[turchiac]

Hi i have an 86 fullsize bronco with a rebuilt 351w engine. performer manifold, 600cfm edelbrock carb, comp xtreme 4x4 cam (1,000-5,000rpm) headman elite headers and true dual 2 1/2" exhaust. I advanced the timing until the starter started kicking back, then i backed it off just enough where it would start normally. Truck has 33x9.50 tires with 4.11 gears and stock/rv converter. The problem that i'm having is the truck has zero power. The truck is horrendous, literally. I know its a big heavy truck, but my 100% stock 90,000 mile automatic civic absolutely destroys it in acceleration. There has to be something wrong somewhere, it starts fine, idles smooth. So while trying to figure out the problem i remembered installing the torque converter without filling it with fluid, would this maybe damage the converter and be a possible cause for my problem? Trans shifts fine and doesn't shutter, fluid is bright red. Engine was put together by a reputable shop who knew the engine would be in a truck, so i don't think they put the cam in retarded? Im confused? would the torque converter be a possible culprit? Thanks.

[Mertz]

Been there done that. Going to smaller tires will help. If your tires are bigger than stock it will change the rear gear ratio.

Check this site out
http://www.wallaceracing.com/gearcalc1.php

And this
http://www.wallaceracing.com/gearcalc1.php

http://www.f-body.org/gears/

You also need to check the stall on your converter.

I have two threads on here now that deal with this subject.

[turchiac]

Thanks for the reply Mertz, i understand about the gears. The stock gears were 3.50 with 29" tall tires, when i had the engine and trans rebuilt i switched to the 4.11 gears to compensate for the larger tires. I would like to keep the 4.11's if i could to keep my rpms down on the highway, that is why i didn't go with 4.56's. With the 4.11 and 33" tires my effective gear ratio is 3.61. So with the engine rebuilt with cam, headers, manifold, four barrell i would think it should be able to get out of its own way. I mean this truck moved around better stock. Still confused.

[Mertz]

I am out of my element here but I think you also need to match the cam to the converter. If the cam makes power at very high rpms and the converter stall is low there would be a problem.

I will watch this thread and see what the experts have to say. Keep us informed if you figure this out.

I would think that with my exceptionally tuned 350 with 4.10 gears I would burn rubber anytime I want but it just doesn't. I am going to smaller tires in the rear and see what happens. I have an 1800 stall.

[turchiac]

The cam is a comp X4250H 4x4 cam, duration @50 is 206/214 advertised duration of 250/258 valve lift 448/483 lobe separation is 111. I figured i could use a rv converter with this, i wonder if a slight stall might help? but it is a pretty small cam.

[turchiac]

I recently had the gears swapped to 5.14 in the rear and 5.13 in the front. This helped somewhat but the truck still seems to lugg around. Would a 2,500 stall be too much for this setup? Truck is used only in winter to go to work (about 6 miles each way) so deep snow is the terrain it will see mostly, no rock climbing or trails. The current converter is an RV unit seems to stall around 1300rpm. Thanks

[tnsmith10]

if the cam you have is rated from 1000-5000 rpm, the problem is not the converter, as a stock stall c-6 converter is roughly around 1400 rpm as it is.
as far as the engine is concerned, is this the origional engine thats been rebuilt? or a whole different engine?
what the compression ratio of the engine?
as far as the converter not being prefilled, its not necassary to prefill the converter as its the 1st thing that gets fluid once the engine is running. c-6 converters, even though they do fail, they rarely do.

[turchiac]

Engine was the original motor, 351w HO originally rated at 210hp 305 ft lbs, it has 8:5 compression. Runs smooth and starts right up. Just feels really weak, especially with the steep gears.

[Chazmac]

Your converter is too tight. Get a street/strip or street stall converter so that you can let the engine breathe.
Check it out this way: Get the truck up to or over 40 MPH. Mash the accelerator to the floor. You must get kickdown or the test will fail. Assuming kickdown, if the truck jets and moves like you expected, your converter is too tight for the cam. With 5.14s in the truck the engine should be well past the converter stall effective range.
If it doesn't go like a scared dog, you have engine problems.

[turchiac]

With the 5.14 when the truck is moving along at 30-40mph and i kick it down, it moves pretty good. Its when i hit it from a dead stop that it doesn't feel strong or when using normal part throttle acceleration, this is when it seems as though i have to push the pedal harder than needed to get the truck moving. TCI recommended there breakaway converter 441001. I already have a trans cooler, would this help that much with initial take off and part throttle acceleration?