With the Inherantly Restrictive nature of the Lg4 heads, Would It afford Much Benifit To Go to a Larger, Aftermarket Cam ? I was considering a cam with a lift in the area of .480, While Keeping overlap Under control For the Sniffer. LSA is not something I completely understand

Some cams That Come to mind are the edlebrock performer RPM and the comp cams Xtreme 270 or 268.

This Would Be with edlebrock TES, 3 icnh exhasut, new valve springs to support the lift of the new cam and a 800 CFM ( yeah i know ) Qjet ontop a Performer RPM manifold.

How Much are My Stocker Heads Going to restrict Me, And Is it going to be worth It ?

Ive got No Dillusions about being the Fastest, I just want to be a little faster

TIA

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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

Perhaps the Comp 268H, but that dual patter extreme energy 270 or 268 is going to be a little big for the stock-headed 305. You could always have the heads ported rather inexpensively, or have them CNC'd if money allows, but bottom line, for emissions and for the fact it simply won't rev high enough to use that power and you'll lose lower RPM torque, stick with a smaller cam profile. That 270H extreme energy would work well even on a 383, you aren't breathing heavy enough for it. Good Luck!



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Dan Young
1995 Z28/M6
Groton, CT

1985 Z28/A4
(Prospective purchase)

 

Those cams are way too much for that engine as it sits, without substantial modifications elsewhere.

The first, biggest thing to do is the exhaust, all the way from the heads to the bumper. DO NOT get the TES for the LG4: it has the puny little Y-pipe size to hook to the LG4's dinky cat, which sort of defeats the whole purpose. Get the TES for either the L69 or the L98, and a cat and cat-back to match, since those have the larger Y-pipe size.

Your best valve train combo IMHO would be a Comp XE262H; their 1.52 steel roller-tip rockers (1412?); and their 981 valve springs to match. Don't waste your time and money on the carb you are talking about. You will derive absolutely no benefit whatsoever, and in fact you will actually slow the car down. The problems with the carb that you have now are all driveability-related, not WOT; it's plenty big as it stands for speed. Plus of course, there are no 800 CFM computer-controlled Q-Jets; so you will have to replace the distributor at the same time in order to use such a thing.

The same goes for the RPM manifold. It's way too much for the rest of the engine, and will decrease low-end torque without giving a corresponding increase in high-RPM flow, for a net loss in performance.

Think of your engine as being like a series of pieces of garden hose of various sizes. You want all the pieces to be about the same size for optimum flow characteristics; so what you need to do is pick out the pieces that flow less than the rest, and make them match the others. If any one piece has significantly larger flow capacity than the others it makes no improvement to the overall flow of the system; but instead, the velocity of flow in that one piece is slower than the rest of the system, so the water has to speed up and slow down as it passes through, which uses up energy. Your engine works the same way. A matched combo will beat a stock motor with a few giant misfit bolt-ons every time.

In the case of that particular engine the limiting factor is the heads. No matter how big all the pieces around them are, ultimately the motor will only flow the capacity of the heads. Choose parts that realistically match their characteristics for best results.

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"So many Mustangs, so little time..."

 

Thanks For the Responses, RB and Meangreen.

In getting TES, yes I understand that I should get the L98 or L69 Versions. AS for cat back, I Currently Have A 3" Cat backed By 3" Pipe back to a Single In, Dual Out Flowmaster.


I understand your Concern about the Carb, Rb, But that is The Only Working Carb I have Right Now. Once I get a Chance, I am going to rebuild the E4ME, Wich I assume Is better Matched to my Engine. Ive Got No Dillusions that This 800 CFM qjet is the Best For My Motor, But It is the only Working 4bbl Carb I have at this time, and its sitting On the Motor Right Now.

And Yes, I have a Vaccum Controlled Dist.

I Understand Fully the Water in the Hose Theory, And perhaps I mistakenly Identified the Cam as the Biggest Restriction In Flow. I had selected the performer RPM manifold Without Much in depth Thought on the Subject, And if You could Suggest a Better Suited Manifold For My application, I would Appriciate it.

I will look into the Comp XE262H and matching components.

Thanks For Your informative answer Rb, that is exactly what I was Looking For. Its hard to Get Good information On this Subject



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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

As far as an intake, I belive the Performer not RPM or the Weiand equivalent (Action + ?) would be good choices. However, there's nothing really wrong with the stock one, as it flows enough to feed those heads adequately. IMHO if yours is in good shape it is money better spent elsewhere.

