high rpm drop in gear

[mrendos]

to maintain 700rpm in gear i must have 1500 in park, seems to be hard on tranny and is embarasing to sit in park reving high, i have checked brake booster by pressing on brake,it does not effect idle at all, only when i put it in gear does it drop, anyideas or is that how it is thanks

[Will Marsh]

We need more details to help you. What truck, what trans, what carb, where's your timing set.

In general I'd guess that your timing's too advanced and the idle screws on the carb are too lean, but that's just a SWAG without details of your setup. That's where I'd start anyhow.

Running the VAC advance on the distributor from manifold instead of timed vacuum would make it even worse if that's the case. But at 1500 your Vac is all in at idle in either case.

HTH,

Will Marsh

[mrendos]

304,727 auto, 7448 350cfm 8dg timing, i have turned in idle screws due to really fumey at idle,but acted the same before ,the thing is really a fuming wagon i have been trying to settle that maybe it is all conected ,but the plugs look fine ,msd ing.

[Will Marsh]

"Fumy" with a 2300 Holley shrieks "Blown Power Valve" to me. Is this a NEW or "new to you" carb? The 7448 is supposed to have the backfire blowout prevention, but it isn't foolproof. If it's not NEW I'd suggest you start there.

Ok, timing is 8 BTDC with the vac advance disconnected, right? I'd start by dropping that to 4 BTDC, or to 0 if it starts and idles OK there. Set the Idle mix screws at 2 turns out, Start it and let it idle, and set the Idle speed screw to 800 rpm.

Now adjust the idle mixture down 1/2 turn on each screw alternately until you hear rhe idle speed drop. Back up to the last adjustment, and repeat with 1/4 turn increments. The spec is a 50 rpm drop and leave it there for now. You should end up somewhere around 1.5 turns. If you can't kill it with one IMS all the way in you have a vacuum leak or internal carb problems.

Check the timing again and reset if necessary. Then I would rev it slowly to 3500-4000 rpm and verify that the mechanical advance in the distributor keeps advancing and doesn't stop somewhere along the way, advance at 3500 should be ~26 or above from 0 initial. If it stops or doesn't get there, you need to replace or adjust the advance springs in the distributor, and you might as well stop here until that happens, then start over.

Now attach the vac advance to the timed vacuum port on the carburetor (either the high one on the front or the one in the metering block). At 750 rpm, you should see less than 1 degree change in the timing, if it's more, you have the wrong port. Find the right one.

Now have your helper put it in gear and see where it drops to. I like between 650 and 700, but a good SV will idle at 600 just fine if it's right. Adjust the ISS to get there.

Put it back in Neutral/park and repeat the adjustments at the new ISS setting.

HTH,

Will Marsh

[mrendos]

the carb is about six months old, thanks for all the input ,i will try it today and let you know ,thanks again

[mrendos]

thanks will,


put timing to 0, and adjusted idles screws, she seems alot better not as fumey but a little sluggish thinking of going uo to 4 deg on timing but will run like this for a while and see hhow it feels , thanks would have never thought over timed would cause my issues thanks again for your help

[Will Marsh]

You're welcome. That's what we try to do here.

Will Marsh