Edelbrock Performer vs Edelbrock RPM Airgap

So just wondering if a swap from my Edelbrock Performer manifold to and Edelbrock RPM Airgap would make any noticeable difference in performance. Or maybe at lease help with vapor lock issues during the summer.?

My current setup:
'71 model 318 - 30 over
Machine shop got the pistons for me, they said the engine should be about 9:1 compression
340 auto cam
Heads are later model U heads, suppost to be 318-4bbl heads. They have 1.60 - 1.88 valves
Edelbrock Performer manifold
Edelbrock 1406 4bbl carb
Early 340 exhaust manifolds
Dual 2-1/4" exhaust with H pipe, Walker quietflow muffs
Stock 904 Automatic
8-3/4 rear with 3:23's
26" rear tires

Runs good, but just seems a little sluggish. Not really crisp throttle response.
Planning on getting a wideband 02 gauge/sensor so I can get the carb dialed in better. But was also maybe thinking of a cam and manifold change.

Your thoughts on the Airgap ?
And would a more modern cam grind wake this thing up a little?

What's the ignition timing, initial and total?

That will make a big difference in lots of cases if the initial is low with a sluggish engine.

Put a 1" open spacer under the carb.

IMO, going to an air gap isn't worth the hassle.

I'd say no with the cam you have. Step up the cam and maybe, but that might entail a converter and gears.

I agree with the above, get it carb and ignition dialed in, then move forward with new parts. If you changed anything I would replace the manifolds with headsers, TTI or Dougs.

What about cam timing or, carb? Was cam degreed? Lot of variables that can make an engine sluggish. I had a 1406 600 eddy on a 340 w an iron 340 intake manifold and a .444 cam car always had a slight hesitation. I swapped to a 650 holley double bumper and the difference in throttle response was unbelievable. Of course timing and everything else should be checked 1st. Maybe just me, but I have have tried a few edelbrock carbs and none of them had a crisp throttle response.

I messed with the ignition timing a little last summer, that helped.
I cant tell you what my initial timing is set at, cause I thing the outer ring on my vibration damper has slipped a little or something, If you try to use the mark on the ring to set the timing, its way retarded.
I set it by ear last summer by using this method. Disconnected and plugged the vacume line. Advance it till it pinged a little under moderate acceleration. Then started backing it off a little at a time till no pinging.
Then reconnected the vacume hose, drove it, pinged, then backed off the adjustment that's inside the vacume canister by putting an allen wrench in through the hole where the vacume line goes. Backed that off a little at a time till no more pinging.

So not sure what its actually set at, but its running good. I don't have a dialback timing light so I have no way of knowing what my total timing is, or at what rpm its "all in".
Really don't know much about changing advance curves, etc. Its all greek to me.



Also, the car has the Mopar Perf, electronic ignition on it.

As far as the carb, when I first put this engine together , it did have the common, off idle hesitation. I rejetted the carb, changed out some metering rods/springs, etc.
Which got rid of hesitation and got it jetted down a little for my 5000 ft elevation in Colorado. But I think it's still a little rich, that's why I want to get the wideband 02 gauge so I can get the carb set just right.

p.s., the cam was installed "straight up" I did not degree it.

I'd consider a converter change, but just a little higher than stock stall.
And I wont be changing gears. I don't race the car, its just a cruiser, and 90% of my driving is on the highway
at 60mph, so don't want to go with a steeper gear.

It could have very little initial if it's a stock MP distributor.

Total timing is a rotten method for setting up a car.

If the balancer has marks you can read, you can still set initial and not be out of bounds on total. You know where it pings now, so you now need to find the point it still starts when hot or use a vacuum gauge method. Take that timing reading at idle, vacuum adv disconnected, and subtract the two. That's the mechanical advance you need in the distributor.

It takes work but cars run much better when initial is in a more optimal spot than most total timing set ups end up with.

Every time I have used the Eddy Performer 4 barrels they have had a sort of flat spot off idle, like the engine just kind of falls on its face for a split second. Get the timing dialed in first. The only tuning I have had to do with the Edelbrock carbs is to switch the pivot point of the accelerator pump (move the linkage to the inside hole) then fine tune with springs and metering rods. The O2 sensor and gauge might make it easier to tune, but probably isn't necessary. In my opinion, the carb / manifold setup you have should work just fine. With the setup you have, i would be willing to bet the stock jets that were in that carb would do you just fine. As Crackedback stated, initial timing at the distributor will make a big difference.

Heads are later model U heads, suppost to be 318-4bbl heads. They have 1.60 - 1.88 valves

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360 heads they are.

I'd degree the cam and mess with the distributor.

Between the two intakes you'll probably make more power with the air gap but be super hard pressed to feel the difference much less see it at the track.

318 4-barrels received 360 heads from the factory.

Find TDC and remark the balancer. Set your initial timing where the engine likes it best. Once that's set, check the total timing. You may have to weld up the slots in the distributor to limit the mechanical advance. My 318 with 340 cam has an initial setting of 15 degrees. The MP distributor I have has 20 degrees mechanical advance built in...total of 35 degrees.

Not in letter castings they didn't!

I thought they got the big valve heads.

Don't think the manifold will help with your vapor lock issue. My 340 is bad for that. I have aluminum heads, eddy rpm airgap manifold, and tti headers. No room for carb spacer when using factory air cleaner. I was thinking of trying out that new street demon carb, looks like a modern thermoquad !

burdar said:

318 4-barrels received 360 heads from the factory.

Find TDC and remark the balancer. Set your initial timing where the engine likes it best. Once that's set, check the total timing. You may have to weld up the slots in the distributor to limit the mechanical advance. My 318 with 340 cam has an initial setting of 15 degrees. The MP distributor I have has 20 degrees mechanical advance built in...total of 35 degrees.

Click to expand...

So what do I want for total?

crackedback said:

What's the ignition timing, initial and total?

That will make a big difference in lots of cases if the initial is low with a sluggish engine.

Put a 1" open spacer under the carb.

IMO, going to an air gap isn't worth the hassle.

Click to expand...

This,everywhere...And have you done a custom distributor curve,to match?
n

burdar said:

I thought they got the big valve heads.

Click to expand...

The 318 did get the big valves when it went to a 4bbl. Set up. By ten, the letter head series was gone.