2 questions unrealated
1)recently swapped to a carbed 350, pretty lopey cam (don't ahve exact specs) it was a complete crate motor from phx muscle car. my problem is a vibration around (really noticable) around 2400 rpm in park. now on the road it's worse and was thinking it could be the drive shaft (new) or rearend (new) but today I left it in park and you can feel the whole car shake for a second and then off a second then on a second and so on. they told me the motor was completely balanced before it left their shop. any ideas?

2) open air cleaner on a hot day (85-90*) shouldn't I be able to "tune" out a bog? a guy that helped me tune my carb said it is sucking too much hot air at a dead stop and I need to find a new air cleaner more like the stock one?

 

You can (and should) try a cold air induction setup. I have heard many people say an open style air cleaner caused (or exacerbated) a bog. You should be able to tune it mostly away, but i'd highly recommend pulling in cold air.

Hmm... How's the engine mounts? tranny mount? Check those first. If the engine mounts are worn out, the engine will rest on metal, and shake your teeth out, and go back and forth depending on where it's resting. If it's out of balance it should shake you around all the time, I think it's in how the engine is mounted to your car.

 

the engine and transmission mounts are brand new so those shouldn't be an issue, i'll double check though. what do you mean about "how it is mounted in the car?" should I disconnect the coverter, slide it away and then try it to isolat just the motor?

 

Hmm, well if it's not a constant shaking, I doubt it's the engine that's out of balance.
You may be on to something, maybe disco the tranny and see if it's better.

 

Does it have the clutch fan on the engine...take it off and try it!

 

good suggestion, but I have an electric fan setup. any others? i'm willing to check anything

 

what are the RPMS like when it starts to shake at idle... what does the engine sound like.... how much timing are you running

 

Rpm in park/neutral at about 2400 RRM, it is very very subtle so when in gear (and a load I'm guessing) it gets more noticeable. for instance If i leave it in third gear (auto) and run it at 65-70 MPH RPMs at 4000 it pulses really really strong. once over 80 its just an all out vibration. when vibrating the engine sounds fine, rpms are constant no dipping at all. timing about 9*BTDC and 34* total. the vibration only comes at 2300/2400 rpm, if I cruise at 60 in overdrive down the freeway it runs smooth as silk (unless I just cannot feel it) and that's at 2100 RPM, soon as I step on it a bit and get going 70-75 and reach 2400 RPM it starts to rythmic pulse and over 80 all out shake.