Headers vs 340 manifolds

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junkyardhero said:
while i won't address the stance on headers, can you shed any light on how you came to that conclusion on the 3/4 cam?
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As stated before the 3/4 cam was the flat head era not a 3/4 mile track pretty sure junkie knows that
Headers are a 1/10 to 3/10s all else being equal on the tune with or with out on a 340 1/10 for the pinch on the drivers side
Why did my stock 60 gts 340 727 3.23s 80k miles beat the 70 duster fresh 340 intake carb headers 3.55s bigger tires then me at the drag strip tune and driver.
340s dont pick up 5/10s from headers maybe a stock big block gets 35 hp if the manifolds or the exhaust is 1 7/8 and suck
5/10s across the board total bs
 
junkyardhero said:
while i won't address the stance on headers, can you shed any light on how you came to that conclusion on the 3/4 cam?
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I always assumed the 3/4 cam was basically 3/4 of the specs between the typical stock cam and race cam of the day.
 
Good thing about headers it one of the few mods that adds power everywhere.
As for the power amount I would expect around what the others are saying at least around 15 hp.

If looking for more power obviously cam is gonna give most gain with stock short block don't necessarily got to go bigger (duration) a more aggressive cam (faster ramps) would also gain.
 
I would think a modern era @ 50 spec 3/4 cam would be something like a 245 give or take 10°.
 
3/4 cam is actually a little smaller than a 13/16 cam which was used on the larger 13/16 mile circle track.
 
A 3/4" cam can be effective on a circle track that is as big as 1 mile as long as you stay in the inside lane.
Couldn't resist guys....I think i've been in this hobby too long!
 
ir3333 said:
A 3/4" cam can be effective on a circle track that is as big as 1 mile as long as you stay in the inside lane.
Couldn't resist guys....I think i've been in this hobby too long!
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Yes obviously. The inside lane is shorter, so you need a shorter camshaft. And shorter tires on the inside too.
 
a-bodyguy said:
340s dont pick up 5/10s from headers maybe a stock big block gets 35 hp if the manifolds or the exhaust is 1 7/8 and suck
5/10s across the board total bs
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Read again, not "across the board", said "up to".

When I install headers, I tune it as nec, make other changes learned thru experience.
I have absolutely no idea what conditions their base was set.

But after years and dozens of cars coming back saying they picked uptime, some 2, some 3, some4 and yes 5/10s.

Did I verify all these dozens of cars, of coarse not, but the resulting happy customers speak volumes.

Maybe your cars woulda picked up more time with a different driver?
 
Inertia said:
Read again, not "across the board", said "up to".

When I install headers, I tune it as nec, make other changes learned thru experience.
I have absolutely no idea what conditions their base was set.

But after years and dozens of cars coming back saying they picked uptime, some 2, some 3, some4 and yes 5/10s.

Did I verify all these dozens of cars, of coarse not, but the resulting happy customers speak volumes.

Maybe your cars woulda picked up more time with a different driver?
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Tuning is the key. The Try Y's I put on my 73 340 didn't do much if at all. There were no 60' timers back then. It might have had more low rpm torque but not that I could measure at the track. I didn't change a thing including rejetting the carb or even resetting the timing. That being said, even the smaller 73 manifolds were about the same as the small tube Try Y headers.
 
ir3333 said:
headers on a stock 340 through mufflers aren't going to gain anything noticeable.
3/4 cam was a cam ground specifically for the rpm operating range on 3/4 mile stock car track which would have
no low rpm requirement....or maybe a cam with 12 lobes?
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I'm going to go with the expression '3/4 race cam' coming from teenagers who knew not much about engines. It just means its not a race cam but almost :) Remember back in the day people used to use the term balanced and blueprinted? I had no idea what that meant but it sounded good.
 
This might clear up the 3/4 race history:

""The original 3/4 race cams are the forerunners of today’s street-performance grinds.
The term likely originated in the ‘50s as the burgeoning hot-rod industry was modifying Ford Flatheads to drag race on airport runways and attempt top-speed runs on dry lake beds. The legendary Ed Winfield was one the early pioneers in grinding camshafts with more aggressive lobe profiles, and the cams were often labeled as full race for promotional purposes.



