1969 250 help

[sberman431]

Ok so i thought i had this but i guess not. Timing is set at 0 btdc idle is at 650-700 when i take off in first it is ok but going to 2nd and 3rd it stumbles . Any help is welcomed

[prodjay10]

Have you checked for vacuum leaks? Use some propane around the intake manifold, carburetor base, and any vacuum lines.

[sberman431]

I had found a vacuum leak and fixed that . But now this is happening unless a exhaust leak can cause this ?

[prodjay10]

I doubt it. It'll just get you high as a kite when you drive with your windows closed.

When cruising and you accelerate does it hesitate? Or is it only when shifting?

[sberman431]

Its when i am shifting then it just hesitates . Maybe carb problem?

[geezer#99]

Timing is zero, eh!!
Try 12 initial and likely no stumble.

[sberman431]

Ok so ill try 12 btdc and see thanks much appreciated

[sberman431]

K tried it got alot better . But still some puttering or stumble . Need more time to adjust carb and timing but does seem beeter

[geezer#99]

Are you checking and setting your timing with the vac advance plugged off?

[LongBox]

Do you have a vacuum gauge handy? If so, it would be a good way to see if there's a vacuum leak somewhere. Also, check that all the intake manifold hold down nuts/bolts are tightened properly, as well as the carb to manifold fasteners and gasket.

[sberman431]

I actually didnt close the vacuum when i did that opps . Ill do it again and try do i close both the one on the carb and the vacuum advance
Im getting a gauge this week

[VWNate1]

Don't forget to use flammable aerosol product to check for intake to head vacuum leaks ~

I had one that only leaked from underneath , burned my hand a bit finding that one .

[sberman431]

Ive been using gas to spray and check ,is that good ? Kidding

[prodjay10]

Make sure you soak everything when it's at operating temp! Jk.

This thread helped me. My 250cid hesitated pretty bad. Changed timing from 4btdc to 12btdc and its way more responsive. It hesitates a bit but nothing compared to what it was. Vacuum went up and temp went down. Thanks geezer.

[sberman431]

im going to try it once I get a chance . also when you block the vacuum do u just do the one on the vacuum advance or the one on the carb ?

[prodjay10]

Only block the port on the carb.

[sberman431]

that's what I thought ,just wanted to be sure ,been a bit since I have worked on these

[VWNate1]

Make sure you're using the correct vacuum port on the carby ~ there must be no vacuum signal to the dizzy when the engine is idling, very important for proper power and eliminating flat spots .

12 degrees BTDC is a lot, maybe too much ~ to test, do a " Throttle Ping Test " by driving the fully warmed up engine @ 35 MPH in top gear on a level , depress the throttle to the floor , windows closed , radio off ~ even *one* ping, knock or click as it begins to take off, means too much total advance ~ return to idle and back the timing off one degree and try again .

This is GM's method of ignition tuning to each individual engine .

Most ' mechanics ' are far too lazy to do this simple thing .

[sberman431]

Thanks nate and prodjay 10 . Im hoping to try this today

[VWNate1]

You're most welcome .

I've been working with and on , InLine 6 Bangers since before your rig was made .

I only have them as work rigs, no need for a thirsty, short lived V8 in my shop/house/life .

[sberman431]

I keep them for a bit then trade them for cars ,but always come back to a truck .how do you like yours its a automatic mines 3 on the column

[VWNate1]

My current truck is a 1969 Chevy C/10 short bed, step side ranch truck from TEXAS .

It was originally a three on the tree total stripper , the DPO added a TH350 slushbox and power steering , I've added power brakes and will be adding AC as I work in the Desert a lot and I'm also old fat and disabled .

.

Sorry, no pics of it on this computer, look in other threads to see it . looks nice .

[sberman431]

Ok will do .i think youve answered some of my older threads from years back youve been a big help in the past .

I just tried the truck got someone better reverse is good going into first seems good then going into second it is missing ,unless the clutch is slipping some im hoping to get more time on sat

[demian5]

We don't know condition of anything Plugs, wires, cap rotor, is the carb a POS and needs rebuild?
Points or electronic ignition?
Is the choke hanging closed a bit or unhooked and flopping closed when you are shifting?
So many variables that are left with a ?? here when trying to diagnose in a forum.

[sberman431]

Good points you bring up have had truck a couple weeks

But plugs new ,wires look good ,cap new, points new,rotor new
Carb appears good but might need rebuild i have a kit on the way . The previous owner did drive it here to me and thats a 2 hour drive so has been running like this for awhile