I'm may be getting a great deal on a fresh 305, and since it will be out of the car, I was wondering what the max cam I can run with the stock heads is. What lift will the springs handle? also, can I install 1.6 rockers, or does that depend on the cam profile?

Thanks for the help. The engine is out of an 85 Chevy truck, by the way.

 

Well, since we are talking about a 'not so crazy' engine you dont want to go too crazy. especially on stock heads where the valve guides are going to limit your lift.

Best bet is probably a comp XE268

It would also be nice to know the casting number of the head to confirm but i doubt you will get 1.6 rockers on it without some work.

 

Stock springs are inadequate for a stock cam, and should be avoided like the plaque with a performance cam.

But it depends what you mean by 'work'... I had some stock 601 castings machined to handle more valve lift, and used an XE274 and it was fantastic with those heads - but you can't use a cam with that much lift w/o machining the guides. Other than that, they were stock.. as in, no port work or anything.

If you are talking totally 100% as they are shipped from GM, then I'd go no bigger than the XE262 (though thats still a pretty healthy cam). Limit the valve lift to around .460 or so with stock valve guides.

 

The 262 has a nice idle also... It's a good cam. I may be going to an xe268, though.

http://www.youtube.com/watch?v=cjXKi8dNlHE

 

The XE268 is a pretty big cam for a 305, even a modified one... The XE262 is still my recommendation, its a very good cam for a 305. You have to remember, that whatever cam you use in a 305 will act about 15-20% "bigger" than the same cam in a 350, so keep that in mind.

 

It really depends on what hes doing with it too, he never said if he was leaving it entirely stock or if hes going to open it up a bit...

BTW, as stated in my sig, im running the 268 on 305 (406cast) heads and no clearance issues with 1.5 rockers(close, but not an issue. 1.6's wouldnt have a chance...

To be extra safe you can go with the 262 and not have to worry.

 

I'm not too familiar with valve guides, although I'd be open to swapping some springs or getting some minor machining done. Are you referring to broze guides?

Iv'e heard alot about beehive springs, too. Would those be good with the .460 lift?

Thanks!

 

Super L98 cam

http://www.tpis.com/index.php?module=2_29_08

 

.460 isn't enough lift to worry about beehives.

 

why do the cam? u would get more outa a head upgrade

 

Or the exhaust.

 

stock 305 heads is like sucking a basket ball through a garden hose... dont even waste ur time wit the cam unless u upgrade the heads... and yes with apeiron wit the exhaust... that should be the first modd to any 3rd gen.

also since its a truck engine... its gona be even worse wit the heads...since they will most likely flow like CR@P in the higher lift ranges since trucks need low end grunt.

 

Actually, 2 of the 3 castings used on 3rdgen 305s were actually quite good heads (#416 and #081). They are commonly used on larger small blocks as budget-build performance heads, as they are as good or better than the old factory hi-perf stuff from the muscle car days. I used a set of 305 heads on my 350 and they were great, made lots of power.

 

I plan on possibly upgrading the heads later, when I have more cash flow, and the exhaust will happen before that. I just wanted to stab a cam while the engine is out of the car. I'd like to put in the most aggressive cam that would still be driveable with the stock heads, so when I upgrade it will be a good match.

If I get the engine this weekend, I'll have more info on head castings, etc.

 

Don't shatter his illusions!

Although, he may have a point with the mid 80s truck heads... im not sure what an 80s truck head would look like...

 

I ran a comp DEH275 cam with mildy ported 416/081 305 heads and had no problems w/ guide clearance. The DEH275 is 0.462/0.482. This was on a 327. Turned 6500 rpms with that motor

The 416/081 heads are more than enough head for a 305. They are not the limiting factor w/ the small bore/long stroke 305. If you need more power, build a bigger engine. Spending $$$ on heads on a 305 is not cost effective, for the limited increases you'll get