I want to spice up my L69 a little bit. The motor is rebuilt stock with about 20,000 miles on it. Its in my 84 with a WC T5, and a 4.10 posi rear. I just want to run high 13's-low 14's with it. A couple people told me it would be a lot easier than you would think. Can anyone help me here? What are the L69's weak points?

 

Nobody knows??

 

Same principle that has you running 10.70's in the Dart.

Cam, heads (or head work) and exhaust.

W/4.10's, I'd expect you'll need some suspension work to keep it hooking as well.

 

Are you running 14.78 on stock exhaust?? If so, headers, Y, '86 and newer cat, and a cat back should put you in the low 14's. I'd say 14.3 easy.

 

I didnt know how much of what I did to my Dart applied to my TA, simply because of the computer and stuff. But I ran that 14.78 with everything bone stock....except for the 4.10's. Stock exhaust and everything. So youre saying exhaust will get me low 14's?

 

Headers, exhaust, cleaned up heads and either a little bigger cam or 1.6 rockers. With that, you'd hit very low 14s at the slowest i bet.

 

If you are running 14.78 stock (except gears) that is VERY good. A set of '86 or newer TPI Edelbrock headers and Y pipe, an '86 or newer TPI cat, and a cat back for '86 or newer TPI will shave .5 or better off your 1/4mile times instantly, which would put you at 14.28. The stock exhaust is THAT bad. I'm pretty confident that' you'd see better than .5, seeing as you're already running the 14.78. To me that shows you have a strong engine (for a stock 305) and the better your engine, the more the stock exhuast is hurting you.

I say '86 and newer, because the 82-85 cat is tiny. To install headers, Y, and catback and still force the exhaust through the tiny stock cat, will not gain you the full benefits of the purchased items

IMO, do the exhaust, do a 160 T-stat, loose the smog pump, put on an electric fan, and with a hard hook, I believe you could tag 13.999's

You don't need to be porting heads and switching cams to realize your goal. However, those mods wouldn't hurt, and the retarded computer your car has won't ever notice the difference.

 

That sounds very good. I was planning on eventually doing the exhaust, but now that everyone says that i'll pick up that much...i'm that much more excited about doing it. I didnt know the L69 exhaust sucked that bad. On my old 83 TA, I picked up .95 in the quarter by adding Edelbrock headers and y-pipe, 3" cat, and a 3" catback for a 87-93 TPI 350. I went from 16.00 to 15.05, on a stock LG4 with 3.73's. What cam would this motor like? I heard the Comp 2030 was a nice choice with the L69. Would I have to worry about breaking the T5 or the 10-bolt launching it on DR's with the added power? Id love to be able to tell people "my 305 runs 13's". So I take it the stock intake manifold is a good enough piece to hang onto for a while then? Thanks for all the great info, it is very encouraging.

 

I think you'll be fine with the T-5/10 bolt in to the high 13's. Mine's held up fine, see the sig.

As for the intake, I would replace that after exhaust, and cam, but before head porting. With a stockish combo, I think the stock intake is fine, but they're SO CHEAP, you can't go too far wrong ever putting one on.

I don't think having a 305 that runs 13's is THAT impressive (pretty good though), however, I think having a 305 running 13's with just headers and exhaust.... now to me, that's impressive. A lot of folks at the track woudl have a hard time believing you, IMO.

Edit; I forgot the cam. Probably an extreme energy cam would be the best but the only time I tried one of those cams, it wiped in a month(yes, it recieved proper install and breakin). I've had GREAT luck and results with Summit brand cams. I know there's better out there but for 69 bucks, I loped a full second off my 1/4 mile times in my OLD LG4 T/A (16.3 to 15.3) a looong time ago.

 

I respectfully disagree that 13's are'nt impressive for a 305. I'd expect 13's with a 400.... (if not better), but it's pretty rare for a 305 n/a to run those times.

AFAIK, the HO 305's are capable of high 14's to low 15's stock. Look at my sig, and yes, mines far from stock, and I'd be lucky to reach into the high 13's (I think), although I haven't ran it at the track yet. But I have been told by others that it "hauls" and they were suprised at the power it has.

DISCLAIMER: The statement below is not meant to be a bash on those who have 350's...

There's 350's out there that can't get into the 13's - that's with a cam and exhaust!!

 

So hows the Crane 2040 working for you in your 305? Is it a good cam with the 5-speed, and more importantly....is it emissions legal?

