busmechanic Posted March 28, 2004 Share Posted March 28, 2004 Ok here is what I had, TH 350 with a set of 3.31 rear end gears. Was running a stock manifold with a 4bbl rochester quad. I swapped out the 350 for a 2004R kept the same gears and added a dual quad mainifold with 2 600 CFM Edelbrocks. My take offs and low end torge is terrible. I played around with the detent cable. Did not make much change. So I then install the correct lever for the edelbrock carbs and kickdown cable assembly. It helped some but my launch is still bad. Seems to be a bit of a drag on motor when coming to a stop so I am thinking the convertor is stock and not enough stall for my cam setup. Could that be killing my launch? Or maybe it is the gear diffrence from the 350 to the 2004r that has me messed up. What rear end gears would you recommend with the 2004r. 3.31 in it now. Quote Link to comment Share on other sites More sharing options...
ejw71 Posted March 28, 2004 Share Posted March 28, 2004 Bus, Suspect the dual carbs kills low speed torque and that 500 cfms would be better for cruising. If I remember correctly, in a previous post, you explained that rear 4bbl comes in very late. Correct? Does this mean the rear two barrels of the rear carb some in late or does all four come in late? Does rear carb have an idle curcuit? What are intake/exhaust durations at .050 lift? High duration cam also kills low speed torque. Low gear overall ratio is lower with 200R than was TH350 so that's not the problem. I'd think that at least 373s are needed. Someone else will have to answer the comverter/cam question. Ed Quote Link to comment Share on other sites More sharing options...
busmechanic Posted March 28, 2004 Author Share Posted March 28, 2004 The two carbs are identical and both have an idle circuit. As far as the rear coming in late that is refering to adjusting the linkage between the two carbs to either have both carbs accelarate at the same time or you can adjust it so that the rear carb accelarates first then the front carb comes into play after you accelarter futher down in your travel. This gives you the opertunity to cruise with just the rear carb. At least that is my understanding of it. The secondaries on both carbs are mechanical in that they open at a predetermined position. From the artical that I read from hot rod mag that was posted, I should be getting better torgue at low end. I have a filling that my problem in lost of power in take offs is because of the 2004R. with those 3.31 rear end gears. Ed, If I understand what you are saying? The ratio between the 2004R and the 350 are close enough that you think the lost of power is not in the tranny. And if I install a set of 3.73 or 4.10 I'd have a better hole shot. Now I know I will have a better hole shot with the 3.73 or 4.10 but I am trying to determine what killed my great burn outs. The 2 4bbls or the 2004R. Like a dummy I installed both at the same time. So I can not figure out what caused the slow take offs. I do get a little scratch in 2nd gear so I know I have the power it just not waking up till I get moving pretty good. Quote Link to comment Share on other sites More sharing options...
ejw71 Posted March 29, 2004 Share Posted March 29, 2004 The 200R4 has a lower 1st gear than the TH350. Your present overall 1st gear ratio is lower with 200R4 than it was with TH350. To me this means it's the carbs. Ed Quote Link to comment Share on other sites More sharing options...
busmechanic Posted March 30, 2004 Author Share Posted March 30, 2004 Ed I think I got it figured out. Today I went out and removed the progressive linkage from front carb and ran just the rear carb and yes it did well. So I went back to garage and set up the linkage so that the rear carb has to open up half throttle before the front carb comes off idle, Drove it again and this time she launch pretty good and when it hit second she was off and running. Got back and won a 2300 stall converter off of Ebay and I believe that will help even more now that I got the carbs dialed in pretty good. Drag strip is opening up next week so I hope to take it out on its first maiden voyage. Quote Link to comment Share on other sites More sharing options...
monte70car Posted March 30, 2004 Share Posted March 30, 2004 bus is the trans sit up for the 3:31 gears? i have a 408 big block with a 700r4 in and 2:73. if the trans aint sit up for the rear gears it will seen different compare to the 350. i had a truck trans(400) put a shift kit in it and u couldnt feel it shift any. Quote Link to comment Share on other sites More sharing options...
chuckash Posted March 31, 2004 Share Posted March 31, 2004 I run 3.73 with a th350 trans and love it. Sometimes overdrive would be nice, but since I just cruise around it doesn't much matter to me. Â I don't know what motor or mods you have, but 1200 cfm of carb is an awful lot of carb for anything but an all out race motor. I suspect that you picked up some acceleration when disconnecting the second carb because it likes having less carb, not because of the timing of the events. Just my 2 cents. Quote Link to comment Share on other sites More sharing options...
monzaz Posted June 21, 2004 Share Posted June 21, 2004 I think chuckash is on to some thing there. I agree. Jim Quote Link to comment Share on other sites More sharing options...
