crossflow porting

**keefallan** · 04-19-2019, 06:34 PM

I have ported a few crossflows in the past..........all v6's. I am gonna mess with a v4 sometime as well. As I was pondering things about my big bore 175 that I am cleaning up an tweaking, I started thinking about the intake ports. Is there any power to be had with smoothing(chamfering) the intake ports on the inspection cover side? Or is it a waste of time? I am just curious, because I am going to take all the covers off to look at every one and clean up casting etc. I am already installing the good heads and cleaning up the intake manifold with stuffers and reeds from CCMS.

**keefallan** · 04-21-2019, 11:48 AM

nobody with an opinion? The scallop at the bottom of the cylinder gets smoothed. ports also? Anyone?

**racer** · 04-21-2019, 01:37 PM

What are you going to run it on? Intended RPM, Fuel available? Lots to be gained but the more power you make the shorter the life.

**Dave S** · 04-21-2019, 08:35 PM

Opinion..... Things are slow round here.....be patience GRASSHOPPER.......I like old motors... can get em' cheep..... Most best is copy what factory did......JMO.....

**powerabout** · 04-21-2019, 08:39 PM

Originally Posted by keefallan

nobody with an opinion? The scallop at the bottom of the cylinder gets smoothed. ports also? Anyone?

Your engine already has a scalloped block?

**keefallan** · 04-22-2019, 03:22 PM

I am going to run it on a lightweight hull.......800lb max..............hull to be determined. I know that is heavy for some racer guys but still at least 400 lbs lighter than the average bassboat. I am looking at a V-king for sale on CL right now......been wanting one. the motor is not scalloped yet. I just know that the scalloped edge gets smoothed towards the ports. I had the inspection covers off to see the pistons and they look amazing(the sides), the rings are not gummed up and no scratches. I will be porting the intake side to remove the fangs left from the factory milling.....and maybe the corners of the ports a little. I am opening up the reed cages with Chris Carson's 2+2 reeds. I was going to emphasize the smoothing of the intake tract from the reeds to the ports removing any lip, bump etc. I was even contemplating chamfering the bottom of the cylinder lip to open up the intake area more(versus scalloping). I have stuffers to go behind the cages and the original factory stuffers to go on top of the cages(the black rubber ones). That is why I was asking about chamfering around the intake holes for the air to be able to get into the ports easier. A blended edge is always better than a sharp edge for airflow right?

I had to buy a new adapter because the original one was messed up. I can already see where to blend down the square walls in there for a smooth transition........and plenty of metal there to do it without adding any new metal.

And yes, I love the old crossflows.........simple to maintain and not hard to find. I grew up on them from a kid. Now as an older man(46) I am into making them a better air pump.......... if you know what I mean. This is my third 235 and I want to make it the best one yet. I sold the others for various reasons.

As far as rpm's go, 6000-6200...........93 octane.............24 degrees timing.

This is where things stand right now.

Thanks to you all for responding to this.

**racer** · 04-23-2019, 06:23 AM

Yes rounded edges flow air around corners better. Removing all casting imperfections does help. At your target rpm porting not really needed IMO just clean it up.