Should I mill my edelbrock performer rpm intake?

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LovetheA's

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I’m trying to get my aluminum edelbrock performer rpm intake to line up and bolt down to my aluminum edelbrock performer rpm heads. The engine is a 383 and I don’t believe the deck has been milled at all? Not positive about that because I didn’t build the motor when it was done about 20 years ago. I tried putting the intake directly on the metal valley pan and it has been a nightmare to get it to seal tight with no vacuum leaks. I’ve had the intake on and off 3 times already and I’m done doing it without the gaskets. I decided to use the thin felpro intake manifold gaskets. I’m not positive but I think the gaskets are about .030. I wanted to use one set between the valley pan and head and above the valley pan up against the intake. The problem is that even though the gaskets are thin using both sets which I think will give a great seal isn’t possible to line up and bolt down. Does it make better sense to mill the intake slightly maybe .030? I’m thinking mill it as little as possible to make it fit. If I recall correctly the bolt holes still line up with one gasket so milling it .030 would work. I thought it would be a better idea to mill the intake which is much cheaper than milling brand new heads that are already on the engine. Is that something that can be done very easily by most machine shops? My only concern is that if I ever want to use the intake on another engine I will have to use gaskets from now on.
 
My only concern is that if I ever want to use the intake on another engine I will have to use gaskets from now on.
And it'll lose value in the resale, if it ever comes to that.
But here's the deal, if you don't mill something, the port floors won't line up, nor the roofs so the port window shrinks double the amount of the missmatch.
That might not sound like a big deal, but when the airflow hits those steps, chaos is the result.
But if I had to mill something, it would not be the heads,lol.

But here's another thought;
What if the angles are wrong, and the intake even after milling, still ends up standing open, either on the topside or on the underside? Won't you be pissed!
I think some detective work is in order.
 
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Reseal value is the least of anything on a list of things to worry about. In fact it’s insane to even be bothered with such an item. You need to get that intake manifold to work, if it needs to be milled, mill it!

Now go get it done and burn rubber!
 
I absolutely agree. I’ve been messing around with this intake and valley pan for far too long. I need to just mill the intake slightly and be done with it. It appears after looking at the setup in various forms. Going from no gaskets to using both sets the only difference in the bolt hole alignment is with both sets of gaskets installed the bolt holes are just a touch off all the way around. It doesn’t appear that the heads are not square or true at all. Does .030 seem like a good place to start? Are the standard thin felpro gaskets .030?
 
Pictures would help.

I had the same problem. The intake would fit perfectly without the gasket. Measured up the gasket and told the machinist to mill that amount. He said he would take off just a tad more. It worked excellent!
 
I can tell you this. "However" you get the bolt holes to align perfectly, is how you should run it. If the bolt holes are aligned, then the ports are aligned about as good as you can hope for. On mine, I ended up using JUST the intake valley pan gasket right by itself and it lined up perfectly, so that's all it got. With a liberal coat of K&W Copper Coat of course.
 
I can tell you this. "However" you get the bolt holes to align perfectly, is how you should run it. If the bolt holes are aligned, then the ports are aligned about as good as you can hope for. On mine, I ended up using JUST the intake valley pan gasket right by itself and it lined up perfectly, so that's all it got. With a liberal coat of K&W Copper Coat of course.

Twere it me , I`d make sure the gasket /heads/intake ports are perfectly lined up ,and elongate the bolt holes , then recheck how they line up and adjust it as needed , .030 aint much to over size a hole , it would only be .015 on each side the ports are the most important !
I check every engine I `ve built for port alignment , a lot of them aint what their supposed to be to start with.
 
I’m no expert but I’d remove the valley pan gasket, set the intake on and see if I could get the bolts to start. If you can get the bolts in, left and right side, you should be able to check the intake face angle to the heads as well as the gaps to give you an idea of where you need to be. My thought is if the bolts go in without the gasket it will align the intake with cylinder heads.
 
I’m no expert but I’d remove the valley pan gasket, set the intake on and see if I could get the bolts to start. If you can get the bolts in, left and right side, you should be able to check the intake face angle to the heads as well as the gaps to give you an idea of where you need to be. My thought is if the bolts go in without the gasket it will align the intake with cylinder heads.


