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  #31 (permalink)  
Old 04-06-2019, 09:38 AM
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Quote:
Originally Posted by chasracer View Post
The ports might need to be matched to the heads but it would be worth the effort.
Do not port match the manifold to the heads unless you are prepared to enlarge the ports all the way from beginning to end of the ports. Most fellows will cut the ports bigger for only maybe a half inch back from the transition, making a larger port diameter and thus volume at that mating point. The port ends up looking in cross section like an Anaconda that swallowed a pig. What happens then is that the slug of air/fuel mixture is travelling down the manifold at a certain speed and suddenly sees that the port volume has increased. This slows the mixture down to the point that some of the liquid fuel in the mixture falls out of suspension and lays on the floor of the port, so that the intake valve allows a lean mixture into the cylinder. Some of the mixture will be picked up in subsequent firings, so that you will have lean/rich/lean/rich mixtures entering the cylinder.

Research of fluid dynamics has proved that the lion's share of mixture goes directly down the center of the port and that mating of the intake and head exits and entries is a waste of time, unless like I said, if you start at the top of the manifold and make the ports the same diameter and the head ports the same diameter from start to finish, with no diameter change at the manifold/head intersection. This operation would take an ungodly amount of time and effort and might prove to be the biggest waste of time and effort that you ever spent on a motor build.

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  #32 (permalink)  
Old 04-06-2019, 09:48 AM
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Originally Posted by 55 Tony View Post
I should pull the left one just to see. I've heard that's most always the first one to twist, it was for me anyway.
There's a reason for that. Front-motor, rear-drive cars and trucks twist the chassis under acceleration in a way that the right front and left rear of the vehicle get heavy, while the left front and right rear get light. This is why you'll see Ricky Racers, when doing a "one-wheel peel", will always be peeling the right rear, because it is the light tire. The left rear is taking all the torque from the motor, so it will wear out parts quicker than the right rear. You can witness this "light left front" at the drags too, watch any of the faster cars at launch. The left front will catch air, while the right front stays planted.

The backyard way to equalize traction on an open differential is to install an air shock on the right rear only, increasing air pressure a little at a time during testing until you have two equal skid marks. This will leave the right rear of the vehicle sitting a little higher than the left when parked, but if you can get over that, it's a cheap and easy way to make a posi for yourself. Savvy racers have been doing it for years.
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  #33 (permalink)  
Old 04-06-2019, 10:00 AM
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Originally Posted by 55 Tony View Post
Or are all the twists and turns in the runners going to slow things down?
For a street driver, the tallest dual plane you can find is going to make the most power in a range that is useful. The longer runners have proven to be the answer for motors that are used up to about 6000 rpm's. Chrysler Corporation engineers experimented with some off-the-wall intake manifolds in the late '50's, early '60's, like the ram induction two-4 barrel unit. It was a cross-ram with the left bank carburetor sitting above the right bank valve cover and the right bank carburetor sitting over the left bank valve cover. It was the longer runners that made the best power.
https://www.pinterest.com/pin/84864774207681420/

If I had to buy an intake manifold for you, it would be an Edelbrock 7164, Chevrolet Performance 12363420 or Professional Products 53001 (carb pad height 5.750").

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Last edited by techinspector1; 04-06-2019 at 10:20 AM.
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  #34 (permalink)  
Old 04-06-2019, 10:40 AM
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I finally put the valve checking springs on today and I came back here for notes. I have the dial indicator on #1 exhaust retainer and was having a hard time zeroing it. I believe with just these weak springs the lifter is collapsing as I watch. I push down on the roller tip to see how much clearance there is and after I let it go it's way off zero and slowly climbing. It had climbed .110" before I came in here to post.
BTW, yes these Comp lifters were like this or worse when new. On startup they always took some oil pressure till they got quiet, sometimes 10 or so minutes on one or two. They're actually better now than when new.



Anyway going past TDC the least I got so far is about .400". That was not trying to zero it, just looking at the indicator to see how much it moves back and forth without time for the lifter to collapse. I'm going to back up and check BTDC. Am I doing this right? And I have a note to myself here that says minimum clearance is .100 exhaust and .080 intake. I'm just getting some idea of what kind of interference I may get with the big valves in the aluminum heads, like are things close now or do I have a lot of room.
Valve train geometry must be checked with a solid lifter, a hydraulic always suffers some amount of bleed down leading to erroneous results. If you're running a flat tappet hydraulic cam then just lay your hands on a solid lifter to use. If you are running something other than a flat tappet cam or can't lay your hands on a solid lifter there are several options:

- There are test substitutes sold that replace flat and roller liters, these can be found under "Tools" or "Valve Train Parts" in any hotrod catalog, be that online or paper.

