73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: rick_c on September 19, 2009, 11:02:28 pm
-
Hello again, been gone for a while...
Have an 82 swb, just built a 350 9.7:1 flats .030 over 4 bolt main 010 block.
A lunati 489/504 lift voodoo cam 268/276 duration, 1.5 roller rockers, untouched 76cc heads with 1.94/1.50 valves with 550 max lift springs, edel rpm intake a 1406 carb. Built a TH350 with a tci pump red eagle clutches koleen steels and a b&m stage 2 kit. Also a jegs 2200-2400 stall (that doesnt stall right). Oh and a melling high vol. pump (big mistake)...don't ever use one of those...I run 80psi at 1000 rpm! all my seals are starting to leak.
just so everyone knows where I'm at.
Ok so the problem I'm having is figuring out what gears I need to run.
I've always thought this truck had a 3.08 geared 10bolt.
i serviced the diff today and counted the teeth.
Apparently it is a 2.73? which I didn't even know existed.
With what I'm running, the truck runs okayish on the street, I can pretty much take anything in my neck of the woods except a couple of sleepers( a stroked 05 GTO, and a wrx with a huge turbo).
I can smoke the tire(no posi) on a 20 roll manually shifting it at about 6000rpm.(very fun!)
I can make the dotted lines blurry in 2nd gear going into third running about 6300rpm. Don't know how fast that is because the speedo stops at 85.
My question is, what gear would yall recommend to keep my highway running conditions but be able to tear up the street on take off?
Right now if I stomp on it from a stop it will spin the tire but it lags real bad.
I'm thinking a 3.90ish gear...if thats even possible with the low numbered carrier.
I hear the old heavy halfs had a factory 12 bolt 4.10 posi...
All advise is appreciated...Thanks
-
I personally would get a 3.42... Still decent rpm's when highway driving but should be a great improvement off the line.
-
Forgot about that gear...just wonder how much harder it would pull off the line.
I also have destroyed a new set of brute force u joints from shifting too hard I guess..
Is there a more heavy duty brand than that? Thats all we sell at auto zone
-
you got dura gold lol. well building that engine at the zone, i hope you didn't buy from them causes there probably investigating you right now the hole "shrink" thing .when you say it lags at take off what do you mean. if your spinning at 20 with a wot then i wouldn't go and lower than what you have, you will just being putting more money into the tires but i mean your running above 6k spinning and all i would eather invest in a posi about the same ratio or traction bars or better tires or all three. whats your 1/4 time? spinning ain't winning.
-
How about a 3.73 with a 700R4? A high volume oil pump won't make all your seals leak.
-
How about a 3.73 with a 700R4? A high volume oil pump won't make all your seals leak.
+1, make sure your PVC system is working properly.
-
Look for a 12 bolt rear, buy a posi, with the TH350 you have I'd go for 342 gears, 373 gears will be about 3000RPM at 70mph. forget about getting that GTO, and the WRX you might get him off the line but he'll be eating your lunch at half track.
-
A high volume oil pump won't make all your seals leak.
It'll just rob you of power and suck your stock pan dry at 6000 rpm.
-
If you have .0035" bearing clearance or more then a high volume oil pump is fine. If you have a high capicity oiling system then fine. Otherwise a standard volume pump is proven fine. A prelube system is a better investment.
-
you got dura gold lol. well building that engine at the zone, i hope you didn't buy from them causes there probably investigating you right now the hole "shrink" thing .when you say it lags at take off what do you mean. if your spinning at 20 with a wot then i wouldn't go and lower than what you have, you will just being putting more money into the tires but i mean your running above 6k spinning and all i would eather invest in a posi about the same ratio or traction bars or better tires or all three. whats your 1/4 time? spinning ain't winning.
Yea the duragold...bought all my stuff there kept the reciepts though.
The lag thing is I dont pull as hard off the line as I do if I'm rolling and stomp on it.
I guess that has to do with not being in the cam at take off.
I'm thinking about spooling the rear but I hear it annoying to drive with one.
Don't know the 1/4 time but I doubt its anything to write home about...the nearest track is over 100 miles away.
I wouldnt spin on the track like that I don't think. I'm doing that on asphalt roads that arent prepped.
Is there a u joint on the market that I won't destroy or am I stuck with changing them every 1000 miles?
-
The oil pump problem is weird...I thought it would be a good idea at the time, but I'm not happy. Maybe the motor will loosen up over time but right now at idle in gear I'm running 65psi when its warmed up when drive it under normal conditions it runs about 75 to 80 psi cruising around. my gauge stops at 80 and its pegged at full throttle.
I'm getting oil seeping into the valleys the center bolts on the intake go through.
The front seal is seeping and the motor only has about 1500 miles or so on it.
I think I need to check the vacuum too, but I don't know what it should anyways so that wont help me any. Unless someone here knows, and can tell me.
The GTO and WRX can suck it, I'm not wasting my gas on them.
