Hi all, back again. Well, I put my exhaust on the LG4. For those of you that dont remember, it consisted of Edelbrock headers, 3" y-pipe, 3" high flow cat, and a 3" SLP catback. I installed this on my 83 Trans Am. The only other mods are 3.73 posi, bumped timing, open element, "G" hanger w/ "DR" rods. The car runs unbelievably strong now with the new exhaust. I ran a 15.79 before the exhaust. My question is....is there a good cam out there that my wee-05 will like? For about 3 days a while back, I had the XE-262 in there and it barely idled. Anyway, im looking for a nice cam, maybe 1000-5000 rpm that will work fine with the stock computer and still bring decent fuel economy.

But Jesus, that exhaust REALLY woke this motor up. I raced my friend in his 98 Dakota R/T that runs 15.5 and totally walked all over him I would have to guess im knocking on 14's door. BTW, the motor only has 79,000 original miles on it. Any info guys and gals??? Thanks in advance.

 

nobody knows?

 

Wow, do i have some EXCELLENT info for you....

I have the famed lg4 in my 86 firebird, here is what i got, and here is what i am approximately running in HP and e/t's

i ran a 14.8 with:
your SAME exhaust setup, minus the headers, some carb tuning, carb spacer (made a pretty noticable diff) 3.42 gears.

i am now in the 13's SOMEWHERE (have run supposed mid 13 sec car and edged em out by almost a car)
full exhuast, exactly like yours, edlebrock 1 5/8 TES headers, new heads (untouched, just decked for flatness, and new guides valves, etc), crane compucam2030 (these are approx numbers) 208/210 duration, 448/448 lift, 110 lsa (again not too sure, but gives you an idea on it anyways) edlebrock performer intake, holley 670 street avenger carb, vacum advance distributor.

Estimates put me around 275 at the crank for hp. The crane compucam that i have installed is VERY simliar to the 84, 305 HO cam... so its more or less a stock cam for comparisons sake.

I have yet to put on the 1.6 roller rockers (still have the stock steel stamped, roller rockers free up some hp loss due to friction) and recurve the timing (i think full advance isnt kickin in till like 4000rpm!)

That said, the car is pretty friggin quick, i did swap in a 5 spd however. I am looking forward to having some cash to either get it dynoed, or just wait till spring comes and the tracks open backup to get some solid numbers. I fully expect to see high 13's no problem, and maybe a mid 13 will peak in as the motor sits now. After the roller rockers and the re curving of the timing, and some fine tuning onthe carb, i think and extra tenth or two will be on order....

Hope this all helps, i'll tell you right now, going to the holley and getting rid of the computer crap was the best thing i did. I didnt hack it all apart, i'll have to take some pics and post them. I used the stock harnes, for the guages and stuff, didnt cut anything up etc. The main harness and stuff is all coiled up neer the fan box for the interior ducting.

Future plans for this motor are prob gonna spell junkyard, since i think it is not going to last to long with some beating (lg4 305 with 168k on the odo, still has excellent oil pressure, so i''mnot too worried!) But, before it gets pulled for a 350, i will likely port the set of heads myself, and maybe throw in a little bit bigger cam to take advantage of the heads... i kinda wish i had gotten a bigger cam from the start, but this one i have right now is an excellent choice.


shoot me an im if ya have anymore questions.

Steve

 

Isn't that a little over estimated without major head work? Just asking, by no means a flame.

 

FB305SVS,

Thanks a bunch for the info. Its really incouraging to know you can pull a little out of these motors without and major mods. Anyway, Im off to the track Saturday morning. If anybody wants me to, I can post my times for everyone to see. Thanks again.

 

Well i was talking crank numbers, definately not RWHp, if that clears anything up. From all indications i have gotten, racing people who have tried and true 13 sec cars, if i were to use a hp calc and use an e/t and mph from a mid to high 13 sec car, it comes out to about 300 on the one i used.. i figuer thats a bit off, and that i probably have closer to 275 with the mods i have. Its a stock cam as far as duration and lift go, but the lsa and the lobe shape is quite different, and that is where the power difference comes in. The mods i did most definately woke this 305 up, and i only wish that the tracks were open here all year long.


Ttopgta- i would be very intrested to knwo your times. Like i said before, i have a 14.8 timeslip with just 342 gears, cat back, some carb tuning and 3600 lbs with me inthe car, and 1/4 tank of gas.

If they have scales where you are going to race, try to get a weight on your car with however much fuel you have...


Steve

 

Sorry dude.. no way in hell you can run mid 13s with 275 crank hp unless your car weighs like 2600lbs. Im pulling 265RWHP and I can't pull off mid 13s.

 

Well, i have already had this arguement with people over at camaroz28.com... i'm not arguing it here. Maybe i have more power than that... who knows. I dont have the cash to get it dynoed yet... hopefully i will at some point

Steve

 

89t-topGTA: Congrats. Sounds like it's getting pretty stout for a little 305. In the past I have had success with a mild Crane Compucam grind. The one that is ~214* intake, more on the exhaust running a 112* lobe sep. However, I see no reason why an Xtreme 262 wouldn't work. I suspect you had maybe a valve or two tightened down too far and were hanging a vavle or two off it's seat. I have worked on several cc-carbed 305s and they are VERY forgiving of cam changes. Hottest cam I ever dropped in one was a Comp 280 Magnum (with a bunch of other mods and 350ci motor) and it ran strong without throwing any codes.

I totally agree with FB305 on his HP estimate. My 100% dead stock 275HP (flywheel factory rated) 1994 Formula ran a 13.7 @ 103 the first time at the track. It weighs about 3500 with me in it.

You are experiencing first had the reason that dyno numbers mean nothing execpt when compared against other runs on the same dyno. The raw HP number can be manipulated in a zillion different ways. The track tells the truth. Especially the MPH number through the traps when compared to a vehicle's weight.