- A hydraulic can be taken apart and a stack of washers substituted for the plunger apparatus till the push rod cup is supported in its operational height. When done just clean it and reassemble.

Bogie
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  #35 (permalink)  
Old 04-06-2019, 10:53 AM
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Quote:
Originally Posted by techinspector1 View Post
For a street driver, the tallest dual plane you can find is going to make the most power in a range that is useful. The longer runners have proven to be the answer for motors that are used up to about 6000 rpm's. Chrysler Corporation engineers experimented with some off-the-wall intake manifolds in the late '50's, early '60's, like the ram induction two-4 barrel unit. It was a cross-ram with the left bank carburetor sitting above the right bank valve cover and the right bank carburetor sitting over the left bank valve cover. It was the longer runners that made the best power.
https://www.pinterest.com/pin/84864774207681420/

If I had to buy an intake manifold for you, it would be an Edelbrock 7164, Chevrolet Performance 12363420 or Professional Products 53001 (carb pad height 5.750").

.
We shopped a 1995 C1500 a few years ago with a conversion to a LT1 roller cam and carb mounted on a Professioal Products 53021 Typhoon intake and Edelbrock 600 CFM Performer. Even with the Swirl Port heads the thing is an animal! Like Swirl Ports tend to behave it does not scream on the top end but it sure is sudden up to that point which demonstrates great torque numbers are being produced.

I like that intake but you need underhood space for it unless you're willing to bulge the hood with a scoop. I'm using an EBay sourced used one for my upcoming cheap top end build for my class report about what I did on my summer vacation.

Bogie
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  #36 (permalink)  
Old 04-06-2019, 06:37 PM
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Quote:
Originally Posted by techinspector1 View Post
…. if you start at the top of the manifold and make the ports the same diameter and the head ports the same diameter from start to finish, with no diameter change at the manifold/head intersection.....
I've got to step in and amend one bit of your info here, Techinspector, that isn't a true statement.

The section I highlighted in bold is not correct, you don't want the port to be the same size from inlet to choke point, whether that be pushrod pinch, short turn, or seat ring.
Ideally, you want the port to taper from larger at the inlet to smaller at the choke point. I'd have to dig around and look the figure up, but just from memory right now I think the taper figure is about 5. Think of it as a very gradual funnel.

Also, port will generally need to get bigger at the short turn and valve bowl, to allow the mixture to slow a little and make the turn down toward the valve seat and past the valve into the cylinder.

You are correct however you don't want to go grinding the port bigger to match the head port opening or a gasket if you don't rework the intake port in the manifold all the way back to either the plenum below the carb or a point the port is big enough to match the taper formula.

You are completely correct that ust your basic magazine photo "port match" back 1" or so deep into the ports in each direction from the intake gasket is a complete loser.
AFR Cylinder Heads even makes a point in their instructions to NOT grind the 1/2" radius corners of their ports to the common 1/4" or 3/8" radius that is on the intake gaskets....it will hurt flow!

Picking a gasket and then just grinding the port to match makes the huge assumption that the gasket was the correct port shape and/or size for best flow....it typically isn't.
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  #37 (permalink)  
Old 04-06-2019, 10:14 PM
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The L31 Vortec port takes the idea of widening the short side turn to the extreme by widening the port floor for its entire length. Interesting in that common accepted practice that was also advocated by Vizard was to enlarge the port where the greatest flow was which typically is the top of the long wall on the bore wall side of the passage. The net resulting battle of concepts here is whether greater volume of port here actually makes space for the greater flow amount or whether by the gas laws it slows velocity, increasing pressure and that aids in getting more total flow into the cylinder. I'm sure in some F1, USAC, and NASCAR shop there is a math model that's more zone finite than measuring total flow on a flow bench as in Computational Fluid Dynamics. Somewhere there's a computer geek that knows more about this than all the guys with grinders breathing metal and cutting stone dust in the world and that's a sad thought.

