New Gears!

[73Runner4spd]

Finally got the 3.91 suregrip back from the tranny shop! 2 months for a bench job...But whatever, he charged me less than he quoted me, I tossed them in the other day to replace my worn out 3.55s on my stock bottom end 400, with 915 heads. It pulls considerably more but the thing I enjoy most about the swap is the how quick the clutch seems to grab compared to the 3.55s. Have yet to try and launch it but the engine definitely seems to enjoy the higher rpms when it comes to laying into it from a roll. Still trying to sort out a nasty rpm related vibration in my shifter, tranny mount and motor mounts are solid, happens when sitting with clutch in and in neutral, however it seems magnified under a load (only happens at high rpm) I am starting to think that it is a linkage or shifter mechanism issue, as the clutch finally feels nice, and it has a new flywheel. Up next I think is a speed demon 750 to go on top of my dp4b intake (replacing my edelbrock 1407). unless you guys feel I will be unhappy with the swap ha. I have my eye on a holley dual feed 750 as well for the same price, the Demon is just a little newer. Good news is, my buddy with a heavy breathing 10.5 to 1 compression 390 ford got a jump on me and only had me by a fender when we let off. That was with the 3.55s and his 3.50s. I didnt think it was too bad for a smogger!

 

[Budnicks]

sounds like a balance issue, somewhere in the bottom end, our you dive-line/drivetrain, clutch, flywheel, universals or trans something's out of balance, or badly worn bearing or something alone those lines, possibly causing the vibrations... could be a loose flywheel or clutch too... could be a bad pilot bushing too....

 

[73Runner4spd]

sounds like a balance issue, somewhere in the bottom end, our you dive-line/drivetrain, clutch, flywheel, universals or trans something's out of balance, or badly worn bearing or something alone those lines, possibly causing the vibrations... could be a loose flywheel or clutch too... could be a bad pilot bushing too....

Yes, I used a new fly wheel, clutch and everything went on perfect, it shifts great, with the exception of going from 4th to 3rd at a high speed, I replaced the pilot bushing when I did the clutch, last year. I thought, maybe the drive shaft or the pinion angle or something, but the noise/vibration continues when I am completely stopped, although it is significantly amplified under a high rpm load. As Soon as I get a good tac, I will let you know what rpms in each gear it starts to happen and where it is the worst. From both going down the road and sitting. Thanks Budnicks

 

[ykf7b0]

I think you will making an improvement on the carb with either the Holley or Speed Demon. The Holley sure woke my engine up compared to the Edlebrock 1407.

 

[bm02tj]

was the vibration there with the old flywheel as well
your 400 is externally balanced and may not match

 

[73Runner4spd]

was the vibration there with the old flywheel as well
your 400 is externally balanced and may not match

No, but I made sure I used the correct flywheel, I also double checked with my harmonic balancer afterwards. I think it is in the shifter linkage, I had a fairly new shifter mechanism that I put in and adjusted all of the linkage rods and "fine tuned" them and it went away a lot. I still have a little bit. If I had the wrong fly wheel on it, I think the vibration would have been a lot worse than it was. I checked all of my mounts as well. I have a forged 400 crank in it not a cast.

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I think you will making an improvement on the carb with either the Holley or Speed Demon. The Holley sure woke my engine up compared to the Edlebrock 1407.

hope so, for the fall id like to put a holley or speed demon on it and maybe a hughes whiplash cam to build up some cylinder pressure. Thanks for the input guys!