“And then some guys wanted a milder cam that could also be used on the street, so they called it a three-quarter race cam because it didn’t have as much duration and lift,” explains John MacKichan of the Speedway Motors Museum of American Speed in Lincoln, Nebraska.""


www.enginelabs.com

TECH QUICKIE: What is a '3/4 Race' Camshaft?

The term "3/4 race" camshaft was introduced in the '50s and is a forerunner to today's multitude of street-performance grinds. Learn more about them here!
www.enginelabs.com www.enginelabs.com
 
I have a few sixties speed equipment catalogs. There were full race cams, 3/4 race cams, 3/4 full cams. Had nothing to do with 3/4 mile tracks; 3/4 was hotter than stock, milder than full race. The terms date back to the flathead Ford V8 days. Instead of trying to copy a page out of one of my old catalogs, I'll offer something I lifted off another forum, written by Jack Vines, who specialized in building hot Packard V8s and who knows Ed Iskendarian (Isky cams) personally:

From Ed Isky's lips to my ear: "The 3/4-grind came from Ed Winfield. Lots of guys had to be able to drive their race cars to the track and wanted a street/strip cam for the flathead Ford V8. His 3/4-cam was streetable, would idle. A full-race grind wouldn't maintain an acceptable idle on the 255-276" engines. When I got going, our flathead 3/4-cams were usually around 250-260 degrees advertised duration and around .325-365" lift. The full-race grinds were 262-270 degrees and .404" lift.

When OHVs came along, the E4 was a street/strip 3/4 grind of 260 degrees and .425" lift on a cast iron billet core. The E2 was a track 3/4 grind of 256 degrees and .450" lift on a welded-hard-face core. The tungsten carbide, chrome, nickel alloy was developed in germany and introduced to the US by GE. It required chilled iron lifters and was the best we had then for high spring pressures. A full race grind hard-face cam started at 270 degrees/.450" lift and eventually got up to 320 degrees/.510" on the 505-C Magnum. These were a very low-intensity grind, as the springs and pushrods back then wouldn't handle the acceleration rates we see today.
thnx, jack vines


Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
 
The "3/4 cam" didn't come from ignorant teenagers, but from the cam makers themselves. Today, it is a completely outdated term, and meaningless with regard to modern cams.
 
From a 1966 Speed Equipment Company catalog circa 1966. Isky is already getting away from the 3/4, 3/4 full and full race terms, having Road and Drag and Super Road and Drag, plus "Magnum" and "Magnum Super Le Gerra," etc., but still uses the terms "3/4" and "3/4 full." Below is a partial listing for B engine Chrysler cams:

1730320246765.jpeg
 
65 Cuda 340 said:
Had to check to make sure I had not already posted in this thread. Back in the late 70s-early 80s, I had a 73 Duster 340. Stock except for a spread bore Holley, it ran 15.05 at about 93-94. Put on a cheap set of Black Jack headers, no other changes, ran 14.40s at 98 despite now having a serious traction problem with its open rear (3.21 ratio). Just a sure grip would have got me into the 14.20s. I was amazed at how much faster this almost totally stock low compression motor was with headers.

Fast forward to 8-10 years ago. I sold the early model 340 hi-po manifolds I was running on the 360 in my 67 Barracuda, got rid of the muffler shop 2.25 exhaust and replaced it all with TTI step headers and TTI 2.50 inch X-pipe system. Again, a low compression motor, albeit with thin head gaskets and heads milled.030 (but the pistons are .100 down at TDC). Cam is a Mopar Performance 761, which is basically one step above stock. Again, I was amazed at how much more power it had - everywhere. No traction at all anywhere in low gear; had to swap to drag radials (for the street) because it was scary to drive with street tires (I think roads around Tallahassee are slicker than farther north, maybe heat/humidity). No times, because I haven't been to the strip since, but no question it was a huge improvement.

