I think it's almost about time to take the next step in my mods. I've been doing some research around the Web, but I'd like to get some questions I have that are specific to my situation answered before I do something I regret.

I have elected to go with the Comp XE 256H for my application as the engine I am working with is a 1985 LG4 which to my understanding has a flat tappet cam. The engine itself is completely stock and only has 37k miles on it. My first question is, should I change springs/lifters/rockers with this cam? Or would I be okay with just shaping the cam itself? I want to make sure I don't break something.

Secondly, is the XE 256 H good for my setup? As of now my car has a full 3" exhaust with an L69 dual snorkel, other than that it's pretty much stock.

Lastly, I was thinking about doing the swap myself in my garage. Is this something that someone who has basic experience with working on cars can do in a couple of days? I did my full exhaust swap on my own in my driveway. So would this be that much more challenging? Are there any special tools I would need? I'm just curious about doing it myself so I could save the money I would use to pay a shop to do it and buy other things for my car with it. Plus I would get the satisfaction of saying I did the work myself just like I do with the exhaust.

One more thing, would a guess of 250 horses be about right for this combo of cam, exhaust, and intake? I've also got an electric fan unit that I'm going to replace the mechanical unit with.

Thanks for all the help in advance guys!

 

That would be a decent choice, but the XE cams are going to want upgraded springs to work with them- even the small ones. It's not just the lift and duration, it's how fast the lobe profile accelerates and decelerates the valve. A set of Comp 981 springs will do the trick and they are drop-in replacements for your stock ones. You can even reuse the stock exhaust valve rotator/retainers (you'll need a 1/16" shim in the exhaust spring pocket if you replace the rotator/retainers with standard retainers like the intake side uses).

Alternate choice, less aggressive, but still TONS better than the stock peanut cam: Summit house brand K1102. $90 including lifters (you always use new lifters with a new cam). It's a notch hotter than the factory L69 HO cam, but won't stress the valvetrain like an XE cam will. You don't even need to replace the stock springs if you keep the revs below ~5500.

I've replaced the stock cams in plenty of 305s with that cheap (but still good quality) cam and the difference is pretty dramatic. It'll still work with the computer controlled QJet and ECM no problem, too.

A Cam swap can be done in your garage without removing the engine. You're going to have to remove the radiator, A/C condenser and the hood latch support to give yourself enough room to slide the old cam out and the new one in, though. Also, the oil pan is going to have to be dropped down in front to get the timing chain cover off and on again (lots of chances for leaks when you reassemble, so do it carefully). Aside from that, it's not too challenging. Just a lot of steps involved.

 

Thanks for clearing that up for me, Damon. As for dropping the oil pan in the front, is there some sort of gasket that I'm trying not to break?

 

rainmaster when changing a cam always change your lifters , springs , retainers and timing chain . comp cams makes what they call a k kit more expensive but gives you everything you need to match the valve train . you will still need gaskets ,rtv ,plus oil,
antifreeze. if this is your first time diving into an engine take your time . you did not say
how many miles are on you ride

 

The engine has 37k miles on it. I'm guessing that they aren't worn out, but should I still change the timing chain and retainers?

 

yes I just rebuilt my lg4 for my car , I got the 981-16 springs when I was installing them I was just going to use the stock retainers with the comp keepers they would not sit right . If they don't and you don't see this the minute you fire the motor it will drop the valve . then you will have a real mess. the factory chain is a single row chain , the
com is a double row chain for added strength. that cam would be nice ,you can also run
the factory 350 300hp cam too

 

on the springs they will most likely work but just think how many times you hit the loud pedal, think how many times they compressed and the heat cycles. if they are weak you will experience valve float ,then you lose power

 

Is this the sort of kit I should look into?

http://www.summitracing.com/parts/cc...make/chevrolet

 

yes , make you get some quality gaskets , get a full engine gasket set you will have some extra valve stem o rings and some little gaskets you might not need .

 

you will also have head gaskets but you wont be using them unless you going to have a machine shop doing the springs

 

I dig the car my brother in law had the same one color and all ,he had gta rims on his I have not seen to many in that color

 

Thanks man! I actually just put on GTA wheels last week.

 

On the oil pan question- yes, there is a half-moon gasket that goes under the bottom lip of the timing chain cover. It meets up with the corners of the oil pan side gaskets at that point. Around 87 or so GM started using a one-piece gasket on factory motors, but your earlier motor should still have the multi-piece gasket set. When you break that seal, you increase your chances of having a leak there.

Now, the factory should already have put RTV in the corners where those gaskets meet in the corners where they touch the timing chain cover. So there's two ways you can go about this:

1. DON'T just tear everything apart. Leave the factory RTV in place (it will hold the half-moon gasket at the side gaskets together) and then put another little dab in the corners when you reassemble.

2. Replace the oil pan gaskets completely. Swapping to a later-style one piece oil pan gasket (FelPro and others make them) where the side gaskets and half-moons are all one molded piece is advised in these situations, especially since you'll be working on the floor, laying on your back.

It may not be exactly clear to you what I'm describing here, but when you see it with your own eyes it will make sense.

As for the valve springs and retainers.... I say again, if you're going to replace the factory rotator/retainers on the exhaust valves you MUST shim the exhaust spring pocket by about 1/16" to get the installed height of the springs back up to factory 1.7" factory spec. Lot of people breeze past this like it doesn't matter, but your spring pressures won't be correct if you don't and you'll likely float the valves in the higher RPMs, especially with an aggressive cam design like the XE series.

I should have mentioned that a new timing chain is always a good idea when swapping cams, even on low mileage engines, but others caught that, above, already. Cheap insurance. Summit sells a house-brand full-roller double row chain set for about $30. It's the cheapest chain set I've found that is still a quality piece. Cloyes also makes a very good quality full-roller chain set for about $45-50. You can get a timing chain set as cheap as $18 these days (Chinese made), but nothing that cheap has any quality to it- they stretch like salt water taffy in only the first few hundred miles.

 

Thanks again for the info. I was looking at the timing chains, is this something that would be worth investing in?

http://www.summitracing.com/parts/su...make/chevrolet

I'm also somewhat confused about what a good max advance/retard spec should be for my setup.

Thanks again!

 

Yeah, that's the one.

Drop it in on ZERO unless you plan to degree the cam. Almost all aftermarket cams already have about 4* advance ground into them from the factory.

 

I'd like to post an update on my progress. I ended up going with Comp's XE268H-10. I got the kit, which came with the cam, lifters, retainers, locks, springs, and a timing set. The only things I did not use from the kit were the retainers because they would not fit properly without some shimming (as mentioned before).

Some of you may be thinking that the XE268 is too much cam for a 305, but I think it works great with it. I would say that as long as the 305 is carbed, it should be able to handle it just fine. It sounds great at idle and you can really feel it pulling through the rpm band.

As of now, I still have to get my carb tuned and engine timed so that I know I'm getting the most out of my set up. I'm hoping to get it dyno'd as well, so it will be interesting to see what exactly my gains have been since I started modifying my car. As of now it has intake, cam, and exhaust. I'll be sure to post my results here on TGO for those interested.

Overall, I'd like to say that I am really satisfied with my decision and I'm glad I went with five7kid's suggestion on other threads about getting an XE268. Moreover, I feel really accomplished now that I did a cam swap all on my own. It may have taken several days to do it, but the experience I gained has great value. Plus I didn't have to cough up more cash (something I don't have a lot of since I'm in school) to pay someone else to do it. The only cost to me other than the parts was a couple of F-Bombs and some skinned knuckles.

Here is a video of what my car sounds like at idle: