So it sounded like fun to attempt to take my carburetor apart and use a repair kit for the first time, but now I'm having an issue. The car starts perfectly, revs just fine in neutral and will idle but the tach is jumping 100-200. If I put it in drive the rpms drop and then it dies. If I give it a little gas it will start to move but as soon as I give it real gas it stutters. I also replaced the radiator at the same time.
What did I do wrong? I know very little, but it almost seems like my timing is off, but I didn't do anything with the timing...

1972 cutlass 455, TH400, Edelbrock 600cfm 1406.

Thanks for the help!

 

Check your vacuum with a vacuum gauge if possible. Evaluate your A/F mixture (screws) possible your A/F mixture is now off.

 

Assume you meant a Cutlass 455?

 

Starting from scratch by performing a proper tune-up is really where you should begin. Dwell>Timing>A/F mixture

 

I did turn the A/F screws drastically both directions and the problem still persisted.
I do have a vacuum gauge, do I just connected it to a line coming off the carb/manifold and if the gauge fluctuates, thats my problem?

I appreciate the help, and love the bike!

 

I just did what I said above: I used the brake booster line which is coming from the back of the carb. The gauge was going crazy jumping from 8 - 15psi.

 

You want a "steady" vacuum - if you have a large cam you might be in the 15"Hg range but steady. A normal (nominal) range for a stock 455 should be ~17"Hg - 20"Hg. But in all cases you want a steady vacuum reading. Rotate each A/F mixture screw (one at a time) until you have the highest reading (generally the highest RPM) and the engine RPM begins to hesitate somewhat. Back off the A/F mixture screw until the reading and RPM are steady - perform the exact same for the other A/F mixture. Ensure you have your low idle set appropriately when you're done. Can't recall what yours should be - depends if you have A/C. The sticker should be on the fan shroud and it's definitely in your CSM.

 

I forgot to mention. Most will use a "T" (tee) in the vacuum when measuring. If you remove the brake booster and tap into the manifold vacuum port that's fine. Of course, ensure you have all the vacuum ports connected &/or blocked as an open vacuum line can produce a shaking vacuum reading.
You can perform the top LH test to evaluate your vacuum. Snap the throttle linkage and note the reading. It should fall immediately to 5"Hg then return to steady.

 

Well, either I'm doing something wrong, or that didn't do anything.
The engine is most definitely pulsing every 2 or 3ish seconds. The vacuum gauge jumped back and fourth very quickly between 9-13 and then pulsed up to 15. I turned the A/F screws all the way clockwise and many turns counter clockwise (One at a time) and I didn't see any change on the vacuum gauge or the RPM.

Is this is a vacuum leak? Could I have just screwed up putting a gasket on somewhere? As I wrote this I just looked on the floor and found the gasket that goes on the bottom of the carb. I must have reused the one that was on the mounting plate. Is this my problem....

 

Could very well be.

Focus on what you changed (assuming car ran ok before).

 

I'll let you decide after you install the proper gasket. There's a reason for a gasket.

 

Well egg on my face...
I'll have to try this again in the morning.
Thanks again for the help! That vacuum gauge picture is awesome! I made sure to save that for future screw ups.

 

We've all been there ourselves. NOTE: Ensure you used the correct gaskets for your carburetor from the kit.

 

So I took the carb off this morning to replace the gasket and noticed something. Unless I'm mistaken (which is often) I have a spread bore carb and a spread bore intake, so there's no reason to be using the square mounting plate. Am I wrong? If I'm right, could there be some reason the last owner used this square plate?

 

See attached discussion...

https://edelbrock-instructions-v1.s3...brock/1406.pdf

 

I think you are referring to lines 4 & 5...
So according to line 5, I would only need the square adapter if my carb was a square bore and my intake was a spread bore.

But I have both spread bore intake and carb. So I just need the spread bore gasket!

 

The 1406 is considered a square bore carburetor. I don't know what intake you have - looks like dual-plane spread/square - no idea (7111?). I don't have a great deal of experience with Edelbrock carb/intake matings outside of understanding the delta between a square bore and spread bore. Again, w/ that said, the 1406 is considered a square bore carburetor - you can research this on your own.

 

Thank you! I guess my understanding of what a spread bore is, is wrong. I got 2 new square gaskets, for both sides of the square plate and got them on. Things have improved. The car is drivable now but still off. I had to turn the A/F screws almost to the point where they came out. I tried the vacuum test and the needle is furiously jumping between 9 - 13. When i gave it heavy throttle the needle dropped to 0 but then shot up to 20+ and then back down to 9 - 13. Driving the car, it's sluggish while giving it a little gas. It bogs down once I give it a lot of gas but then it recovers and pulls strong.

 

Sounds like you're trending in a positive direction. As I said earlier, it really is in your best interest to perform a full proper tune-up on the engine as described in the CSM: Dwell>Timing>A/F Mixture. I don't know anything about the history of your car. As you become better acquainted it wouldn't hurt to evaluate the engine w/ a compression reading (both dry & wet) for each cylinder, have you ever removed the valve covers to peak at the valve guides/seals/rods/rocker arms, etc.? Some things take time to get to the point you know what is and what is not OK on the car. Good Luck!

 

BTW, since it bugs me and most likely bugs others, Oldsmobile never produced a 450 engine. Step-up your game and demonstrate to others you're on the same page, I mentioned this in an earlier post - you'll garner better responses if folks can at least glean you know what a 455 BBO engine is. Stay informed & good luck.

HINT: You can click Edit and fix this at any time.

 

Better? 😀
I do know what a 455 is.... it's a Toyota engine right!??

 

 

I think I solved my problem.
The rebuild kit I bought came with little springs (meter rod retainer springs) that, according to the instructions, go on top of the rods. I did notice that my carburetor didn't have these when I was taking it apart. So I removed them to see what would happen and sure enough, the car is back to normal.

I'm trying to educate myself on why this worked but also, should this have worked??? Since this did work, does that mean something else isn't working correctly?

 

I am clueless regarding the liver and kidneys of that carburetor.

 

DO THIS!!!

Go to Mike's Carburetor Parts. He is the best in the business, and has done many step by step videos.
Either go to his site, or right to youbube.

Prepare to watch many hours of info.

 

Well I fixed my problem..... I just bought a new carb.
I had a 600cfm which was way too small for the 455 anyways.

I'm pretty sure my problem had something to do with the accelerator pump. I watched a lot of carb rebuild/issue videos, including Mikes Carburetors (and yes those are good vids). I think I also had a separate issue going on as well. The mixture screws did NOT change the engine run no matter how far I turned them. I suspect the jets in the carb as were too big (previous owner) and may have been cheap Chinese crap. In addition, I was getting 4mpg, so that was an issue as well.