 

I personally like the cam. It seemed to give it much better midrange and upper end power. It's emissions legal with a carb E.O. number assigned. What sold me on it was that it's actually a Crane Compu-cam meant to work with your CCC computer, which basically gives you more lift, w/o a duration that would "wig-out" your computer. I've also heard there are Extreme Energy cams that work well.

I was a little disappointed when I put the intake on....didn't really feel a huge diff like I wanted.

The stock intake breathes pretty well I guess. Your stock exhaust (if it's still stock) is also a bit better than a LG-4 exhaust. But I think my headers gave me the best bang for the buck, along with a cat-back sys.

But i already had the cam in....

 

You may want to check Chevrolet HiPerformance magazine, they just did a project 305 with an automatic and a 3.73 that they got into the 13's. They later changed to a 350, but the little (almost stock)305 was pretty impressive. I will also have to say that any street car that can run 13's is a good ride. Even back in the good old days of the 60's and early 70's most cars would only run in the 13's. It was mostly due to the tires of the day, but a 13 second daily driver is a good performer.

 

Was that in this month's Chevy HiPerformance? If not, do you have the month?

 

There were several articles over the last year, try their websight
http://www.chevyhiperformance.com/projectbuild/48198/
That should get you close.

 

I have a couple thoughts.....

First, thanks for the link. Very informative!

I just glanced through it, and I can't believe they only ran 13's with all that along with heads and NOS!!!!!...

If that's all I can expect from my car if I add SR Torker heads and nitrous, then forget bout it....it's 400 time!

I'll read it over closer. Thanks again.

 

Like I said, anyone running 13's in a daily driver does pretty good, it's a lot harder than it looks.

 

Yeah, I know what you're saying, but the car in that article had issues of some sort....waaay too slow for all the mods added.

I'm pretty sure I could save money by not buying heads and go straight for the nitrous! And hit low 13's or high 12's doing it.

 

Well, I think that you have several advantages starting out on the magazine car, first, your car doesn't have a slushbox, it has a T5 trans. (it may be a broken T5 in a little while but that's another story) You also have a 4.11. Both of these are huge advantages to start out with. I know conventional wisdom dictates that the biggest h/p improvement is to add headers to the car. That may be true from strictly a h/p point of view, but it has always been my experience that if you want to make the biggest improvement in acceleration, leave the headers alone a put a gear in it. Let me know how this works out, I have the exact same set up in my 83 Z28.

 

Hope not. It has a upgrade gearset and input shaft in it from G Force, and is rated for 600 HP and 500 Ft. lbs. torque. I shouldn't have near enough power to break it, unless I rip the synchos out of it speed-shifting.

Strictly for acceleration, yes I agree- gears will be the biggest improvement. Does nothing to the engine though.

And as you said, I already had 4.11's (actually 3.73 open), but headers made a decent improvement on my car. I figure anything that makes it "breath" better is always an improvement.

But as I said earlier, I already had a Crane cam in it when I rebuilt it, so I most likely felt more of an improvement when I installed the headers - vice a stock cam. That make sense???

Anyways, I'll quit babbling now.....

 

Yes, I would agree, anything to help the engine breathe is usually a good thing, and 305s are hurting in this area., but again, if you want the best over-all improvement I would go with a gear. So. do you have 3.73's or 4.11's?, and a posi unit will definately be a plus. Try www.reiderracing.com I think they're about the best out there.

 

The L69 exhaust, for what it is, isn't that bad. Below notice the difference between the LG4 and L69 y-pipe--don't get me wrong, I'm not arguing against headers. With this exhaust, however, L69s were capable of, I think, 138 mph top end and were capable of whacking some 350's.

JamesC

 

The stock intermediate pipe is larger than the after market catback that I was previously using. You can see the difference, perhaps better, in the pic above to the right.

JamesC

 

For sure the L69 has better breathing than the LG4, in the heads too.

 

Why do people keep making this up? Why does this myth just refuse to go away?

Of all the things that are different between the 2 motors, heads are not one of them. They are identical in every way. They are both 416 castings, 1.84"/1.5" valves, etc. etc. The exact same heads with all the same parts were also used on the 85-86 305 TPI motors. After those years, after the L69 was no longer available in these cars but could be had elsewhere, they remained the same castings; they both used the 081 casting, wihch is also the same one the 305 TPI motors used from 87 up.

