poor upper RPM power
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Junior User
Joined: Dec 2005
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poor upper RPM power
with engine warm it idles around and launches good all day long. from a dead stop if you were to punch it, it would spin a little, but pull down way to fast for a 460 engine.
with it held to the floor itll hit 3500rpm n shift in ever gear. it just dont seem to rev out like i think (or want) it to. id like to make a nice street truck. weekend street warrior i guess. ive been told anything from cam indexin to heads. ive tried timing it all over with differnt methods. even different dist. i had the 600 holley on it, ran great, no big top end pull. went to a 800 and same story. so its down to cam? or heads? or tourqe converter? the truck did sit for 5yrs + before i got it.
mods include:
d1ve block bored .30 over
crank n rods turned .10
stock crank n rods
edelbrock performer plus cam
edelbrock double roller timing set (set to "straight up")
edelbrock performer plus intake
stock d3 heads.
holley brand headers and flowmaster 40s? i think
tried a 600 vac holley and 800 DP holley with little difference.
C6 trans
3:50 gears with smaller than stock tires. ( cant member tire size, but @ 60mph is turnin 3000rpm.)
its in a 79 f150 reg cab long box 2wd.
ideas other than whats been tried would be great. thanks
dave.
with it held to the floor itll hit 3500rpm n shift in ever gear. it just dont seem to rev out like i think (or want) it to. id like to make a nice street truck. weekend street warrior i guess. ive been told anything from cam indexin to heads. ive tried timing it all over with differnt methods. even different dist. i had the 600 holley on it, ran great, no big top end pull. went to a 800 and same story. so its down to cam? or heads? or tourqe converter? the truck did sit for 5yrs + before i got it.
mods include:
d1ve block bored .30 over
crank n rods turned .10
stock crank n rods
edelbrock performer plus cam
edelbrock double roller timing set (set to "straight up")
edelbrock performer plus intake
stock d3 heads.
holley brand headers and flowmaster 40s? i think
tried a 600 vac holley and 800 DP holley with little difference.
C6 trans
3:50 gears with smaller than stock tires. ( cant member tire size, but @ 60mph is turnin 3000rpm.)
its in a 79 f150 reg cab long box 2wd.
ideas other than whats been tried would be great. thanks
dave.
Senior User
Joined: Jan 2004
Posts: 156
Likes: 0
From: Carmichael, ca
Improving upper rpm power
At this point what you have is basically a freshened up stock 460 with a new RV cam (what are the spec's?), a new intake which and a new slightly larger carb. If you want a hot rod any engine, you need to look at the whole engine as a big air pump and then look at improving all the pieces of the package. Heads, cam and exhaust all have to be impoved to really see a difference. Just sticking a cam, intake manifold and carborator on a basically stock engine will not give you big improvements.
You can have your cast iron heads ported or buy a set of ported heads, add tupe headers & a dual exhaust to go with the new manifold, cam & carb. The cam then becomes the limiting factor that you have to look at depending on what you want to do with the truck. The next thing would be to increase your compression ratio.
It's only time & money . . . hope this helps.
You can have your cast iron heads ported or buy a set of ported heads, add tupe headers & a dual exhaust to go with the new manifold, cam & carb. The cam then becomes the limiting factor that you have to look at depending on what you want to do with the truck. The next thing would be to increase your compression ratio.
It's only time & money . . . hope this helps.
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Junior User
Joined: Dec 2005
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Edelbrock.com - Ford Big Block Camshafts and Matching Components
the performer plus is the cam im runnin now, but for 350$ i could up grade to the performer RPM but to achive the total package it would be best to upgrade intake also. after i did post i took the truck out on a new quiet area of pavement, stuck it in 1st and did a brake stand. 4 grand is all she rev under load. i can get edelbrock RPM aluminum heads for a decent price. bolt on and go for less than i could get my steel d3's to flow at a good rate. so its lookin if i want more power its bigger cam, heads, intake, and make sure the headers i have are rated to the previous.
thanks
the performer plus is the cam im runnin now, but for 350$ i could up grade to the performer RPM but to achive the total package it would be best to upgrade intake also. after i did post i took the truck out on a new quiet area of pavement, stuck it in 1st and did a brake stand. 4 grand is all she rev under load. i can get edelbrock RPM aluminum heads for a decent price. bolt on and go for less than i could get my steel d3's to flow at a good rate. so its lookin if i want more power its bigger cam, heads, intake, and make sure the headers i have are rated to the previous.
thanks
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Junior User
Joined: Dec 2005
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i pulled a dist. from a good runnin engine, same outcome. am i 1 tooth out maybe? wires are in good visable shape, but are old. could try new cap, rotor n wires i guess. plugs were new last yr and gapped to spec. they are NGK's i believe.
thanks.
thanks.
Senior User
Joined: Jan 2004
Posts: 156
Likes: 0
From: Carmichael, ca
Diesel,
What rpm are you looking for? Remember that the 460 is not a high winding engine. Big blocks do not have to wind up to 8,000 rpm to make power. I built a stoked 460 that is now a 545. I'm running a rather small cam for the engine size and still make 500 hp @ 5,000 rpm and over 600 ftlbs of torque from 2,000 thru 4,500 rpm. I use my truck for pulling a toy hauler and for fun. I can easily make over 600 hp with a cam change and again, it's at 5,000 rpm.
That's why Henry Ford put the 427 into the GT40 to kick Ferrari's *** at Le Mans. Low rpms with mucho power & torque meant very fast dependability. The GT40's ran away from the high reving Ferrari's.
I would increase the compression ratio if you can afford it. I agree that the aluminum heads are the way to go. Do you have dual exhaust on it now?
