Port matching a ramhorn

[AcampoDave]

I'm getting ready to send my exhaust manifolds to Jet-Hot for a ceramic coat. It was mentioned by a member in a different thread I had started on a related topic that I should clean up the ports prior to sending them out. My question is if it is really worth it on a warmed up 283, and if so how do I do that? I have a Dremmel tool and the manifolds are off now. Looking at the pictures, do I just bevel out the sooty areas on the flanges where I'm assuming they were shrouding the head ports. These were running without gaskets so my novice brain tells me that the carbon around the manifold ports was deposited there because those areas were shrouding the head. Is it simply a matter of evening those areas out with a bevel that tapers into the port?

Thank you for any advice you may have. You can see I tried it once before in the center. It was slow going and it was hard to keep it even. Time was short back then so I just quit. Now I have time if it is worth doing.

[burnin oil]

Others may disagree but I would bevel those soot areas back into the manifold. A better word would be taper. Although it isn't to bad on those manifolds it does cause a turbulence at that area which hurts flow. Personally I would take out a tad bit extra to account for slop in the mounting bolts.

[Getter-Done]

It does help the performance.
If you just do the exhaust manifolds,
It will not affect your gas mileage that much.

If you do a full port and polish job of both Intake and Exhaust in the cylinder head and manifolds,
You will notice a significate increase in performance and fuel consumption.

Getting the balance of flow is the key.
The path of least resistance is the key in porting and polishing.

[AcampoDave]

Originally Posted by Getter-Done

It does help the performance.
If you just do the exhaust manifolds,
It will not affect your gas mileage that much.

If you do a full port and polish job of both Intake and Exhaust in the cylinder head and manifolds,
You will notice a significate increase in performance and fuel consumption.

Getting the balance of flow is the key.
The path of least resistance is the key in porting and polishing.

You mean an increase in fuel economy right? The heads have been done actually. They are 416 heads for a 305 which were all done up at a machine shop for a different customer but the deal went sour. I got them for a good price being at the right place at the right time.
I've been working on the manifolds all morning. They're looking good.

[AcampoDave]

Done...I used a Fel Pro 1444 one peice gasket as a template too since it really fit the head well. Thanks for your help.

[AcampoDave]

Pic didn't fly.

[Getter-Done]

Originally Posted by AcampoDave

You mean an increase in fuel economy right? The heads have been done actually. They are 416 heads for a 305 which were all done up at a machine shop for a different customer but the deal went sour. I got them for a good price being at the right place at the right time.
I've been working on the manifolds all morning. They're looking good.

Yes

My statement was before I seen you have the heads done.
The manifolds alone will not make much difference.
You should notice a Big improvement.
Manifolds look good

[mattfranklin]

I'd like to see the Engine Masters guys do an episode on that. The ram manifolds are the coolest looking for sure and that's what I plan to use. But what difference does it make to performance? Ported vs. not. 1962 Corvette large diameter outlet rams vs newer small outlet rams. vs. headers. vs. 1970s LT-1 manifolds. The whole spectrum. Enquiring minds want to know.

[AcampoDave]

I completely agree. Real world stuff. Send them an email and tell them to do it!

[burnin oil]

Easy answer guys. The rams horns will out perform a log manifold any day. It's more balanced off a flow. They are not as good as headers for all out performance but work well for a street motor. On a 5500 rpm motor I wouldn't question running them. As for the 2.5" vet vs truck manifolds. They appear to flow way more CFMs. Side by side is pretty obvious. I believe that Bob vizzard discussed them in his hot rodding a SBC book. 2.5" vs headers should ne about 20HP for a 350 performance street motor.


As far as the OPs motor goes. The stock rams with port matching is more than enough. The 305 heads flow better than stock but we arnt talking max CFM SBC stuff here. The 305 heads barely flow enough to work a 350 properly. Even with some mild porting. The smaller exhaust manifolds should be more in the flow requirements of his motor and may even provide some scavenging effect. Run what ya got.