LUVTruck.com

This is again on the 80 model Luv 4 wheel drive. I had the high RPM miss and double checked vacuum lines, timing and everything else and somehow eliminated it by rechecking things. My questions are at this point I do not have an exhaust system on the truck - I'm running straight off the header going down the road it will sometimes pop back a little bit. Is this normal or is it running a little rich because of no exhaust system. It idles good, cranks good, just need more information. Also, I've read on there that the gears on the 4 wheel drive model are 4.56 to 1 and also in the Haynes/Hayes repair manual lists it as a 4.56 to 1. Has anybody nailed that down to be true? The reason I ask I know the speedometer is going to be off because it has 31X10.50X15 inch tires. The best I can get out of the speedometer is about 50 miles an hour. How fast should the thing run? I know this is lengthy, but one more question. Has anybody ever used one of the chrome open sided air cleaners on their Luv truck 4 cylinder. Since there's no bolt coming up from the center of the carberator, what do you do in that case?

Thanks alot for all your information. We could not have got it running without ya'll's help.

804X4

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A 1980 luv that chevy 4x4

No exhaust system can cause a bunch of odd things. (Besides hearing loss...) It might be the source of your trouble. These little 4 banger Isuzu motors do run better with something behind them for exhaust, especially in the low end of the RPM range. I've never run one for very long dumping right out the manifold or header, so I'm not sure exactly what kind of difference we're talking about here.

I don't recall ever seeing anyone post here that they did an actual check of the ratio (turn the yoke and count wheel revs). Somewhere I have a rear axle that came out of my 77 with different gearing though. The truck came with an auto trans(which I yanked out) and the pinion bearing went on the original rear. When I replaced it with one from a stock stick shift truck, I could tell the difference in the gearing. SO... yeah there are really different gears for different models, but I'm not absolutely sure what is in the 4x4s.
31" tires should put your speedo somewhere around 12-15% off, maybe a bit more. So at a reading of 50, you're probably doing something like 57-58. My 4x4 with ~28-29" tires is just about dead on 10% off. 50=55MPH. Find a speedo check zone on a nearby interstate, or one of those mobile speed displays the cops put out to show you're going too fast. Topping out at 50 seems like you might have a problem somewhere. My tires aren't that much smaller and I can get 70-75 on the speedo(80+ in reality), and that is with a motor that hasn't had anything major done for it in the last 10 years.
Finally the air cleaner bit. The stocker is held on with a pipe clamp sort of deal around the carb neck and bolts to the valve cover. In order to use something that is setup for a through center bolt, you'll have to get creative and fab something up. Personally, I'd just buy a K&N filter for the stock cleaner. If you're trying to dress it up, sand the stocker real well and shoot it with some paint to match your tastes. Just stay away from the hobo chrome.

my luv has 31x10.50 on it also.and have been clocked doing 60 when the gauge said 50.

The rear and front diff. ratio in a 80 4x4 is 4:10.

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1980 4X4 LUV

I had a problem just like that, buit come to find out it was my coil. I dont know if it was an original coil but it was finally toasted, I would get up to like 50 or so and it would start popping and backfiring and kinds of embarrassing crap! just my two pennies
Later
Husker

Good point Husker, weak spark in general (coil, dizzy, points, condensor, wires, or plugs) could cause lack of power in the higher RPMs but seem to run perfect at idle.

luvmuddin: 50MPH on the speedo is the perfect number to check. We can double the 60 to 120 and and that is the percentage of the speedo reading that is reality. If that 60 at 50 is dead on accurate, you can just take your speed as 1.2 times what the speedo reads, mileage on the odometer too. For every 100 miles of odometer, you went 120. For Every 10 on the speed, its 12. 20 is 24, 30 is 36, 40 is 48, and 50 is 60. Seems a little high to me, but I've never had tires bigger than the 235/75/15s I have on now, so I might be underestimating.

The high RPM misses are usually indicative of some sort of a distributor advance issue. You say you checked the vacuum lines and timing and it went away. Have you looked into your carb being part of the culprit? If timing is verified as being good and the vacuum advance on the distributor has been ruled out, then I would definately be eyeing my carb. Sometimes, especially at higher RPM misses, its hard to tell whether its the carb or the ignition system.

I upgraded my LUV ignition to a Crane Cams XR3000 electronic. You keep the same distributor but can toss the points/condensor junk. Let me tell you, $100 later and it starts faster, runs smoother, has more power, and I NEVER again have to worry about replacing or adjusting points. LUVs have Nippon Denso distributors and they are supported by the Crane ignition system. You need a coil that can support the higher voltage and electronic system, but again, small price to pay. Its easy to install too, you might want to look into it. If you decide to do it and need help or more info, let me know and I'd be happy to help.

With running at this time with no exhaust system, just straight out of the header it's hard to tell about a miss because of the noise. Cranking is fine, the carberator was almost new on the engine when I got the thing. Tell me about the resister that is attached to the side of the coil. Could it be bad or what does it do? Would a standard coil fit and I keep the resister on there or do I have to have a special coil. I just know that when the speedometer is reading around 50 mph the engine is turning a good many rpms - I don't have a tach on it.

Again what do you think.

Thanks alot.

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A 1980 luv that chevy 4x4

My understanding of that resistor is that it is called a ballast resistor and is necessary from keeping the coil from overheating due to an influx of high voltage when it doesn't need it. There is a relay that is supposed to override it when necessary and provide full juice to the coil. Again, if you update your ignition system you can pretty much toss that by switching to a coil that is internally resisted. Mine was broken anyway...

The resistor on the coil is used to lower the voltage through the points so they don't burn. If you eliminate the resistor, your points will burn up in a very short time.If you have a problem with the points depositing metal on one side or the other, forming a peak, the capasitor is bad or of the wrong value. It is used to absorb the DC current to prevent arcing of the points.

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1980 4X4 LUV

Woohooo Husker learned something new today !!!!!

Thats only true in automatic transmission 4x4's. In a manual tranny 4x4, the gears are 4.56.

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Currently no more luv's... But in search of one!

Well seeing as I have had mine apart and the ratio IS 4:10. I can count. I have understand that other 80 Luv4X4 owners said theirs was 4:10. The books you read are not always correct. Have you had the diff apart in your Luv? Maybe the ratio is different for the 79s.

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1980 4X4 LUV

There were NO automatic 4X4

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1980 4X4 LUV

There were too automatic transmision 4x4's. I almost bought one.

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Currently no more luv's... But in search of one!

I have a 79 4x4.... ratio is 4.10.

is it an automatic or manual?

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Currently no more luv's... But in search of one!

Manual.

i have a solution for a custom air cleaner for the stock carb. the stock aircleaner clamps around the carb. this part on the carb measures 3in. i had one of those custom cone air filters that u see on imports and it fit right on. the only problem is the hood won't shut. i looked on ebay and they have mushroom shaped foam filters that should fit they have a 3in. fitting and just clamp on with a hose clap. i haven't tried this but am going to if i can't get a weber.

I looked in my FACTORY shop manual. It states that only 4X4 were available with only manual trans and 4:10 ratio. The 2 wheel drive had the option of a Turbo Hydramatic 200. and either 4:10 or 3:73 rear ratio. Maybe you saw a truck customized with an aftermarket conversion.

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1980 4X4 LUV