I have a bone stock LG4 motor and I was wanting to do a cam swap. I have a few questions.

1. What are the specs for my stock cam?
2. What size of cam would you recommend--I plan to run stock heads (will be rebuilt) with stock springs and want to maintain my computer controlled quadrajet. I also plan to install headers.
3. Will I need a new chip?
4. How much adjusting will my carb require?

Thanks.

 

The stock lift specs for the peanut cam are .350 and .385--pathetic, eh?

The Comp Cams XE256 is probably the best 305 cam out there for a daily driver.

 

Thanks, but how much adjustment will the carb require? I'm not really good with Q-jets. Also, with stock heads, are headers going to do a lot of good for the expense? This may be a dumb question, but I'm just trying to do some good research.

 

Headers will absolutely help, but only if you take care of the rest of the exhaust as well. The LG4 exhaust stinks from heads to bumper (I'd say it sucks, but that would be a good thing for an exhaust to do).

Put new valve springs on when you do the heads, whatever's recommended by the cam manufacturer. The stock springs mimic the exhaust. Tell the machine shop what cam you're putting in so they can make sure there's enough clearance available when it's all back together (you'll probably have to ask them to do this, it's not a "standard" valve job thing).

I haven't done back-to-back chip comparisons, couldn't tell you if they do anything for you.

FWIW, after I did my mods, I adjusted the idle speed, fast idle speed (choke), and choke pull-off. That's it. I had already put DR rods & B hanger on the secondaries, and adjusted the AV opening (check the tech articles for more on doing that kind of stuff).

Oh, do something about that single-snorkel air cleaner. Absolutely a performance killer.

 

I was reading in my Chevy High Performance and saw an ad for a place called Performance Heads. They sell remanufactured GM heads and they say they have a 3 angle valve job and are milled and have new valves and everything for like $350 a pair. Also, they can be ordered with porting work already done, and can be ordered with larger valves. What size valves do my stock heads have? If I go with the Comp Cams XE256, would I be better off ordering these heads with larger valves, or would doing a good rebuild on the ones I have be good enough?

 

The 305 heads are almost unique in that they have a 58cc combustion chamber. The ones you are considering are almost certainly larger and would thus require a very thin gasket, a shave job, or both.

The fun thing would be to get the Standard Abrasives head porting kit and do your 305 heads yourself. Then have the intake valve reemed out to 1.94 for an extra ten hp. Should be a solid 30 hp from the heads alone, and another 30 or so from the cam. Mmm, mmm, good

 

I considered getting some from them. They specifically say "Your choice 58*64*76 cc in 194/150 or 202/160". I would assume that 1.94/1.50 is all that's avaiable in 58cc, though.

That may be a good way for you to go, Eric. The price ain't bad, if they do a good job, and the ad even says free shipping. The price does not appear to include rocker studs, though (I've got an extra set sitting around - long story). Let them know what cam you intend to use so they can at least have a shot at getting it right.

 

Oh, stock 305 valves are 1.84"/1.50".

Bull, if you do the porting yourself and have larger intake valves put in, it's a good idea to have the larger seats roughed in before you do the bowl work. Not "necessary", necessarily, just a good idea.

Eric, I decided on the World heads rather than these guys, just because I thought they would be better overall with the big cam I intended to use. The difference was about $200. Also, like Bull said, the idea of the "fun" of porting my own heads just wouldn't leave me alone...

 

Thanks guys. I'll maybe try and call the cam manufacturer and the place that sells those heads and see what information I can get from them. My friend has a valve grinder and said he'd help me rebuild the heads. We were also thinking about port matching them. This would be the more economical way to go, but having the larger valves would be nice too. Luckily, I'm not doing it until summer, so I have time to do some research.

Eric

 

Okay, I called Comp Cams and first the guy told me to get an XE256, and then when I asked him if this would cause problems with the computer, he told me he didn't realize I was talking about a computerized car and said I had to use an XE249 for computer controlled cars. I really don't know how the computer runs the carburetor, but he said the computer controls the metering rods and that the XE256 has too much duration and the overlap will cause problems with driveability due to the computerized carburetor. Has anybody put either of these cams in an LG4? Does what this guy told me make sense? I couldn't find the specs on the XE249, but I think its something like 0.433/0.444 lift. I know very little about cams. What kind of power increase will this get me?

 

I have a Comp XM264HR-12 in my 305... it passes CA emissions with the stock 83 computer-controlled carb, unmodified.

I can't imagine that a cam with less duration would have trouble. A number of people on this BBS have the XE256 and XE262 in their 305s, they seem to work fine except that the 262 in an auto car with a stock converter and highway gears is sluggish off the line.

If you want to be sure, get the FI version of the 256 cam, catalog # XE256H-12 which is ground on a 112° lobe separation instead of the regular 110°. That will raise the idle quality and vaccum somewhat.

Comp's recommendations (like most of the major cam mfrs to street buyers) tend to be very conservative. They don't want to get the "I put this greatest thing since fornication cam in my car and now it's slower" phone call.

 

Did you flow bench ur heads
after u ported them?

 

If you mean me, I haven't gotten the heads yet. What I plan to do is get the rebuilt GM heads from Performance Heads. I called them and for $330.00 to my door with no core, the heads come milled, fully rebuilt with new valves and other hardware, 58cc chambers, with 1.90/1.50 valves. They can be ordered with 2.02 valves, but for a 305, the smaller ones should be plenty. The only decision I'm still trying to make is which cam to get, but everybody that posts keeps giving me good ideas. I'm thinking I'll probably go with the XE256. For anybody who has this, what is the idle quality?