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02-05-2014, 07:32 PM
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#1 |
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Registered User
Join Date: Aug 2012
Location: Grant NE
Posts: 78
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anyone running LT1's
I have an LT1 in my 71 Chevy and it doesn't seem to be pulling the MPG's. its has new O2's and I have a 700R4 with a 3.23POSI 12 bolt. Down the Highway at 60 I'm running 1500RPM and interstate at 80 its running 1900RPM
Do you think I just need a better tune? when its not to operatering temp and I do a quick romp it chugs and pops. |
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02-05-2014, 07:56 PM
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#2 |
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Registered User
 
Join Date: Jul 2013
Location: Forestburg, Texas
Posts: 659
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Re: anyone running LT1's
Sounds like something is very wrong. The RPM's seem OK, but the LT-1 should flat scream. The chugging and popping is a problem. Check for vacuum leaks and make sure you have plenty of fuel pressure. The Opti-Spark on these engines are problematic as well.
I have two LT-1s. one (1993) is in an 87IROC that flat screams. The other (1996) is waiting to go in my boat.
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Mark Jesus is the Way! 2003 2500HD CCLB Duramax/Ali (Clifford) 2014 2SS/RS black on black Camaro (Betty) 2006 Pontiac SOLSTICE silver/black (Lula-Bell) 1970 C/10 Short Wide (Peggy) 1964 C/10 Short Step (Hambone) RIP Jimmy Hamilton Thank you for the trucks |
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02-05-2014, 09:43 PM
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#3 |
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Registered User
Join Date: Aug 2012
Location: Grant NE
Posts: 78
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Re: anyone running LT1's
After it's warmed up it does flat scream. Fuel pressure is good and opti was new when I installed engine. Guess I'll do the old carb cleaner check for a vacuum leak when it weather gets warmer the high was like 3 here today and rhe lows have been -15
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02-06-2014, 12:06 AM
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#4 |
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70+ ( Old Skool Club )
Join Date: Nov 2003
Location: Saskatoon, Saskatchewan ,Canada
Posts: 9,143
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Re: anyone running LT1's
When you stomped on the gas pedal in the 94/96 Caprices with the LT1's they sounded like a 4 barrel carb being opened up. They are quite the engine with the pounding they would take in the cop cars and would usually go 150,000 miles before needing any major work.
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1972 C10 Custom/Deluxe 613 Highlander 406/700R4 1999 White Tahoe LS 4x2 with Z56 Police Package 1992 K1500 GMC Suburban Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601 " Circumsatances Do Not Change Responsibility " " The Sky is not the Limit, Your Mind is." Marilyn Monroe .. RIP Charlie Watts 1941 - 2021 |
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02-27-2014, 04:57 PM
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#5 |
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Registered User
Join Date: Aug 2012
Location: Grant NE
Posts: 78
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Re: anyone running LT1's
ok after fixing exhaust leaks and it still doing the same thing I went on ebay and bought a different PCM, received it today put it on my truck and WOW found out all this time the guy didn't tune it correctly it runs like it never has before. Time to read that tune change the fans temps and put it on my PCM to make it run right, Yes with that different PCM it runs like a RAPED APE!!!!
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02-27-2014, 05:10 PM
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#6 |
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Florida Edition
 
Join Date: Oct 2010
Location: Fruitland Park, FL
Posts: 4,028
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Re: anyone running LT1's
I have a stock LT1 in my 97 Z28 and it is bad azz for a stock high mileage engine.
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70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394 |
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02-27-2014, 07:26 PM
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#7 |
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Registered User
Join Date: Jul 2012
Location: Ft Wayne Indiana
Posts: 1,204
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Re: anyone running LT1's
Talk to member Andy4639. He used to have an LT1 in his truck
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71 K20 64 GMC mud truck |
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02-27-2014, 08:31 PM
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#8 |
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Registered User
Join Date: Aug 2008
Location: Lantana, TX
Posts: 419
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Re: anyone running LT1's
Glad you got it squared away. I was going to say tune as well, especially since your problems were in open loop and only got a little better in closed.
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Anthony '67 Shortstep (555/T56) '67 Parts Truck (TBA) |
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02-27-2014, 09:44 PM
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#9 |
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Old member
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 19,945
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Re: anyone running LT1's
I just swapped to a LSx 6.0. in my 71! I never knew the old truck could run like it does. A good ECU and tune and you should be getting close to 20MPG.
 
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1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. |
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