Guest Posted June 21, 2004 Share Posted June 21, 2004 I would like to say I agree with Chuckash also... I think the problem is carbs. Â Part of the difficulty is that two things were changed at once. However, since the 200R4 has lower gearing than the TH350, your launches should have been improved. Â The reason why it's possible to overcarb is the same as when you put your thumb over your garden hose to make it spray farther. By putting a bit of restriction on there, the pressure forces the water out farther. In the case of carbs, if you have it closed off a bit, then the increased airspeed helps break up the gasoline droplets, which makes the fuel burn better. The problem is when the carb is so big that there is no restriction suddenly the fuel doesn't vaporize (what the heck is the term for that it's slipping my mind and driving me crazy) as well so it's harder to burn. This would make you more sluggish off the line. Overcarbing can hurt off the line, but may help somewhat at the top end. Â Note that this is the same problem people have when they hook up monster exhausts to a stock motor. It's like putting a fire hose on a kitchen sink and wondering why more water doesn't come out. With a monster exhaust you don't have the SPEED of the previous exhaust going fast to help PULL out the next charge of exhaust. Â My two cents. Fiddle with the carbs. 3.31 gears should be great with a 200R4 on the other end--nice launches AND night highway manners. Â Will Quote Link to comment Share on other sites More sharing options...
busmechanic Posted June 21, 2004 Author Share Posted June 21, 2004 The word you were looking for is atomize. I think I may try a set of one inch spacers which in theroy should give it more air. Quote Link to comment Share on other sites More sharing options...
wallaby Posted June 22, 2004 Share Posted June 22, 2004 Carb spacers increase the intake plenum area, and make the carbs behave as if they were bigger. Quote Link to comment Share on other sites More sharing options...
busmechanic Posted June 22, 2004 Author Share Posted June 22, 2004 I guess I will nix that Ideal. Quote Link to comment Share on other sites More sharing options...
Bob Hansen Posted June 22, 2004 Share Posted June 22, 2004 I think the spacers will help the atomization of the fuel and improve the performance. I would also consider smaller jets in the carbs. Bob Quote Link to comment Share on other sites More sharing options...
monzaz Posted June 22, 2004 Share Posted June 22, 2004 Hey busmechanic , Just remember to have FUN no matter what happens ...lol I am trying to keep that in mind when ever I have a wierd problem on the race car...lol It's a hobby choose the set-up you want and try and make it work. we're just trying to help... having fun. Quote Link to comment Share on other sites More sharing options...
busmechanic Posted June 22, 2004 Author Share Posted June 22, 2004 I hear you Jim. I think I am quoting from the A Team. I just love it when a plan comes togeather. I pulled the transmission last night. everytime I have dropped the pan it has way to much clutch material. I have another 200r4 that I will try out. If that helps with the some on the launch, then I will go with the spacers then the 3.73 gears. and if that dont work then I will try a diffrent Carb setup. I may sell the 3.31 gears I have if the 3.73 work out. Quote Link to comment Share on other sites More sharing options...
busmechanic Posted June 22, 2004 Author Share Posted June 22, 2004 Well I am on to something. Biggest problem was that 200r4 transmission. It just would not hook up. hence the clutch material in pan every time I dropped it. stuck a diffrent 2004r in today and took it out, drove it easy for the first three miles. (It was a used transmission that look real clean inside). I stuck a spring kit in it. for better performance. I came to a stop and laid into it and she took off like the old 350 use to. Long burn out and it barked the tires in second never could get the other 2004r to do that. But when I hit third the front seal let loose (YUK what a mess). I will stick a new seal in and a line pressure gauge and go from there. Quote Link to comment Share on other sites More sharing options...
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