3rd Gen / L98 Engine Tech 1982 - 1992 Engine Related

Need help with Mods on 305?

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Old 06-08-2002, 04:50 PM
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Question Need help with Mods on 305?

I am going to sup up my 85 Z-28 with the LG4 305 4brll 5 speed. I need to know what will work best with this motor. The first thing I plan to do is put in a Cam and a 600 carb and a intake manifold. I need to know where to look for the cam and what kind will give me the most power. Also I dont know how to install it so does any one know how much it would cost me to have it installed. The next thing is a set of new heads if not that I going to get mine ported. I dont know where to find a set of heads for a 305 so I need to know where to look. If I decided to get them ported how much would that cost me.

Any help or suggestions would be appreicated to get this thing running fast.

Thanks Adam
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Old 06-08-2002, 06:41 PM
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<font face="Verdana, Arial" size="2">Originally posted by CamaroZ2885:
I am going to sup up my 85 Z-28 with the LG4 305 4brll 5 speed. I need to know what will work best with this motor. The first thing I plan to do is put in a Cam and a 600 carb and a intake manifold. I need to know where to look for the cam and what kind will give me the most power. Also I dont know how to install it so does any one know how much it would cost me to have it installed. The next thing is a set of new heads if not that I going to get mine ported. I dont know where to find a set of heads for a 305 so I need to know where to look. If I decided to get them ported how much would that cost me.

Any help or suggestions would be appreicated to get this thing running fast.

Thanks Adam
</font>
Adam,

A search of the past postings on this forum will give you more info than you can imagine!

In any event, the exhaust is the first thing to modify on the LG4. 1 5/8 inch shorty style headers into a 3 inch intermediate pipe into a low restriction muffler with dual 2 1/2 inch outlets (it doesn't need to be loud) will add a good solid 30 hp just like that.

Then add a Performer (or clone) intake, port and polish your stock 305 heads using the Standard Abrasives kit and put in a Comp Cams XE 256 cam and you ought to be pushing 300 hp.
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Old 06-08-2002, 11:19 PM
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<font face="Verdana, Arial" size="2">Originally posted by Sitting Bull:
Adam,

A search of the past postings on this forum will give you more info than you can imagine!

In any event, the exhaust is the first thing to modify on the LG4. 1 5/8 inch shorty style headers into a 3 inch intermediate pipe into a low restriction muffler with dual 2 1/2 inch outlets (it doesn't need to be loud) will add a good solid 30 hp just like that.

Then add a Performer (or clone) intake, port and polish your stock 305 heads using the Standard Abrasives kit and put in a Comp Cams XE 256 cam and you ought to be pushing 300 hp.
</font>
Thanks alot for the info!!!
The next thing I need to know is where to find these things. Im kinda new too all of this stuff so youll have to cope with me. First I looked for both the cam and the headers but couldnt find them. I found the 1 5/8inch shorty headers but they were for 5.0 mustang's only. I need to know where to find both of these where I can purchase them. About the standard abbrasive kit where can I get this? Also im only 16 so are you sure Im going to be able to do this and how does it work. Im guessing if I cant my dad will know how to. I need to know where to get this too. I understand about the headers but not the 3 inch intermediate pipe? I have flowmasters with dual with 3 1/2 inch tips which im guessing your refering to 2 1/2 inch outlets too? Any others help would be appreicated!!! Also what is (a clone) or performer Intake i think you mean just anykind of Intake manifold but im not for sure, I got lost when I saw the (or clone) part. After I get my engine stable enough for some NOS im going to put a dry kit. I pretty sure they make a dry kit for my car if you know of any I would appreicate you letting me know which one would go best. When I add this new cam is this going to solve my car winding up so quickly!! Im sure you know what Im talking about If you have a car like mine. And one other thing do you know how much it will cost me to get a cam installed ballbark figure would be great.

Thanks alot for the help!!!!
Im glad to know there is someone that still has faith in the 305 LG4.
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Old 06-09-2002, 01:08 AM
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In the states you should be able to get all your parts at the local speed shop. If your town is too small, order from one of the big mail order companies like Jeg's or Summit. Every hot rod magazine has their ads and they are also on the internet at http://www.jegs.com/ and http://store.summitracing.com/

Hooker and Heddman make good shorty style headers.

