Even a good converter will be too loose with that gear.
Why does my car feel sluggish?
- Thread starter magnumdust
- Start date
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Bulldozer
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i completely agree with this with the exception of the 4.10 . a nice holley 750 ~ a 2800-3200 stall ~and a 3.91 and you will be in business..in my HO. this combo with your cam choice should run very decent, given your timing is exactly where it needs to be.
AdamR
Big Member
I respectfully disagree. I ran 3.91s with a 28" tall tire and a 8" 3800 stall T/A converter on the street for years. It was certainly not sluggish
.
What size tire is on the car ? a 26" tire and 355 gears will feel the same as a 391 with 28" tall tires.
Think about it. Regardless of your experience, if your gear is too high, that requires more torque from the engine to get the car moving. More torque makes any converter flash higher. You also had 3.91 gears which would certainly not be sluggish. 3.55s on the other hand would have made your combo act entirely differently. Differently in this case would be slower because the converter would flash higher wasting power. Yours was fast because it was geared correctly.
The 3.91 would work much better than his 3.55 for sure...but the 4.10 would set his eyes back in his head. lol
magnumdust
Well-Known Member
Its the throttle plate, I rechecked it after the post(w/ the carb pics) because i made that mistake of looking at the air door the first time.
If i manually move the throttle linkage to WOT(making the cable irrelevant) it still doesnt fully open those rear plates.
Adam:
The Convertor is a PTC i bought from a member on here.
Tire size on my street tires is a believe a 245/45/17 which is a 25.7" tire.(according to the conversion app. in the laptop tuner for my truck) And being that this isnt a pure drag car, i'd probably stay around that size for the rear when i get around to a pair of slicks/skinny's for it.
Stroker Scamp- I dont wanna go much higher than 3.55s until i either have a Gear vendors overdrive or a overdrive tranny in the car. I have to drive an hour each way to the track and 3.91s/4.10s will get awful mileage at highway speeds.
AdamR
Big Member
Your not taking tire diameter in to consideration and theres a big difference in driveabilty a cheap converter and a quality converter. Just ask anyone that bout a $200 converter and replaced it with a $800. Just because it flashes high doesnt mean it pull hard. How much is the converter slipping ?
Either way I dont feel the converter is his problem if its a PTC they are usually fairly efficient . I would finish up the distributor and either tune the carb (which I feel theres nothing wrong with an edelbrock) or replace it with a Holley that will also need tuning.
With a short 26" tall tire gearing isnt the issue either.
So the throttle plates are only open 1/8 when you manually open the linkage? You have a MAJOR issue with that if the case. Do the primaries open to straight up/down or very close when using pedal and manually?
Is the choke assembly locking it up? Any interference with intake and carb linkage?
Have you tried to remove the carb and see if the linkage will open fully?
Until you get the ignition and full throttle issue solved, anything else is just a waste of time.
IMO, the converter and gears are not the issue here. Especially with the short tire he has.
No, I'm not even considering tire diameter. I am simply talking about the gear's effect on the converter, period. I don't have to ask anybody. I've built a lot of them. A high gear has the effect I described. Damn I think you'd argue with me just because it's me. I swear to God. Go do it to somebody else.
Bulldozer
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my jeep has 33" tires on 15" rims. the factory calibrated the speedo with a 225/75/15, which equates to a 28" tall tire. that is a difference of 2 1/2 inches of rolling circumference. the jeep has a 3.55 ratio. i wanted to find out how much of a difference the tire switch really affected mph and rpms. with my GF side by side and talking on cell phones lol, with her at exactly 50mph , my speedo read 47 mph and lowered the rpm by 150 with the 33s. the difference between a 26 to a 28" tire results in 1" of tire height. and if someone were to do the math , which i am too lazy to do, the 355 to 391 or even a 410 is going to make a world of difference regardless of the 26 or 28 inch tire. sure the bigger tire is going to slow you down, but when all the parts are working together, the HP , stall speed and gearing (it would seem to me)are not going to really notice that much of a change in tire. especially since we arent talking the NHRA
AdamR
Big Member
Im arguing with you because you refused to listen to what Im saying. Tire diameter has just as much to do with it as gear ratio does. Especially before when we didnt know what size tire he was running. His 355 gears with a 25" tall tire is no different then running 391s with a 28" tire. Now that we know hes running a real short tire we can pretty much rule that out as being the issue. Most guys that are running 391 or 410s are running much taller tires to increase the foot print and traction then gear up to over the difference in diameter.
