Help with Cam selection (again)

Greyhounds_AMX wrote: I'm still hung up on the compression ratio though. With iron heads and standard 93 octane fuel 9.5:1 is what most people consider the limit. Are you going to run octane booster in every tank, or maybe race fuel? We have ethanol free 93 octane here at the pumps, but that's as good as it gets. I think someone mentioned E85, but in my mind more ethanol is not a good thing with our old tech gasket materials, fuel pumps diaphragms, etc. Granted you can back the timing off if it's pinging, but then they tend to overheat. Overheating and pinging = new pistons.  Another thing to consider: The single plane intake manifold will have a more aggressive idle than a dual plane intake, so if you really want the beefiest idle sound possible you might want to go with the Torker.

Do you think that gas today has that much less octane rating than in 1969? Back then , you could run 11:1 with no problem on premium with the 350/350 (223 at .050) cam that I mentioned. From what I understand, today's 93 octane is about like 1969's 97 octane or so. I know it isn't 100 octane , but 100 back then would run 10.2 with a stock cam in an AMX.

The Thumpr line of cams were designed mostly to get that "cackling" idle most like ... but they also tend to bleed off compression, have a rougher idle and lower idle vacuum. Some like them. Some not so much ... and yes, Comp tech aren't always the best to deal with.

FWIW, I'm running a Bullet cam and also found them quite helpful and good to work with, so I wouldn't be afraid of going with their recommendation ... but I also don't know your tolerance level for a bigger cam ... although not overly "big" compared to some. My cam is 250@0.050", 0.616"/0.624", solid roller, a 6 speed and power brakes. Works fine for me and I'm not a racer - just wanted a fun street toy. The stick makes a big difference in cam tolerance as you can basically pick your "stall speed". May want a bit more rear gear with the 2.23 1st to slip the clutch less ... and maybe eventually a 5 speed if you do much interstate cruising ... but expect that cam should have pretty good torque.
exhaust sound

Hope this helps,RD

Edited by Red Devil - Oct/11/2018 at 11:45am

https://lh4.googleusercontent.com/axs8EuRyZpoMEjfWkP_CVbDa4dQrOrUGvv0O2LIY-4O73ITwvdZL4nt_uU8=w2400

Greyhounds_AMX wrote: I disabled the static compression ratio limits on the spreadsheet and then it came up with just 4 off the shelf cams. Three really, as the Elgin and Summit are the same cam. I couldn't get a very clear screen shot, so here's a link. I had it plot the smallest and largest just for fun. https://lh4.googleusercontent.com/axs8EuRyZpoMEjfWkP_CVbDa4dQrOrUGvv0O2LIY-4O73ITwvdZL4nt_uU8=w2400 The revised Bullet cam came in at 8.25 DCR so it didn't make the cut.