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#1 |
Registered User
Join Date: Dec 2013
Location: Nj
Posts: 26
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Any suggestions?
I know it's been touch on a lot but I'm getting stumped.. Having poop fuel economy 8mpg tops. That's w a very light foot. This is what I have done to improve the issue but it still occurs
1 new msd dis 2 new wires 3 plugs gapped at 40 4 sealed all vac leaks 5 new edelbrock 600 tuned w vac gauge 6 new air filter 7 initial timming is at 12 advanced 8 vacume gauge reads 20-21hg at idle which I think is really great for a old 350 9 bfg tires inflated to 30 psi 35" 10 456 gears 11 700r4 trans Reading on here people w similar combos are reporting closer to 12-14 mph and tips? Am I missing something
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84 k10 350ci 7004r 1/2 axles 456 gears. 4 inch lift Last edited by Govern; 02-25-2014 at 10:15 AM. |
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#2 |
Registered User
Join Date: Jul 2011
Location: back 40, bc
Posts: 3,817
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Re: Any suggestions?
gears-4:56's are not for mpg's, even with a od, be thankful you have that, i got a t400 with 4:56's & 38's. turns at 31-3200 at 55mph-maybe 5mpg's if i'm lucky.
personally i would throw 3:73's in it. some will say 4:10's, but for the expense of regearing, your not going to see a big increase in your mpg's. i ran 35's on my k5 with 3:73's, more than enuff power, but still reasonable on fuel |
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#3 |
Registered User
Join Date: Dec 2013
Location: Nj
Posts: 26
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Re: Any suggestions?
I think 456 w 35"a and and overdrive is a nice combo only turning 1700 rpm at 60 mph.. You would expect that to yield better mpg
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84 k10 350ci 7004r 1/2 axles 456 gears. 4 inch lift |
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#4 |
Registered User
Join Date: Jul 2011
Location: back 40, bc
Posts: 3,817
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Re: Any suggestions?
yeah, thats pretty reasonable rpm's.
brakes are'nt dragging? maybe put synthetics in your axles, t-case, etc i have 33's on my stepper with 3:73's & run the tires at 35 psi (BF M/T's) & manage about 15 on the freeway,12-13 in town (350 tbi), so i dont think you will get huge changes, but yes, it would be nice to bring that 8 up to 12 or so |
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#5 |
Registered User
Join Date: Dec 2013
Location: Nj
Posts: 26
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Re: Any suggestions?
O yea if I could go from 8 to 12 id be ecstatic. Brakes are fine fluid in diff is new not sure if synthetic tho. I'm not a huge fan of the tires they r alittle noisy but when u are coasting at a high speed it doesn't drop down in speed very fast like some other nobby tires..
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84 k10 350ci 7004r 1/2 axles 456 gears. 4 inch lift |
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#6 |
Registered User
Join Date: Dec 2013
Location: Nj
Posts: 26
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Re: Any suggestions?
I plan to buy a set of summit headers, x pipe and 2.25 pipe do you think they would help the economy much?? Currently it has manifolds and cherry bombs
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84 k10 350ci 7004r 1/2 axles 456 gears. 4 inch lift |
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#7 |
Registered User
Join Date: Jul 2011
Location: back 40, bc
Posts: 3,817
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Re: Any suggestions?
might get a small increase, but most likely you will blow that playing with your throttle listening to them new headers!
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#8 |
Registered User
Join Date: Dec 2013
Location: Nj
Posts: 26
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Re: Any suggestions?
Haha good point. Really the truck rarely goes over 2300 rpm so would headers really even come in to play? Aren't they more top end ?
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84 k10 350ci 7004r 1/2 axles 456 gears. 4 inch lift |
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#9 |
Registered User
Join Date: Aug 2009
Location: S.C.
Posts: 1,593
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Re: Any suggestions?
New distributor with 12* initial. Total? When does it start? All in?
Initial is a starting point. Ideally 32-36* by about 3000rpm, then see where the initial lands. I would imagine MSD is close to what you want, not like cheap e-bay unit that didn't start advancing until about 1800 rpm. (there is a good sticky in the engine and drivetrain FAQ on playing with advance curves. sbc ignition timing iirc) My K-20, an x-pipe wouldn't work. ended up with H-pipe. (transfer case...)
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'86 C-30 dually, 454/tbh400 '73 K-20 350/350/205 (sold ![]() I'm kinda like duct tape- no real purpose, but handy to have around. |
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#10 |
Registered User
Join Date: Dec 2013
Location: Nj
Posts: 26
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Re: Any suggestions?
12 initial, never checked the total. Instructions seemed like you set the initial and waalaa your good. Did you just solve my problem? Do I need timing tape to set the total timing currently it just has the little metal comb looking thing
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84 k10 350ci 7004r 1/2 axles 456 gears. 4 inch lift |
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#11 |
Registered User
Join Date: Aug 2009
Location: S.C.
Posts: 1,593
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Re: Any suggestions?
http://67-72chevytrucks.com/vboard/s...d.php?t=290498 Start reading. I use a timing tape and standard timing light. Many folks use a dial-back light.
This may or may not help, for all I know your MSD already has a good curve. Were there any instructions? Chinese dizzy benefited greatly from this, drive ability greatly improved. Stock HEI in the C-30 hasn't been checked yet, though PO did throw in initial advance. I honestly don't know if I solved your problem, but it's something you haven't looked at yet. It's actually a combination of little things that add up.
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'86 C-30 dually, 454/tbh400 '73 K-20 350/350/205 (sold ![]() I'm kinda like duct tape- no real purpose, but handy to have around. |
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#12 |
Parts and more parts
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,821
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Re: Any suggestions?
#1, Check the type of drivng that you do. All Highway, all city, mixed
#2, Check timing with a timing light that has advance capability to ge the total timing #3, How much effort do you expend to get up to speed---tire combo calcs #4, Are you positive the carb is set to the optimum jet settings or are you running rich #6 inflate the tires just a little more to go to 37 to 38 psi
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Frank |
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