Adapter Plate-Flat Head 5hp

[rob194]

I am currently building a new bench and was wondering the options I have in adapter plates. I wanted to flow the block with the carburetor mounted. I know there will be slight differences in bore size between (0.0-0.1") and I did not know how to get a good seal in the cylinder bore. I also do not know how much difference it will make if you locate the adapter up and down the cylinder will make. Thanks.

[Brucepts]

Most small engines use a false side cover with a 90 attached to the side which goes into the flowbench. Make it large enough that it does not restrict airflow. Plug all the open holes in the block.

On my flathead engines my pan was open so I machined up adapters from PVC pipe with an o-ring at the top to seal on the bore, this pipe was attached to the top of my bench and I would slide my blocks over it.

[DaveMcLain]

When I did some flow work for a customer who was racing a 10hp Techumseh flathead engine on a go kart. I just laid the block minus side cover down flat onto the top of the bench(Superflow 110) and then plugged the crankshaft hole(now on the top) with clay. I had a couple of other holes, oil return and valve lifter holes to plug with clay but that was about all. I just put a light spring on each valve and then opened the valve to each lift point by using a few carefully measured washers. It was not difficult, it was repeatable and it worked fine.

I was able to mount the intake manifold, cylinder head etc without trouble too. I would say that most small engines would be similar. As long as the flow bench has a reasonable amount of flat area around the air inlet hole it'll be easy to get it working with a reasonably low amount of leakage.

[fchp]

Rob,
The Superflow adapter is basically a flat plate that mounts to the bench, then (2) 2"-sch 80 PVC 90's put together that go up into the bore with a rubber seal around the outside of the 90. I'll have to see if I can get a picture on here of mine.

[rob194]

Hey thanks, I was thinking about using something similar to that. My only worry was that getting a good seal for the different bore sizes.