348 409 Speed-Port Intake, Machined & Installed !

Yes, Carl... that's exactly what I'll be doing.
First manifold to use, is a stock 63-65 340 HP 409 cast iron intake
Next, will be an Edlbrock Performer.
Then this Speed-port manifold.

The same carburetor will be used on each one. I'll get a baseline with the stock manifold, and get the mixture right. Then the Performer, and see what it wants for jetting. Then my manifol, and do a couple pulls to see what it needs. This is going to be a pretty thorough test, by a highly respected race engine builder. I have a major magazine nibbling for an article on it... but their concern is that they're not in control ( after what we just saw regarding the Hilborn system, I wouldn't let them near it:crazy ).
This is why the fair, unbiased results are absolutely crucial.

Originally, I planned on using a 750 Holley. However, I spoke with a tech guy at Edelbrock, and he wanted to see one of their 800 AVS carbs on their manifold. Seems too much much for a small port 49 inch engine:dunno. Anhow, I spoke wih my dyno guy, and he too, thought I should use an 800 CFM carb. He has a "Quck Fuel" on hand, that we can use on the dyno. So, that's likely what we'll be using.


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A bigger carb might actually bias the results in favor of the dual plane manifolds. :scratch
They say a single plane can get away with a smaller carb because the engine can draw from all four barrels at once.
No matter, I'm sure your manifold is going to do great. I think you'll leave the factory intake in the dust, especially as the rpm's climb, but from what I've seen on other engines, the Performer RPM is a good manifold, even at higher rpm's. If you can beat it, you'll have really accomplished something. :deal

You might want to try some carb spacers while you're at it to see what difference they make.

I'm REALLY interested to see how your Speed-Port 7,000 does against the Edelbrock dual quad on a 500 plus horsepower stroker. I think your manifold will make more power right through the entire rpm range. :deal
I don't know if you're planing on doing that test but you know someone will. I think that manifold will become popular on strokers, not only for the power but the simplicity and money savings of only having to buy one carb, one spacer, one air cleaner, one linkage, etc.
Thank you, Jim, for the information, advice, and support:bow.
Intersting about the big carb / dual plane:rub
I just watched a few dyno tests on youtube. Curious ? Am I missing something ?
Why is no one using an air cleaner base of sorts ? On the dyno, my Stocker engine picked up 12 HP:eek by simply remembering to put the air cleaner bae on:think

At this point, it doesn't look like a large port test will be possible. It's almost $1000 a day, and I'm just not that well endowed:hide

I have to get this dyno test out of the way, so I can get the information off to the pattern maker, for final adjustments.


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Supporting Member 2
I think it will give something to the edelbrock on the low end but beat it in the mid and upper ranges. On a stroker it should kick the edelbrocks ass up and down the block.


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Supporting Member 5
I think it will give something to the edelbrock on the low end but beat it in the mid and upper ranges. On a stroker it should kick the edelbrocks ass up and down the block.
Yeah, that's what I think too. I've seen tests with Edelbrocks RPM manifold VS their own Victor Junior single plane and that's pretty much how it goes. At some point the single plane will pass the dual plane. On a smaller engine the crossing point might be right at the top of the rpm range but on a bigger engine the single plane takes over much earlier in the range.
The single plane also tends to make more power beyond the peak horsepower point. That's important too because if an engine peaks at 5,800 you'll usually shift it at 6,000 or higher.

Single plane manifolds are very popular with racers and hot street cars for good reason. These manifolds should fill a hole in the market.
Dan, it's not so much that I hope or think it might kick Edelbrock's a$$... I want it to be in addition to what's out there. It's different from anything that has ever been commercially available. If a person has a modest build, say up to about 420 cubic inches, with a cam that suggests peak HP under... oh... 5200 RPM... especially street driven with just an automatic ( I ALWAYS say "just an automatic";) ).... then by all means, the Edlbrock Performer IS THE manifold to use.
This is for the more aggressive builds / big cubic inches. No, I would not recommend it for the "street rodder" croud, who runs 30" tall tires, with 3.00:1 gear in a 9 inch, using an overdrive transmission:crazy:yawn. The engine would have to see no less than about 2700 RPM highway cruise.... / around a 3:08 final drive ratio.

Jim, that's actually what scares me. The engine that this manifold is on right now, is the most valuable engine I own... a complete standard size, balanced ( underside of piston domes milled ) 1963 425 HP 409. I'm worried that the manifold may want the engine to spin past where I want to limit it to. These heads on it, are pretty "whizzy" ( I have about 10 hours of port and bowl work on them )... so they're not limiting RPM either.

First, let's have a little Easter breakfast:coffee
Jason, I used one of my cam combinations, made by Comp... my part number M242595D.
Flat tappet mechanical... net lift at valve .565"/.578", 242/246 duration @ .050", 272/276 adv duration, on a 108 lobe center sep. To really use the manifold, it would be ideal to have about 10 degrees more duration... but I wanted to do a "typical" setup, for real world results.
Haven't changed the valve springs yet, but I did get out on the highway, to see how it runs. Didn't run it hard, and never exceeded about 4500 RPM. Just wanted to see how it felt. For the record, it IS a little "soft" on the bottom end. However, after about 2000, it gathers up nicely. After 3000 ? quite frankly ? ... now I'm really worried:eek... feels like a turbo "spooling up".

My son, Donovan was with me ( he's 12 ), he took this photos that he wanted me to post:
well, I guess you can at least put a face to all this stupidity:crazy
Thanks, Dave:bow
One thing I forgot to mention...
I devised a very simple, quite unique shield arangement for the underside of the manifold, to prevent oil from being pushed out of the PCV provision ( this manifold uses the basic factory design ).
It appears to be quite effective. I ran the car to about 4500 RPM in high gear, at full load. I deliberately left the opening at the rear of the manifold, disconnected... so, if there was any oil at all, it would certainly show up. The fact that this is by no means a race prepared engine, with zero blow-by, would increase the potential for such a problem.
All good. Not a drop.

Valve springs are done.
Tomorrow, I'll install a 4.11 gear set in the rear end... and go out for a real test.
Just about to remove the engine... thought I should take a couple last photos.
I've been trying out a few different air cleaners, for fit, effieciency, and appearance.
This chrome Moroso 14" "racing air cleaner" seems to ne the best for all of the above:deal
I LIKE it:cool:
It provides ample hood clearance, which would allow the use of a 1/2" carb spacer, even on the "7000" ( large port ) model.
It clears the throttle linkage an d accessories.
and... I really like how the top ( which is chromed MUCH better than the generic air cleaners ) is a bit of a rounded "bubble". Matches the valve covers nicely.



That'll be it for photos in this car. Engine is coming out in a few hours.
For the dyno session, I'm going to be replacing these valve covers, with a pait of beat up ones that I have, which I will be adding simple crankcase breather openings to. It became apparent that this old engine ( re-ringed in 2006 ), has a little too much "leak down":(. On the up side, it's loose, and spins freely.

I hope to get a number of photos and video of the dyno session tomorrow