Here is the Standard Abrasives website: http://www.sa-motorsports.com/ They have complete instructions for porting and polishing the heads right on their site and it also comes as part of the porting kit. Should add 30 hp or so, if you also enlarge the intake valves out to 1.94 from their current 1.82.

The intermediate pipe it the one that goes from the y-pipe (off of the headers) to the muffler inlet. What you have will be fine. But the installation and fabrication is easier if left to a good muffler shop, unless your dad is good at it. He'll know what it's all about.

A Performer is an alluminum dual plane 4 barrel intake manifold made by Edelbrock. Works well on a 305 or 350. Weiand and Holley also make similar intakes. It should be good for around 20 to 25 hp. Your stock QJet carb is fine, but go to www.thirdgen.org and look up the Tech Article on tuning the QJet.

The Comp Cams XE 256 cam (the Crane PowerMax 266 is good too) will add their power gradually, after the 2500 rpm mark. By 5500 rpm you should gain a solid 30 hp from it. Will solve your "winding up" problem, as you say It's easier to do if the engine is out of the car but is about an 8 or 10 hour job for a good mechanic otherwise. Figure their labour rates for that, as well as the coast of gaskets and parts like that.

Nitrous I don't work with but the LG4 should withstand the occasional 100 hp shot without hysterics. Don't go crazy here or your engine will be toast.

All these mods should get you into the low 14s in the quarter, and the NOS will push the Camaro into the 13s

Hope that helps!

By the way, this makes for a completely streetable daily driver that gets 15 mpg around town and 25 or so on the highway. I think that is what 99% of us want.

PS If money is no problem, then check out the Chevy Vortec heads and Vortec intake manifold. They are fairly cheap ($450 for the heads and another $150 or so for the intake) at any Chevy dealership. They will be worth another 20 hp or so over the Performer and Standard Abrasives approach.

[This message has been edited by Sitting Bull (edited June 09, 2002).]
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Old 06-09-2002, 03:36 AM
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i have a performer intake you would need if you are interested....its yours for $75 shipped

toosloz@team.camaroz28.com
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Old 06-09-2002, 11:32 AM
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i have pretty much everything sittingbull mentioned, except for the nitrous, and head porting on my car, as listed below, the car has more potential than a 15.17sec pass that is listed, it still has some tuning issues, that we haven't figured out yet, it needs a stall torque convertor, (so that the engine will rev higher before it tries to move the car when you mash the gas) you'll never need this since you have a manual tranny. i also have some trouble putting the power down, we are guessing it makes in the neighbor hood of 265 to 270 hp at the flywheel. if you have any questions just ask someone will answer


------------------
Pics of the Firebird


84' Firebird, 305ci lg4, 700R4, 288/292 duration .450/.460 lift,Edelbrock Performer intake, Holley 600cfm 4 barrel, K&N, Pacesetter Headers, 3' exhuast, dual tips directly behind the rear wheels, no cat,Motive 3.73's and Auburn Posi
1/4mile 15.17sec @ 92.5mph
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Old 06-09-2002, 11:12 PM
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<font face="Verdana, Arial" size="2">Originally posted by Sitting Bull:
In the states you should be able to get all your parts at the local speed shop. If your town is too small, order from one of the big mail order companies like Jeg's or Summit. Every hot rod magazine has their ads and they are also on the internet at http://www.jegs.com/ and http://store.summitracing.com/

Hooker and Heddman make good shorty style headers.

Here is the Standard Abrasives website: http://www.sa-motorsports.com/ They have complete instructions for porting and polishing the heads right on their site and it also comes as part of the porting kit. Should add 30 hp or so, if you also enlarge the intake valves out to 1.94 from their current 1.82.

The intermediate pipe it the one that goes from the y-pipe (off of the headers) to the muffler inlet. What you have will be fine. But the installation and fabrication is easier if left to a good muffler shop, unless your dad is good at it. He'll know what it's all about.

