I tried to start my 454 tonight.

[Paranoid]

The starter fired right up, good cranking power. Then we (my daughters & I) caught our first leak. A bad AN fitting feeding to the carb line. It was sprouting like a water fountain. Tightened it up, still leaking. Looked around and made a new line from the pump to the carb double feed line. Start her up? Still got a small leak from the new fittings. Tightened them up and got a couple water leaks from the temp sensors. Also had a small oil leak from the fittings. No problem just needed tightened.

End Result? I have the evil back-fire thru the carb syndrome. That's what I feared most. I really think one of my mechanical weak spots is anything related to the distributor and timing. So help me out here guys.

I guess it's a timing issue, but I was very sure I had everything dead on. When I started it, it ran for about 10-15sec and then BOOM! Scared the crap outa my kids. I repeated the start about 3 more times with the same result. One of those times I had it running for about 30 seconds before the boom, but I slowly took the idle speed up. I couldn't believe the tach, I was slowly giving it gas but the tach was moving very slowly, then Boom. I wanted to get the RPM's up because I knew a new engine shouldn't run at idle at the first start up.

Prior to this I instructed my daughter that if she saw a roaring flame thru the carb to hit it with some water. Well it was no roaring flame but she doused the carb with the hose anyway. :eek

I'll tell you though, it was a great relief, after 2 and 1/2 years, to hear that monster speak. It sounded loud and angry. Like I woke it up from a long rest.

I guess it's good news that I got cranking going, I have spark and combustion. The worst could have happened, but didn't, that being when I turn the key I get just a click. :cry

So steer me in the right direction here .....what do I checkout first?

Len

I like C1-C2 better that's why I'm posting here.

 

[MoeJr]

My guess is you are off a tooth on the distributor. Need to get it back to top dead center on compression stroke and reset distributor and make sure rotor is pointed at the #1 plug wire poll.

 

[jerrybramlett]

Your carburetor has no choke. I'm surprised the engine would continue running at all after a cold start.

Try partially covering the primary venturis (NOT WITH YOUR HANDS) to simulate a choke until the engine warms up.

 

[Paranoid]

The carb & distributor were recent working units from my 350 engine.

 

[bradfordsvettes]

Your carburetor has no choke. I'm surprised the engine would continue running at all after a cold start.

Try partially covering the primary venturis (NOT WITH YOUR HANDS) to simulate a choke until the engine warms up.

this is a good point this could be the whole problem but check out the rest of the basics steve

 

[skids]

Is that a pcv valve on your left valve cover? The other end of hose isn,t connected. Have you possibly also have an open vac port on carb or intake?

 

[vetteboy86]

What will cause an occasional backfire through the carb? My 455 has done that twice since I have owned it. I have been having carb issues, but does timing cause this, or could there be another culprit at work here.

By the way that is one sweet vette. I just love the way it looks, and the engine sure does look awesome. You have done a good job on the car.

Thanks to all.

Craig

 

[IH2LOSE]

Prior to this I instructed my daughter that if she saw a roaring flame thru the carb to hit it with some water. Well it was no roaring flame but she doused the carb with the hose anyway.

I use my welding jacket handy for this.I just throw it over the the flame .It would be better for you to get some type of a rag then water.

This is real easey compaired to what you have done so far.Lossen the distibutor nut just a bit so it bairley moves then have the daughter in the car working the starter You goin to work the distributor back and forth till she starts and runs while she is cranking.Just use caution by the carb when it does shoot a flame,also dont jump back and get hurt

Good Luck and your right around the corner from driving it again

 

[67HEAVEN]

Len,

Check your spark plug wires. They don't look right. Maybe they're off a position or two.

1-8-4-3-6-5-7-2

 

[jerrybramlett]

Try partially covering the primary venturis (NOT WITH YOUR HANDS) to simulate a choke until the engine warms up.

Why not try it?

 

[studiog]

All good points above. I would go back and throughly check everything one more time: Dist. on right tooth, timing, plug wires, carb & choke, vacuum hoses etc. You really want this thing to start, keep running at good RPM and break in correctly.

 

[Rowdy1]

All The Above

I'd start from step one, top dead center cylinder #1, check each wire and the rotor. If they're all correct, while cranking it, move the distributor slowly. I would NOT use water in the carb in the event of a backfire, especially if you have ANY leaks, put an air cleaner on it or stuff a rag on it. Worse comes to worse, pull the coil wire and crank it, it will suck the flames back in. Keep us posted.

 

[allcoupedup]

"The worst could have happened, but didn't, that being when I turn the key I get just a click. :cry "


It's a good thing that fuel fountain didn't meet a backfire! Would have been worse than a flatline!!!

