I just got my 360 rebuilt to a 390. I also changed it to a 4 barrel with edelbrock aluminum manifold with an edelbrock carburetor. I bought the attachment from edelbrock so the throttle linkage and kickdown lever will attach to the carb. One problem is that the kickdown lever does not seem to be adjusted right. At least the transmission does not want to down shift when I increase speed (it takes a lot longer now then before the new install, also not very smooth changing gears).
However, I think there might be a bigger problem then just the kickdown linkage. I can adjust the idle and timing in park and the engine will run smooth. But when I change it from Park to Drive the truck starts to vibrate and shake quite noticeably. Once I start driving it settles out until I get to a stop light. I went through the drive thru and it was a little embarrassing having the truck shaking. Any ideas on what is causing this and a way to fix it?
fordamericana wrote:So you tuned your carb at idle, and it does fine, even if you give throttle? But when you put the transmission in a drive gear, it shakes violently?
Yep, pretty much. But once foot is off brake and pushing on gas the shake starts to go away. (idle with foot off brake will make it move forward shaking)
I'm not very familiar with your carb, but perhaps the transition circuit isn't tuned properly. Vacuum changes whenever going from idle in neutral to being in gear.
Also, the kickdown lever should have an adjustment screw at the carb linkage. If the shifting isn't quite how you like it, you may need to adjust the vacuum modulator on the trans.
Well, I think I do have a vacuum problem. Still having trouble with idle and timing unless RPM are around 1200. I checked my vacuum with a vacuum gauge and it is about 14. That is not normal, right? Decided to look at spark plugs and they all look good except for #1. It is black with oil on it. I checked spark and spark plug is getting spark to it. Looked at valves while cranking over to make sure they are moving and they all seem ok.
I guess my next step is compression? Does that sound right? If it is a fresh rebuild from a shop, is this the time to take the truck to the shop and have them look at it?
float_tested wrote: If it is a fresh rebuild from a shop, is this the time to take the truck to the shop and have them look at it?
In a word, YES!!!
I would do that immediately, before spending any more time and/or money on it.
The more you do to it, the better the chance that the shop will blame you for whatever is wrong...
Wise men talk because they have something to say; fools talk because they have to say something.--Plato
Why is it that there's seldom time to fix it right the first time, but there's always time to fix it right the second time???
That's not an oil leakThat's SWEATfrom all thatHORSEPOWER!!
Well, did some work on it since last post. I found the problem with the transmission, the elbow connection from the hardline to the transmission was disconnected. I was assuming it was connected because the vacuum line from the intake manifold to the hardline was attached in the engine compartment. So no more problems with transmission.
However, the engine is still running rough and having hard time with timing. Bought a rebuilt distributor and a MSD ignition with coil to help with spark. Didn't change any symptoms once starting the engine again. Finally decided to do a compression on #1 and came out with 60. Put some oil in and did it again and no change, other cylinders are around 125. Also put a heat sensor on each tube of the headers and cylinder #1 is reading 300 degrees while the other seven are reading about 600 degrees.
Calling machinist tomorrow. Only 100 miles on rebuild, bummer.
He probably broke a ring while installing the pistons.
Wise men talk because they have something to say; fools talk because they have to say something.--Plato
Why is it that there's seldom time to fix it right the first time, but there's always time to fix it right the second time???
That's not an oil leakThat's SWEATfrom all thatHORSEPOWER!!
Got the truck back from the machinist today. Running way better. I guess the push rods were too long and it was effecting #1 cylinder. I'm not sure exactly why it was only on one???? Anyways, shorter pushrods were put in and it is driving without any missing.
I'll be keeping an eye on the performance and see how it goes.
Once I start driving it settles out until I get to a stop light. I went through the drive thru and it was a little embarrassing having the truck shaking. 
Any ideas on what is causing this and a way to fix it?
That's SWEAT from all that HORSEPOWER!! 