Ok.....rebuilt my 454 over the winter. while it was apart I had bigger valves cut in. (2.19/1,88), and did a little and I do mean little head work.
No other changes where made, some parts were replaced but with the same thing.

Here's the ?. With the bigger valves do I need to give it more fuel. Reason for this ? is I had it running the other day and it will not idle. The carb I put on was running fine when I took it off a has not been touched since.

So does it need more fuel or is the timing out. Or is it just that it is cold and needs to warm up a little more? Unable to have it running to long as there is no mufflers on it yet :rolleyes: .

Assuming everything was put together correctly, I would check for a vacuum leak.. forget a carb gasket, forget to connect power brake line, other little vacuum lines, manifold tightended correctly? Check the timing and your float levels. Maybe the idle mixture got screwed up somehow.

Anything beyond that is higher than my level of mechanical competence so someone else will have to chime in. Are you in really cold weather and the choke is not functioning correctly, or does the problem go away when itts warm? I had a car not idle right that I kept trying to start and idle that ended up blowing the starter off the side of the block because there was condensation inside the rotor cap from sitting in mucky cold humid weather for so long.. could the gas be really old and watery?
I find usually for me I jump to these horrible conclusions when its usually something dumb someone who is well versed with cars can point out to me quickly.


matt

Thanks Matt I'll have to check for a vacuum leak after I get the new exhaust on. We're sitting at about 0* right now,so a little on the chilly side. No choke hooked up so I think (now you have mentioned it ;) ) it could be a combination of little things.
Just was not sure if after putting bigger valves in, it might want more fuel at idle so I thought I would ask first then look at the other things so as not to chase a bunch of ghosts

I would first check for a vac leak.
I had one because the intake mainfold bolts were loose. I have not got around to setting the timing on it yet but I am pretty sure that is where the leak is coming from.
Check for leaks around the base of the carb,
check all lines, if you still cannot find it hook up a vac guage to your manifold port and see what the reading says.

The engine may not idle the same without mufflers due to the backpressure created by the mufflers. You might install, then see how it runs

Thanks guys.

Matt I have a vac gauge hooked up and have about 12-15 inch of vac at about 1500 rpm, and seems to hold there. Have slightly more than last year, but it's real hard to get an accurate reading when it will not idle.

Steve exhaust is getting done within the next day or two. Then I be able to see if it just because it's not warmed up enough, as the drive back across town will get it warm enough ;) .

How I found my vack leak was I unplugged the vac guage from the rubber hose from the manifold.
The engine idled with the vac guage unplugged. Then when I put my finger over the hose (effectively partially sealing the manfold area) the engine stumbled. It stumbled because the bolts were loose and air was escaping.

Originally posted by MonteMan454:
How I found my vack leak was I unplugged the vac guage from the rubber hose from the manifold.
The engine idled with the vac guage unplugged. With the guage unplugged and the hose open, you have a bigger vacuum leak. That doesn't really prove anything.

For sure Shaun, and I would go through and recheck your valve lash first. It actually sounds like more of a lash /timing issue OR simply that it isn't warmed up fully ( I'm freaking out about even starting the 427 at 0 degrees ( 32F)) due to wear.

Larger valves SHOULD produce a stronger fuel signal and actually draw fuel better. A strong fuel signal might actually make the old carb settings a bit lean, so you're thinking right on that. I.E., I wouldn't be surprised if you end up jetting up a size or two to maintain a good A/F ratio. But it's not going to effect idle all that much.

Also, I had a very freaky problem with a 750 DP that literally sat on a fence rail while we swapped the 396 for the 427. Four hours of sitting. Ran mint prior. Well, one of the high speed bleeds must have been slightly plugeed or something, sicne it started, ran well, but when you got into the throttle it leaned out bad. Might be that somehow one of your idle bleeds got plugged or restricted. I've taken to wrapping carbs that come off the motor in saran wrap anymore. It took alot of screwing around before I got the carb off and found the problem. Easy check is to blow some air down all the bleeds.

Anytime you increase the fuel signal, bigger valves, smaller carb, etc, the carb usually goes a bit lean. ( Or in reverse, if you have too much carb, you usually jet it lean to compensate - like the 1125 cfm trips I run, it's lean becuase the fuel signal isn;t that strong EXCEPT for the center carb , which is jetted a bit rich).

But I beleive that is not your current issue. Something to tweak down the road once you get a good plug reading.

A fluttering vaccum reading means something isn't quite set right. In my case it's usually valves OR that the throttle linkage is holding a secodnary carb open. Misadjusted timing would do this as well ( as would a bad valve, plug, wire etc etc) A steady but low reading would indicate a vacuum leak.

Either way, if the motor wasn't fully warmed up, the vacuum reading isn't valid. Don't fret yet. But do set the timing next time you fire it up, like on the way to the muffler shop. And if you havent rechecked your valve lash once since the motor was fired up, I think I'd bother with that one more time.

My understanding is that those XE grinds like a loose 1/4 turn. If they're tight 1/2-3/4 of a turn it does idle a bit rougher, and in Framer's case, lost some seat-of-the pants pull.

And I know you won't mind if it clatters a bit more at that setting! tongue.gif

Gene, guess I have to put the hearing aids in and see if the valves are making any noise. ;)

Picked it up from the muffler shop yestarday and got to drive it home.

In order to get it to idle a bit better I let it warm up a bit more. This seemed to help but what I did that really help was give it more timing and turned up the ilde screw on the carb. It seemed to run well across town (under 3000rpm), missing a little seat of the pant performance but...

Still have not put a timing light on it but will this weekend. smile.gif .

Only prblem was when I shut it off it was really hard turning over with the amount of timing I had given it. Backed it off and started much easier, but got the idle problem back. :confused:

As far as valve setting goes I set them at zero + 1/4. Vacuum 12 -15, just pluses up and down about 1-2" while Idleing.

Its most likely just a timing /idle mix setting thing.

I didn't mean the hearing aids you dummy! I meant that you wanted a solid cam in there anyway!

And remember, it's a tight, fresh mill. Give it some time.

Dummy?
Donchu be beatin on my Wingman Gene. tongue.gif

Sorry boys I made a mistake. I thought I figured out the vacuum leak problem but I was wrong. I shouldn't have jumped to conclusions.
Now I will have to post something in trouble shooting.

The rotor is probably covered in hot wings sauce from Hooters.. :D

I think what it was, was the wing sauce was too cold (maybe even frozen) :D .

Last couple of days it's been a little warmer and things seem to be a bit better. Gave it a lot of timimg and it would idle BUT would not start after running and getting hot, so backed it back down and things appear to be better.

Still needs a bit of work but seems to be running well graemlins/hurray.gif

So which one of you wants to fine tune it for me :rolleyes: because I think I found my limit and that is being the "nuts n bolt" guy. That is to say I can get it in and running just not to the best it can be :( .

Thanks for all the help. graemlins/beers.gif

besides what would make you think it could be "Hooter" (http://www.chevelles.com/showroom/BLT4FN/hooters3.jpg) wing sauce :rolleyes: .

I've seen you in action at Hooters. :D
Bring the car down anytime. graemlins/thumbsup.gif

Thanks Tom....

Can we tune it up in Hooters parking lot :D