PV question - 67 L79

[Patrick H.]

Re: PV question - 67 L79

I'll be interested to hear about the results. My friend recently purchased a NOM 1970 350/350, and I hope we can incorporate some of your findings into our eventual build of the motor.

Patrick

[Duke W.]

Re: PV question - 67 L79

The handful of SB OE rocker arms I've measured are pretty consistent at 1.37:1 at the lash point/low lift and 1.44:1 at maximum lift with about a 0.3" lobe.

I've never measured any of these aftermarket roller tip rocker arms and have never seen any actual measurements on them, but I would bet that they exhibit similar variable behavior.

Beyond that even if they do have greater than OE peak ratio, the increase in top end power is marginal and there is usually an associated loss of low end torque.

Rather than install these hot rod parts that I think are of marginal utility (and for most you have to buy a special thin wall socket to turn the nuts) I'd rather spend the money on massaging and flow testing the heads, then work out the best valve timing to achieve the desired torque curve and idle characteristics. The resulting custom cam is only about a hundred bucks more expensive than an off-the-shelf cam, and the incremental cost is less than a set of hot rod rocker arms.

Roller trunion rockers are very expensive and I don't think any will fit under the OE valve covers. And with the typical high overlap cams that guys usually install with these, any fuel economy improvements they might offer due to lower friction will be buried in the noise. On a vintage engine, they only have real value in a racing engine that will see sustained high revs.

Duke

[Michael M.]

Re: PV question - 67 L79

Just had to add this. I asked the same question about a set of roller rockers a few days ago. What I found out was that NOS "0" rocker bring a higher price than the roller. X-Bay 450.00 and 499.00 within the last few weeks. I don`t dispute anything said except OE rockers are getting very expensive. I wish I had put a few up years ago. Mike

[Duke W.]

Re: PV question - 67 L79

I believe those are OTC non-production rockers that are only required with higher than OE lift cams, which aren't suitable for a road engine, so who needs them? But since they are out of production "NOS" parts, guys will pay dearly for them whether needed or not.

Look up the Sealed Power or Clevite (NAPA) OE replacements. I bet they're inexpensive.

With a few exceptions (like 327 connecting rods) road engines don't need to be filled up with "racing" or aftermarket hot rod parts.

Duke