If you can get the intake to line up without the gasket, that’s how much you need to mill off the face of the intake manifold, plus an extra .010.

RRR nailed it. The bolt holes need to line up to get the ports lined up.
 
Sweet thank you for all the suggestions. I’m on it. I checked the location without the gaskets and it lines up dead on. I’ll have to compensate for both thin fel pro gaskets and maybe subtract .010 because of compression once the intake is torqued down. I’ll double check this and talk with the machinist.
Carl
 
Sweet thank you for all the suggestions. I’m on it. I checked the location without the gaskets and it lines up dead on. I’ll have to compensate for both thin fel pro gaskets and maybe subtract .010 because of compression once the intake is torqued down. I’ll double check this and talk with the machinist.
Carl


Don’t try and account for gasket compression. Measure the thickness of the gasket and take that, plus another .010 because even brand new intakes are not flat.

Don’t make it harder than it is.
 
As usual Rusty and YR are on point, regarding bolt/port alignment. One more thing to consider is how the faces mate with the heads, angle-wise. AJ alluded to it earlier--sometimes (pretty much any edelbrock intake I've used--my luck) there is more gap at the bottom of the rails than the top, or vice-versa and they can be off front-to-back as well. If this isn't right, or real close, you'll have sealing problems.
Go look on Hughes' site, they used to have a tutorial on checking this using those wax-wire strips. I've always just used pieces of solder, it crushes down good and the caliper doesn't wreck your measurement so easy. It's a simple process and worth the time to get a good seal. Gaskets will only get you so far if the gaps are off..
 
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Good point Beanhead. I’ll have to make sure the milled angle on the bottoms of the intake match up to the angle of the heads. In addition to the bolt holes being “Bang dead nut ball crackin snappin on”.
 
One more thing to consider is how the faces mate with the heads, angle-wise. AJ alluded to it earlier
This was a problem for me after the first decking. One deck was high at the back. the other high at the front. And they were not at 90* to eachother. But I did not know this. So when I bolted on my cast-iron thermoquad intake, nothing "gave". But I didn't find that out until after the cam break-in, when it idled like crap.
After I figured it out, I bolted on an aluminum intake which twisted enough to do the job. The next winter, I yanked the engine and found me a different machine shop, who was able to straighten it out pretty close. And by this time I had me an AirGap! I was pumped.
 
Well I’m pleased to report I took my edelbrock performer rpm intake to a machinist I trust explained the situation to him and had him mill my intake .040 on each side. That is the same thickness as the two felpro gaskets under and above the valley pan. The intake lined up perfectly now with the gaskets and I’m glad to report no intake or carb leaks. Checked for leaks with starter fluid previously based on the engine idling much higher than before it was taken apart. It used to idle at @1000rpm and with the leaks I had it idled noticeably higher at 1500. Now it is back idling at 1000 again. I sprayed the starter fluid at various points where intake meets heads and carburetor gasket with no sucking in of fluid or change in rpm as it did before. I hooked up a vacuum gauge to the constant vacuum draw on the side of my speed demon. At idle it currently has 10-12 in vacuum that is after I moved the distributor around to find the steadiest and highest vacuum reading at idle.
However it seems like I have another issue. The engine doesn’t idle as smooth as it used to and the gauge bounces around by about 2 inHg. I should mention that it is a 383 4 speed 67 Dart with the older Mopar performance camshaft 484 lift 284 duration. What would be my next logical step check plugs, wires and distributor cap or is idle mixture screw on speed demon carb off? Is there an easy way to do this without pulling all the plugs. Some are a bear to get to with TTI headers. I didn't touch the carb just put it back on after changing old cast iron to edelbrock performer heads and updating Harland sharps with Mikes geometry kit from B3 racing. I’m trying to get it running as smooth as it did before by process of elimination and learning as I go. I have included a video of the engine idling and the gauge. When I rev it up it also feels like it is running rough.
 
