Post your cruising rpms @60mph
 

Post your set up,

383 small cam headers intake q-jet 3" exhaust
200-4r
3.08
29.4" tires 255/45/20

Getting roughly 16.5 mpg

Rpm@60= 1300 roughly
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Re: Post your cruising rpms @60mph
 

454 781 heads
Edelbrock 750 and Performer
Headers
Torque ground cam and roller rockers
4L80E
3.73
32" tires
1850@60

Re: Post your cruising rpms @60mph
 

don't have the tach hook'd up yet but it sound's like 12000 at 60 MPH, I need overdrive and a 3.73 gear bad !

Re: Post your cruising rpms @60mph
 

Stock 305 smokes and burns oil. 31 inch tires. SM465 creeper box with 3.08 gears. 2000 at 60
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Re: Post your cruising rpms @60mph
 

26.5 tires and 3:73 gears and th350. 3000rpm at 60mph 3500 at 70mph which is where I cruise at haha. I need a nice 200r4
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Re: Post your cruising rpms @60mph
 

28" tires 3.73 gears and a nv3500, roughly like 2200-2500 rpms around 70-75

Re: Post your cruising rpms @60mph
 

Stock 305
Edelbrock 1406
700r4
No clue rear gears
235/75/15
1750 @ 60
1950-2000 @ 72
about 22 mpg

Re: Post your cruising rpms @60mph
 

My 200-4r was free ha, I have an older friend and he can not stand o/d auto trannies. He is a hot rod guy and... MOPAR. Any way I'm thinking of swapping gears to raise my rpms. I think 1200-1400 is too few rpms for a first gen sbc.

Keep posting them up!
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Re: Post your cruising rpms @60mph
 

Tell him about the MOPAR A833 manual overdrive trans that you could get in these trucks....

http://www.customclassictrucks.com/t..._transmission/

K

Re: Post your cruising rpms @60mph
 

3.42 :metal:

Re: Post your cruising rpms @60mph
 

My father had an 87 short bed 2WD, 4 speed manual with OD. He loved it.

Re: Post your cruising rpms @60mph
 

Just tested out this morning:

60 MPH
1,600 RPM's
350/700r4
4.10 gears
35" Tires

70 MPH
1,900 RPM's

Re: Post your cruising rpms @60mph
 

60 mph
350 with vortec heads
4L80e
4.10

2000 rpm
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Re: Post your cruising rpms @60mph
 

I didn't know that, I think he has a couple of these laying around. Right now he is building a t-bucket powered by a 283 with corvette intake with 2 4 barrels and a Saginaw 4 speed.

I have 2 sets if gears, 3.08 and 4.56. Everyone says no to 4.56 but my rpms will be at 2100 at 60 and furthest I drive the truck is like 45 miles and the speed limits are 55 around here.
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Re: Post your cruising rpms @60mph
 

At 65mph I'm only doing 1400 RPM so at 80:

87
TBI 5.7L
2.73's
700R4
.7 final drive gear
80mph@1800 RPM
17mpg Highway 14 city

I used to think something was wrong with my RPM gauge.

Re: Post your cruising rpms @60mph
 

This is a useful thread, as it caused me to notice a discrepancy in my rig:

1980 K10 Suburban
350/TH350 & NP205
32" Cooper Disco STT's
~2400 rpm @ 60mph
~2700 rpm @ 70mph

The SPID says its supposed to have 3.42 gears, but the tach doesn't lie and it sure looks like they are actually 3.73's
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Re: Post your cruising rpms @60mph
 

My old 79 had 3.08's and a 2004-R so I was about 1500@80mph. With a stock vortec 350 with RPM intake, 600 edelbrock carb, 2" ramhorns with 2.5" exhaust I'd get 16mpg freeway when I was lucky. I never did get the carb dialed in.

My 78 has never gotten anything other then 10mpg combined, and thats with 3 different engines.

Re: Post your cruising rpms @60mph
 

I don't ever get on the interstate, all my driving is on a 2 lane highway and small towns. I live in a rural area woo! The 16.5 mpg is a combined amount between city and highway.
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Re: Post your cruising rpms @60mph
 

What's your final gear in the trans? That will tell you

Re: Post your cruising rpms @60mph
 

haven't had my truck up to 60 in awhile, for fuel sake i cruise at 55 & my tach hangs at 2800
'85 crew, 454 (efi), t400, 205, 4:56's, 38.5" tires

Re: Post your cruising rpms @60mph
 

I was just looking at your sound proofing the other day, you have a nice truck!
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Re: Post your cruising rpms @60mph
 

Ls1, 4l60, 3.73 with a 29" tire I'm around 1800 ish at 60. Cruising at 75 I was averaging 19.5...
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Re: Post your cruising rpms @60mph
 

No need to come in here and make us feel bad! Haha
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Re: Post your cruising rpms @60mph
 

How much would you say that your conversion cost you, in the end? I'm trying to gather up data on what I should pay for my 5.3 swap next year.

