Converter really loose?
4.10's, 33's, 4l80e
4.10's, 33's, 4l80e
CK5
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Cooling System Overhaul - Stumped and Frustrated
- Thread starter dhcomp
- Start date
If it's needing to be in 1st gear while towing, I would think if it's NOT 4.10's, it needs them.
Edit: Just playing around, with 3.73's and 33's, in OD:
at 65MPH you are pulling 1851RPM's
50MPH=1424RPM's
4.10's actually don't make enough change to make a difference in my opinion, +~100RPM at 50MPH.
4.56's
65MPH=2263
50MPH=1741
Dropping 4.56's to 3rd gear would still only be 3000RPM at 65MPH.
With those RPM figures, if you've got 4.10's or 3.73's, I think the transmission is having to work a lot harder than it needs to, and that would explain it's temperature for certain. I would expect the engine to respond favorably as well if you were better able to keep up vehicle speed.
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black dawg
1/2 ton status
does it feel like a fairly high stall speed.
4xcrazy
3/4 ton status
4 core/row radiator, fan shroud in place, heavy duty fan clutch and 195* t-stat, never had any problems with towing in my Burb in the summer months out here, even up through the mountains.
if you haven't replaced everything with heavy duty components, due to your towing that much weight, I would, If you're still having issues with overheating, I would suspect something inside the motor, possibly a slight head gasket leak or something.
I had a head gasket leaking on the original engine in the Burb for quite awhile, just enough to lose coolant, but not notice it coming out of the tailpipe. It did get warm on some days, but still never overheated mainly because of the bigger radiator and especially that heavy duty fan clutch, those things work hard. May drop a mpg or two, but it keeps things cool.
Not a pro with cooling systems, but living in Phoenix desert for the past 25 years and dealing with cooling issues on just about every car I have owned, the only solution I could come up with, was extra capacity and heavy duty everything. Always works.
if you haven't replaced everything with heavy duty components, due to your towing that much weight, I would, If you're still having issues with overheating, I would suspect something inside the motor, possibly a slight head gasket leak or something.
I had a head gasket leaking on the original engine in the Burb for quite awhile, just enough to lose coolant, but not notice it coming out of the tailpipe. It did get warm on some days, but still never overheated mainly because of the bigger radiator and especially that heavy duty fan clutch, those things work hard. May drop a mpg or two, but it keeps things cool.
Not a pro with cooling systems, but living in Phoenix desert for the past 25 years and dealing with cooling issues on just about every car I have owned, the only solution I could come up with, was extra capacity and heavy duty everything. Always works.
I think you've got the wrong OD ratio for the 4l80e. I run about 2k at 55mph.
Either way, 4.56's would be better, but my highway cruise RPM's would be too high. I know, its a "have your cake and eat it too" scenario.
Guess more power is the ticket. Back thinking about 6.0's.....
Torque converter is stock stall speed.
OD on the 4L80E is .75. I used the bottom calc here, do you get different? http://www.csgnetwork.com/multirpmcalc.html
33" tires, 65MPH, .75 trans ratio, 3.73 gears, I get 1851.
Even with 4.10's @55 I come up with 1700RPM. You say 2000RPM @ 55MPH, ~300RPM is torque converter lock/unlock difference normally...
33" tires, 65MPH, .75 trans ratio, 3.73 gears, I get 1851.
Even with 4.10's @55 I come up with 1700RPM. You say 2000RPM @ 55MPH, ~300RPM is torque converter lock/unlock difference normally...
Hm, wonder what is off. Its supposed to be .75, as you used.
With torque converter locked, i'm closer to 2k at 55 then 1700.
Edit: I'm getting the same data at 4lo.com
Who knows what's going on, but maybe i'm an idiot. Maybe its 65 at 2k. That sounds a lot better. When was the last time i went 55
Sorry for the confusion.
No, no worries, just wanted to be sure.
I'd like to hear from some other folks that tow fairly heavy loads, but it would seem to me that if you are bogging down that much on a climb, you aren't geared steep enough. 3000RPM I don't think would be excessive on a small block for climbing.
I'd like to hear from some other folks that tow fairly heavy loads, but it would seem to me that if you are bogging down that much on a climb, you aren't geared steep enough. 3000RPM I don't think would be excessive on a small block for climbing.
Whats weird is how much this TBI 350 doesn't like to Rev.
The 350TBI in my 94 blazer would pull at 3k+ all day long, and would rev til 4700, 4800, 4900 before shifting at WOT.
This one doesn't rev much over 3-3500, ever. Dont' quote me on those numbers, but it revs WAY lower than the 94 did. If i could wind it up more, i'd be able to pull grades in 1st at a higher speed, or in 2nd.
How do other people's 350's with 4l80e rev? Wonder if whatever motor i have isn't a stock cam.
Should probably check the ID plate on the block...and see if i can figure out WTF crate motor is in there.
The 350TBI in my 94 blazer would pull at 3k+ all day long, and would rev til 4700, 4800, 4900 before shifting at WOT.
This one doesn't rev much over 3-3500, ever. Dont' quote me on those numbers, but it revs WAY lower than the 94 did. If i could wind it up more, i'd be able to pull grades in 1st at a higher speed, or in 2nd.
How do other people's 350's with 4l80e rev? Wonder if whatever motor i have isn't a stock cam.
Should probably check the ID plate on the block...and see if i can figure out WTF crate motor is in there.
You can change WOT shift points in the ECM.
Hm. This is the same shift points before the "performance" rebuild though, so i figured they are stock.
Who knows....
Does it shift differently while towing? I wouldn't think anyone had changed the factory chip.
Does it just run out of power, or start running poorly as the RPM's get up there?
Line pressures were increased physically and electronically. It shifts way firmer than it did stock, both loaded and unloaded.
When i had it built, i said make it shift firm, and something along the lines of " I've never driven an auto that shifted hard enough". Well, i was back in there the next week to have him tone it down
Still feel the springs wrap when the thing shifts under load though. I can be sure that i'm generating NO extra heat from slipped shifts.
How many miles are on the motor? You say crate motor. Has it been changed that you know of?
Hard to tell what it would run like above 3500, as it shifts shortly after that. If not at 3500, at 4. I need to go wail on it, and remember what it shifts at.
It doesn't have much power in that high range at all though, where in my 94 it felt like peak power was in the 2500-3k range.
black dawg
1/2 ton status
My burb stock 91 tbi 350/th400/3.73 gears, I would have to turn 3500 or better on long grades (6-7% pulling 6-7k) to get any power out of it. It would pull to 4 grand, but I really hated even having to turn it 3500 wot for several miles. (NO coolant temp problems and under 230 for trans temp)
This is the reason I went TBI454, and now it will pull the same load at 2500-3000rpm without going wot. Towing mpg increased.
Thats good info right there, thanks. I need to figure out WTF motor i've got.
Don't anyone search the forums for how many times i've said that...
Thats good info right there, thanks. I need to figure out WTF motor i've got.
Don't anyone search the forums for how many times i've said that...
Check timing too. If too much it will run hot. Be sure to disconnect that wire when you do.
black dawg
1/2 ton status
MY post kinda made it sound like I could accel to those (with the tbi 350) rpms. Basically it will hold its own down to 3500, but any slower and I would have to slow down and down shift to first.
Even with the 454, I am considering lower gears. Probably 4.56. gotta get an overdrive figured out first though. With a 4l80 I would go 4.56 in a heartbeat.
Even with the 454, I am considering lower gears. Probably 4.56. gotta get an overdrive figured out first though. With a 4l80 I would go 4.56 in a heartbeat.