James' pictures of exhaust show one of the main differences between the L69 and LG4. In addition, the cam was different; the carb calibration was different; the L69 cars came with 3.73 gears, instead of the 2.73 and 3.23 gears so common in LG4 cars; and flat-top pistons, which ended up in the LG4 in later years too.

The L69 responds to the same things as any other engine, subject to the fact that some things are already done for you. Headers of course (the rest of the exhaust is adequate), and a better cam, and porting the heads with maybe a valve size upgrade, and a torque converter if it's an auto car. Leave the carb and intake alone, they aren't costing it any power, until alot of other things are upgraded first.

 

Ok, so help me out then, The LG4 and the L69 engines have the same heads? I was always told (by some people on this very board) that they were different. I know that the exhausts are different, are the exhaust manifolds the same? The L69's that I own both have flat tops (9.6 I think) and 1.84 valves. I know that the H/O cam is also different. One is out of an 83, the other an 84, both appear identical, aluminum intake,q-jet and all.
The reason I want to clear this up, hpefully forever, is that I have freshened up one of the 305's with new rings and bearings. I also installed a slightly hotter cam (I don't have the specs in front of me) it's going into an 83 Z28 with a T5 and a 4.11 posi.
I know all of the people that hate the little 305, but it seems that the H/O version ran pretty darn good, even with 210,000 miles on it. (that is not the one I freshened up by the way).
So, I'm listening, enlighten me.

 

they definetly used the same heads

 

Heads are the same, in every way.

Exhaust manifolds are very different. Everything about the L69 ones is bigger than the LG4 ones. The outlet is 2¼" on the L69, 2" on the LG4; which may not sound like much, until you realize that the inner diameter is nearly ½" less than that, which means that the hole in the LG4 one is about 1½" in diameter vs. 1¾" for the L69, which results in a cross-sectional area difference of about 3 sq.in. vs. 2¼ sq.in. That's huge.

Cams are also very different. The LG4 got the "peanut" cam, the L69 cam is almost something decent but not quite. The earlier 350 TPI cam which is posted in the tech data on this site is basically a roller copy of the L69 profile.

The intakes were the same, on the US versions anyway; numerous Canada people report that their version of the LG4 got a really crappy cast-iron one.

You're right, the L69 cars ran real good, by far the fastest of their day. They were so much faster than the CFI 350 Vettes that it was almost humiliating for those people (even more so the CFI 305 F cars). Horsepower "ratings" aside, mine had no trouble outrunning the auto TPI cars up until the 350s came out; usually ran ahead of the 305 TPI 5-speeds; and even against the 350 TPI cars, it would often get quite a jump on them, but the larger motor would eventually catch and pass it, although usually it took considerably more than 1320' for it to do so.

I had 2 friends who rushed out and bought 350 TPI Vettes in 85, one auto and one the 4+3, so I had plenty of opportunity to compare my virtually showroom-stock 83 L69 car to those combos. They were both a bit disappointed that they had just spent over $30,000 on a car, with the "state-of-the-art" port-injected 350, and they weren't materially faster than a carbed 305.

 

I'm no expert, but RB's probably right.

I know he's given me advice in the past that was accurate.

........ Although he did try to tell me to "get a 350" instead of rebuilding the L69..........

I've seen LG4's in the junkyard with the same heads as mine.

Agreed, the rest of the exhaust is adaquate...but you commit yourself when you buy the headers. The only ones I've seen come with thier own custom Y-pipe, to bolt up to the 4 bolt cat. So there goes the great breathing stock Y-pipe, which BTW, is sitting in the corner of my garage.

Of course, for some $$$, you could get your headers adapted to a stock Y-pipe, but why bother??

The next "mod" I plan to do is change out the secondary rods/hangers on the carb. Maybe CK's and B hangers....gotta find out where to get them.

Also plan to get a posi rear in the near future, hopefully with 3.43's or higher. Any other recommendations to go faster RB??

And before ya say it, NO - I'm not getting a 350.

Next one I rebuild will be a 400. So any mods I do, I want them to work with a 400 also.

 

i dunno, i guess you can say i went all out on my LG4

intake, cam, carb, heads slightly worked, full true dual exhaust, headers


i want to take it to the track to see what she runs

mines a roller cam/centerbolt version, btw

 

Thanks, so I can carve that in stone then.. Lg 4and L69's had the same heads.

 

Got my near stock L69 into the low 14's with mods in sig below.
Stock exhaust except gutted cat (no headers). 1.6 rockers will
turn the stock cam into decent cam.