Live and learn, the text books say a tall narrow port will out flow a square or mild rectanglular port of the same area. The LS cathedral port, however, rather disappointed those book worm believers.

Back to the grinder to ruin another head then test the results. Gotta get one of them 3D prototyping machines so I can build cheap plastic port models instead of hacking ideas on otherwise perfectly good heads only to make them contributions to the local metals recycler.

Bogie
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  #38 (permalink)  
Old 04-07-2019, 04:06 AM
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So if I get an Edlelbrock RPM I shouldn't really touch the ports that are notoriously small at the end? I did in the Performer 2-0, but had crappy bits and never got them near the gasket size. Guess I won't be able to sell that here!
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  #39 (permalink)  
Old 04-07-2019, 05:40 AM
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If the manifold's ports at the gasket face is deliberately left smaller than both the port opening in the head, and the upstream potion of the port in the manifold, it will be okay to do some form of matching.
You just don't want to go in there and grind the opening to a big gasket hole that is already bigger than the rest of the port in the manifold....Like Techs example of a port that looks like a rattlesnake that swallowed an ostrich egg scenario.
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  #40 (permalink)  
Old 04-07-2019, 06:06 AM
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Is there a good/easy way to install the manifold loosely with or without gaskets and some type of marking compound?


With my current Performer, I do now recall calling Edlebrock about the small ports and they said they leave them that way so port matching can be done. But to me it seems like they really go overboard making them small. Lot's of reviews I've seen claim they are made for peanut port heads.


Also, where do I buy good die grinder bits? The crap I had didn't even hold up to aluminum. Didn't get clogged up, just wore out.
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  #41 (permalink)  
Old 04-07-2019, 12:17 PM
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Quote:
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Also, where do I buy good die grinder bits? The crap I had didn't even hold up to aluminum. Didn't get clogged up, just wore out.
https://www.mcmaster.com/die-grinder-bits
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  #42 (permalink)  
Old 04-07-2019, 05:23 PM
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Thanks.

Do they make ones special for aluminum and different for steel? Someone told me the aluminum ones have bigger spacing between the cutting edges so they don't load up. He also told me that they go dull fast if you use them at lower rpms.
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  #43 (permalink)  
Old 04-07-2019, 05:35 PM
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Quote:
Originally Posted by 55 Tony View Post
Is there a good/easy way to install the manifold loosely with or without gaskets and some type of marking compound?


Also, where do I buy good die grinder bits? The crap I had didn't even hold up to aluminum. Didn't get clogged up, just wore out.
Cutters have to be carbide, and aluminum cut. Tool Steel/Cobalt/High Speed Steel won't last for squat. Single cut and double cut for steel/harder materials just plugs up on a soft metal like aluminum and brass or copper. Get nothing but the course aluminum cut. Only 5 or 6 flutes on a 1/4 to 3/8" burr

I hunt on Ebay for close-outs and deals, often find foreclosure reselers letting stuff go for half price or less.

https://www.ebay.com/itm/Grobet-USA-...ss!49036!US!-1
https://www.ebay.com/itm/SA-1-NF-S-C...UAAOSwNWBckVCv
Although I don't like this burr shape due to the fact if not kept square with the area you are working the square nose corners rip things up something awful.

https://www.ebay.com/itm/TEMO-SF-3-N...ss!49036!US!-1

As far as shape, "straight round nose", "flame", "round nose tree", "oval" will be most useful for port matching, you'll need a 1/4" or 3/8" "round ball" if you intend to do any valve bowl work in heads.
"Oval" or "Egg" in 3/8" diameter is the most universal shape if choosing just one, followed by "round nose tree" or "flame". You could go 1/2" if all you plan to do with it is port runner work as it tends to be too big to fit in the valve bowl between the port wall and the valveguide in most cases.

I find "straight shank square nose", "cone shape", and "pointed tree" all to be almost worthless.
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  #44 (permalink)  
Old 04-08-2019, 06:05 AM
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Thanks for the tips on the tips! No I won't be doing any valve bowl work, I'd have no idea what I'm doing, unless there is crap in there from the casting process.
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Old 04-08-2019, 08:49 AM
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We used to use Buckeye Carbide stuff exclusively in the shop, for what little aluminum grinding we do (we CNC our aluminum castings for our transmissions & transfer cases). They were extremely good quality; but it seems like they're no longer in the business; although you can find leftovers on e-Bay.
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