I'm with all the other guys - check the firing order and make extra sure you have the distributor on the right tooth.

I worked on a van one time where you actually work on the car from the INSIDE.. Tried to start it after changing the plug wires and POW I had flames on the inside ... picture a 20 year old kid not knowing what the hell just happened and trying to fan the flames with his hand and blow out the flames... yep that was me. I had the wrong firing order.

Brian

 

[vette-dude]

Just a suggestion but could you have a vacuum leak?? Does this carb have a large outlet on the backside base that connects to the PCV valve? If it isn't capped you will have a lean condition and thus the backfire. Second, if you have backfired through the carb you most likely have blown the power valve in the carb unless it has been retrofitted with a ball check backfire damage prevention kit. Third, have you checked the float levels? They might be too low dependent on the angle of the BB manifold. I know you said it came off another engine but if the level is low it might be going lean. I would start from scratch as other have suggested ( Ignition set up) then make sure the carb is not damaged, i.e, power valve and set up. Then check for the vaccum leak on the base. Good luck and let us know the results.


Randy

 

[Paranoid]

Thanks for the input guys. In reference to the gas fountain, I saw that immediately and she her down pronto. My eyes were running everywhere during that initial startup and think I could tell something was wrong when I have a fountain in the engine compartment. :L

Here's what I did today. Checked lash-ok, checked wiring at distr--ok, checked plug wire routing--ok. I didn't need to change anything. I rotated the distributor about 1/8 of a turn as pictured. I did clean out the carbon from the carb. Fortunately the butterflies were closed when my daughter squirted the carb. No water present in oil.
So I double checked everything again and fired her up. I was able to slowly increase rpm's to about 2500. Smoke was everywhere, burn off from the exhaust manifold coating I guess. I'll tell you this baby really heats up fast.
It ran for about 2-3 min between 1500-2500 maybe a little higher. Mostly between 2000-2500rpm's. Oil pressure was 40-50, water temp was 160. I'm working alone here, so I tried to tie the throttle back to about 2000rpm's. That was working fine until the tie down wire slipped and then another backfire thru the carb before it died.
I got a leak from an intake temp unit and an intake plug I have to take care of before I fire her back up. I'm going to let it cool and wrap the threads with teflon(water fittings).
During this session I accidentally removed my foot from the pedal and the engine fell to idle and settled there, and ran. I quickly tried to bring the throttle back up.
But it ran great until my throttle rope slipped and it died.
Any ideas? Still think I'm off a tooth?

 

[Paranoid]

Is that a pcv valve on your left valve cover? The other end of hose isn,t connected. Have you possibly also have an open vac port on carb or intake?

It was connected prior to start up.

 

[Paranoid]

Just a suggestion but could you have a vacuum leak?? Does this carb have a large outlet on the backside base that connects to the PCV valve? If it isn't capped you will have a lean condition and thus the backfire. Second, if you have backfired through the carb you most likely have blown the power valve in the carb unless it has been retrofitted with a ball check backfire damage prevention kit. Third, have you checked the float levels? They might be too low dependent on the angle of the BB manifold. I know you said it came off another engine but if the level is low it might be going lean. I would start from scratch as other have suggested ( Ignition set up) then make sure the carb is not damaged, i.e, power valve and set up. Then check for the vaccum leak on the base. Good luck and let us know the results.


Randy

I thought the new Holley's were blow proof. This carb over the last few years has had a few backfires and then ran great. That's why I'm using it here. I have an 830 & 1000 still in the garage. I didn't want to tune & adjust a new Holley at the same time.

Actually I adjusted the float levels not too long ago.

I'll try a new carb gasket.

 

[vette-dude]

Have you checked the Dwell on the points or has the Dist been converted to Electronic?? I think the dwell should be around 32 degrees. this will cause a backfire also. Still thin it might be in the carb but just throwing out other ideas.

As for the backfire protection, Yes and no. Depends on the year of the carb and who has been in it before. If it has Back fired and you don't have gas coming out the vent tubes you are probably okay.


Randy

 

[ctjackster]

saw you mention putting some teflon tape or goo (perhaps on your temp sending unit?) to solve a coolant drip - know that doing so might render the temp gauge inaccurate, as it intereferes with the ground the sending unit needs to make.

 

[Paranoid]

saw you mention putting some teflon tape or goo (perhaps on your temp sending unit?) to solve a coolant drip - know that doing so might render the temp gauge inaccurate, as it intereferes with the ground the sending unit needs to make.

Thanks, I thought of that as I was pulling the unit. No tape on that leak, just tightened it more. I put take on one intake plug and the by pass hose fittings.