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troubleshoot: hard to accelerate truck.... still

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by R72K5, Jan 8, 2003.

  1. R72K5

    R72K5 Banned

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    troubleshooting posts are one of the worst types of posts in my opinion, but i have to post one cuz im stumped, so read this only if you can stand posts like these lol


    oK i recently swAPped 305 out OF the 81 iN favoR OF a nICe 350 because of real problem trying to accelerate even from a dead stop even after swapping timing chain carb and dizzy

    still havingt hard time getting truck to get moving and is still making popping when try to get it to go a little more than taking basically a whole block to get it up to 30 or 35 mph

    i originally also thought maybe plugged up cat or stuck torque converter but now ive got headers and 2.5" duals and a brand new converter so.,,,,,,,,

    rear axle ratio of 2.73 cant be helping much, is a really crappy low rpm ratio to have but am unsure if the 3.73 14 bolt is gonna help this problem or not.

    popping out carb indicates to me that firing position is too soon or cam is too late but they arent, ive been through all that and ive timed a zillion chevy engines without a hitch in the past, its cakewalk to do this, thats why i dont get this..

    theres gotta be soemthing ive been overlooking ever since even before swapping engine out but no clue what that could possibly be

    the engine makes that kinda chugging like when engine is cold and not enough choke/too lean mixture, the carb is a remanufactured 454 Qjet in good shape

    im lost


    thanks for any ideas or suggestions and for your time
     
  2. 74Chev

    74Chev 1/2 ton status

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    Sounds like the distributor is fawked. I can almost guarantee that is the problem. Either the shaft is very worn or the advance weights and springs are screwed up. Check it over closely. I would recommend just getting a stock HEI from the dealer or whoever. I don't think those super high dollar ones are worth the money. I just use stock GM dist. on both my rigs with no problems.
     
  3. R72K5

    R72K5 Banned

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    i dont believe in aftermarket dizzies either, i always run GM i really dont see the need to run anything else cept maybe different advance curve, unless are really on the race track or something serious

    its 1 vote for dizzy so far

    thanks /forums/images/graemlins/laugh.gif
     
  4. wrathORC

    wrathORC 1/2 ton status

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    Keep the timing light on it and watch the advance curve as you bring up the RPMs. It might have problems.

    If you've got it timed at cylinder #6's TDC then you can get similar symptoms but you said you know what you're doing.

    You are using the right ignition control module, right?

    Take a look at the spark plugs. They can tell you if it's a carburetion problem.

    If you decide to get a distributor get one from an older truck. Preferably the no-bullshit HEI with the 4 pin ICM (no smog-inclined computer controlled timing).
     
  5. R72K5

    R72K5 Banned

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    its had non EST dizzy in it ever sicn ei swapped out the original EST oen out of the original engine thatw a sin the truck.

    i just got done swapping out dizzy again for another non ECM dizzy and its runnign strong and correctly now, ive got three different modules around, Standard, Wells, and GM(old dirty) the dizzy i just swapped out had a Standard one and the cap is Standard brand also currently


    so far so good not a single misfire yet and i can hit normal RPM range now, i just didnt beleive it could be dizzy after swapping it out already, hmm... glad its not the carb though, or anything else for that matter, i got to a point where i was tired of trying to guess and swapping out components, you know how that goes sometimes,..

    i do stil have to add that 2.73 gears are complete crap though, hard on the tranny if you drive loaded downa nd if you try to drive truck like it has lower ratio axle, still debating on either 4.56 locker dana 60 or 14 bolt ff 3.73 swap, either would really wake up the truck.
    i used to have a 68 c-10 with 3.73 and th350 and 355ci and the thing would flat out lift up and move! so.... i strongly stay with the belief that axle ratio is what mainly makes the vehicle.. as far as performance goes.

    both that 355 and this 350 i put in the 81 have stock iron 4bbl intakes and roch q jets and gm HEI, but this 350 has headers and duals and the 355 only had 60's 2" exit ram horns and duals, the 68 weighed 3850, the 81 i dont know yet, i need to go weigh it, im gonna call gravel pit and see if i can have weighed

    anyone know weight of a FF D60 or FF 14 bolt ?


    thanks
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    the 68 weighed 3850

    [/ QUOTE ]

    Are you kidding me? Holy crap thats light, thats almost the same weight as GM's mid size 80's cars! My '86 K5 comes in at 5000 even.
     
  7. 90K5

    90K5 1/2 ton status

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    Did you have the Wells module on there when it didn't run right? I've found that wells is total crap, anytime one of their parts is on my or anyone else's truck, it doesnt run right, once its swapped out for something non-wells it is good
     
  8. wrathORC

    wrathORC 1/2 ton status

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    It could've been the control module. I keep an extra in my truck along with some paste.