So while I agree that a 355 gear will make a converter flash higher then a 391 gear will with his rock hard short diameter street I very seriously doubt that its the case here.
Heres some good reading on the difference between torque multiplication and converter efficiency
http://www.protorque.com/techi/ti_faq.htm#4
Now maybe we can get back to helping this guy instead of looking way to deep in to a mild 350hp street car.
So while I agree that a 355 gear will make a converter flash higher then a 391 gear will with his rock hard short diameter street I very seriously doubt that its the case here.
Heres some good reading on the difference between torque multiplication and converter efficiency
http://www.protorque.com/techi/ti_faq.htm#4
Now maybe we can get back to helping this guy instead of looking way to deep in to a mild 350hp street car.
I know it does....I understand that completely. What I was saying was that for the sake of simplicity, I was leaving tire size OUT of the equation. Just direct effect of gear on converter is what I was talking about. Nothing more.
...and Adam sorry for snappin at you. I've not had a good day today. Not your fault.
Bulldozer
free ice cream sandwiches
i am getting out of this before i get into trouble lol...if it were my combination, i would stick with a 750cfm, a good 2800-3200 stall and a 391 gear with a 27" tire.with all the timing it can possibly take . no the 391 is not exactly a highway gear but drive it there with a 323 pig, and drop in 391 OR 410 when you get to the track
Carb isn't opening fully and people want to change gears and converters. I feel dumber today.
Good luck to the OP...
Kyles Demon with less cam, less head and less gear/converter would run circles around this current combo.
Good luck to the OP...
Kyles Demon with less cam, less head and less gear/converter would run circles around this current combo.
AdamR
Big Member
But thats like saying for the sake of simplicity lets focus on intial timing and leave total timing out. They need to work together.
Either way, He needs to get the distributor set up, then move on to tuningthe carb. Then if his problem is not solved he can move on to the trans-rear AND tires,
I would start by making sure TDC on the balancer is in fact TDC. Piston stop and timing tape. Then get that distributor properly curved.
AdamR
Big Member
Exactly, I was done with the gear and converter thing at post 107 were I said it wasnt the issue anyways.
Bulldozer
free ice cream sandwiches
lol i know , i didnt help matters any my bad, but at least its out there lol
You should expect nothing less from an online diagnosis.
Bulldozer
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had to express my laughter at that one LMAO.. to the OP...good luck with the build...
AdamR
Big Member
So heres my point. BossVegas old car ran 12.80s at 108mph with a stock converter, 354 gears and a 235-60-15 street tire. stock rebuild bottom end, good heads, intake, carb and a .470" hyd cam. Its all in the tuning
Start from the beginning. Verify were top dead center is with a piston stop and mark the balance with timing tape. Get the distributor curved correctly an get someone to help you set up the carb. Worry about the rest after.
Start from the beginning. Verify were top dead center is with a piston stop and mark the balance with timing tape. Get the distributor curved correctly an get someone to help you set up the carb. Worry about the rest after.
Spot on...
Get the carb to open full throttle. It will make a world of difference in how the car runs. get that solved, readjust the throttle pressure set up for the trans and see where you are. When you say that the carb is at WOT and the plates are still closed up you aren't at WOT. You might be pushing the linkage as far back as it will go, but, that may not and in your case is not WOT.
The trans shifting at 3K at full throttle is another issue which may rectify itself with the carb running actual WOT.
AdamR
Big Member
If the throttle cable and/or throttle bracket are off a 2bbl car and not a 4bbl car that may be the issue as well.
Yep, Using the stock bracket, not extending it up and putting the cable in a bind condition will cause issues too. Carb hook point on 10 floor, bracket on first floor. even the 4bbl bracket really need to be taller to get it right.
I've used 2bbl cables without too much issue.
I've used 2bbl cables without too much issue.
magnumdust
Well-Known Member
The primaries open up fully, but the secondaries do not. The choke is not locked up and does work. Have not removed the carb yet, apt. manager had a fit when i was doing some work today.
Wow quite bit of bickering, so here is some new info:
Used a piston stop, it appears that the balancer markings are "correct", but not for a magnum. i need to get the timing tab from a magnum @ the junkyard to accurately time it. Hopefully that'll come monday when its not raining and my *insert bad word* apartment manager isnt on my *** about working on my car.
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