/.480, 110º.
 
pastortom1 said:
OK..............here's da' scoop............

I have a nice 1967 273 numbers matching in a survivor Barracuda. I absolutely HATE and ABHOR the stinking rockers........I am SICK and TIRED of the blessed little boogers, and I want them GONE, GONE, GONE.

At the same time, my valve seals are old and tired too.......the "morning puffs", don't ya' know..........

I'm wondering if I can swap out the whole head for a suitable 318 set-up perhaps...........BUT then, I'd be up against a cam swap too, would I not? (to match the non-adjustable rockers, I mean........I'd have to install a hydraulic cam and a new set of lifters to use with the heads, right?)

......and would the exhaust manifolds mate up properly, or would I need to buy the manifolds along with the replacement heads?

I want to keep the 273 in the car, solve the adjustable rocker problem, and keep it looking stock. This is my dilemma.

WHAT TO DO?? I really need to decide NOW, and round up my parts.....I'm going to NY shortly to work on this car and drive it back to Florida. Any help or suggestions will be appreciated......I'll be looking for parts too if the swap is the best way to go......need shipping to NY 13339. I'm looking for the EASIEST way out of those stinking rockers.

What say ye ?:read2::read2::read2::read2::read2:
Click to expand...

Tom...you dont have to change the heads to get non-adjustable rocker gear in there...just use the all hydraulic rocker gear (pushrods,shafts,rockers and hold-downs) on your current 273 heads. Yes, you'll have to change to a hydraulic cam and lifters.

What's the problem with the adjustable rockers???...screws backing off??? You can get an aftermarket set of adjustment screws with locknuts that solve that problem.
 
pastortom1 said:
OK.......... Let's say I get a set of the 302 casting heads complete.....I still have to change out the cam and lifters to support the new rockers.

What do you guys recommend for a stock 273 2BBL set-up ?
Click to expand...

Yep. Suggest that when you pull the cam and lifters, be sure to label where they came from. e.g. #1 Intake. That way if you want to put it back, you'll avoid potential lifter problems.

You may also need different pushrods for the hydraulic lifter. The ones from the 302 donor engine won't work. They're short so they can work with a roller cam.

If you are making no other changes to the car, IMO it would be counterproductive to get too much wilder than the stock cam. My reasoning is that the wilder the cam, the more compression and rear gear it's going to want.
 
72 Demon said:
Yep. Suggest that when you pull the cam and lifters, be sure to label where they came from. e.g. #1 Intake. That way if you want to put it back, you'll avoid potential lifter problems.

You may also need different pushrods for the hydraulic lifter. The ones from the 302 donor engine won't work. They're short so they can work with a roller cam.

If you are making no other changes to the car, IMO it would be counterproductive to get too much wilder than the stock cam. My reasoning is that the wilder the cam, the more compression and rear gear it's going to want.
Click to expand...

2 things...#1...if you change to a hydraulic cam, you dont have to worry about numbering the solid pushrods and lifters as they wont be going back in.

...and #2...going to a wilder cam KILLS compression, not increases it. Thats why putting a .509 Purple cam in a stock motor turns a relatively spunky engine into a complete dog.

If you want a juice cam recommend...I'd go with a stock '68 340 4-speed grind, or similar...really nice in a 273.
 
65Val said:
2 things...#1...if you change to a hydraulic cam, you dont have to worry about numbering the solid pushrods and lifters as they wont be going back in.

...and #2...going to a wilder cam KILLS compression, not increases it. Thats why putting a .509 Purple cam in a stock motor turns a relatively spunky engine into a complete dog.

If you want a juice cam recommend...I'd go with a stock '68 340 4-speed grind, or similar...really nice in a 273.
Click to expand...

I second the 340 cam selection!!! Geof
 
65Val said:
If you want a juice cam recommend...I'd go with a stock '68 340 4-speed grind, or similar...really nice in a 273.
Click to expand...

I'd just like to point out that the 'stock '68 340 automatic cam' is almost IDENTICAL to the Comp 268. Yes, the manual version was slightly hotter. '68 340 cam specs are 268/276 with .430/.444 lift. The Comp 268 provides a little more lift at the valve (.047 in. and .04" ex.) and 4 more degrees of exhaust opening. Probably not enough to make a noticeable difference.

The '68 340 manual trans. cam specs are 276/284 and .444/.453 lift.
 
6T9 V-100 said:
I'll back 'rmchgr'- the 302 castings are the best flowing production heads for a 273/318. Did a set w/ an Edelbrock cam kit (close to stock 340 spec's), an M1 dual plane intake, and a 600 CFM Edelbrock carb with a friend for a runner 318 in his '68 270 Dart. Only the cam kit and the carb were new, the heads were just freshened up, and that little sedan is a great street performer. Better mileage than before, too!
Click to expand...

So lets see some flow numbers to back that claim up.
 
Just to give an idea of stock 302-casting flow #'s, here's some info taken from Shady Dell Speed Shop's '302' page:

FLOW #’s

LIFT-------AS CAST------PORTED​
.100”-----51.8/N/A--------71.8/N/A
.200”-----92.5/70.7--------148.4/86.3
.300”-----130.1/104.3-----212.2/113.9
.400”-----163.9/113.2-----241.5/131.1
.450”-----169.1/115.2-----244.6/137.7
.500”-----170.4/117.3-----246.7/139.7
.550”-----172.2/119.0-----242.6/144.9
.600”-----172.5/120.4-----240.8/144.9

All #’s at 28” of water
No flow tube on exhaust
As cast #’s are 1.78”/1.50” valves,
Ported is with 2.02”/1.60” Ferrea 5000 Series, No Back Cut.
Ported Intake Runner Volume is 151 CC’s
 
rmchrgr said:
Just to give an idea of stock 302-casting flow #'s, here's some info taken from Shady Dell Speed Shop's '302' page:

FLOW #’s

LIFT-------AS CAST------PORTED​
.100”-----51.8/N/A--------71.8/N/A
.200”-----92.5/70.7--------148.4/86.3
.300”-----130.1/104.3-----212.2/113.9
.400”-----163.9/113.2-----241.5/131.1
.450”-----169.1/115.2-----244.6/137.7
.500”-----170.4/117.3-----246.7/139.7
.550”-----172.2/119.0-----242.6/144.9
.600”-----172.5/120.4-----240.8/144.9

All #’s at 28” of water
No flow tube on exhaust
As cast #’s are 1.78”/1.50” valves,
Ported is with 2.02”/1.60” Ferrea 5000 Series, No Back Cut.
Ported Intake Runner Volume is 151 CC’s
Click to expand...


I was talking about the flow numbers on the heads on the motor you were referring to, not some test of some heads at 28" Of course you are going to get better numbers at 28" but that's not a realistic, real world application./
 
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