Ya I ran the 273 intake for quite a while and it performs very well, I would recommend it. It is very heavy though. If you can find an LD4B I hear that is a very good intake as well, and much lighter.
Small port heads, big port intake. How bad?
- Thread starter DionR
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Ya I ran the 273 intake for quite a while and it performs very well, I would recommend it. It is very heavy though. If you can find an LD4B I hear that is a very good intake as well, and much lighter.
x2
I do like the fact that it's causing the roof to be raised at the heads port entrance but..........................
When the air speed gets to slow, fuel drops out.
In other words, you could loose some low end torque.
NOW, with all that said.................you have the manifold, you have port matched one port and marked up another......
Finish up the port matching, install it and get back to us.
I thing you might just have improved the flow of the head by raising the roof entrance.
From my experience/experiment with my 360 head i would say, Don't worry to much about port matching the floor and DON'T port into the floor at all!!!!
Keep doing what your doing with the roof and port divider wall.
And let us know the resonates
P.S. You have pretty good control of the grinder!:tongue8:
DionR
Well-Known Member
There is a bit of confusion in this thread.
First, the picture above is one I found on the internet, not something I am doing. It is from the Junkyard Jewel 318 Hot Rod did some time ago. I was looking for the port sizes and tripped over the picture, so I though it might be worth adding to the conversation.
Second, I don't know the history of the car or motor as I didn't build it. I acquired the car as is and I'm just trying to figure out the best course of action. The first being, is the port mis-match hurting me enough to make a change necessary. For all I know, someone matched the ports before bolting it together, but I doubt it. Based on the things I have worked on so far, there wasn't a lot of experience put into the build, for example I get to try and extract a broken VC bolt because they used ones that were too long.
BTW, the car is 71 Dart more door, came with a 318 and 904, Kelsey Hayes disks, 8.75" rear, big front sway bar, Cordoba buckets (drivers side power seat), the afore mentioned M1 dual plane intake, 625 cfm Carter Competition carb, and even a early (69?) 340 unsilenced air cleaner.
First, the picture above is one I found on the internet, not something I am doing. It is from the Junkyard Jewel 318 Hot Rod did some time ago. I was looking for the port sizes and tripped over the picture, so I though it might be worth adding to the conversation.
Second, I don't know the history of the car or motor as I didn't build it. I acquired the car as is and I'm just trying to figure out the best course of action. The first being, is the port mis-match hurting me enough to make a change necessary. For all I know, someone matched the ports before bolting it together, but I doubt it. Based on the things I have worked on so far, there wasn't a lot of experience put into the build, for example I get to try and extract a broken VC bolt because they used ones that were too long.
BTW, the car is 71 Dart more door, came with a 318 and 904, Kelsey Hayes disks, 8.75" rear, big front sway bar, Cordoba buckets (drivers side power seat), the afore mentioned M1 dual plane intake, 625 cfm Carter Competition carb, and even a early (69?) 340 unsilenced air cleaner.
DionR
Well-Known Member
I wish, that is Steve Dulcich's work, not mine.
LOL
If you haven't started grinding on the head, i would recommend the smaller 273/318 manifold for the reasons posted above.
I thing it will work better for your car, and the eng's present state of tune or power.
daredevil
Well-Known Member
Exactly the opposite. The air charge will flow a path similar to the head port and the sides will have lazy air that slowly siphons off onto the path of velocity. The only downfall to this is lazy air doesn't let the fuel stay dispersed and you will develop droplets at the outside of the lazy air causing wet spots In your intake that will occassionally be pulled in the runner causing a momentary rich condition.
Guitar Jones
aka Angry Johnny
This was an old manifold, they quit selling it decades ago. I don't recall which came first, if there even was a first. All I'm trying to say is the port mismatch is the least of his concerns, it really doesn't make that much of a difference especially with a mild build like that.
SirDan
Well-Known Member
thats good to know! thanks.
1wild&crazyguy
Banned
get the right manifold...
For a street grocery getter your probably not going to see much improvement by going with a small port intake. But with that said you are loosing some low RPM torque, which will hurt fuel economy some. If you were using this on a truck that was towing I'd say make the change. As for the carb you are using that should work quite well with the 318 though they are normally jetted for motors in the 350ci size so dropping down one jet size or going up one rod size will also help. Try to take it to someone who can load test it either with a dyno or at least with an O2 sensor and doing a brake stand (redneck version).
Like i said before. the large port manifold will slow air speed down......when air is slow, fuel drop out of the air stream, and runs into the cylinder as liquid fuel(only vapors are flammable!)
And, "TURBULENCE",..... It's like a "WET DOG" It Shakes all the fuel out of the air!
You will gain performance with the small manifold, compared to the large, Even tho the "large port" is more attractive.
JMHO.
And, "TURBULENCE",..... It's like a "WET DOG" It Shakes all the fuel out of the air!
You will gain performance with the small manifold, compared to the large, Even tho the "large port" is more attractive.
JMHO.
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