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

86' 305, need advice

Thread Tools
 
Search this Thread
 
Old Oct 3, 2004 | 03:29 PM
  #16  
Yossarian14's Avatar
Thread Starter
Registered User
 
Joined: Sep 2004
Posts: 228
From: South Bend, Indiana
Re: 86' 305, need advice

If you take a 305 out and stick a 350 in a 1986 Camaro, how much work will it be? Will the 350 work with the motor mounts, transmission, etc?
Old Oct 3, 2004 | 07:17 PM
  #17  
Pneumatic_Tire's Avatar
Registered User
 
Joined: May 2004
Posts: 439
From: Kettering Ohio
Re: 86' 305, need advice

Motor mounts are the same, same block size. You can't tell the difference just by looking at the blocks side by side. As far as the transmission bolt pattern, im about 98% sure they are the same too. Somebody else should be able to come in and confirm my other 2%.
Old Oct 3, 2004 | 07:37 PM
  #18  
fbodyfreak's Avatar
Registered User
 
Joined: Sep 2004
Posts: 98
Re: 86' 305, need advice

I am in the process of swapping an 88 305 tbi for a 350, I decided to go back with the tbi for isnpection purposes. You will get a lot more power from a 350, but at fifteen, I sugest you get some driving experience under your belt before you go for more power, you dont want to waste a good f-body by wrapping it around a tree or worse another car.
Old Oct 3, 2004 | 09:04 PM
  #19  
Nate86's Avatar
Registered User
 
Joined: Oct 2004
Posts: 29
Re: 86' 305, need advice

There's no doubt that a 350 would make much more power than a 305 with equivalent work done to each. However, there's nothing stopping you from making the most of what you have.

I'm going to assume you have the standard LG4 V8 which was rated at around 145-160 HP, depending on the year. If you have an L69 (same engine except with some minor changes and a "beefier" 190HP), then you have a lot of the work done for you already.

Start with the very basics. The stock air cleaner is a horrible choice for air induction. The air cleaner only has one snorkel, and the snorkel is tiny at that. Grab a dual snorkel air cleaner off of eBay for a 5.0L H.O. Camaro which has two large snorkels which draw in air from two places, rather than one. However, the dual snorkel air cleaners are becoming exceedingly rare and expensive. Alternatively, you could buy an open element air cleaner (which cost about $40 at AutoZone) but the drawback here is that it draws in hot, less dense air from the engine bay compared to the cool air of the dual snorkel. You could also fabricate a custom cold air intake for your car, but you would have to take measurements, buy all the parts, and fix everything up youself which could be costly and time consuming. The best bang-for-the-buck here would be a dual snorkel air cleaner if you can find one at a local boneyard.

Moving on, once you get more air flowing into the engine, you're going to need to work on getting more air out of it as well. The best way to go about this is to upgrade the entire exhaust, all at one time, "from the heads to the street," to quote RB. Plan on putting on headers, a y-pipe with a 3" outlet, a 3" in/out high flow catalytic converter, and a 3" in/out high flow muffler. If you plan on using this exhaust later on down the line, pick parts that are made of stainless steel. I would have the headers ceramic coated as well (reduces underhood temperatures; protects against rust), but you can decide whether or not to do that based on your budget. As far as what brand to buy, you're on your own there. There are too many different headers, cats and mufflers on the market for any one person to say "this is the best." You're basically going to have to do some research and use your best judgement and preference when picking out your parts.

The next step would be a cam upgrade. The peanut cam that the LG4s came with is by far one of the worst (if not THE worst) cams ever put into a GM engine. I'll be honest with you: I'm far from an expert on cams. The least I can recommend for you about this would be to go with a computer-compatible cam. This will keep the ECM from throwing a fit due to the change of camshaft. Ask around this site or thirdgen.org for camshaft recommendations.

The heads that come with the LG4 weren't nearly as bad as the cam, though. They can be self ported and polished to flow extremely well and there are numerous places you can go to find out how (one resource is already provided for you in Sitting Bull's signature). Your '86 will have the heads of the 416 casting and used 1.84" intake and 1.50" exhaust valves. If you decide to P&P these heads, install some 1.94" intake valves with it... as well as upgraded valve springs to match your cam and screw-in rocker studs. After all that, these heads will flow quite well. Alternatively, you could always buy World Castings S/R Torquer 305 heads and port them. The rest of the stuff is included.

Your engine should be a lot more powerful by now, but if you still want more out of it, take a look at the intake and ignition. As far as intakes go, I hear Weiand Action+ or the GMPP Quadrajet intake manifold are both good choices. Don't bother with the Edelbrock Performer intake though... it's not much, if at all, better than the stock intake. Looking at ignition, you'll want to pick up an aftermarket control module and coil. The stock ones are fine for a stock LG4, but are quite weak and failure prone when the engine is beefed up. MSD and Accel both good choices for these parts. Quality plug wires don't hurt either (8.8mm wires should work great). As far as spark plugs, just stick with the regular AC Delcos... platinum and multi-electrode plugs weren't designed based on our HEI style ignition and therefore offer no benefit.

