Ramhorns vs. Headers for MPG gains?

[grancuda]

I got the 350cu 260hp GM crate long block with Edelbrock 600 carb, Edelbrock Performer RPM(non-air gap) and the factory 71 truck ram horn manifolds and I was considering getting some headers and I didn't know how much if any it would help hwy gas mileage. Any ideas?

[Longhorn Man]

in theory, they should help.
I know a member on here who had the same engine as you do, had a 5 speed manual and a 3.07 gear rear in a 71 C/10. When he installed the headers, MPG dropped. He also noticed a MPG drop with the performer intake. There was tuning done on each mod.
He ended up swapping the manifolds and cast iron intake back on for MPG gains.
What this says, is the 260 horse engine is optimized at it's stock tune and dress.
The over drive and tall gears may have been enough to make your aplication have the oposite result.

In the end, there are so many variables, there is no telling.


On my old well worn 300,000 mile old 350 in my first truck, the performer intake and crusty junk headers did improve my MPG, but only by 1 MPG. However, that was a 10% increase.... which is beyond considerable. My combination was an untuned edelbrock 600, a very worn engine, with a TH350 and 4.10 gears.
Compairing the two is apples to oranges.

[sleepertruck72]

If you read the Engine Specification booklet that the crate engine came with it tells you what they recommend as far as exhaust, timing, oil, etc etc. At least mine did. Mine was the 350HO and it recommended headers of 1 3/4" primaries. It might be in there in it might not. I did remember reading that the engine shouldnt be broke in with headers because the heat cycles will burn the coating off or something like that... Anyhow good luck with it
On my engine the MPG's did increase.

[jim zag]

If you want fuel moleage you will want hot exhaust going through the intake under the carb. This helps to vaporize the fuel. Edelbrock makes two 600 carbs one is calibrated for performance and the other one is calibrated for mileage. I would suggest you use an electric choke to help with start up. Take the time to set the choke spring and fast idle speed to YOUR likeing. You may have to adjust again when the weather gets colder.

[Southern C10]

Another noob question. What is a ram horn and whats the difference's from headers? Thanks.

[Tx Firefighter]

For mileage, I have always run an Edelbrock SP-2P manifold. They were sold in the 70s as a mileage manifold. You can find them on Ebay most any time pretty cheap. They have small runners for increased velocity of the fuel/ air charge. Super off idle performance too.

[Yukon Jack]

Originally Posted by Southern C10

Another noob question. What is a ram horn and whats the difference's from headers? Thanks.

A ram horn is shown in this picture.



It flows better than a log style manifold that you might find on a later model sbc. The one in the picture is a repo of the Corvette 2 1/2" dump ram horn. A benefit is good sealing against the block and less fitment issues than headers. Also should outlast most headers.

These flow pretty good but less than a good quality set of headers. For mild SBC's these are a great alternative.

[big mike71]

When I put my headers on my mileage went down because I get on it more.

[Gray Ghost]

Andy is right...it should help but in all reality it didn't for me. I now have ramhorns and have gained power on the lower end and the mileage is the same...11 mpg with a 3.07 rear axle.

I'll never have headers again at this point...they're just too much damn trouble. I haven't tightened a heeader bolt in weeks!!

[capev86]

the stock ram horn manifolds are supposed to have great flow, but its efficient flow, not volume of flow. if you want a top hp motor and want to spend money, get the headers. if you want good low end torque and throttle response (and better mpg) use the ram horns. i plan to swap the stock manifolds onto my 406sbc when i put it in my 72 suburban. will likely blast them and have them coated up. i do plan to run that nice stainless magnaflow dual exhaust w/ x-pipe from lmc truck. thats where most of the restriction is on these trucks. thats true on many vehicles....the restriction is after the manifold. and you don't necessarily need huge pipes (unless it has forced induction) because too much volume lowers exhaust velocity and only gives you better performance when the engine is at full throttle (moving more air).

[grancuda]

Anyone try the corvette 2.5" ramhorns that Dorman makes?

[Huck]

I was the guy Andy referred to with trial and error testing intakes--and headers. Started with crate--and stock with just HEI and Edel 1406. Was getting like 16mpg--went to OD 5spd and that kicked up mpg like 3--to 18-19mpg hwy. Then did headers and 2101 edel intake and lost 3mpg. If you look, the stock intake has small primaries (front) which work like a restrictor plate. I tried headman then hooker headers--totaly waste--was running straight duals which I should have had spliced together down stream for maximum perf butttt- I backed off to stock ram horns and regained 2mpg then back to stock intake and got another 2mpg and could get 20 mpg hwy crusing at 70. My low end torque was back and I didn't really care about high end power as the truck didin't like running over 90 anyway---way too much wind resistance. That's my story and I'm sticking to it. Best investment was the 5speed OD by far!!
I kind of think that headers and custom intakes need matching heads and cam shafts to give you any significant positive results. Huck

[Longhorn Man]

yep... I was talking about your blue truck. Just wasn't gonna throw your name out for ppl to bombard with PMs and crap.
I still don't understand how the h*ll you got those MPG... most ppl get crappy MPG with OD and a 3.07 gear.
Insane
Always one exception to every rule.

[mclairmo]

Headers should help higher rpm horsepower but will create more noise and more heat under the hood. They also may interfere with the steering or shifter linkage. If they are full length headers, they also hang down low, which can cause problems if your truck is extremely lowered. The bolts can also loosen up over time and they can be hard to seal against the head and where they connect to the exhaust system. If you do go with headers, get the ceramic coating to cut down on heat and for longevity and make sure the headers will work with you exact set up, such as column shift, manual transmission, power steering, etc. I prefer good flowing exhaust manifolds after using both. Sanderson also makes good flowing cast iron exhaust manifolds as an option.

[UltraBlue71]

Originally Posted by Gray Ghost

Andy is right...it should help but in all reality it didn't for me. I now have ramhorns and have gained power on the lower end and the mileage is the same...11 mpg with a 3.07 rear axle.

I'll never have headers again at this point...they're just too much damn trouble. I haven't tightened a heeader bolt in weeks!!

Here Here! I never had anything but trouble with headers, but I never have spent much money on a set either, you probbably get what you pay for as with 99.9% of things in life, those old rams horns fit good and will usually seal up tight.