I am having a hard time getting my 454 to trun right. It's got about 550 horse, about 10:1 compression, bored .30, dual edelbrock 500 carbs, mallory unilite magnetic breakerless distributor. It idles fine around 900-1000 rpm but has no power when you get on it. I have initial timing set at 12 degrees. total advance is what ever comes stock on the unilite.

the cam is a crane cam:

296/304 duration
.610/.632 lift w/ 1.7 ratio rockers
cruise rpm 3200
rpm range 3000-6500

according to desktop dyno max torque is at about 4500-5000 and max hp is at 6400

The plugs don't look like it's running really rich...(although it sure smells like it). the plugs have a little bit of brown on them around the electrode. To me it seems mainly like a timing problem.

 

Sounds like a timing problem. Put a timing light on it and see just how much advance it's getting by 3000 rpm.

Is this for street/strip or strip only?

 

it is pretty much just a weekend warrior that will be street raced. how do I check my total timeing if the tab on the balancer only goes up to 16?

 

You either need some timing tape on the balancer, a degree'd balancer or an advance timing light.

Do you see the timing marks moving when the rpm's are increased? It would at least indicate that the timing is advancing.

A good start point for total timing would be 36*

Explain the "no power when you get on it". Does it just die, sluggish, etc. It might even be a fuel problem.

Were the heads set up for that much lift? How much piston to valve clearance is there? I originally tried a .588/.593 lift cam with LS6 pistons on a block that was zero decked and kept smaking the valves into the pistons. Having all the pistons fly cut helped. I've since gone to a higher lift cam and JE race pistons.

 

its real sluggish and delayed throttle response but it doesn't die.I know the dist. is advancing the timing because with the timing light I can see the mark move when it is revved. The motor was professionally built so I'm guessing there are no clearance issues. It's got 2.08/1.90 valves, trw forged piston, and 1.7 ratio rockers. I have used a stethescope to check the valve train after I set the valve lash and did not hear any abnormal valvetrain noise. I do have one rocker on the #6 cylinder that is not adjusted all the way and is making a loud tick. The rocker lock nut and tightening nut are seized onto the stud and I haven't been able to get them broken free from the stud yet. but even still it should still run decently even with one not adjusted (it still opens and closes).

 

oh yeah, I'm also getting some popping at cruise.

 

There's no way you're going to have 550 hp with tiny valves like that. 2.19/1.88 minimum is needed or are we talking about a very large SBC? If so then are the 1.7 rockers designed for the SBC heads or are they BBC rockers. BBC and SBC rockers are not interchangable. The ratio differences are wrong.

The lock screw in the rocker nut should be very tight. I use a 7/32 allen key socket to tighten mine. It sounds like you should reset all the valve lashes before doing anything else.

 

I'll try that. but also it is possible to make that power with my valves if you have ported heads right?

ps-it is a big block.

 

I have dual Edelbrock 600s on a SBC. Welcome to dual carburetion!
Are you running the Edelbrock progressive linkage, or are the carbs just connected with a rod? I just have a rod, and it seems to work fine. I'm guessing that you smack the throttle open from idle and it almost seems like the engine is going to die. Does it happen if you floor it from 1500 or 2000 rpm?
What is your idle vacuum, and what color step-up springs are you running? What size metering rods and jets? What hole is the accelerator pump link in?

While you're poking around under the hood anyway, check the linkage to make sure you get 100% opening of the primaries when the pedal is on the floor. I had my linkage in the big holes near the tops of the throttle arms, and they weren't opening all the way. I fabricated a different linkage that attaches at lower points and now it's all good.

 

everything on the 500s is how it comes when you buy it. I am also using a rod that connects the two. If the engine is off and you pull the throttle wide open should you see the gass spraying into the secondaries or does it run off of vacum. The idle vacuum is jumpy and I suspect it's because of the lifter that is not adjusted. when I check the vacuum do you think I should run a tee fitting so I pull vacuum from each carb to get a more accurate reading?

 

Don't worry about a t-fitting for now, just let me know approximately what the idle vacuum is. If you have more than about 6" you may need stiffer step-up springs.
You should see gas squirt out the accelerator pump nozzles into the primary venturis (under the choke towers). The secondaries have no accelerator pump.
I'm guessing the jetting is close, so let's not worry about that for now. Try moving the accelerator pump drive links to a hole closer to the carb body. That will give you more accelerator pump shot. If that doesn't work, adjust it the other way and see if that helps.

Also, how much fuel pressure are you running? Edelbrock carbs don't like more than about 6psi.

 

I've got 5 inches of vacuum. but it's hard to read because the needle is pretty jumpy. and i am running about 5.75 psi

 

Good. You need to find a way to adjust that rocker arm nut soon.

Just try the accelerator pump arm adjustment and see how that works. Let us know.

 

I just figured out what my main problem is. THE REAR IS EITHER A 2.41 OR A 2.29!!!! I figured it would have to be at least a 2.73 or higher. It must be lugging the engine just to get it moving.

 

Set your intial timing around 20 total around 40. you'll have to see if you have any detonation, if you do back off the timing. My big block camaro I'm running 25 degrees intial around 45 total but I'm running a msd distributor. Big blocks love timing just make sure you don't go over board. also if your distributor has timing springs in it play around till you get the right combo.