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Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Originally Posted by AZC4Guy
27 mpg out of an 11 sec car?
How much money do you have this is an absolute fact. I am also willing to bet there are plenty of other 6 speed cars aout there that have simmilar numbers. Ripping the fuel injection off and slapping a carb on will definatly kill any chance you ever had at getting good gas milage with a motor that even makes modest power.
Some informative reading, just to let you know that I am not the only one out there and you are calling BS on a bunch of people.
http://forums.corvetteforum.com/show...45&forum_id=48
Last edited by FD2BLK; Oct 23, 2005 at 09:33 AM.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Bogus had some great tips and remember that it needs four things spark, fuel, compression and timing. Just a few things I would check if I was in a similar situation.
Spark,
Use a spark test tool to ensure that you not only have spark but it is the proper intensity (The tool is about $5 and any auto parts store.
If you don't have proper spark at the plugs check the coil.
If no spark out of the coil then check the coil pack and start looking at the signals from the Opti spark and ECM (You will need a Scope for this one)
Fuel,
You stated you have FP so the first check is done,
Second using a test light see if the ECM is sending the pulse signal to fire the injectors.
If the ECM is sending the pulse signal then check the injectors for proper resistance (around 14 ohms)
If the injectors check out ohm wise then pull the fuel rail (Takes about 5 min on the LT1) and place each injector in a catch can, then turn the motor over and see if all injectors are firing. (If not and the ECM is providing the signal with good FP probably a bad injector)
Compression,
Perform a compression, or better yet leak down, check.
Spark,
Use a spark test tool to ensure that you not only have spark but it is the proper intensity (The tool is about $5 and any auto parts store.
If you don't have proper spark at the plugs check the coil.
If no spark out of the coil then check the coil pack and start looking at the signals from the Opti spark and ECM (You will need a Scope for this one)
Fuel,
You stated you have FP so the first check is done,
Second using a test light see if the ECM is sending the pulse signal to fire the injectors.
If the ECM is sending the pulse signal then check the injectors for proper resistance (around 14 ohms)
If the injectors check out ohm wise then pull the fuel rail (Takes about 5 min on the LT1) and place each injector in a catch can, then turn the motor over and see if all injectors are firing. (If not and the ECM is providing the signal with good FP probably a bad injector)
Compression,
Perform a compression, or better yet leak down, check.
Last edited by FD2BLK; Oct 23, 2005 at 09:35 AM.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by FD2BLK
An LT1 is the same as any other SBC as far as the cam gear goes, same hole in the block and same cam gear. The only difernce is the LT1 uses a gear and plate to turn the oil pump and there is no hole in the intake but if you pull the plate out you can drop a standard Gm distributor into it and it will work fine as long as the intake has the hole for the distributor. Some of the F-body guys have modified the LT1 intake and installed a MSD crab style distributor to repace the Opti high voltage side. They take the coil output and run it to tyhe cap simmilar to a conventional distributor but stil use the optical side of the Opti spark.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Originally Posted by Redeasysport
Thanks for the info.Wouldn't they still have to set the timing on the distributor to match the Opti?Sounds like a real pain so is there any real gain to doing this?Will the system work without any input from the opti?What about fault codes on the DIC?Who can tune for this?Still need the ECM right? So many questions so little time......
If we are talking about the MSD rear distributor conversion I agree with you about it is way to much of a pain considering there are systems such as Delteq and LTCC that will do the same thing without having to hack up the intake. It still uses the low voltage side of the opti and the coil it just uses the distributor for the cap and rotor portion. THe ECM does not see the differnce so no codes are set and tuning is not effected.
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Drifting
Joined: May 2005
Posts: 1,302
Likes: 1
From: Tomahawk WI
Originally Posted by FD2BLK
How much money do you have this is an absolute fact. Ripping the fuel injection off and slapping a carb on will definatly kill any chance you ever had at getting good gas milage with a motor that even makes modest power.
I am beginning to doubt you have an 11 sec car. If you do, I'm sticking w/
on your mileage ramble. Then again.. I don't care ... hmm but since you like to prattle about mileage. i have a Saturn that gets somewhere over 30 MPG...... what does that have to do w/ the original conversation?... OH YEAH! NOTHING.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Originally Posted by AZC4Guy
Let me make myself clear... again: I give a rat's *** about gas mileage. You brought up gas mileage as an answer to my claim that putting on a carb didn't reduce HP. I'm still not sure what one has to do with another, except the typical lame excuse to dodge the subject that one's car is a dog.
I am beginning to doubt you have an 11 sec car. If you do, I'm sticking w/ on your mileage ramble. Then again.. I don't care ... hmm but since you like to prattle about mileage. i have a Saturn that gets somewhere over 30 MPG...... what does that have to do w/ the original conversation?... OH YEAH! NOTHING.
I am beginning to doubt you have an 11 sec car. If you do, I'm sticking w/
on your mileage ramble. Then again.. I don't care ... hmm but since you like to prattle about mileage. i have a Saturn that gets somewhere over 30 MPG...... what does that have to do w/ the original conversation?... OH YEAH! NOTHING.Last edited by FD2BLK; Oct 24, 2005 at 08:39 AM.
Instructor
Joined: Feb 2005
Posts: 162
Likes: 0
From: jacksonville N.C.
does your year come with a pass key module? if so, have your mech take a look at it. it may need to be replaced. my 89 had the same problem as you are describing. he ended up replacing mine and got it running again.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Kryptonite,
It might be best to take a step back and try to get back to the original problem. It was mentioned before but after re-reading your post about tapping the original ECM and the car would die, I would take a very good look at the ECM connectors for a broken wire or possible corrosion. I think that taking it to the dealer at this point is a good move on your part. I don’t let others work on my car but if you don’t have the time or the tools top do the job the dealer typically has a lot more experience with these types of problems then the local mechanic.
It might be best to take a step back and try to get back to the original problem. It was mentioned before but after re-reading your post about tapping the original ECM and the car would die, I would take a very good look at the ECM connectors for a broken wire or possible corrosion. I think that taking it to the dealer at this point is a good move on your part. I don’t let others work on my car but if you don’t have the time or the tools top do the job the dealer typically has a lot more experience with these types of problems then the local mechanic.
Burning Brakes
Joined: Feb 2003
Posts: 1,246
Likes: 1
From: SouthBend IN
why is it every time some suggests a carb some people just go crazy on here ? I personally run 12.23 on motor with 3.07 gears and have gone as quick as 10.26 with a carb.You see when you carry a little blue bottle with you ....you can have a tame motor that runs great, drives good and responds really well to spray. The last trip i took i got 26.5 MPG on the HWy at 75 MPH. There not junk, but their not FI . I get discussed with you guys that think a carb is junk. I have $2500 in my complete motor carb to pan, have elec choke ( drove it ALL last winter in NorthWest , IN.) Gas mileage and driveability will suffer weather carbed or FI if the combo just sucks. period.
That being said, there's NO WAY i would take an LT-1 and make it carbed. The TPI stuff is not very good for performance and the upgrades are just too expensive for what you get.
I'm sure you will be plenty happy with your car when it's fixed. Just stay away from the old mechanic.
Mike
That being said, there's NO WAY i would take an LT-1 and make it carbed. The TPI stuff is not very good for performance and the upgrades are just too expensive for what you get.
I'm sure you will be plenty happy with your car when it's fixed. Just stay away from the old mechanic.
Mike
Last edited by mike 1985; Oct 24, 2005 at 02:23 PM.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
I don't hate carbs... I just would not do it on an LT1 either.
With that said, I will repeat that I don't like them very much. I much prefer fuel injection, cause all things being equal, FI will give better MPG and drivability.
I agree that the TPI is a nasty pig... and that a carb is the best way to advance power at an affordable price. However, the LT1 FI is light years more advanced and I would never consider swapping a carb on it. No way!
However, if I was to build a 60s hotrod, I would use an aftermarket EFI of some sort... for the drivability and reliabilty. The tuneability.
You can make a carb get good gas mileage or get good performance... For some reason, I don't buy your 26+ MPG... I am NOT accusing you of lying... just a simple math error... it does not make sense... My 92, LT1, EFI, 6psd was near 26mpg highway, but only on open highway... for some reason, my paradigm does not accept that a carb can provide good performance AND economy... it just doesn't make sense.
With that said, I will repeat that I don't like them very much. I much prefer fuel injection, cause all things being equal, FI will give better MPG and drivability.
I agree that the TPI is a nasty pig... and that a carb is the best way to advance power at an affordable price. However, the LT1 FI is light years more advanced and I would never consider swapping a carb on it. No way!
However, if I was to build a 60s hotrod, I would use an aftermarket EFI of some sort... for the drivability and reliabilty. The tuneability.
You can make a carb get good gas mileage or get good performance... For some reason, I don't buy your 26+ MPG... I am NOT accusing you of lying... just a simple math error... it does not make sense... My 92, LT1, EFI, 6psd was near 26mpg highway, but only on open highway... for some reason, my paradigm does not accept that a carb can provide good performance AND economy... it just doesn't make sense.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
OK AZC4 lets see your back up to prove your point.FD2BLK has helped many people fix ther cars what have you done.Everyone here who knows LT1's will tell you it is no problem to get the MPG he gets with his car.These engines are that good.Not only that but they can be modded and still get it.Back up what you say with something other than the BS flag or shut the hell up.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Originally Posted by Redeasysport
OK AZC4 lets see your back up to prove your point.FD2BLK has helped many people fix ther cars what have you done.Everyone here who knows LT1's will tell you it is no problem to get the MPG he gets with his car.These engines are that good.Not only that but they can be modded and still get it.Back up what you say with something other than the BS flag or shut the hell up.
but it is really just a waist of time this is the same person who was laughing at Jeb’s advice. This thread has a real person who would probably rather that all this nonsense would just stop, Kryptonite sorry for going off topic and I hope you had some success today with the dealer.