motor questions

[scejmer]

when i bought this truck it needed alot of work, the motor was supposed to have been just gone throw, it seems to have decent power off the line and mid range, seems to fall off on the top end, as for gears all i can say is the speedo is off about 15 mph. and dont now any specs on motor, edlbrock intake and carb, headers, full exhaust.i am looking for something i can drive every day but still have power when i want it, probly going to pull a trailer with it, and play on the dunes, has 35 on and th350,does anyone have a good combination to use or are using with results,

[Yukon Jack]

I'm guessing the gears are 3.73's and that is the problem. An easy way to check your gear ratio is to mark a line on your tire and driveshaft. Have someone move the truck forward very slowly so you can count how many times the driveshaft turns for one revolution of the tire. About 3 revolutions of the driveshaft will be 3.08 gears, 3 3/4 revolutions of the driveshaft will be 3.73 gears, a little over 4 revolutions will be 4.10's.

Doing it this way rather than jacked up makes it a little easier as you don't have to know if there is a locker or posi in the diff.

4.10 or 4.56 gears should keep the engine more in it's power band.

[jaros44sr]

I have a pdf file on Dana, if you give me numbers off the top of your axle tube I can run them for ya. Doen't mean someone didn't change the gears, but it will tell ya what came with your Dana

[truckster]

Originally Posted by Yukon Jack

I'm guessing the gears are 3.73's and that is the problem. An easy way to check your gear ratio is to mark a line on your tire and driveshaft. Have someone move the truck forward very slowly so you can count how many times the driveshaft turns for one revolution of the tire. About 3 revolutions of the driveshaft will be 3.08 gears, 3 3/4 revolutions of the driveshaft will be 3.73 gears, a little over 4 revolutions will be 4.10's.

Doing it this way rather than jacked up makes it a little easier as you don't have to know if there is a locker or posi in the diff.

4.10 or 4.56 gears should keep the engine more in it's power band.

Not that I want to start an argument, but it seems to me that if he has good power off the line but it falls off at higher speeds, he's probably going to have less power with 4.10 or 4.56 gears on the highway. The higher ratio gears would help more off the line.

I'd probably look at the points, do a good tune up, etc.

[Chevyman63]

Originally Posted by truckster

Not that I want to start an argument, but it seems to me that if he has good power off the line but it falls off at higher speeds, he's probably going to have less power with 4.10 or 4.56 gears on the highway. The higher ratio gears would help more off the line.

I'd probably look at the points, do a good tune up, etc.

I was kind of thinking the same thing...maybe even a carb rebiuld.

[vtblazer]

Originally Posted by scejmer

when i bought this truck it needed alot of work, the motor was supposed to have been just gone throw, it seems to have decent power off the line and mid range, seems to fall off on the top end, as for gears all i can say is the speedo is off about 15 mph. and dont now any specs on motor, edlbrock intake and carb, headers, full exhaust.i am looking for something i can drive every day but still have power when i want it, probly going to pull a trailer with it, and play on the dunes, has 35 on and th350,does anyone have a good combination to use or are using with results,

Your starting off just guessing by only looking from the outside.
You need to figure out what heads, cam and compression ratio your currently running and work from there.

Asking for a daily driver, tow rig, dune runner all in one package is asking alot.

Although being in somewhat the same boat, I'll tell ya where I'm at.

I'm going to run a 355 crate motor with a stock TBI set up and serpentine belt.
(dependable and simple)
700r tranny for the .30 overdrive and 3.06 first gear.
Dumping the anemic 1.96 205 T-case for a 241 which has a 2.72 reduction.
Then running a set of 4:56's with 36" rubber.

This combo will net a 1st gear crawl ratio of 76:1
(very good considering no doubler)
Highway travel is also very good being it will run right around 1900rpm's @ 65mph.

May be more than you were looking to do but if your wanting to do it all, ya gotta spend the bucks.

[Chevyman63]

Originally Posted by vtblazer

Your starting off just guessing by only looking from the outside.
You need to figure out what heads, cam and compression ratio your currently running and work from there.

Asking for a daily driver, tow rig, dune runner all in one package is asking alot.

Although being in somewhat the same boat, I'll tell ya where I'm at.

I'm going to run a 355 crate motor with a stock TBI set up and serpentine belt.
(dependable and simple)
700r tranny for the .30 overdrive and 3.06 first gear.
Dumping the anemic 1.96 205 T-case for a 241 which has a 2.72 reduction.
Then running a set of 4:56's with 36" rubber.

This combo will net a 1st gear crawl ratio of 76:1
(very good considering no doubler)
Highway travel is also very good being it will run right around 1900rpm's @ 65mph.

May be more than you were looking to do but if your wanting to do it all, ya gotta spend the bucks.

Wow Kurt...my response was a lot easier.

Good info, you've obviously done your homework!

[scejmer]

i guess what is going on, is it takes off good from a stop, but doesnt seem to want to want to string a gear, tach up if you will. thats when i was wondering if that was how it was built, rv style cam motor possibly. it runs good on highway 90 mph, but i havent had a chance to run in low lock yet, as for the heads, cam, timing, pistons ratio, i was thinking the same thing, i guess i could dial indicat the cam to find lift and deration, do a comp check and go from there.

[old man jimmy]

When you say "It doesn't want to tach up through the gears" Does it fall on it's face like it's running out of gas? If so the floats in carb. could be set too low. Or could be a fuel pump or filter problem. When your foot is in it, and all four barrels are open, it's going to take fuel to keep it going. Need more info. on what it is doing. Or if it's back firing when it falls down. Or if it kinda sounds like a jake brake. Could be many things.

[OLD SKOOL K5]

I think VTBLAZER is on the money, if you want it all you have to pay! It you want to go low budget start with the simple stuff. what about the kick down cable? is it sedt right so it kicks down to 2nd gear to give you that added umpf?