Well I’m pleased to report I took my edelbrock performer rpm intake to a machinist I trust explained the situation to him and had him mill my intake .040 on each side. That is the same thickness as the two felpro gaskets under and above the valley pan. The intake lined up perfectly now with the gaskets and I’m glad to report no intake or carb leaks. Checked for leaks with starter fluid previously based on the engine idling much higher than before it was taken apart. It used to idle at @1000rpm and with the leaks I had it idled noticeably higher at 1500. Now it is back idling at 1000 again. I sprayed the starter fluid at various points where intake meets heads and carburetor gasket with no sucking in of fluid or change in rpm as it did before. I hooked up a vacuum gauge to the constant vacuum draw on the side of my speed demon. At idle it currently has 10-12 in vacuum that is after I moved the distributor around to find the steadiest and highest vacuum reading at idle.
However it seems like I have another issue. The engine doesn’t idle as smooth as it used to and the gauge bounces around by about 2 inHg. I should mention that it is a 383 4 speed 67 Dart with the older Mopar performance camshaft 484 lift 284 duration. What would be my next logical step check plugs, wires and distributor cap or is idle mixture screw on speed demon carb off? Is there an easy way to do this without pulling all the plugs. Some are a bear to get to with TTI headers. I didn't touch the carb just put it back on after changing old cast iron to edelbrock performer heads and updating Harland sharps with Mikes geometry kit from B3 racing. I’m trying to get it running as smooth as it did before by process of elimination and learning as I go. I have included a video of the engine idling and the gauge. When I rev it up it also feels like it is running rough.


Very cool. I usually do gasket thickness and about .010 more because even new intake manifolds aren’t real flat.


Glad you got it ironed out.
 
Well I’m pleased to report I took my edelbrock performer rpm intake to a machinist I trust explained the situation to him and had him mill my intake .040 on each side. That is the same thickness as the two felpro gaskets under and above the valley pan. The intake lined up perfectly now with the gaskets and I’m glad to report no intake or carb leaks. Checked for leaks with starter fluid previously based on the engine idling much higher than before it was taken apart. It used to idle at @1000rpm and with the leaks I had it idled noticeably higher at 1500. Now it is back idling at 1000 again. I sprayed the starter fluid at various points where intake meets heads and carburetor gasket with no sucking in of fluid or change in rpm as it did before. I hooked up a vacuum gauge to the constant vacuum draw on the side of my speed demon. At idle it currently has 10-12 in vacuum that is after I moved the distributor around to find the steadiest and highest vacuum reading at idle.
However it seems like I have another issue. The engine doesn’t idle as smooth as it used to and the gauge bounces around by about 2 inHg. I should mention that it is a 383 4 speed 67 Dart with the older Mopar performance camshaft 484 lift 284 duration. What would be my next logical step check plugs, wires and distributor cap or is idle mixture screw on speed demon carb off? Is there an easy way to do this without pulling all the plugs. Some are a bear to get to with TTI headers. I didn't touch the carb just put it back on after changing old cast iron to edelbrock performer heads and updating Harland sharps with Mikes geometry kit from B3 racing. I’m trying to get it running as smooth as it did before by process of elimination and learning as I go. I have included a video of the engine idling and the gauge. When I rev it up it also feels like it is running rough.
Running rough can be a lot of things....but you can kinda hear the idle jump around more than it should a few times, and the gauge reacts with it. I kinda doubt it's a plug issue, but there are quick ways to test for misfiring cylinders--ground one wire at a time and listen for a change, measure the header temp at each exhaust port, etc. New cap and rotor are cheap and if it doesn't help, you'll have a spare set.
Double-check your lifter preload and make sure they're all set evenly. I know you don't wanna hear this, if plug hole access is tight, but honestly (because it's easy for me) I would compression test all 8 before doing anything else.
It could be very well be a carb issue too, it's so tough to tell from the video..it doesn't take much sitting around for them to crud up. If you cleaned it good before re-installing; that's good. Get it back to it's baseline settings and go from there--ignition idle timing, float levels, throttle blade adjustment (T-slot exposure) and idle mix.
Oh! And double check the PCV and vacuum connections and make sure they're in good shape..and of course check all your ignition parts and connections. Goofy things can happen when cars get sidelined for upgrades..
 
Beanhead thank you for the suggestions. I recently posted an update that I timed the engine and adjusted the air/fuel mixture on the carb and both idle set screws and the dart idles much smoother at 1000rpm the rockers are much quieter and it now has about 12-13 in Hg. You can also really hear the lope of the cam.

 
If you have not changed your spark plugs since correcting the intake vacuum leak, that is step one. Step two is 20° initial timing with vacuum advance disconnected
 
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