84L69TA

I put the XE256 Comp cam in my LG4 83 TA. Before the cam I was running a best of 14.96@90mph with the only mods being Edelbrock headers and y-pipe, 3" hi-flow cat, and a 3" Flowmaster catback, 3.73's, and a G hanger and DR rods. The motor itself has almost 80,000 miles on it. Now, i took it to the track last week and could only run a best of 15.31@91mph with a 2.26 60ft time. My 60ft times before were in the 2.0 range. I cant figure it out. I pulled the timing cover to see if the dots were lined up correctly on the chain, and tried adjusting the rocker arms twice. I just dont get it, everyone told me to get that cam for my 305...im just puzzled as to how much it slowed it down. Not only did it slow down at the track under the same weather and humidity ocnditions, it FEELS a lot slower. Please help me out here. Im tempted to buy the L69 cam and try that. Any ideas here? THanks in advance.

rezinn

It didn't slow you down, it made you faster. You gained 1mph. I don't understand your 60ft times, they were in 2.0 without the cam and 2.26 with it? What timing are you running?

84L69TA

im running 10 degrees of timing...same with the stock cam. Im not even running a full mph faster though. my E.T. slowed down almost 4 tenths though.

Tom91Bird

iTrader: (5)

I'm not sure what the durations are for your two cams but generally, more duration cams with want more ignition timing. So if your XE256 has more duration, I would try bumping the timing up a little first.

felo72

Your geometry sounds like it might be off. You have 3.73 gears, but what is the RPM range of your cam? You have to match the rpm range with the stall converter, gear ratio, and tire size to get the right performance. I'd check the difference in the rpm range for your stock cam and the Comp Cam, if it's off more then 500 rpm, get a stall that will match your combo. Don't bother changing the cam again, now all you have to do is finish the equation.

Mark W. Winning

If you are still running the stock convertor that may hold you back too. New cam with a slightly higher powerband and a stock convertor will not let you get the motor up to its new powerband for a launch. I have found that a tenth of a second gained in the 60 foot is worth almost two tenths on the long end. If you can get the 60 foot times back to the 2.0 range, it should give you almost 4 tenths of a second ET.

84L69TA

Well, I have a "variable stall".....its a 5-speed. But I have tires that hook up every time, same launch RPM, same shift points, powershift every gear...etc. I just dont get it.

RICHRAD

Thanks for the post....I was gett'in ready to ditch my Crane Cam for something similar to this XE256 for my lg4. now I'm having seconds thoughts

Ray87Z

What are the specs the 256?, can't imagine you would actually lose power unless you messed something up. If you launched as well and hit a 2.0 sixty foot you wouldn't have actually run any worse 1/4 time IMO though. Still would have expected better MPH and a better time though. I think CompCams are ground like 4 or 6 degrees advanced already, might try pulling your timing back a bit to account for that and see if that helps. Anyway, go back to the track and try to match that 2.0 60 foot launch and see what the times come out at... When had you previously run? Don't forget heat/humidity will play a big part in it if conditions weren't similar between runs. Make sure you don't need to make some carb changes now for the bigger cam.

CHP picked up like 30+ hp in a LG4 with similar mods to yours by throwing in the XE262. Sometime is definitely amiss. Check out the article HERE It goes on into Vortec heads and such, but the bolt ons up to the cam are pretty interesting for bolt on LG4 discussions...

[EDIT]Nevermind about the specs, looked it up (212/218 dur with .447/.454 lift if anyone else wondered). That seems almost perfectly ideal in my opinion, definitely should have made a big difference... You change your valvesprings? If not, I wonder if the old stockers aren't up to the challenge and are sapping power with float. I'm ran a .420/.442 cam on the stock springs in my old 86 305 TPI with no problems, but I don't know if the LG4 setup had the same springs... Just an idea.

Sitting Bull

That XE 256 cam is an excellent choice.

I just put a Crane PowerMax 260 in my 305 last week and I can assure you it added MANY hp! These two cams are very similar:

- XE 256, .447 and .454, 110 LSA

- PM 260, .427 and .454, 112 LSA

I'll bet you need new valve springs. 80,000 miles on the peanut cam's springs and then stuffing in a much larger cam will likely expose the springs as tired out.

