454 engine improvements for better mileage

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garym
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454 engine improvements for better mileage

Post by garym » Tue Apr 17, 2018 8:46 am

I am planning on a cam change and intake/carb change on my 84 C30 crew cab truck.I haual a 38 ft GN trailer and the gas mileage is not good.I was planning on the Edelbrock cam #2162 cam .500 lift on int&ex 218 deg int&228ex @.050 114 deg lobe sep.
Comp has two cams 260H .475 lift on int&ex 212 dur@.050 on int&ex lobe sep 110 deg
Comp 268H .485 lift on int&ex 218 dur@.050 lobe sep 110 deg.
The comp cams above are towing cams, but the 268H cam "IS GREAT FOR HEAVY TOWING IN 454" So what would be the best cam for my truck? The rear gear is 4.10 and I do not know if changing to a 3.73 rear gear would be better o r not.As far as carbs go I was going to maybe go with the Edelbrock # 1411 750 carb with the electric choke on the Edelbrock Per former 2-0 #2161 intake. Planning on removing the smog/air pump and cast iron exhaust as well. I also would like any other advice/input on the above cams, as I know the mileage is not going to be great but I want to improve what I have a little bit.Fuel injection is something I do not want or considering. THANKS garym

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Re: 454 engine improvements for better mileage

Post by travis » Tue Apr 17, 2018 9:11 am

If your towing heavy loads, taller gears will make it worse. I’ve done a couple of trucks with similar mods...a ‘77 C30 dually, 454/TH400/4.10’s and a ‘78 C30 454/TH400/3.73’s. Mods were rejetted stock q-jet, performer intake, recurved HEI, 2 1/2” duals with free flowing mufflers and stock iron manifolds and no cats, and a generic 214/224@.050 hft cam on a 112 lsa (probably not optimal but cheap and available at the time). Both were a lot stronger from idle up, and seen 2-3 mpg increases. Synthetic oils and fluids help too, as well as some sort of cold air induction. High inflation pressure highway tires and driving a bit slower also helps a lot.

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Re: 454 engine improvements for better mileage

Post by Truckedup » Tue Apr 17, 2018 11:45 am

Do you know what intake vacuum the engine has when cruising with a load? For a carburetor gas engine to get decent fuel mileage at normal road speeds you need higher vacuum and lower RPM's...A higher rear axle gear often puts more load on the engine and lowers the vacuum and it may go into the power circuit more often.High vacuum also helps to vaporize fuel..You probably have only three forward gears? In my opinion , you'll get better results from a transmission set up giving 5 or 6 useful gears...Some sort of secondary transmission, or a main trans with more speeds... This works well if you drive in hilly areas...
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Re: 454 engine improvements for better mileage

Post by FC-Pilot » Tue Apr 17, 2018 1:08 pm

My old 454 crew cab Dually picked up 1.5 MPG when I put small diameter long tube headers on and another 1 MPG when I then when from dual 2" exhaust to 2.5" dual exhaust. I also had a vacuum gauge mounted in the dash and I drove by that. I tried not to have the vacuum drop too low while accelerating and cruising. I would love to have played with the heads and cam to get better performance at the same time.

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Re: 454 engine improvements for better mileage

Post by garym » Tue Apr 17, 2018 10:28 pm

Thanks for the replies.So I have not decided on a camshaft, but the ERSON CAM grind #RV 15 H has the following specs
LIFT int .495 ex .495 dur @.050 214 on int&ex. lobe sep 112+4 OR the other cams in my first post. THANKS garym

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Re: 454 engine improvements for better mileage

Post by F-BIRD'88 » Wed Apr 18, 2018 3:49 pm

Slow down or get a smaller trailer..
The vaccum guage is the best tip yet.

Improve wind drag.. Big front spoiler.
Roof spoiler. areodynamic towing mirrors.

Make the truck and trailer pair more areo at speed.

Increase tire pressure.

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Re: 454 engine improvements for better mileage

Post by Geoff2 » Thu Apr 19, 2018 4:28 am

Remove two cylinders...

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Re: 454 engine improvements for better mileage

Post by Alan Roehrich » Thu Apr 19, 2018 6:43 am

How much work are you willing to do?

How much money are you willing to spend?

How serious are you about modifying and tuning it?

What is your skill level?

I can tell you with certainty that the greatest impediment to efficiency in those old engines is an abysmal compression ratio, it is actually down around 7.5:1, which kills both torque and fuel economy.

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Re: 454 engine improvements for better mileage

Post by gnicholson » Thu Apr 19, 2018 7:35 am

A pair of 96 and later l29 heads would be a big improvement

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Re: 454 engine improvements for better mileage

Post by Truckedup » Thu Apr 19, 2018 8:45 am

Alan Roehrich wrote:
Thu Apr 19, 2018 6:43 am
How much work are you willing to do?

How much money are you willing to spend?

How serious are you about modifying and tuning it?

What is your skill level?

I can tell you with certainty that the greatest impediment to efficiency in those old engines is an abysmal compression ratio, it is actually down around 7.5:1, which kills both torque and fuel economy.
Gas truck engines designed for hauling loads always have lower compression ratios. Keeping up with traffic in a loaded gas engine truck means relatively high rpm's with deep throttle openings and low intake vacuum..By loaded I mean at least 12000 pounds gross...Cruising along at 55 on flat ground is a different story..
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