I am having a 131 built with RevPer 4.250 cyl, 4 5/8 S&S crank and 650 gear drive cams, good heads. As things come togather other cost are coming up and my money is running out. We just added temkin bearings which was a new cost now rocker rollers just came up which I cant really afford now. What is the biggest cam that can go with my 131 without needing rocker rollers and will it give me a good performance gain.

 

I'd go with what the builder recommends. If he's building you a 131" engine he's obviously a experienced mechanic and knows what parts play well together. If you go with a lesser cam, you 131" won't reach it's potential and you won't be pleased. Use whatever financial means possible to get the job done right the first time, you'll be happier in the long run.
Been there, done that, went back and did it right the second time.

 

You seem to have two choices: buy a second set of new cams, or buy the new rocker rollers. Either way, in time you are going to pay again, to get the best out of your new motor. You would be better off telling your builder to sit on it for a few weeks and have the job done right first time, or wave your plastic, or whatever. You cannot save money by spending more!

I'm with Gearhead3.

 

I have heard anything over .590 lift roller rockers are recommended.

Roller rockers are not going to gain you any realizable performance. They are going to prolong your valve train. If money is tight, put it together with stock rocker arms and save until you can afford the rollers. It's an easy swap that takes a couple of hours. If you do it within the first few thousand miles of completing the engine, you won't hurt anything.

Zach

 

You said timkin bearings, What about having the crank welded cause it wont take it. I twisted mine with a 103

 

You definitely shouldnt weld an S&S crank, they are bulletproof and ready to go out of the box. They press them together with 30t force and you wont put one out of true as long as you run a rev limiter at a reasonable rpm.

Besides that I agree with the other posters:

With a 131 I suspect you will want 640 for big mid range, or 680+ for top end. These cams will need rollers. I would stop the build and wait if it was me, but biggzed is spot on, the roller rockers prolong life and reduce friction, the power gain isnt huge. The change is quick and easy to do later.

The best person to ask about the cam is your builder.

 

How did you twist the crank ? What did you do ?

 

It was probably a stock HD item, very different standard to S&S.

 

How exactly did you get this far down the path with your builder and not have the "extra" items you are now paying for accounted? Sounds a little off to me.

I sincerely hope this all turns out as you hope.

Zach

 

Thats why I am having to rebuild mine. It was a stage 3 95ci but I twisted my OEM flywheel and I had to sit on it a year to get my money right so that I could rebuild it from the bottom up. Just trying to make sure all is correct. I was surprised that the 120R crate Race motor has no warrenty so I figured I would have a 131 built.