Besides adding nitrous, that's pretty much as far as the average car enthusiast is going to go with the LG4. Any other modifications besides these can get tricky or expensive.

That said, there are still lots of things that you will need to do to take advantage of your engine's newfound power. You'll definately want a higher stall torque converter to take advantage of your new cam's powerband. A posi unit for your rear end is essential to have if you don't already have one, and lower gears (higher numerically) will improve your acceleration from a stop immensely... although it will lower gas milage and top speed slightly.

Your chassis is next up on the list (should actually be the first, but since you asked about "more power" I put it below). A hard tops' chassis should hold up relatively well even without mods, but T-Tops are prone to cracking at the sail panels from flex caused by the higher torque of the engine--to be fair, I've even heard of cracks being made with the engine completely stock. To combat this, you'll want subframe connectors at the very least. A steering brace and a strut tower brace would be even better, but not necessarily required. However, SFCs are a must.

Chances are the suspension in your car is probably garbage, with the exception of perhaps sway bars (if you have large ones). The rest of the suspension is weak and needs replacement. Plan on buying high performance struts/shocks, springs, lower control arms & relocation brackets, a panhard bar and a torque arm if you want to put any of that power to the ground. An aluminum driveshaft would free up some weight and remove high speed vibration as well.

Now that we've talked about what will make your engine more powerful, let's talk about what will NOT:

-An aftermarket carb. The quadrajet flows up to 600CFM when in stock form! That's more than enough for your 305... and it can be tuned to flow even more. Not to mention that if you do get a different carb, you will have to change the distributor as well.
-Plugging the EGR. Some people falsely believe that the EGR system hinders performance, when in actuality it could be helping it! The EGR is intended to reduce combustion chamber temperatures which has the side benefit of allowing the ECM to advance the timing further than it normally could.
-Removing emissions equipment.If you're going to be ripping out emissions stuff, make sure you know exactly what you're doing and why. The only two systems I can think of that can be taken out without any adverse effects are the A.I.R. injection system and the EFE system. Everything else pretty much serves a purpose... emissions related or not.

I commend you if you're still reading this far, because this has taken me more than an hour to type out. I'm almost done though.

Finally, there's some stuff I should have mentioned before any of this but I forgot to put it in the beginning. The very FIRST thing you should do to your car is give it a complete tuneup. I can't emphasize that enough. When you do a full tuneup on your engine, you pretty much return it to the way it was when it rolled off the showroom floor. If you take a beater with old plugs, wires, oil, coolant and the like and try to make it faster, you'll be left scratching your head as to why your car isn't making more power after spending lots of money and time on parts and labor. Do a tuneup to avoid all that.

As far as oil goes, I won't tell you what oil to buy or how to change your oil, but I will tell you what I do to my own car based on my experience and research. I only use Mobil 1 synthetic 10W-30 in my car. Without going into detail, synthetic oil is in every way better than conventional oil. It breaks down much slower than "dino" oil, it has better heat resistance and it works as a cleaning agent to remove old sludge and carbon that has built up from the breakdown of dino oil in the engine. I use Mobil 1 for the convience and price, but there are plenty of other synthetics out there as well. I try to use the AC Delco PF35L oil filter with my car, but if it's out of stock I stick with the PF1218. Both of them flow well and filter plenty of dirt.

Tuning the carb is something a tad different than everything else I've discussed. It doesn't really fit into the "make-more-power parts" discussion mentioned ealier but it doesn't belong in a general tuneup and maintenence discussion all that well either. Fortunately, it's not too hard to do... even for a novice. Instead of typing the whole procedure out, I'll just give you the link to a tech article on how to do it:

http://www.thirdgen.org/newdesign/tech/quadrajet.shtml

After ALLLLLL of this, you should have one hell of a car which will be plenty capable of low- to mid-14s in the quarter without any power adders. Add a 75-100 shot and you've got a 13 second car (stock LS1 territory).

Anyway, good luck and have fun with your car... whatever you decide to do with it.

Last edited by Nate86; Oct 3, 2004 at 09:12 PM.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
David Dempsey
New Member Introduction
5
Mar 12, 2016 12:42 AM
68camaroboltz
Fuel and Ignition
2
Oct 5, 2015 01:46 PM
Tarizza
3rd Gen / L98 Engine Tech
2
Sep 20, 2015 03:26 PM
gonzo275rltw
LT1 Based Engine Tech
4
Sep 5, 2015 06:26 PM
gonzo275rltw
LS1 Based Engine Tech
2
Sep 5, 2015 06:24 PM




All times are GMT -5. The time now is 06:55 PM.