    2.73s do suck. With 33s overdrive is useless. Even with my 235s I run in the winter time they're iffy. I think 3.08 would be perfect for 235s.

    The nice thing is that with 2.73s your spider gears will go AWOL before the ring gear will spit teeth. Not that I know from experience or anything. haha.

    I think 4.11s would be perfect for 33s and a 700R4. I've got a 3.73 14FF waiting for me though.

    My truck weighs 4400lbs on 31x10.50s fully loaded. That includes a 235x75r15 spare tire, 40 gallons of gas (~300lbs), two batteries, a bedmat (~70lbs), and 80-100lbs of survival junk behind the seat. With one gas tank 1/4 of the way full, the bedmat, one battery, no spare tire, and only an ammo can with tools in it behind the seat my truck weighed just under 3900.

    I suspect the 14FF weighs around 375lbs. My back complains when I pick mine up. Perhaps someone else knows how much they really do weigh? I just know they make a 10bolt feel like a twig.
     
  9. R72K5

    R72K5 Banned

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    yeah the CST era trucks were alot lighter, im unsure of the shorter era before that, 80% of all the models of 67-72 trucks weighed in well under 4,000#, i can get specific info on most models- 4x2 and 4x4 both- of the era
     
  10. R72K5

    R72K5 Banned

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    this one had a Standard one on it, i have other dizzies with wells ones on them, after much research i have found that brands such as wells were manufactured by Dana Corp, they also make the vacuum advance units too, plus zillions of other components,

    I found info that Eaton Corp bought out Dana Corp, cant find the page now, hmm...... wonder who will make em now, Eaton ?
     
  11. R72K5

    R72K5 Banned

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    probably could have been since the shaft of the other dizzy didnt have any more side or end wear than in the dizzy i replaced it with,

    2.73 just flat out s*ck, i hate them, if i dont sell truck then i want to get either the 4.56 or 3.73 axle under it, i could care less about fuel economy or highway rpm, tire size increase can help offset that, only has 29.5" tall on it currently, so,, bad with 2.73 though, lug lug lug lug..

    thanks@
     
  12. JakeInAZ

    JakeInAZ Registered Member

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    Well, it's my personal opinion that you're putting too much stock in gearing. I have the the stock original t/c, rear end (posi lock), and transfer case pushed by the run of the mill TH350 tranny and I have NO problems. I run 32" BFG's and can still roast them off (even with posi-lock) from a standstill. Granted, gear ratios can definately make a difference but if I can run mid 15's in a 4,500 lb blazer that's completely stock other than the built 350 and a custom rear driveline then there's definately more to get up and go than gear ratios. Again, just an opinion and I don't expect agreement....but I speak from my own experience. If a 2 ton blazer with 31 gallons of gas and 4 passengers can keep up with a camaro then it's obviously not all about gears.
     
  13. R72K5

    R72K5 Banned

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    you running 2.73 ?
     
  14. wrathORC

    wrathORC 1/2 ton status

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    What is your stock gearing though?

    There is a gigantic difference between just 2.73s and 3.42s... and 3.73 makes even more of a change. We're talking turning 1500rpm in overdrive with 2.73s and 235 (29") tires at 60mph and turning 1500rpm in overdrive with 2.73s and 33" (32.1") tires at 70mph. That's a big difference. I don't know about you but my truck doesn't make many ponies at 1500rpm and not much torque either.

    Let's say you stick with the 33" (32.1") tires and switch to 3.73 gears. We're talking turning 2100 rpm at 70mph in overdrive. That's enough rpm to build enough torque and horsepower for most 350s to overcome the barn door aerodynamics and maintain overdrive.

    Of course, if you don't have overdrive then it's not as big of an issue for cruising.


    But gears still make a large difference in city driving. The difference between 2.73 and 3.42 can be enough to improve fuel economy since you don't always have your foot in it.

    I can do peg-leg burnouts with my 2.73s without trying... but that happens to cause spider gears to grenade. I can beat a 5.4L Ford easy and I've beaten a couple 5.3L-equipped Chevys but still... they are more driveable than my truck with the obnoxiously tall gears.

    To quote my Dad (who has an 89 pickup) "I have 33s with 3.42s, TBI with 200 horses, decent aerodynamics, and the truck is a dog. You have 33s with 2.73s, a carburetor, and barn door aerodynamics. You must have some beefy squirrels workin' overtime under the hood to get around as good as you do."
     