A Performer is an alluminum dual plane 4 barrel intake manifold made by Edelbrock. Works well on a 305 or 350. Weiand and Holley also make similar intakes. It should be good for around 20 to 25 hp. Your stock QJet carb is fine, but go to www.thirdgen.org and look up the Tech Article on tuning the QJet.

The Comp Cams XE 256 cam (the Crane PowerMax 266 is good too) will add their power gradually, after the 2500 rpm mark. By 5500 rpm you should gain a solid 30 hp from it. Will solve your "winding up" problem, as you say It's easier to do if the engine is out of the car but is about an 8 or 10 hour job for a good mechanic otherwise. Figure their labour rates for that, as well as the coast of gaskets and parts like that.

Nitrous I don't work with but the LG4 should withstand the occasional 100 hp shot without hysterics. Don't go crazy here or your engine will be toast.

All these mods should get you into the low 14s in the quarter, and the NOS will push the Camaro into the 13s

Hope that helps!

By the way, this makes for a completely streetable daily driver that gets 15 mpg around town and 25 or so on the highway. I think that is what 99% of us want.

PS If money is no problem, then check out the Chevy Vortec heads and Vortec intake manifold. They are fairly cheap ($450 for the heads and another $150 or so for the intake) at any Chevy dealership. They will be worth another 20 hp or so over the Performer and Standard Abrasives approach.

[This message has been edited by Sitting Bull (edited June 09, 2002).]
</font>
Thanks alot for the info!!
I am pretty sure about going with the Vortec heads on my car instead of going threw the hassle of porting my heads. I went to goodwrench.com to look for them. This is where I get confused. Is this the place I should look for them, and if so my dealership isnt even on the web site for carrying these kind of parts. I live in Midland Tx, so its a pretty big town, so my dealership should have this right? I need to know what kind to get because I dont know or understand which goes with my car. Everything else I completly understand. I am interested about the intake manifold that the guy offered me for 75.00. Im thinking this is a very good deal.

Thanks for the help and sorry to bother you
Adam

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Old 06-10-2002, 01:56 AM
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<font face="Verdana, Arial" size="2">Originally posted by CamaroZ2885:
Thanks alot for the info!!
I am pretty sure about going with the Vortec heads on my car instead of going threw the hassle of porting my heads. I went to goodwrench.com to look for them. This is where I get confused. Is this the place I should look for them, and if so my dealership isnt even on the web site for carrying these kind of parts. I live in Midland Tx, so its a pretty big town, so my dealership should have this right? I need to know what kind to get because I dont know or understand which goes with my car. Everything else I completly understand. I am interested about the intake manifold that the guy offered me for 75.00. Im thinking this is a very good deal.

Thanks for the help and sorry to bother you
Adam

</font>
The Vortec heads and intake manifold are made for each other and the standard smallblock Chevy parts, like the Performer, will not work with them. They are a slightly different design that just doesn't line up properly with the original smallblock intake.

The Vortec heads you want are the L31 heads. Your dealership either has them or can get them for you very quickly. Same with the GM Vortec 4 barrel intake. Texas has a huge GM warehouse.

It is NO bother to help people out on a forum like this. That is what it is for

All these parts will bolt right onto a 350, too, when the 305 finally kicks the bucket, so this is a very wise investment

Jusr make sure you keep the camshaft choice to the two we discussed, the Comp Cams XE 256 or the Crane PowerMax 266. If you get into any higher lift then you have to do machine work to the Vortecs to compensate for it. That costs money and the cams I suggested are as far as you want to go for a street-worthy, daily driven 305.