-
The center two bolts on either side of the manifold need thread sealant or they will leak, regardless of your oil pressure. Apply this stuff (http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm) to the threads.
The front seal should have RTV applied to the outside of the metal shell before installing it. And that would also NOT be affected by oil pressure.
If your oil pressure were 150 psi, neither of these locations should leak.
-
I had a 2.76 open 12 bolt when my motor work (see sig) was done last May. I certainly didn't have the traction or u-joint problems you do but I've always felt my carb is screwed up and I just haven't done anything about it. My trans shifts HARD though on the 1-2, enough to (I think) cause the crush sleeve in my diff to keep moving around, wiping out 3 ring and pinions now. Anyway, it sounds like your have some power to play with and that's great. Not sure why you are having such u-joint problems though. Are you having any vibrations that come through the floor or seat? Does your trans shift pretty hard? Do you do neutral drops? Is your pinion to driveshaft angle appear to not be inline even closely?
I went from a 2.76 to a 3.40 to a 3.73 ratio. My 3.73s with 295/50-15 tires spins at about 3000 at 60 mph. Kinda high but that's about my tolerance limit. A 3.42 you might like.
As for traction on street vs strip, for some reason I seem to have more traction problems at the track.
-
The center two bolts on either side of the manifold need thread sealant or they will leak, regardless of your oil pressure. Apply this stuff (http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm) to the threads.
The front seal should have RTV applied to the outside of the metal shell before installing it. And that would also NOT be affected by oil pressure.
If your oil pressure were 150 psi, neither of these locations should leak.
Thanks for the info. Funny thing is we sell that stuff at my work, but I never thought to use it.
I used an aftermarket timing cover so I think the seal might be cheap.
Going to pull it off and change it to a felpro. I have to put a timing tab on it anyways
-
I had a 2.76 open 12 bolt when my motor work (see sig) was done last May. I certainly didn't have the traction or u-joint problems you do but I've always felt my carb is screwed up and I just haven't done anything about it. My trans shifts HARD though on the 1-2, enough to (I think) cause the crush sleeve in my diff to keep moving around, wiping out 3 ring and pinions now. Anyway, it sounds like your have some power to play with and that's great. Not sure why you are having such u-joint problems though. Are you having any vibrations that come through the floor or seat? Does your trans shift pretty hard? Do you do neutral drops? Is your pinion to driveshaft angle appear to not be inline even closely?
I went from a 2.76 to a 3.40 to a 3.73 ratio. My 3.73s with 295/50-15 tires spins at about 3000 at 60 mph. Kinda high but that's about my tolerance limit. A 3.42 you might like.
As for traction on street vs strip, for some reason I seem to have more traction problems at the track.
No vibrations that I've noticed unless I'm stopping because I cooked on of the rotors when a caliper stuck and havent replaced it yet.
The trans shifts hard enough that Ive replaced the rear pass side tire three times since April because I keep popping the belts. Was using BFG T/A radials but switched to Firestone indy 500 tires and havent broke one yet. 275/60r15 is the size Ive been using.
I never do neutral drops, and always make sure that I completely stop before going from reverse to drive... The pinion angle might be an issue under torque load because I had someone tell me that it looked like the pinion yoke goes down some when I take off. Don't know what would cause that though. I'll try to take a pic of it a try to figure out how to post it on here so yall can tell me what yall think.
BTW, you have a sort of similar setup to mine, so what is your timeslip?
Like to know ballpark where I'm at since I can't take it to the track...
-
Breaking tire belts from hard shifts? Wow, never heard of that before. It must give you a real kick in the seat. My truck has ran a best of 14.88 @ 93 but that was with the 3.40 ratio and a non-working posi. I was hoping to see some improvements with the new 3.73 setup but I keep wiping out ring and pinions before I get a chance to hit the track! There might be enough spring wrap happening to affect how your pinion to driveshaft angle is changing under load, but I'm no expert.
-
Breaking tire belts from hard shifts? Wow, never heard of that before. It must give you a real kick in the seat. My truck has ran a best of 14.88 @ 93 but that was with the 3.40 ratio and a non-working posi. I was hoping to see some improvements with the new 3.73 setup but I keep wiping out ring and pinions before I get a chance to hit the track! There might be enough spring wrap happening to affect how your pinion to driveshaft angle is changing under load, but I'm no expert.
That has crossed my mind..the spring wrap thing, don't know how to get the spring rate checked. Gonna call a suspension shop I know of and see what they say.
Thats not too bad on your time I guess, I'm hoping for 13's but based on that number I don't think I'll be there.
-
Hello again, been gone for a while...
Have an 82 swb, just built a 350 9.7:1 flats .030 over 4 bolt main 010 block.
A lunati 489/504 lift voodoo cam 268/276 duration, 1.5 roller rockers, untouched 76cc heads with 1.94/1.50 valves with 550 max lift springs, edel rpm intake a 1406 carb. Built a TH350 with a tci pump red eagle clutches koleen steels and a b&m stage 2 kit. Also a jegs 2200-2400 stall (that doesnt stall right). Oh and a melling high vol. pump (big mistake)...don't ever use one of those...I run 80psi at 1000 rpm! all my seals are starting to leak.
just so everyone knows where I'm at.
