Cam/exhaust question

[jg480]

I'am changing the heads and intake on my 87 350 magnum. I was considering changing the cam also at this time however I still want to use the stock exhaust this season. What kind of duration cam can I run without reversion problems? The other option I was considering was to stick with the original cam and just use 1.6 rockers. What do you guys think?
BTW. it's a flat tappet cam.

Thanks Jim

[maddad]

Hi jg480, you may want to consider doing all the external breathing stuff first(heads,intake and exhaust)so when you swap the cam, it can take full advantage. Getting rid of the exhaust gas seems to be a huge part of getting real power out of a marine engine.

[MOP]

Mike sell him the factory cam out of my old Tempest, that ran fine with stock exhaust. It was rater at 300 prop shaft, would be perfect for his app.

Phil

[jg480]

I'm kind of limited on the cam I can use. I only have .520 lift springs in the heads. I have a set of 1.5 and 1.6 ratio rockers and the engine has 270 hrs. on it

[MOP]

The Tempest cam lobe lift is: Int. 298 Ex. 303 Duration Int. 291 Ex. 288 those specs are of the factory spec sheet. Gross lift at the rocker is Int. 444 Ex. 454. It ran 9.1 compression, it pushed my 3400 lbs. 22 to 61+ an 18 would do a lot better. You have enough spring for that cam even with the 1.6's on the exhausts. I have 6 pages of info on the Tempest engine courtesy of Rob from Michigan. Then again maybe Mike is going to freshen it for a spare!

Phil

[maddad]

Jim, the tempest was a strong running motor and sounded great too. I have that camshaft and it appears to be in good condition, but a better idea may be take note of those specs Phil posted and find something like that new, with new lifters etc.

[MOP]

See I was right!!! You are a hoarder!!! Probably as bad as I am!!!

[jg480]

Phil, those cam spec's will help alot I'll look through the comp website tonight after work

Thanks Jim