Help! 454 bog/die on accel

[Dylan86]

I have advanced it an extreme amount with little change.... Also another thing I noticed is this engine heats up super fast and easily overheated with my old rad. Had to upgrade to a 4 core but it still gets hot fast. With no thermostat.

[LynnJr]

Dylan
Didn't realize it was a new motor.
Fire it up and twist the distributor at idle until the highest rpm is reached.Take your timing light and tell us what that timing is after you un-plug the vacuum and block it off.
Also plug it back in and take it for a ride bringing your timing light with you.If it pings back the timing off 2 degrees at a time until it doesn't ping anymore.
If its the same distributor you had in the 350 I would check the carb next as I doubt the distributor went bad while you were installing the 454.

[rich weyand]

Originally Posted by LynnJr

Rich
I think bad wires or weak ignition would prevent him from getting to 4500 rpm.I dont think a coil change will help unless the old one is defective.Plenty of big blocks with free flowing heads using points and a $10 coil without issue.
Also free flowing heads will make the charge less dense not more dense at his rpm level because they are not constricted or choked off like small peanut port heads would be at a given rpm.
Stumbles on acceleration usually mean wires plugs points cap rotor or carb not working together or defective.
He can run at 4500 he is just having trouble getting it there smoothly.

The key to my way of thinking is how did it run before the carb was swapped? If it ran good before I would look at that first.

No, free flow heads let more charge into the cylinder, otherwise why bother?

He can get to 4500, but not at low vacuum, ie high throttle settings.

The backfires (actually after-fires) are a big clue. Unburned charge is getting into the exhaust.

I'm still betting on spark strong enough for high vacuum charges, but too weak for low vacuum charges.

BTDT.

[Dylan86]

If that's the case shouldn't my exhaust reak of fuel when I accelerate in gear... When I hold the brake and let the back spin there's no smell of fuel at all

[Dylan86]

If it's getting hot super quick. No smell of fuel. And acting like it's leaning right out on acell. You think it would be carb problems not timing at all

[slam59]

My wifes 77 C20 does this. We put a new Edlebrock carb on it awhile back and upon take off it bogs a bit then goes fine. 454 motor. Might have to try some of these suggestions that you guys say and see if it cures it. Stock motor.

[geezer#99]

Originally Posted by Dylan86

If it's getting hot super quick. No smell of fuel. And acting like it's leaning right out on acell. You think it would be carb problems not timing at all

Old skool rule of thumb!!
Timing first, Carb second!!
Retarded timing is a heat builder.

[Dylan86]

Ya mines much more severe. I almost cannot accelerate at all unless it's under 1/16th throttle... And yes I've played with the timing and saw little change. Judging by the heat I should be going more advanced. But it's at almost 35° at idle with the vacuum advance hooked up.

[geezer#99]

Originally Posted by Dylan86

But it's at almost 35° at idle with the vacuum advance hooked up.

That's just speculation until you prove #1 tdc aligns with your timing marks.
You know what the vac advance is giving you, but not the initial.

http://www.crankshaftcoalition.com/w...op_dead_center

[Dylan86]

Ok here's a update. The spark plugs I'm running are acdelco rapid fires part #1. My plugs when I pulled them are actually fowled which means it's running rich. Which throws off everything I thought.... And also my timing mark is in the correct position. Now what..?

[geezer#99]

That was fast!!
What did you use for a piston stop?

[Dylan86]

Also I was playing with it more put a good known hei Distributer on it and it acted the same. But I found I can get it to bog and backfire out the carb when you really snap the throttle... What direction does all this point to? Sorry I don't know what a piston stop is?

[geezer#99]

How did you determine your timing mark is good?
Piston stop is in the link. Using a piston stop is the only way to determine true tdc #1.

[Dylan86]

I put a screw driver in #1 cylinder turned the engine over till the piston climaxed and the mark lines up...

[geezer#99]

Thanks for the chuckle!!
I wish you luck finding your problem!!

[LynnJr]

Guys lets not get crazy here.You can put your finger on the number one hole and crank the engine over until it pushes your finger with pressure.You can then look at the timing mark to see if it is in the ballpark.If its a quarter turn out you have problems like a missing key in the key-way(sp) or a slipped outer ring on your damper.
In reality this is not your problem.
If you have a map torch handy burn the spark plugs with it as they are gas fouled and won't work for you or simply replace them.
Crank the engine over without any plugs in it to get rid of any unburned or puddled fuel.
Set the timing by ear as I instructed earlier looking for peak rpm.
Let us know how it runs.
Oh yeah 18436572 is your firing order unless you put an aftermarket cam in it with a 7/4 swap.

[Dylan86]

Cleaned plugs. Timed and tested the same.

[Dylan86]

The rpm barely changes even when playing with the timing aggressively.

[LynnJr]

If the idle rpm is not changing your plugs are probably toasted.I would expect a 500 rpm variation at idle.

[rich weyand]

Back from the weekend. Hard to stay in touch, so sorry replies have been so late.

Ditch the rapid-fire plugs; lots of complaints about those on the net. And the ACDelco standard plugs can foul easier than others. Get a set of the Autolite plugs noted above and see what you get.

I'm still worried about a stock coil having enough pizzazz with that cam. But let's get some more reliable plugs in there.

[Jake Wade]

Is this a crate 454 you bought? What are some of the details? Camshaft style and size, compression ratio?

Do you have a vacuum gauge? What are the reading? How is the needle on the vacuum gauge acting?

Do you have a compression tester? What is the readings?

I would run through the valve lash setting to make sure they are set right.

[Dylan86]

The plugs can't be the issue. It's done this since first crank. They weren't carbonized then. And there not bad now. They just show sighns of being rich. There not fowled beyond use.. Not even close. I built this engine. Comp 262 cam. 9.5:1 compression. Vacuum gauge reads about 12psi vacuum at idle. Seems to be acting normal with throttle change. Valve lash is all good. Haven't done a compression test. Is there a throw in cool for these hei's that I could buy and try?

[LynnJr]

Dylan
I'm normally a Holley type person so I called up my cousin who uses edelbrock.
He said he has never seen a edelbrock that didn't need the float level set and he said they all stumble unless you change the springs from orange to blue.
He said you can go to the edelbrock website and look at there videos or look on you tube.
He also said don't remove the rods just lift them enough to swap out the springs.
If that doesn't work call edelbrock.

[Dylan86]

Originally Posted by LynnJr

Dylan
I'm normally a Holley type person so I called up my cousin who uses edelbrock.
He said he has never seen a edelbrock that didn't need the float level set and he said they all stumble unless you change the springs from orange to blue.
He said you can go to the edelbrock website and look at there videos or look on you tube.
He also said don't remove the rods just lift them enough to swap out the springs.
If that doesn't work call edelbrock.

I called edelbrock and they recommended going up with the accel pump jet size and metering rod. I cannot find this orange to blue spring part number..?

[LynnJr]

Dylan
He said the springs were under a couple torx head screws.