If you already have a non-computer dist, I would suggest not going back to the OE E4ME. Reason being, you would have to have the ECM active and controlling the carb for it to work right; but then you'd also have to have the computer dist and all the sensors and everything else. If you've already gone that far, you'd be better off getting a new carb. I like the Holley 6210; but the Edelbrock Q-Jet or their Carter might be OK as well. Someday I'm going to try a Demon which looks on paper, and Barry Grant's reputation is a strong recommendation in itself.

Your exhaust sounds like it's good to go.

Yes I've noticed that it's hard to get good info in general about engine mods. You can get lots of beat off and mouth racing and little fact, alot of talk about how you should do this or that, with no reasoning why or understanding of what the options are; many people on this BBS can do alot better than that. Some other people on this board have the XE262 cam in that motor with good results so I don't hesitate to recommend it even though I don't fool with 305s myself very much.

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"So many Mustangs, so little time..."

 

the LG4 heads arent all that restrictive they are the same heads on L69s, one of the better GM 305 heads actually, #416 casting. I use them on my car
the most restrictive thing on the LG4 is its pathetic compression ratio but thats due to the pistons

 

I'd stick with the Edelbrock Performer EGR manifold port matched to mildly ported stock heads for the 305. As far as cams, I think the biggest you could ever get by with and see high-end gains with this would be the 268H comp cams stick. There's a bunch of small things you could do to up the ante, most of which would be your preference and your budget allowing, you could see pretty decent numbers out of a well-build, budget minded 305. Bigger is not always better, and the man from Carlsbad hit it right on the money with that. Improve your incoming airflow if possible, free up your exhaust, and work on the proven power builders, along with proper tuning. A dual snorkel setup would help a little with a K&N, so would a K&N Stubstack, a 1" open plenum spacer (if you have underhood clearance) and a re-jetted carburetor. Headers, 3" y-pipe and cat back are a must with cam and head modifications, and roller rockers with matched-to-cam spec valvesprings would help as well. There's a ton of things to consider, so just take your time and try to get it all right the first time. Dig in the books and take in all everyone tells ya and decide for yourself what you want your car to do and what will work best for ya, good luck!



------------------
Dan Young
1995 Z28/M6
Groton, CT

1984 Z28/A4 - Prospective purchase

 

Thanks again, Rb, Pablo, and KidIROC.

I am Suprised to hear that the stock intake Is Sufficent to Flow AS Much as The Heads can handle, But I Belive You all the Same. The one I have is in perfect Condition, Would Pulling it and Doing a little port matching Be to My advantage ?

Let me explain My Situation a little more In depth, So that You can understand My Motivation For using the E4ME.

When I bought the Car, It was completely un Modified, Untouched and in Great Shape. After Owning it a while the TPS Went South, and In the Financial Situation I was, the alternative I took was to Bolt On this Mech Qjet and Drop in a Vaccum advance Dist ( Both laying around the garage, out of My Wrecked Firebird ) I still have the Computer Controlled Dist, and all the Sensors are Intact. I could easily Reinstae the Car to its stock Condition If the Carb Were Functioning properly. My Motivation For using the E4ME was In an effort To maximize gas Milage, But perhaps I Am Wrong In assuming that this computer controlled Carb would yeild a signifigant Gain Over an aftermarket Unit, in this aspect.

If I elect To Go with an aftermarket, Mechanical Carb, I have had great Sucess With the Edlebrock performer In the past, and WOuld Probrably Look Down this Path.

Pablo : You bring up a Good Point, I had Forgotten that the LG4 differs from the L69 Mainly in Camshaft, Exahust, And Compression.
The L69 puts up some impressive Numbers, And I imagine with a Little aftermarket Work, I could Squeeze Out a Little More. Perhaps the HEads are Not Going to Be the limiting Factor For me.

Airflow and Exhaust and "little things " are All things that I pretty much have under control. Its the Matching of Internal engine Components That I like to Seek advice On

So lets bench race a bit here. If I were to Pull the Stocker Intake, and Port match and Gasget match it to My heads, Install the 268H or 262 Comp Cam With Corresponding valvetrain upgrades ( lets assume Merely Roller Tip Rockers, for now.. The ones Rb listed at 1.52 Lift... ). Tops this Off with a 600 CFM Edlebbrock carb ( either AFb or Qjet ) And use the Exhasut Described, With An open Element air Filter, Recurved Dist, And MSD ignition ( assume just Coil and wires, The Jury is out on the effectiveness of the 6AL) . With a Solid LG4 Shortblock, What Sort of Numbers Could WE Be talking here ?

the Stock LG4 is rated at a Measily 150bhp, Correct ? Can I reasonably Expect To approach 225 Hp Or so, With these aforementioned Mods ? IMO a Hp Figure In that range, Appropriatly backed by a Solid Drivetrain and Suspension, Would Give me A fairly Quick street Car, one that I could Have Fun with at the track On weekends, yet Still Drive 50 Miles round trip To school every Day.