Re: Post your cruising rpms @60mph
 

Hehe

Ehhh I probably have around 4k in it. My biggest expense though was I bought the parts little by little as I had the cash and found a deal. I completely rebuilt my engine, new pistons, rods, crank, cam, springs etc. it was a new engine when I installed it. Also I bought a fully built trans and new converter. If you go 5.3 take out and can get say an engine and trans with the accessories and wiring, you should easily come under 2k total. I was just picky and wanted the aluminum 5.7 rather then an iron block so they tend to me a bit more expensive.
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Re: Post your cruising rpms @60mph
 

79
350 quadrajet
All stock
4.10's
35x12.50's
10 city 13 highway @ 2500 rpm
Would get better if i'd keep my foot out of it lol
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Re: Post your cruising rpms @60mph
 

Yeah I could get an all aluminum 5.3, but the difference in weight is only 40lbs. Still might do it, don't know. Putting spark plugs in aluminum heads may not be stress that I want in my life. Unless they got smart and started making that part iron. Then again, maybe the iron blocks still have aluminum heads...

Re: Post your cruising rpms @60mph
 

They actually make an all iron ls engine. cant remember the year but it is a 6.0 and usually they are in 2500 hd trucks. There should be no reason to change plugs but maybe every 2-3 years unless you drive a bunch. 50k on a set of plugs is normal life. There is 0 difference in putting plugs in an aluminum head over an iron head. Our shop car gets new plugs every 2-3 passes down the track. With 1300 hp you have to keep fresh plugs in so you dont burn up the engine. we are yet to have an issue. Also the aluminum block is around 65-70 lbs lighter then its iron counter part.

Re: Post your cruising rpms @60mph
 

I'll porbably sell the 4.56 gears to some pretty cheap and try to trade my 20s for some 15 wire wheels that will raise my rpms up a bit
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Re: Post your cruising rpms @60mph
 

87 st cab long bed 4x4
350tbi /th400 / 4.11 grears at 55mph= 2400rpm= 8mpg


89 crew/dually 4x4
454tbi / th400 / 4.11 gears at 55mph=2400rpm=8mpg

Need to add an OD!!

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85 C10
Stock 305 Headers
T56 .50 6th
29" tire
3:70 r&p
1600@80mph
No idea at 60mph, who drives that slow?

Re: Post your cruising rpms @60mph
 

1326@60
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77 K10
350 TBI 700R4 NP 208
StarFire 285/75R16
4.10 Gear Ratio
1750 & 60 MPH
Gets 16 MPG on long cruise.

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'78 short box 2wd lowered

350 Diesel,t400,GV o/d-.78 final drive, 3.40 in the rear. With a 27" tire I was at 2300 RPM at 70 MPH and if I drove all highway I got 23 MPG. 18 MPG in the city

I just swapped in 3:73's with limited slip in the rear which should put me around 2500 RPM at 70. We'll see what I get this next week for fuel mileage.
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Re: Post your cruising rpms @60mph
 

I have the same tranny in my 82 K25, 6.2/833/208/3.73.. It's howling a bit in OD,but it still gets 20mpg on highway in 3rd at 60 mph. Not bad for a 6" lift on 35s . 22-2300 @ 60. I like this tranny better than the 465, lot shorter throws too..
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Re: Post your cruising rpms @60mph
 

86 K20 350/465/208/4.10s 7" lift on 35s runs about 2500 rpm @60 about12-14 mpg
81 K35 CCLB 454/400/205/4.56 rpm unknown,6-8 mpg.
86 K25 6.2/400/208/3.73s 4" lift on 33s runs about 2600 @60 about 16-18 mpg.
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Yea, I had 373 gears & a 350 3 sppeed at one time , & youre right on at 3000 rpms at 60 mph . Too steep for me , put in a 3.08 ,didnt like the performance , ended up with A 342 (BOUT 2500-2600 RANGE AT 60) Still not great over 70 , but I got tired of throwjng money at ring & pinions , plus the labor of someone else doing the work. Oh well you live & learn :waah:. I did a lot of things to my truck before I GOT ON THIS FORUM . yOU ARE SMART IF YOU GET ADVICE ON THIS FORUM, LIKE A LOT OF YOU ARE DOING, BEFORE YOU MAKE YOUR MODIFICATIONS

Re: Post your cruising rpms @60mph
 

Sorry to be joining so late, but I've been away on business and haven't been driving the truck.

Looks like about 1900 rpm; 4.3L V6, MY6 manual overdrive trans (.73 ratio), 3.73 rear axle, P235/75R15 tires.

K

Re: Post your cruising rpms @60mph
 

ZZ4 355 HP!!!
700R4 custom built
3.08 gears
255/60R15
1950 RPMS @ 70 MPH
18.5 MPG :METAL: