new L31 crate motor to replace 87 5.7 tbi

[rfmaster]

2 cents it will be worth at about 150k with worn rings and high oil consumption. Many of my friends have LO5 with 225 to 250k on the clock driven very hard. Most of them need valve job due to worn valve guides, but the bottom ends are still good enough. EFI keeps excess fuel from washing down oil from cylinder walls. On the other hand SBC cast iron valve guides naturally wear out - that's a well known problem. By today's standards TBI is a very simple system, that requires virtually no maintenance or routine screwdriver adjustments.

To original poster - Go with L31 long block P/N 12530283. Stock TBI ECM - service number 1227747 with ASDU calibration will be good enough to fire and drive. Check engine light will turn on due to missing EGR function - this can be easily disabled in the EPROM. OE distributor will work in L31 with a stock camshaft. L31 camshaft is a roller cam which will do just fine with today's low zinc oil formulations. If you're after every day drivability (DD) stock L31 camshaft PN 10241264 is just fine. If you're a bit more adventurous marine versions of L31, HT383 were equipped with slightly bigger camshaft p/n 14097395. This cam will need some tuning, but you'll pickup higher RPM HP.

P/N 10241264
Lift 0.414" Int/0.428" Exh; Duration @0.050" 191° Int/196° Ext; LSA 111

P/N 14097395
Lift: 0.431'' Int /0.451'' Exh; Duration @0.050" 196° Int/206° Exh; LSA 109°


For better performance tuning and higher fuel pressure will be required. In general truck needs low end torque, not high RPM HP.

//RF

[rfmaster]

Originally Posted by MikeB

I stand corrected. What years was the L05 engine used?

87 to 95

[jokerz71]

Originally Posted by MikeB

I stand corrected. What years was the L05 engine used?

The L05 was introduced in April 87 as an 88 model.As far as I know, they were all TBI equipped.

[csdineley]

87-95

I still don't believe it's any cheaper to stick with tbi. Or much easier.

[rfmaster]

Originally Posted by csdineley

87-95

I still don't believe it's any cheaper to stick with tbi. Or much easier.

Perhaps you should try before dismissing it. BTW, countless Jeeps and Rock Crawlers of various incarnations prefer TBI for its simplicity and dependability. TBI has been swapped onto older carb engines - it does take some ingenuity to get it done.
//RF

[csdineley]

If it only last 150k that will be fine. Since the Stock L05 only lasted 99k. And a friend of mine is on his 3rd stock L31 at 400K. On the other hand I had a stock 79 G20 350 with a quadrajet that lasted 250k.
I'm not saying FI isn't a good thing, but sometime simpler is better. An Ls engine should be FI any pre Ls should be carbed in most cases in my opinion.

[csdineley]

Originally Posted by rfmaster

Perhaps you should try before dismissing it.
//RF

I did for many years

[jokerz71]

Originally Posted by csdineley

87-95

I still don't believe it's any cheaper to stick with tbi. Or much easier.

In an originally tbi equipped truck, it is.You only need a Vortec intake (needed for a carb also),& to add an afpr to your throttlebody to adjust the fueling for added power/airflow of the L31.Everything else is already there.This is for a stock L31.If you start swapping cams, etc, then it can get a little more complicated.But, for a motor up to approx 300 to 320 HP, it's very cheap & well performing system. As mentioned above, the fuel injection & computer management make these engines last way beyond what a carb & hei will go.
To put the carb on an L05 truck, you have the intake to buy, carb, install a regulator to adjust fuel psi down to a 5 to 6 psi, a return line to the tank,an hei distributor, and quite a bit wiring changes.
My 97 has 610,000 miles on it now.I pulled the original L31 at 248,000 mainly for low idle oil psi & replaced it with an L31 crate, which has over 360,000 miles on it now & still running strong & quiet.When I tore down the original motor, it still had visible cross hatch in the cylinders & no ring ridge at all.IF you get that many miles on a carb'd engine, you will find a totally different story when you open it up.

[csdineley]

Well what else can I say. I guess you guys are right. After working on and building cars for 25 years (with and without Fi). From jeeps to British sports cars and everything in between. And also having a degree in Computer Science. Guess the older I get the simpler I try to keep my rides.