Ok so the problem I'm having is figuring out what gears I need to run.
I've always thought this truck had a 3.08 geared 10bolt.
i serviced the diff today and counted the teeth.
Apparently it is a 2.73? which I didn't even know existed.
With what I'm running, the truck runs okayish on the street, I can pretty much take anything in my neck of the woods except a couple of sleepers( a stroked 05 GTO, and a wrx with a huge turbo).
I can smoke the tire(no posi) on a 20 roll manually shifting it at about 6000rpm.(very fun!)
I can make the dotted lines blurry in 2nd gear going into third running about 6300rpm. Don't know how fast that is because the speedo stops at 85.
My question is, what gear would yall recommend to keep my highway running conditions but be able to tear up the street on take off?
Right now if I stomp on it from a stop it will spin the tire but it lags real bad.
I'm thinking a 3.90ish gear...if thats even possible with the low numbered carrier.
I hear the old heavy halfs had a factory 12 bolt 4.10 posi...
All advise is appreciated...Thanks
here is what i see...
your cam is toobig for your heads killing power
the torque conveter is little on the tight side ESPECIALLY wiht a 2.73 gears.
melling HV op .. they are in every motor i have all 3 sbc and both BBC i have.. never had a problem of draining a 5qt pan either.. at 7000rpm.. granted i make sure my drain holes are clean and free of obstruction... and my cleanace are mid-upper .020" on bearings. but thats me..
3.42 or 3.75 will be a good choice of gear.. with a 28" tire.
275/60/15 =28" tire
~70mph cruising wiht 28" tires and 3.73 is 3100rpm
~70mph cruising with 28" tires and 3.42 is 2900rpm
my 75 is runing with 32" tires and 4.10 is 3000rpm at the same speed.
2.73s are very much highway gearing.. not stop light racing...
and for the record i dont agree with racign on the street.
~6000rpm shift points with 2.73 and 28" tires and a th350 1st gear is 2.52:1 2nd is 1.52:1.. are as follows
1-2 is 73mph
2-3 is 120mph
-
Wow thats the info i've been looking for...whats the formula to figure all that out, so if I decide to change gears and tire size, i'll know what I'm looking at...
-
this ones is kind of a plug and play but it will tell you what you need to know
http://www.idavette.net/tech/ratioc.htm
this one is more of a chart tires vs rpms
http://www.4lo.com/calc/geartable.htm
-
this ones is kind of a plug and play but it will tell you what you need to know
http://www.idavette.net/tech/ratioc.htm
this one is more of a chart tires vs rpms
http://www.4lo.com/calc/geartable.htm
heres then formula that i use
gear ratio * tranny gear * 336 / tire diameter * mph= engine rpm
-
lol the formula use is
rpms x tire size / 336 / mph = ratio
http://forum.73-87chevytrucks.com/smforum/index.php?topic=10879.0
-
lol the formula use is
rpms x tire size / 336 / mph = ratio
http://forum.73-87chevytrucks.com/smforum/index.php?topic=10879.0
nice how you and re-argane a math problem right?
-
what
-
its algebra ;)
a+b=c
c-b=a
c-a=b
-
i don't have anyproblem with algebra just grammer and English ;D
but just look at that link i posted be low my formula it explains it all, it's dated February 08, 2009, 02:19:40
-
Here's some more if you ever need them.
http://conversiontrucks.net/Forum/index.php?topic=55.msg175#new
-
I aint too sure about all these equations...something is missing...DOLLARS...
it's all basically a function of dollars!
works EVERYTIME!
-
I aint too sure about all these equations...something is missing...DOLLARS...
it's all basically a function of dollars!
works EVERYTIME!
everything is possibly with then "cubic" dallor ;D
-
lol the formula use is
rpms x tire size / 336 / mph = ratio
http://forum.73-87chevytrucks.com/smforum/index.php?topic=10879.0
Based on that at 55mph I have a 3.13 gear...doesnt sound good to me.
Thinking a 3.55 will wake it up some if I can get that gear in my carrier.
-
it's probably a 3.08 maybe 3.23. but even if you step it up a little your still going to need better traction even more than b4
-
A guy here in town did pretty good with his hopped up 350 with Th350 and 3.42 gears. It made a big difference in performance and he said he wasn't turning crazy rpms on the highway either. I think you should try some sticky tires too. That truck I mentioned[with 2.73's] lost to a Hemi Ram by a good bit. He put the 3.42's and some sticky tires and came back and beat the Ram by a good bit. Maybe you could throw on some drag radials.
As far as that WRX...you're gonna need to keep up with him off the line. If he smokes you off the line, you're gonna need some rocket boost to catch him on the topend.
-
I've got a 77 heavy half, with a 12 bolt, and it isn'y posi... No idea what the ratio is