cam advice for sbc

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10-02-2008, 08:11 PM
nathan80

cam advice for sbc

hey fellas newby here. i have a good 305 that someone stole the intake, distributor, and carb off of my 305, so its sitting on a motor stand been contimplating on what upgrades with the cam that would really help that turd out.
i was thinking 350 heads and what cam????
So far i have a used performer intake,and a 650 edelbrock carb
i want to go more than an rv, but not so radicul ill have to upgrade everything.
Also this will be my first build
So if anyone might have any valuable advice i would definetly appreciate it!
10-02-2008, 09:53 PM
techinspector1

First off, describe the piston crown configuration. Perfectly flat with valve reliefs or recessed crown with a narrow raised ring around the perimeter of the crown with valve reliefs or what?

Secondly, what is the piston deck height of your motor? That would be the distance from the piston crown to the deck surface of the block with the piston at top dead center. You can measure it with simple tools. Turn the crank so that #1 piston looks to be at TDC. Stand a steel rule on edge across the bore at the 3:00 O'clock or 9:00 O'Clock position as you're standing at the side of the motor. Just stand it up maybe 1/8th of an inch from the edge of the bore and use feeler gauges to measure the gap between the bottom edge of the steel rule and the top of the piston crown. Once you've done that, move the crank just slightly clockwise and measure again. Now,move the crank the other way just past where you measured first and measure again. Sometimes your eye can deceive you and if you move the crank slightly, you'll discover that you were not exactly at top dead center on your initial measurement.

The reason to use the 3 or 9 position for measuring is that if you use the noon or 6 position, the piston can rock on the wrist pin and you'll get an erroneous reading.

What I'm trying to find out here is if you have a good foundation for beginning a build.

My first reaction to the 350 heads is no. The chambers are much larger, resulting in a miserable static compression ratio that is already on the verge of awful, from a performance standpoint. The intake runners will be larger than the 305 heads, so you would really have to buzz the 305 to get any velocity for good cylinder filling. When you buzz the motor, you have to choose a cam that operates in a higher range, then you have to raise the static compression ratio to match the characteristics of the cam and there goes the streetability of the motor.
10-03-2008, 04:56 PM
nathan80

for the techinspector1

Well thank you alots! Finally i got a start on my mission. I have the weekend off so ill tear the heads off and get the spects on every thing mentioned obove and just realize that im a beginner at this. But i appreciate the motive for the rising of a turd so ill do my best with the initial measurments. ill be keepping you advice as soon as i get the info, thanks!
10-04-2008, 04:53 PM
Funderburg

Hello Nathan80,I not sure but I think you asked this on another forum,that I was at.A few a those guys were not nice people,they talked to people like they were below them.I have only been here a few times,but I can tell you these guys here are cool.I glad that you are getting some respect here.
10-04-2008, 07:15 PM
techinspector1

Quote:

Originally Posted by Funderburg

Hello Nathan80,I not sure but I think you asked this on another forum,that I was at.A few a those guys were not nice people,they talked to people like they were below them.I have only been here a few times,but I can tell you these guys here are cool.I glad that you are getting some respect here.

Most everyone on this forum is easy to get along with, except me when I'm on my period:eek: :LOL:
10-04-2008, 08:21 PM
tango

Tech your not so Bad Ha-:LOL:
10-05-2008, 08:38 AM
nathan80

The chevy high performance fellas

Ya, i was on the chevy site and i got a bunch of negative comments but dont get me wrong, there was some good ol boys in there that actuallly were trying to help out, but man, those select few were smartmouts. I guess they just new so much about everything, people like me were just plain out stupid.
i believe that feller likes2gofast recomended this site and i like the atmoshere here a lot better.
if anyone wants to see what i dealing with just look up firstimer threads on chevy high performance and i wont have to say no more.
10-05-2008, 08:48 AM
chevy 37

Nathan80 I did everything Tech says and went with a Xtreme energy cam XE262H-10 which spec out as 218-224 dur. .050,lift .462-.469 at 110 degree lobe. This cam worked for me as I had bored the 305 .060 over. and done some mild porting on the stock heads. The stock heads are terrible even with the porting and I would get something better than the 350 your talking about. Be sure to get the correct valve springs and lifters with your new cam.
10-05-2008, 08:22 PM
nathan80

For the fellas that gives a hoot. My little 305 had a mistaken identity!! The numbers on the block made me a little curious so i asked for the advice of hot rodders an guess what i found out?? Ya your right, it was actually a 95-00 one piece rear main seal 350 cubic inch truck roller camshaft block.
So, the real question is shall i cam it up a bit or just slap the performer intake and 650 edelbrock on it and call it good until i wear it out??
10-26-2008, 07:49 AM
MadMax

Hi nathan80,
seems your mouse motor has been open for some while. You'll have some dirt in it most likely. Of course it depends on exactly what you want to do with it, but if this is your first build and you don't want to change too much performance wise I would do the following.
1. Buy a good Chevy-book (Vizard, Haynes, whatever)
2. Take the engine apart as the author of the book tells you, go step by step.
3. clean all the parts and measure them for out-of-round and whatever is needed.
4. only replace broken or damaged parts.
5. Put it back together in the way the book says.
6. Use good tools.
The reason I'm saying this: Many people buy a junk-yard engine, put a new cam and new heads on it, buy a "big" carb and then go shopping with their "new" engine. This thing won't survive. You want to know the exact specs of the engine and the condition of the parts you're reusing before you determine what is possible with the engine at all.
If you do the atop mentioned you'll get a nicely running motor, which is the best starting point. THEN you can go out and get a different induction system, new heads, a cam. Almost always, the first build doesn't fulfil the expectations of the builder. Don't be put off, just go on, like most things, you need TIME to improve your skills...
JMO, Max