One last thing:
Vortec intake = Both
Afpr = both
Return line already there on a 87 TBI truck = Both
Wiring not bad on a carb swap unplug the computer and run 12v to choke. And unplug the check engine bulb.
HEI = Carb
And of course a Carb

TBI
Tune Computer = couple hundred dollars by the time your done
All new sensors = Not going to reuse old sensors on your brand in motor right. There's a couple hundred more

Seems to be about equal to me

[jokerz71]

FWIW, my goal isn't to turn this into a tbi vs carb thread, but, to simply give some accurate info to the swap that the OP is asking about.Both sides have benefits & drawbacks.Just trying to help the OP make an informed decision for what would work best for his application.I do tend to lean towards the EFI systems vs carb.It's not the big black hole it used to be & is getting more common than ever.Another drawback to carb, at least for older models, is ethanol.It can wreak havoc on carbs.
After reading back thru the thread, I will advise the OP to not try using the 18# spring if retaining the TBI.The only time this spring actually works well is in an application that requires 18 psi & only 18 psi.The fuel needs to be adjustable to your specific need.The recommendation to the spring & an afpr makes no sense to me.With an afpr, there would be no need to even use the spring.

[MikeB]

Originally Posted by jokerz71

The L05 was introduced in April 87 as an 88 model.As far as I know, they were all TBI equipped.

Guess I should have said 73-86 would be more expensive and complex to do!

That's some very good info on this thread from you, Joker.

[bigarmzz]

definitely some good info and part numbers, thanks a lot guys for the info

since its a 87 with stock tbi i'd "prefer" to keep it tbi, not that i'm crazy about it and all as I usually have a big ol pain in the butt when it comes to diagnosing problems with the tbi crap....I usually just end up replacing all those stupid tbi sensors when there's a problem instead of going "one by one".....seems the stock GM tbi does a good job when its all functioning properly but like the one guy said earlier, when there's a problem your all most better off just replacing all those troublesome sensors on the throttle body

I basically built this truck like 6 years ago and I cant wait to get it back...gonna kill me to wait til June

[jokerz71]

Nice truck !!! I like !!!The TBI is really no more than a glorified carb,really.The misunderstood redheaded step child of GM fuel delivery.LOL.the TBI system itself is really not that bad.It the computer that is the real headache,especially the 87 to 92.The baud rate on these was approx. 180.With the addition of the 4L60E in 93 came a lot better computers.Well not a lot,but,better with 10 times the baud rate & much faster & easier to work with.It is still wet flow thru the intake to the cylinder.It does give better fuel atomization & you don't have to worry floats/bowls,etc.That's one reason the Jeep & rock crawler guys love them.
As for diagnosing the TBI system,what you describe has a lot to do with it having a bad name.LOL.So many sensors,etc,get blamed & replaced needlessly.IDK if you are aware,you probably are,but,you can pull codes & troubleshoot the system without very much equip.You can pull the codes with no more than a jumper wire @ the diagnostic terminal & read them thru the SES lamp on your dash.If you are not aware of this,let me know,& i'll post back on how,or,include a link.Another thing about codes.Say you get an EGR code.DO NOT immediately go out & buy a new EGR valve.Check the EGR system first.Check the vacuum lines,check the solenoid,make sure the duct inside the intake has not stopped up with carbon/gunk.Pull the EGR in at idle to see if it misses/cutsout.(it should at idle.The code tells you which circuit is likely having problems,so,you get an idea of where to look.It very well may be something else causing the problem.You just have to take a different approach to troubleshooting as replacing parts can get expensive quik.

[N2TRUX]

Told ya should shouldn't have sold it.

[bigarmzz]

Originally Posted by N2TRUX

Told ya should shouldn't have sold it.

I know, Rub it in Ken

[N2TRUX]

Originally Posted by bigarmzz

I know, Rub it in Ken

Im here for ya brotha


In response to the carb fans, one thing your leaving out is its a dying fuel distribution source. I recently bought an 84 Sierra and noted that the carb seemed to be seeping a slight bit at the accelerator pump plunger. I'm mechanically inclined, but know enough about carbs to know I don't want to rebuild and tune one. For me, carbs and auto transmissions are parts that I would much rather find a professional to do it right.

I searched diligently trying to find someone that could do the job and was pretty dissapointed. Most shops just want to replace the carb rather than build it. I was looking at 700.00+ to do the job. I looked at buying a new or reconditioned carb, and they start at 450.00. The best solution I could find was an older gentleman thats retired, but agreed to build it. Labor starts at 300.00 and doesn't include hard parts. The only up side of this is the retired mechanic did offer some tips that may have resolved my issue.