What rpm are you looking for? Remember that the 460 is not a high winding engine. Big blocks do not have to wind up to 8,000 rpm to make power. I built a stoked 460 that is now a 545. I'm running a rather small cam for the engine size and still make 500 hp @ 5,000 rpm and over 600 ftlbs of torque from 2,000 thru 4,500 rpm. I use my truck for pulling a toy hauler and for fun. I can easily make over 600 hp with a cam change and again, it's at 5,000 rpm.
That's why Henry Ford put the 427 into the GT40 to kick Ferrari's *** at Le Mans. Low rpms with mucho power & torque meant very fast dependability. The GT40's ran away from the high reving Ferrari's.
I would increase the compression ratio if you can afford it. I agree that the aluminum heads are the way to go. Do you have dual exhaust on it now?
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
[QUOTE=F350 Strait;6482821] ............That's why Henry Ford put the 427 into the GT40 to kick Ferrari's *** at Le Mans. Low rpms with mucho power & torque meant very fast dependability. The GT40's ran away from the high reving Ferrari's..................QUOTE]
Out gas mileaged them too, big time using a single 4 barrel carb.
Out gas mileaged them too, big time using a single 4 barrel carb.
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Senior User
Joined: Mar 2008
Posts: 318
Likes: 1
Check for fuel delivery problems. Sounds like a partially clogged filter or line, or a weak pump. Or a plugged main jet. Look at your sparkplugs and see what color their burning in normal use, then do a plug chop (run it wide open for 10-15 seconds, under load, SAFELY) and pull a plug. If the plugs are white, or at least lighter it shows your running lean at wide open. Gas will turn to varnish in 3-6 months if it doesn't have stabilizer added, I see bad gas problems every fall when we break out the dirtbikes for the winter riding season.
Is at least one of the carbs you tried from a currently good running engine? Change the fuel filter and make sure the lines are clear, then swap in known good components, like distributors, coil, plug wires, etc.
Is at least one of the carbs you tried from a currently good running engine? Change the fuel filter and make sure the lines are clear, then swap in known good components, like distributors, coil, plug wires, etc.
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Thread Starter
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Junior User
Joined: Dec 2005
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bear 45/70
on a double pumper holley (800CFM) how could i check to verify the 2ndarys are workin? also is it possible for the fuel pump not to pump volume at higher rpms? it puts out 5-6psi at idle currently.its a stock pump. fuel filter is good, but i can change that just for fun i guess. this afternoon ill change cap, rotor n wires. then while im out on the test drive ill bring my tools to check a plug for lean on the top end.
thanks for the ideas.
on a double pumper holley (800CFM) how could i check to verify the 2ndarys are workin? also is it possible for the fuel pump not to pump volume at higher rpms? it puts out 5-6psi at idle currently.its a stock pump. fuel filter is good, but i can change that just for fun i guess. this afternoon ill change cap, rotor n wires. then while im out on the test drive ill bring my tools to check a plug for lean on the top end.
thanks for the ideas.
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
bear 45/70
on a double pumper holley (800CFM) how could i check to verify the 2ndarys are workin? also is it possible for the fuel pump not to pump volume at higher rpms? it puts out 5-6psi at idle currently.its a stock pump. fuel filter is good, but i can change that just for fun i guess. this afternoon ill change cap, rotor n wires. then while im out on the test drive ill bring my tools to check a plug for lean on the top end.
thanks for the ideas.
on a double pumper holley (800CFM) how could i check to verify the 2ndarys are workin? also is it possible for the fuel pump not to pump volume at higher rpms? it puts out 5-6psi at idle currently.its a stock pump. fuel filter is good, but i can change that just for fun i guess. this afternoon ill change cap, rotor n wires. then while im out on the test drive ill bring my tools to check a plug for lean on the top end.
thanks for the ideas.
Elder User
Joined: Nov 2003
Posts: 778
Likes: 2
From: southeast Idaho
Put a vacuum gauge on if you have not already, it can tell you many things, if you rev it slowly, the vacuum should go up slightly barring any quick throttle movements, mine at about 2800 to 3000 would start dropping, realized my exhaust, which was stock after the headers was just to small and restrictive, now it pulls much better but to go above42 to 4400 I have to shift it manually but it will pull up there if I do.. Just something else to check, I went with 2.5" all the way to the rear bumper, later on I put 3" glass packs on just to avoid trouble cause it was loud!
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Junior User
Joined: Dec 2005
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im runnin Flow Tech headers. 2.5'' pipe to flowmaster 2.5 in and out lets. no tail pipes, mufflers and exaust pipes stop in front of rear diff. i tried a new ignition module on the quarter panel also new coil to no avail. 4 bbls are openin properly and its sqirting fuel like id say it should. in the shop it revs nice ( i know the 460 isnt a 8 grand machine, but mine just dont pull hard thru all the gears). 4800rpm on a qiuck throttle hit. but on the highwaywide open or burn out wide open 3800 she starts to stumble / miss. no popin sounds or backfiring. only thing left is plug wires / cap n rotor. and from there im thinkin its heads / cam.
Elder User
Joined: Sep 2004
Posts: 500
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From: midwest
if it shifts at 3500 rpm held to the floor then the problem is the vacuum modulator or kickdown linkage on the trans. if you pull the vacuum hose off the modulator at the trans there is a flat blade screw inside, turn it clockwise to lengthen the shift points. also make sure your kickdown rod from the carb is hooked up to the trans and when youre at wot the lever is pushed all the way down on the trans lever. a 460 that is near stock will only pull till 4200-4500 then its just flattened out, but it should rev out to at least 4500-4800 at wot before it shifts.