  15. JakeInAZ

    JakeInAZ Registered Member

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    Ok, I'm running 2.73's to begin with. I will agree that gears do make a difference but they are just a percentage of overall performance, torgue, and speed. I'm pushing the beast with a 5.7L 350 that does have a lot of work done to it. It's a 79 4 bolt out of a Cheyanne (as far as I know). Aluminum Edelbrock heads, RV cams, 750cfm Edelbrock performer carb, edelbrock performer intake, ram horns (because headers are a hassle to maintain when off-raoding), 3 inch Edelbrock exhaust with dual chamber flow master muffler, Edelbrock pistons, and zero emissions. There are only 2 main vaccum lines and those are for tranny and for breaks, I removed the A/C (that was destroyed during exhaust upgrade), I only run two belts, high flow Edelbrock water pump and high performance ($87 a set) wires with platinum plugs. I also found great success in changing my oil weight....rather than standard 10W40 I switched to Mobil 1 Super Syn. 15W50 oil which produces consistant performance in almost all conditions and also burns a lot less oil. The tranny is your run of the mill TH350 auto 3 speed w/o overdrive but with a shift kit. I don't know the exact horsepower, but knowing that the engine (pre-modified) pushed around 165 horses, I'm sure I'm up near 200 easily. I would definately like to have a better gear ratio but all I am saying is that you can still pull a lot of power and torgue out of the stock 2.73's (though I will admit that I tore up two stock drivelines and 4 sets of U-joints before stepping up to a custom 3 inch, 3/4 ton driveline with adapted 3/4 ton u-joints)
     
  16. wrathORC

    wrathORC 1/2 ton status

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    As long as it has a good cam in it you're closer to 300 horses than 200.

    I have a 4 bolt LS9 motor out of a HD 77 C20 making 175 ponies stock. It's got an obnoxious cam in it that doesn't start making any horsepower until the 1500rpm mark and won't idle smoothly below 850rpm. I still run the original heads (with 194/150 valves) and the original dual plane intake (witch is non-EGR and not equalized). The only smog on the motor is the evaporative system for the gas tanks, the rest has been removed. It's still got AC on it. There's Hooker Competition headers hooked to dual 2 1/4" exhaust. It has a non-smog distributor (4 pin ICM) for nice timing hooked to Taylor Spiro-Pro wires and AC RapidFire spark plugs. I modified the carburetor and got it running almost perfectly. I can breathe the exhaust fumes and it takes quite a while before you get a headache in the garage. I run DR secondary rods and an O hanger right now but I need to switch to a M or N hanger because of the cold weather. The secondaries are pretty lively.

    This summer the motor is going to come out and get a real-world cam in it. I don't much like having a cam that doesn't start to scare you until you get to 4000rpm.. and a stock SBC bottom end is only good for 4500rpm in my opinion. I'll still do my normal ARP-stud the piss out of everything so it's a 6000rpm motor but I want a cam with more bottom end (and a 550rpm idle).

    There's no way I'm making more than 250 but it works. Sure, I'd like more, but there is a lot more performance to be had by switching to 3.73s than adding 50 horses and keeping the 2.73s. Besides, 11mpg isn't very easy on the pocketbook.
     
  17. schmuck

    schmuck 1/2 ton status

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    i agree i am running 35x12.50s with stock3.08 gears and i am trying to kill the 305 mill (slightly modified) and i can still smoke em so gearing is not every thing but in contrast i had a 68 cutlass convertable with a rocket 350 highly modified about 475hp but it had 2.43 gears and a jetaway tranny (2 speed) 0 to 100-1 minute 100to 150 10seconds so some times it does matter
     
  18. R72K5

    R72K5 Banned

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    well, any ratio can smoke them, ive had 2.41 ratio cars alot with puny 2 bbl 305s with welllllll over 150k on them and will smoke them, IMO its not IF you can smoke them its all about making them NOT smoke,,,, if you wanna win anyways...

    anything under 3.40 sucks as far as i am concerned unless you tryu to offset with deeper first gear and smaller tires or have really light vehicle like an S-10 or 80's malibu or something or have a healthy 425 or 455 or similar torque producing engine, 3.73 wil always be my ultimate fav for all around speed and mileage

    very few racersor rock climbers or mudders who really are in it for the competition would choose soemthign crap like 2 56 or 3 08, etc.

    i would feel better about just posting this reply had i been able to yet get the 2.73 8.5" out so i can trash it and get the 3.73 14 bolt ff under.. but im thinking im just gonna save the problem and trouble by selling the truck off, maybe make a package deal, with 454 engine, dana 60, 14 bolt ff, and a bunch of radiators and all kinds of other stuff, im thinking like 1800 for it all once i get everything together, that has to be a deal for a perfectly well driving truck and parts like that..


    thanks
     

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