So then I bit the bullet and put TTI headers/2.5" exhaust in my 65 Barracuda. Now that was a job. Cam is the same as in my 67 Barracuda, compression ratio is higher. Again, big improvement.

So, I simply don't believe any test that says headers are only worth 10 hp. Maybe with a .380 lift cam. ??

Just my own experience. Yours may differ.
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Just to update a bit, I took my 67 Barracuda to the strip a couple of months ago. I went from 13.70s at 98 with stock 340 hi-po manifolds, 2.25 exhaust and 3.23 gears to 13.07 at 106.5 with TTI headers, 2.5 inch exhaust and 3.55 gears. Both times through the mufflers. With a pretty dinky cam (.450/.455 lift).

That's a 3/4 second improvement from headers with a virtually stock 340 (Duster) and a very mild 360 (Barracuda). Not sure why anyone would be skeptical of a half second improvement with headers over exhaust manifolds with a stock or near stock motor.
 
65 Cuda 340 said:
Just to update a bit, I took my 67 Barracuda to the strip a couple of months ago. I went from 13.70s at 98 with stock 340 hi-po manifolds, 2.25 exhaust and 3.23 gears to 13.07 at 106.5 with TTI headers, 2.5 inch exhaust and 3.55 gears. Both times through the mufflers. With a pretty dinky cam (.450/.455 lift).

That's a 3/4 second improvement from headers with a virtually stock 340 (Duster) and a very mild 360 (Barracuda). Not sure why anyone would be skeptical of a half second improvement with headers over exhaust manifolds with a stock or near stock motor.
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You changed too many things to just compare the headers vs the manifolds. Everything you changed helped you get the half second.
 
65 Cuda 340 said:
Just to update a bit, I took my 67 Barracuda to the strip a couple of months ago. I went from 13.70s at 98 with stock 340 hi-po manifolds, 2.25 exhaust and 3.23 gears to 13.07 at 106.5 with TTI headers, 2.5 inch exhaust and 3.55 gears. Both times through the mufflers. With a pretty dinky cam (.450/.455 lift).

That's a 3/4 second improvement from headers with a virtually stock 340 (Duster) and a very mild 360 (Barracuda). Not sure why anyone would be skeptical of a half second improvement with headers over exhaust manifolds with a stock or near stock motor.
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probably because that equates to a 30 hp increase. Are there any tests showing these kinds of gains? I didn't read through the whole thread again.
 
Inertia said:
Absolutely 100% wrong
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I think that this is 100% BS

I would bet that your customers are reacting to sound and such (I'm glad they are happy!).

With the exhaust system hooked up, I don't think the difference would be noticeable in terms of acceleration. I think 15hp would be optimistic and on a stock 340 with around 300hp it's a max 5% boost. Take the exhaust down and you would either have to re-tune to take advantage (and then what happens when the exhaust is put back up?), or the engine was poorly tuned to start with and the open headers were reacting to a chance improvement in tuning.

Then if the car is mainly a street car you have to live with all the issues of a crowded engine compartment, smashed pipes from speed bumps, etc. After years of 5 different brands of header, I scrapped headers on my street cars and went back to well chosen manifolds and a well designed exhaust system. I never looked back...
 
junkyardhero said:
what's the % torque difference per ci under the curve with each 2* coming and going? is there a dyno chart for that? or possibly a formula?
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From the few LSA shootouts available, I noticed about an average of about 3-4 lbs-ft per degree of LSA, and wider than about 110 seemed to be an bigger average than narrower than 110. And given hp is less than a 100% under 5252 rpm were talking a couple of hp per degree for these engines.

Not saying 3-4 lbs-ft can be considered a rule of thumb for all builds.
 
ir3333 said:
headers on a stock 340 through mufflers aren't going to gain anything noticeable.
3/4 cam was a cam ground specifically for the rpm operating range on 3/4 mile stock car track which would have
no low rpm requirement....or maybe a cam with 12 lobes?
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I’m not insulting you when I say;

This is the biggest bag of bullshit you have ever read in years.
If anything, it shows that you are absolutely clueless and have zero idea of what you speak of.
 
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