Re: 350/255HP Help please
 

Wrong cam

Re: 350/255HP Help please
 

I know what he's going through. I used to have a fairly good running car until I finally just wore my factory block out. I then went and put a Dart little m block in it and 4 years later I still can't make it run no matter what I do. Tried heads, all different kinds of ring packages(total seal luniac etc etc) cams and I've never had it leak less than 10%. Is it possible for a dart block to not be any good. Ive had some pretty impressive machinist hone the block and nothing seems to work. I'm about ready to go back to a factory block. Hope you find out what's wrong.

Re: 350/255HP Help please
 

"-.005" piston to wall as per CP"


This is one area you need to take a look at.

Re: 350/255HP Help please
 

Well, there you go, an expert speaks.

James, do you think that cam is 30-50HP and 600 RPM wrong?

Re: 350/255HP Help please
 

Bill, Dart makes a great product, although their customer service on some things can leave a bit to be desired. That being said, it is possible, but very unlikely, to have a bad block.

I will say that those blocks can drive even an excellent machinist insane trying to get the cylinders done correctly. Really good and experienced guys, way better than me, have struggled with them. A couple shared what they learned, and helped me figure out what I needed to do. I damned near ruined the first one I honed, the truth is, that one didn't seal up really well until we freshened that engine, changing pistons and rings, and honing it again.

A couple of things I can suggest. First, it is necessary to use extremely soft stones, it is near impossible to get them too soft. Second, flood the cylinders with hone oil, good clean fresh hone oil, it is near impossible to flow too much. Third, use light to medium pressure, never more. Finally, use coarse stones right up until the last 0.001" or so, then use your last two finish stone sets for only that last bit of stock removal. Dart blocks are extremely hard, they will glaze over, and load up a set of stones in an instant.

Once you get the bores correct on a Dart block, they'll hold up well and last forever, you can literally touch them up with maybe 5 light strokes of soft 400 grit stones and a finish pass or two with the Total Seal suggested finish technique.

Re: 350/255HP Help please
 

Alan there is no doubt the wrong cam and being in wrong can cause this in a 255. This is several times Bullet has advised putting a cam pretty far off from where we have foud them to run best. I would really suggest Chipper call Woodro and get one of his grinds and degree it per his instructions. A 255 is almost cookie cutter to make run.

Re: 350/255HP Help please
 

Painter, I have no doubt the wrong cam will hurt one. I don't have a ton of experience with the 255-350, just thinking that they had to miss that one by a country mile to cost him 30-50HP and 600 or so RPM, that's a lot of power and RPM from a cam mistake. Bullet is not necessarily my favorite brand, but that's a huge miss.

Re: 350/255HP Help please
 

Alan the 9-10 cold leak down doesn't catch my attention as much as the lack of rpm's does. Those thing run pretty good, pretty easy.

Re: 350/255HP Help please
 

Oh I agree, I think he has more than one thing seriously wrong.

Re: 350/255HP Help please
 

Painter,
I'm with you on the cam deal. It would make sense that the RPM is down if the intake or Ex lobes were not in the right place. (not just the intake C/L)
I still stand by the hot vs cold leak. If your looking for a problem look at all parts of it as the engine runs. The bad ex seats could kill the RPM, too. I would pull the intake and look for signs of bad reversion. That would point to cam and or a couple other issues as well as ex diluting the intake charge. OH, if you can't find an exact cause go slow and just make one change at a time. don't dig yourself deeper in the hole.
Good luck..