I'm having a little trouble with a bog with my 355. I think it's because of the recent severe weather changes. Anyway it's a 355, 9.75:1 hyperrepepetic(I know, it's butchered), comp 270 magnum (224*/.470"), WP s/r torquer (2.02/1.60), performer intake, 625 Demon jr, headers, 2 1/4" duals to cherrybomb turbo2s to turndowns, TH350, shift kit, 2.73 peg leg, 26"X 9" tires.
It's got a bog until about 1500 rpms and it was really bad until I got home and put 18* initial timing (it was 8* before) without the vacuum plus the approximate 15* mechanical (I have no timing tape or whatnot) that the graph shows in my Mr. Gasket kit (silver springs). the more initial timing I give it the better it seems to run but I'm worried about having too much timing. could I be over jetted (they are # 69 w/ plate in rear)? I pulled # 3 and 6 plugs and they were a kinda clean, light gray color. should I give it a little more timing and see what happens? it has stock vacuum advance, HEI with ACCEL tune up kit with the works. my carb has the lightest secondary spring also. I hope I covered everything but I fear I didn't. graemlins/clonk.gif

Ported, or manifold vacuum for the advance?
Do you know how much vacuum the engine produces?
Which power valve?
If it seems to like more timing, try full manifold vacuum for the advance. (if not already)

Originally posted by Zman:
Ported, or manifold vacuum for the advance? ported
Do you know how much vacuum the engine produces? no
Which power valve? whatever comes with a jr., maybe 6???
If it seems to like more timing, try full manifold vacuum for the advance. (if not already) my vacuum tree won't fit behind my secondary float

Isn't there a vacuum port in the lower front corner like a Holley has?
I'll bet manifold vacuum will fix your stumble.
The carb probably came with a6.5 power valve. (most Holleys do)
Borrow, or buy a vacuum gauge. You can't set the carb correctly without one. This is one tool every hotrodder should have in the tool box!

Originally posted by Zman:
Isn't there a vacuum port in the lower front corner like a Holley has?
I'll bet manifold vacuum will fix your stumble.
The carb probably came with a6.5 power valve. (most Holleys do)
Borrow, or buy a vacuum gauge. You can't set the carb correctly without one. This is one tool every hotrodder should have in the tool box! thanks I guess I will just switch my trans and my advance. now that you mention it I remember those are ported and manifold graemlins/clonk.gif graemlins/clonk.gif what's the differance though? one constant and one when you crack the butterflies? where do you hook up the gauge?
Dang, and I thought I was getting real good at the carb stuff. thanks .

Ported vacuum comes in when you open the throttle.
Manifold vacuum is constant.
Hook the gauge to manifold vacuum to make the carb adjustments.
You want the trans to have full manifold vacuum as well.....do whatever you have to do to plumb it.

How is the accelerator pump? Does it give a good shot? Do you have a stall convertor? If not,you could certainly use one.Besides getting better launches with one,the low end response improves greatly.

Originally posted by mr 4 speed:
How is the accelerator pump? Does it give a good shot? Do you have a stall convertor? If not,you could certainly use one.Besides getting better launches with one,the low end response improves greatly. the accelerator pump gives a big steady blast (30cc) stall is on my summer list with gears, tires and a trans cooler. should a 2000-2500 be ok I'm thinking of 3.73s since that's what comp cams recommends (3.73-4.10).

3.73's sound good as well as a convertor that flashes to 2600-2800..a B&M 2400 holeshot might get you there..

Use a stiffer spring in the secondaries. You do not want it coming in before about 3 grand.

Originally posted by TJC:
Use a stiffer spring in the secondaries. You do not want it coming in before about 3 grand. Good observation graemlins/thumbsup.gif I missed that..the lightest spring isn't the best idea with a 350 with no gear and no convertor

well I got a splitter for my vacuum and that helped a bit then I switched from my short yellow to my purple spring which is two steps heavier and one step lighter than stock and it doesn't bog unless I punch it so I think I'll put the stock spring back in and have a go. graemlins/thumbsup.gif it's all coming back to me now.

if this is a car you drive regularly you might consider 3.55 gears, along with a converter that can be put up with daily.

It is a car that I drive everyday exept the days my sister wants me to drive her car for her (she's 14). I can't go with anything between a 3.42 and a 3.70 gear b/c it's a 8.5" 10 bolt, not 8.2 or 12 bolt. I'll be happy with 14-17 mpg on the freeway and 10-13 around town or goofing around. If I have a road trip to go on I could always tune it up for milage right? say 18 highway?