[This message has been edited by Sitting Bull (edited June 10, 2002).]
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Old 06-10-2002, 12:20 PM
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If you have fast internet access, you can download a video of my 86 Trans Am 305 LG4 5 speed car. Converted to TPI, installed Crane Cams PowerMax 2050 Cam Kit, Pacesetter 3" Catback, stock 87 TPI heads, 87 MAF TPI setup converted to 90-92 Speed Density.
Here is the link to the video, http://www.donpagevideo.com/video/ZepherWS6.mpg

There are other videos in that same directory that were taped at the drag strip when I had my LG4 with an Edelbrock Performer RPM Intake and Edelbrock 1406 600cfm carb with stock manifolds and exhaust.
http://www.donpagevideo.com/video/



------------------
1986 Trans Am WS6
LT4 350, LT4 Hot Cam, T56, 52mm TB, , MSD 6A & Blaster 3 Coil, LT1 3.42 Posi/Disc Rear, Lakewood LCA's &
Adjustable Panhard Bar, Jamex Lowering Springs, 17x9 WS6 Wheels,
T-Tops, Custom 4" CAI w/ K&N Filter, 160*stat.
Autometer TriplePod.
High Speed Run: 157mph
Best 1/4 mile run: 14.94@91.67mph This was with the LG4 carb setup.
WS6 Trans Am.
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Old 06-11-2002, 03:37 PM
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I am very dissapointed in the vortec heads. I went to the chevy house with two of my friends to find out it would cost me $1,500 or more. The heads would only cost 350 then he added all this other crap like gaskets and something about two heads and then head added that all up and said it came out to be $750 or something. Then he said another 5 6 7 Hundred just for labor. Man that goes out he dood quick. I dont think he really took me seriously but thats okay. I going to port my heads I just need to know what kit to buy on the webstie to complicated for me to choose one, Im afraid Ill get the wrong one or something.

Thanks alot adam
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Old 06-11-2002, 04:22 PM
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Cool

This is the one you want:

http://www.sa-motorsports.com/cat/p5.htm

You can put the Vortec heads and manifold on yourself, you know? You don't need the Chevy dealership to do it for you, at $75 an hour. Your dad probably knows how to do it, or one of his mechanically inclined friends.

Does your family have a mechanic that turns wrenches for $25/hr? That is the way to go with the stuff you aren't comfy with.
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Old 06-11-2002, 09:04 PM
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Yeah that is true im almost positive he could do it or have someone else do it but paying 750 or something like that over more like 60-70 for a porting kit would better suit him. 20 HP isnt worth that much. I could add something else and get just the same results. About the proting kit, when you order that do you have to have any other kind of tools besides what comes in it and if so what? And is it really hard to get heads off or not really? And Im guessing that it comes with something to show how you do it am I correct?

Thanks for all the help,
Adam
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Old 06-11-2002, 09:23 PM
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hey Adam you got the same car as I do just to let you know with my mods I beat a 5.0L mustang in a race I have the LG4 305 with mods being headman 1 5/8" headers 3" exshust and a mild cam don`t know what kind though you can cheak my car out at my site posted in my sig

------------------
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Old 06-12-2002, 03:16 AM
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<font face="Verdana, Arial" size="2">Originally posted by CamaroZ2885:
Yeah that is true im almost positive he could do it or have someone else do it but paying 750 or something like that over more like 60-70 for a porting kit would better suit him. 20 HP isnt worth that much. I could add something else and get just the same results. About the proting kit, when you order that do you have to have any other kind of tools besides what comes in it and if so what? And is it really hard to get heads off or not really? And Im guessing that it comes with something to show how you do it am I correct?

Thanks for all the help,
Adam
</font>
Yes, you need a die grinder. They are either air-powered or electric and you should be able to rent one.

I think you should go to the library and get a book out that explains in good detail how the internal combustion engine works. You sound like you've never seen one apart before, and it can be intimidating until you actually see how they work.

You also must sit down and carefully budget out what you want to do. There may be cheaper ways of doing what you want, but you MUST do a budget so you can SEE what the alternatives for each piece and procedure are.
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Old 06-13-2002, 01:41 AM
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Adam,

I hope you weren't put off by my last post. We were ALL newbies at one time, even me

In fact, I'll bet there are a LOT of guys and gals on the board who envy you because you are just starting into this great hobby and passion. The 3rd gen Camaro is the finest handling Camaro that GM has produced. With a good engine it is THE best bang for your buck--bar none!!!

YOU are in for a LOT of FUN

[This message has been edited by Sitting Bull (edited June 13, 2002).]
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