My uninformed point is, carbs and the knowledge that it requires to tune or rebuild them is rapidly becoming a thing of the past. This Sierra shows 70k miles on it. Even if thats inaccurate, how many miles do you get from a carb before it needs a rebuild vs an injection system? How many places have the knowledge to diagnose, repair, or replace one vs the other?

Sorry Bigzz, not trying to muck up your thread. Congratulations on getting red back.

[hatzie]

In the long game niether is great...

I repair carbs on small engines and recreational machines like Snowmobiles and ATVs for friends and family. Not as a business. Internal parts as simple as gaskets for Walbro and Mikuni and ... carbs are difficult to source at times.

In comparison to small engine carbs the I6 Rochester 1 B, H, &M and the I6 & V8 2G are bloody easy to rebuild. I've never ever had one that couldn't be brought back with a basic kit and a couple day dip in the old 1960's toxic nasty Berryman B9 Chemdip... excluding carbs that were left out in the weather.
The new Chemdip doesn't work as fast or as well. Find the MSDS for the old stuff and buy the chemicals if you're serious... Just remember the component chemicals are a nasty neurotoxin. Don't get any on your skin, use it outdoors, and stay upwind. I wear heavy rubber gloves and use a pedestal fan behind me. I store it in a glass jug on the floor with water on top.

Quadraboggers are more complicated than I want to mess with. There are still more than a few outfits that specialize in reworking them. That probably will be reduced with time but there will always be a market for that skill.

The main problem with early EFI systems is the same as the Carburetors... ECM components and even sensors will get difficult to find as time marches on. Gaskets will get difficult to find. Hard parts will fail as well... The older electronics I use at work have parts that I can't source anymore... these systems are less than 12 years old. Early TBI systems use ASIC chips and even some TTL chips that are no longer produced because of ROHS. The multilayer circuit boards inner layers can and do corrode. Whole CPUs were expensive new and there are limited numbers available because GM only made a small number of spares. I've actually moved ASIC chips from an LT1 CPU with a corroded circuit board to another with damaged chips. The need for this type of repair will become more common as supplies dry up.
Most folks like to do what I call "Shotgun" or "Hail Mary" repairs on systems they don't understand or are too lazy to troubleshoot. "when there's a problem your all most better off just replacing all those troublesome sensors on the throttle body" They're depleting the supplies fater than would otherwise happen. Some early sensors are already obsolete, for example the 1950s-1980 Nail-head temperature sender, with no perfect equivalent replacements. Temp gauges will still work with a less than perfect replacement. FI computers will need to be re-programmed to compensate or the vehicle mothballed.

[68c10owner]

Originally Posted by N2TRUX

Im here for ya brotha


In response to the carb fans, one thing your leaving out is its a dying fuel distribution source. I recently bought an 84 Sierra and noted that the carb seemed to be seeping a slight bit at the accelerator pump plunger. I'm mechanically inclined, but know enough about carbs to know I don't want to rebuild and tune one. For me, carbs and auto transmissions are parts that I would much rather find a professional to do it right.

I searched diligently trying to find someone that could do the job and was pretty dissapointed. Most shops just want to replace the carb rather than build it. I was looking at 700.00+ to do the job. I looked at buying a new or reconditioned carb, and they start at 450.00. The best solution I could find was an older gentleman thats retired, but agreed to build it. Labor starts at 300.00 and doesn't include hard parts. The only up side of this is the retired mechanic did offer some tips that may have resolved my issue.

My uninformed point is, carbs and the knowledge that it requires to tune or rebuild them is rapidly becoming a thing of the past. This Sierra shows 70k miles on it. Even if thats inaccurate, how many miles do you get from a carb before it needs a rebuild vs an injection system? How many places have the knowledge to diagnose, repair, or replace one vs the other?

Sorry Bigzz, not trying to muck up your thread. Congratulations on getting red back.

Check out Sean Murphy Induction. He builds the later model qjets. Not sure of his prices but from his reputation with Qjets I'd say it's worth what he charges.

[N2TRUX]

Originally Posted by 68c10owner

Check out Sean Murphy Induction. He builds the later model qjets. Not sure of his prices but from his reputation with Qjets I'd say it's worth what he charges.

Excellent information. If my quick fixes that were recommended dont do the job, it looks like Sean Murphy Induction might be my answer.

[68c10owner]

Originally Posted by N2TRUX

Excellent information. If my quick fixes that were recommended dont do the job, it looks like Sean Murphy Induction might be my answer.