Thanks again Guys, the Knowledge of a Few On this Board is of Un-ascertainable Worth.



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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

IMHO 225 crank HP is not at all unreasonable to expect from that setup.

You would get a few more than that if you used the L69 cold-air dual-snorkel air cleaner system instead of an open element type, with a 3/4" spacer ring on top of the carb to get the lid off the choke stack on the air horn.

I don't necessarily think the stock carb and dist are better to re-use, though they're not essential to replace either. Since you've already got the others you don't have to buy them along with everything else, so that's your choice really. I think, having dealt with several of that part # carb, that you'd be better off with something else, but the stock one isn't necessarily all that bad. They can be made to run pretty good with the right massaging.

And yes, with that combo, especially with the 262 cam, you would have a most pleasant daily driver. It should easily get over 20 mpg on the road. It's not going to be a race car or anything as long as that short block is in there, but it will be fairly peppy. Personally I dislike the idea of building a car that is useless for anything but racing, unless of course that's the only thing it's for. Street cars should be driveable on the street.

One thing you didn't mention that deserves some attention is your gears. Most of the LG4 cars came with 3.23 gears at best, and usually worse; if you are like the unfortunate many, you should get the 2.77s out of there and put in 3.42s or so. If you have a 9-bolt you may need to go to a 10-bolt as gears for the 9-bolt are hard to get and $$$. You may also want to consider a good-quality higher stall converter, like in the 2400 RPM neighborhood, especially if you keep the stock highway gear.

------------------
"So many Mustangs, so little time..."

 

Funny You Should Mention the gearing, Rb.

I have Just pciked Up some 3.42's From a guy over at camaroZ28.com, and Am Waiting Till next paycheck To secure some 28 spline axles and the Zexel Torsen Posi.

Is the L69 Dual Snorkel Really Better Than Open element ? I have been Meaning to Build My own Dual snorkel Out of a few extras I have around here, But just hvent Gotten around To It. Maybe I will one of these days...

Yes, a Stall is On the List as well. Do You know Offhand What the Stock Stall Speed Is for the Lg4, Open 3.08 rear end ?

For the carb and Dist, that is Something I will have to toy around with and See what works out best, Providing the Best Power While maintaining a MPG I can live with making 8.00 an Hour part time. I have all the parts For this, Just a matter of Swapping them On and Off ( something Im getting pretty Damn Practiced at, let me tell you )

AS far as the Racing Is Concerned, In an Ideal world, this Car will see Signifigant time On the AutoX track, and occasional Joyrides down the 1/4.

A Motor AS we have described it Will be More than enough To Power me through the twisties, And Will Most definately Be more power than I can use Fully untill I put alot more work Into My suspension, So It wont be the Weak Link.

Sure, Its Not going to get me 12's In the Quarter, But thats Not Really What Im Looking For. If I can get out there and Run 14's All day On the Lg4 Shortblock, and then pile in 3 of my buddies and Drive the 50 Or so Miles Back Home from the track, I will be One Happy Camper


Thanks Rb, You have been, and Im sure will Continue To be, Most Informative.



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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

I think stock stall is right around 1450. Anywhere from 2000-2400 RPM's would be perfect with 3.73's and either the 262 or 268H cam (or similar). There are dual pattern cams that would add a tad of spice to this equation, I just don't know of any others that come in a complete kit, ie: Cam, lifters, lube, springs, seals and timing set. If there are, I'd look into it, hell, the more power the better, and it should be fully streetable. I used an Edelbrock 600 w/EGR on my last '87Z28, and it worked great. Since the short block will retain everything else stock, the stock heads mildly ported with perhaps a 3 angle vavle job should be more than sufficient, and that dual snorkel setup is much better than the single, and if you're feelin' crazy, route some ducting through your highbeam's (cut the back out) and have true ram air. It flows better than open element on the stock hood. Cowl induction is a whole different story. Good luck!



------------------
Dan Young
1995 Z28/M6
Groton, CT

1985 Z28/A4
(Prospective purchase)