Cam selection for a 305

[fabrimacator21]

I've been looking at a few different cams and this one seems to have the best of both worlds. http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=71&sb=2

What do you think? I'm worried about water ingestion. This is on an Omc 800 with log manifolds and stock risers.

 

[xltier]

Re: Cam selection for a 305

I've been looking at a few different cams and this one seems to have the best of both worlds. http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=71&sb=2

What do you think? I'm worried about water ingestion. This is on an Omc 800 with log manifolds and stock risers.------------------------------------------------- When we were runnming stock cars we would call them with the info and they would tell us what would work best.hth

 

[cadunkle]

Re: Cam selection for a 305

That cam is very mild with little valve overlap and short exhaust duration. I wouldn't expect any trouble with this cam and a factory exhaust.

 

[Honest Don]

Re: Cam selection for a 305

I run a lunati voo doo 60103 which is 227/233 and .489/.504 far too much cam for a marine motor on oem exhaust, but with the Rhoads Vmax lifters i have no issues. They also allow everything to work very well together at lower rpms, but without sacrificing top end. When i first put the motor together i had the omc log style, but have since switched ove to center rise. A lot more money than just a cam and lifter package, but you get the best of both worlds, just a slight tap at idle.

 

[n2ostroker]

Re: Cam selection for a 305

Download the comp cam calculator (camquest) and let it help you. I would lean to the XM256H (p/n 12-232-3)or the 260H (p/n 12-206-2). Or a little bigger though I think on a 305 might be a much the 268H or XM262H. All marine specific.

 

[WizeOne]

Re: Cam selection for a 305

IMHO, no cam change would be worth the cost and effort when staying with the stock dished pistons (8.5:1 compression) and the two bbl carb.

Now if you bored that puppy .010 over, put in flat top pistons (about 9.2-9.4:1 compression) and used a 4bbl along with the cam change, then you would have created a monster and you can still burn regular gas.

You also ought to consult Delta Cams in Seattle to see what they could do.

http://www.deltacam.com/

They have a great reputation and will regrind your cam for a fraction of the cost of a new one. If you change cams, be sure to change the lifters and get some of the ZDDP additive to break it in with. As you know from discussions here on iboats, they have taken the ZDDP out of oil to 'protect' the catalytic converters. As such, you will quickly ruin a new cam and lifters during break in, without it.

 

[fabrimacator21]

Re: Cam selection for a 305

I'm liking this one also. Best numbers so far but it's pushing the .450 limit on the vortec heads.

I'm gonna check out delta after I post this and see what they have to say.

http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=83&sb=2

Any chance of water ingestion with that one?

Wizeone: The current cam is the stock peanut cam with less lift so grinding isn't an option... unless theres a way to add lift when grinding.


I've thought about milling the heads and intake to bump the compression. 8.4:1 isn't exactly ideal. 260 bucks for the mill job. I don't want to pull the motor so pistons are out of the question. Could I run 87 octane on 9.4 to 1 with the right timing?

What are your thoughts on roller rockers.. any noticealbe gains at 4500-5000 rpm? They advertise it's a 10-15hp gain but I have a feeling thats at high rpms.

 

[fabrimacator21]

Re: Cam selection for a 305

Download the comp cam calculator (camquest) and let it help you. I would lean to the XM256H (p/n 12-232-3)or the 260H (p/n 12-206-2). Or a little bigger though I think on a 305 might be a much the 268H or XM262H. All marine specific.

I've been running them through desktop dyno...

Camquest is cool but they don't show you any numbers besides the peaks.

The XE250H is the winner so far out of all the ones I've tried (pretty much any comp cam that could possibly work). Nice flat tq curve and decent hp numbers.

Maintains 300+ft lbs from 2000-4000 rpm with a peak of 320 ft lbs at 3000rpm.

Hp is 261 at 5k.

By the way.... is there any other options for exhaust besides the OMC log manifolds?

 

[WizeOne]

Re: Cam selection for a 305

.... Wizeone: The current cam is the stock peanut cam with less lift so grinding isn't an option... unless theres a way to add lift when grinding.

Don't think that is an issue but call them and see what they say.