[stho0785]

After doing the rebuild on my big bear 400, I was doing some piston comparisons and wanted to get some feedback or thoughts. I have redone a couple of Raptor/warrior 350 engines in the past and kept all the old parts. Comparing the pistons on the raptor 350 and big bear 400, the only noticeable differences are the crown on the 400 piston is cut different and the side skirts are a bit longer on the 400 piston. I'm curious if a raptor 350 piston would work on a big bear 400. There are a lot of compression options on the raptor 350 as opposed to the big bear 400. I'm curious if anyone has experience with this situation . I'll post some pics soon of the pistons. Thanks for everyone's time.

 

[stho0785]

piston pic comparison

I have attached the photos for comparison purposes.

 

[reogem]

Have no experience with your idea...one thought is..are you sure the the wrist pen is exactly the same distance to the top of the piston.

I guess for $50.00 I wouldn't chance it.

 

[Vincent]

Best to bring both pistons to competent engine shop and get them to measure everything . You simply can't take a chance on "close enough" when building an engine. Also remember that the piston crown to valves clearances will need to be verified

 

[stho0785]

great points

All great points. I had the mechanics teacher at my school measure it all to see what the differences are. He is a 20 year nascar engine builder and incredible teacher. All the measurements are the same except what I mentioned before, the piston skirts are longer on the 400 piston and the crown is cut different.

I've already put my engine together, but found this topic interesting and wanted to share my experience and photos. Hopefully it might help someone else.