I want to put a Mummert's Y270 cam in my 57 312+.40 but was wondering about the idle RPM it is a cruise-o and has 3.10 stock gears it is a FD.HT. with an auto I don't like a fast idle like 700-800 in drive what can I expect.

I have some experience with the S270 cam. I installed it in my 312 bored 40 over, in a ECZ-C block and heads. I set it using the stock chain and did not degree the cam.



It does not produce very good idle vacuum. I get around 14 to 15 inches. Timing set at 8 degrees BTC. I'm using a 57 dist. that I have not checked for total advance.

Now, it does not like to idle at 500 RPM in gear. It will idel that low just not in gear. I have a Fordomatic and the torque converter is tight on these. If I up the idle in gear I have to stand on the brakes at a stop.



I spoke with Clay Smith Cams the manufacturer of this cam and they tell me it likes a 3 degree advance. Again I did not degree the cam. It might work better if I did. Oh, I could not get NEW 1.54 rokers when I did the rebuild so I purchased the 1.45 rockers.

I have also increased the lash to .022 to help the vacuum. This cam is supposed to WORK with an automatic. In my case just not well.



The car runs good on the road, great pull to 5500 RPM. Good out of the hole too.



I think if I were to do this again I sould go for the 256 degree cam instead, mainly due to the idle issue with my automatic.



I hope this helps.



Jim

  Jim Rowe Elkhorn, NE

As Jim has noted you might not be happy with that 270 cam on a Fordomatic. The 265S Mummert has may be the better choice for you, & that is what he advertises. He used to advertise a 264/ 450 lift Cam but I don't see it in his adds, now. You could also check with Chris Nielson Cams, he does vintage stuff. If by chance you currently have an original 57- 312- 256 degree cam, it might not be worth changing it out unless you are doing a rebuild..     

Paul