There is also a guy on ebay who sells rebuild electronic Qjets but I would rather go through Sean Murphy. I plan to use one of his carbs on my 85 if I don't convert to efi.

[N2TRUX]

Originally Posted by 68c10owner

There is also a guy on ebay who sells rebuild electronic Qjets but I would rather go through Sean Murphy. I plan to use one of his carbs on my 85 if I don't convert to efi.

I looked at his rebuild prices and reviews. His cost for a stage 1 rebuild was 259.00 and includes the following-

Surface baseplate for flatness and glassbead for bright silver finish.
Install APT (ADUSTABLE PART THROTTLE) to allow adjustment of part throttle and cruise speed (steady throttle, 1800-4000 rpm) air/fuel mixture in seconds without any disassembly, tuning can be done while engine is running!
Apply epoxy to main body casting plug to eliminate common "leak down" problem associated with Quadrajets.
Install bushings in baseplate to eliminate any potential vacuum leaks at primary throttle shaft.
Assembled using the highest quality components, including:
High flow .130" needle and seat assembly.
Nitrophyl solid composite float that can't crack or sink.
Premium quality gaskets
High capacity accelerator pump featuring materials that are resistant to alcohol and other additive commonly found in today's fuel
1 YR warranty all parts and labor


He did have some negative reviews out there. What are you basing your decision on?

[68c10owner]

Originally Posted by N2TRUX

I looked at his rebuild prices and reviews. His cost for a stage 1 rebuild was 259.00 and includes the following-

Surface baseplate for flatness and glassbead for bright silver finish.
Install APT (ADUSTABLE PART THROTTLE) to allow adjustment of part throttle and cruise speed (steady throttle, 1800-4000 rpm) air/fuel mixture in seconds without any disassembly, tuning can be done while engine is running!
Apply epoxy to main body casting plug to eliminate common "leak down" problem associated with Quadrajets.
Install bushings in baseplate to eliminate any potential vacuum leaks at primary throttle shaft.
Assembled using the highest quality components, including:
High flow .130" needle and seat assembly.
Nitrophyl solid composite float that can't crack or sink.
Premium quality gaskets
High capacity accelerator pump featuring materials that are resistant to alcohol and other additive commonly found in today's fuel
1 YR warranty all parts and labor


He did have some negative reviews out there. What are you basing your decision on?

Your not going to find many companies that don't have some negative feedback.

I've never used them myself but many of the searches for qjet performance have included his name. A lot of guys on team chevelle use him.

[jokerz71]

From my experience, a person is more likely to leave a bad vs a good review.Most who receive good service or products, are less likely to leave a review than a person who feels he was let down & they want everybody to know how pissed they are about being taken advantage of.

[N2TRUX]

Originally Posted by 68c10owner

Your not going to find many companies that don't have some negative feedback.

I've never used them myself but many of the searches for qjet performance have included his name. A lot of guys on team chevelle use him.

Thats the input Im looking for. Forum groups tend to discuss a vendor more in depth, and quickly root out the bad eggs.

Originally Posted by jokerz71

From my experience, a person is more likely to leave a bad vs a good review.Most who receive good service or products, are less likely to leave a review than a person who feels he was let down & they want everybody to know how pissed they are about being taken advantage of.

I agree. When looking at reviews, I always throw out the top and bottom 10%. There will always be someone who will rant, and one who will rave. Somewhere in the middle is the truth.

[MikeB]

Originally Posted by N2TRUX

Im here for ya brotha

I'm mechanically inclined, but know enough about carbs to know I don't want to rebuild and tune one. For me, carbs and auto transmissions are parts that I would much rather find a professional to do it right.

I searched diligently trying to find someone that could do the job and was pretty dissapointed. Most shops just want to replace the carb rather than build it. I was looking at 700.00+ to do the job. I looked at buying a new or reconditioned carb, and they start at 450.00.

Carbs certainly aren't rocket science if you're mechanically inclined. Installing/replacing throttle shaft bushings (if needed) is probably the most difficult part of the job you would run up against.

Jon at The Carburetor Shop is THE BEST source for original equipment carb parts. He will also rebuild your carb, assuming it's original equipment and not a universal Holley or Edelbrock. I've been reading his posts on various forums for 10+ years, and he really knows carbs inside and out.
http://www.thecarburetorshop.com/

Also, if your carb is a Q-jet, there's a very good book out there written by Cliff Ruggles.