EvilCartman

iTrader: (1)

I've got the same cam but never really drove the car with the stock one in it. The stock cam when I bought the car had 4 lobes that were just about gone and would loose power at 3000 rpm lol. My motor doesn't seem to take off till about 2500 rpm and pulls right up to 5,500. Base timing is set at 15*.

TRAXION

You actually gained in the 1/4. Your times went from 90mph to 91mph. The problem is that with that cam you lose some lowend torque. Lowend torque allows you to 60ft better. Thus - you 60ft'd worse than before. It all makes sense. The way around this is to dump the clutch at 4-5K. I went through the same thing a long time ago. Bumped up to a 218/224 cam with AFR heads. The car bogged bad off the line. Lost a lot of lowend torque. My 60ft times were WORSE after installing heads cam (even though I gained MPH). I installed a PI Vigilante converter and then everything was working together. The converter put the engine in its powerband immediately and I instantly dropped my 60ft times and my ET. Best modification I have ever done. Now, I know you have a manual ... but the theory is the same. You ned to launch the car in its powerband. More gear can help this situation too. Since you have a manual you might want to consider a set of 4.10s.

Tim

Desert86Roc

What kind of tuning did you do to account for the new cam? Are you still using computer controlled setup? What do your 02 readings look like? If you are pulling in more air, you may just need some more fuel.

If it is not tuning, you stated that you are launching at the same rpm... as stated in above post, you need to adjust that upward. Try different launch rpms until you hit your traction limit. Also, what kind of clutch are you running? You might be slipping, and it would be a good time to upgrade to a centerforce or weighted style clutch.

LG4TA

Did you put a new timing set in? I know if you got one for a 1983 T/A , you might have got a retarded set. You should get one that when the dots are lined up they are at true zero.

I am presently looking at Comp Cams computer controlled cams right now to put in my 83 LG4 T/A. Here is the ones I am looking at.

Part # 12-388-4
Advertised duration 252-4 260-7
Duration @ .050 206 212
Valve lift .425 .440
Lobe Separation Angle 112 degrees

I am pretty sure that Summit has the same cam that Edelbrock markets for the LG4, it is part# Sum-K1102. The price is right with these cams from Summit. They are made by Crane.

Duration @.050 204 214
Valve Lift .420 .442
Lobe Separation 112 degrees

As you see these 2 cams are pretty close. Compared to the XE256 cam these have a lot less duration. Lift is less also. So you definately need a higher launching rpm. Also what is the cranking compression of your engine if it is below 160 you are sure losing power. If your compression is up around the 175 or more it should produce some good torqe.

84L69TA

Well, Im going to the track again this friday night. My only question is, will the 7.5" rear hold up to a 4000rpm dump? Im a little worried about that, if I break the rear, it wont really bother me...Im just looking for some opinions as to if it will hold up or not. Thanks to everybody for all the excellent input.

Mortorq

Well, sorry to say, if you have any kind of REAL sticky traction at all, that glorified Vega rear end will probably last only a couple of 4K side steps--if that! (Not to mention that poor T5)
Bring a trailer!

2005Impalla

I would play with timing cuz I think advancing it a little might make a little more power and make sure your not running rich or lean under full throttle. Also if your running the stock intake and carb I would step up to an aluminum duel plane like an edelbrock performer and retune your carb if not replace it with an aftermarket 600 CFM carb. Your intake might not be able to breath well enough to make full use of the cam at higher RPM. I would not replace your cam I think its a great cam for your 305 I would upgrade the intake side of your motor so it matches the rest of your combination.

Orr89RocZ

iTrader: (20)

Holy old post! This was 13 years ago!!!

2005Impalla

O DAM!!!

2005Impalla

What the F body, Mortorq your trying to raise the dead hahaha.

duke22

I have a'88 iroc with an l98 350 with an hsr intake, 24lb injectors,shorty headers and 3:73 gears. Would Knb aluminum heads 200cc runners and 64cc combustion chambers with stainless 2.02 and 1.60 valves and an xr276hr comp cam match up pretty good for a street/strip car? Car runs 14.31 1/4 now. would like to get into low 13s...Thanks