87WS6

iTrader: (1)

This is a mixed TPI/Carb/Engine thread and I couldn't find the exact answers I was looking for using the search function. What I did find leads me to believe that my idea will work, but I'd like to verify it before I start tearing everything apart.

I've got a 1985 Trans Am that I'm restoring right now. The engine sat for a long time and what I drained from the engine wasn't oil anymore. It looked like water and then snot which I know isn't great. In short the LB9 in that car probably needs to be rebuilt, but I won't waste money on that. I've already got a Vortec 4 bolt-main block I'm going to rebuild and drop in that car. I'll be retaining TPI for that, opting probably for a speed density setup on a 383 stroker. Anyway I'm getting off track.

I've also got a 1987 Trans Am that has the original LG4 in it which is basically going to be my daily driver for a little while. Even with fresh tune, plugs, plug wires, distributor, coil, RPM Performer Intake manifold, and a bigger carb, I'm not happy with the performance. Until I got this car I'd always driven TPI cars so the LG4 just feels like a dog to me. Its fine once you get going but it has nothing off the line. I miss the feeling of torque the LB9 and L98 engines provide and I'd like to get that under the hood of my daily driver. As it so happens I've got plenty of donor parts from an 87 TPI car that I have laying around as well as stuff from my 1985 Trans Am which I won't be reusing.

The 1987 Trans Am with the LG4 as I understand it uses a hydraulic roller camshaft just like the TPI engines do. I've got a cam and heads from the 1985 TPI car. I've got the intake manifold from both a 1987 and a 1985 TPI car. I realize the intake manifold bolt pattern of the 1985 heads is different than that of the 1987. I think I can install the 1985 heads and intake manifold on the LG4 and install the LB9 cam from the 1985 car in it as well. Or am I off base here? Are there other differences besides the heads and cam between the 1987 LG4 and LB9 engines that I am not aware of? I'm I correct in thinking I can just swap the 1987 LG4 heads and cam with those from the donor 1985 LB9 engine? What am I missing?

Atilla the Fun

First, the '85 LB9 wasn't a roller cam. But other than that, you can do it as you say. It'd be better to leave the 081 heads on the '87 LG4, and find a matching lower intake, even if you have to buy an aftermarket upgrade.
The induction isn't the main difference in how they launch. The '85 LB9 came with a 3.23:1 rear gear in the Camaro, and a 3.27:1 in the Pontiac. the '87 TPI 350 also came with 3.27:1, while the '87 LG4 / auto came with lame 2.73:1. Also, the torque converters are different.
If the launch is your main concern, then start with a looser converter. The B&M TorkMaster 2400 is a virtual steal, at under $260 from Summit or Jegs. It retains the lockup, so your highway mpg won't suffer.

87WS6

iTrader: (1)

Interesting. I thought all LB9 engines used roller cams. I was also under the impression that the LB9 heads were vastly superior to the LG4 heads. I have an 87 TPI intake manifold so I'm set there. In fact I've got almost everything I need from another 87 car so putting everything into my car should be easy enough. I just wanted to get the most out of my LG4. I didn't want a crappy cam or heads hold me back more than is necessary. Not if I had better parts laying around. My comments about the induction were more based on their respective HP and TQ numbers. Though my LG4 isn't totally stock, it pales in comparison to how my old 1987 car's LB9 performed with the same 2.73 gears and rear end. Essentially the 87 car I have now is virtually identical in options and configuration to my old 87 but the one I have now has an LG4 engine instead of an LB9 engine. That really is basically the only difference between the two but their performance is night and day from each other.

Also, I believe I've got an aftermarket torque converter in my LG4 car. I am not certain of that, but that is my understanding from the guy I purchased the car from. But yeah the rear end gears in the 1987 LG4 car are lame 2.73's. That's for sure. I wasn't entirely sure what gear ratio I had going on in the 85 car. I had planned on moving the 85's disc brake rear end to the LG4 car anyway. I plan on going with 4th generation rear in the 85. The 85 has 26 spline axles and the 4th gens have 28 spline axles and stronger gears which I was going to use as a budget alternative to going with a Moser 12-bolt to start in the 85.

I've also got some headers to throw into the 1987 car so I'll probably do that when I do the TPI swap.

Atilla the Fun

'87-up LB9 heads are superior to pre-'87 LG4 heads. But '87 LG4 heads are superior to pre-'87 LB9 heads. The best 305 heads are the centerbolt-valve-cover, non-swirl, casting-number-081 heads. Roller lifters first appeared in the '82 6.2L diesel, then ford added them to the Mustang for '85, and Olds to their 307, but the passenger-car SBC V8s didn't get them until '87, and the trucks for '96, so there's no way the '85 or '86 LB9s could have come with roller lifters.
Next, most "re-stalled" (loosened) torque converters give a worse launch than stock, particularly on a stock engine. You have to choose carefully.

87WS6

iTrader: (1)

Gotcha.

Not sure what Ford has to do with anything.

five7kid

iTrader: (14)

Just a history lesson about the factory use of roller lifters.

87WS6

iTrader: (1)

Ahh. OK. I appreciate the information.

Zepher

iTrader: (1)

you know what is strange, my 86 Trans Am LG4 5 speed with 3.27 gears, Edelbrock RPM intake, 1406 carb, open element Air Cleaner with K&N was faster than my 88 Formula LB9 5 speed with 3.42 and Holley Stealthram in the 1/4 mile.
14.9 @ 92mph for the LG4
15.2@91 for the LB9. (this has the 195HP motor since it was an Auto)
My Formula also dyno'd 195RWHP and 273RWTQ.

But here is a video of my 86 Trans Am when I converted the topend to TPI and had a larger cam,
http://www.youtube.com/watch?v=nGTLJ9nS2aI

and a little race,
http://www.youtube.com/watch?v=lLBfKEsgFmo

Guest

On Firebirds the 3.27 was actually optional in 85 and 86. The 3.23 may have been optional on the Camaro as well, although I'm not certain. My 85 had the 2.77 and it was fine off the line, no complaints about power of that setup. The 86, even with the optional 3.27, was a turd no matter what RPM it was at. Was better once I got rid of that no lift no duration aka 'LA' aka Peanut cam.

If you want to use the earlier intake on the later heads, you dont have to get a different base. You can modify the holes so it fits. That is an option for those who want to save some money on that swap... but since you have a later base, no need.

87WS6

iTrader: (1)

Well my LG4 isn't. Now the LB9 car I had previously wasn't normal. It performed much better than they normally did. Though I'm not sure why. It appeared to be stock inside and out. Though I never made it into the bottom end of the engine while working on her.

exedore

Hi 87WS6. Sorry if this is a little late, but I've only just read your post. Check out this link http://www.3rdgenformula.com/87/technical.htm . It has been invaluable to me. It shows that the 87 LG4 and LB9 have identical heads. Notice that the LB9 has a much higher compression ratio. 9.3:1 compared to the LG4’s 8.6:1. This is because the pistons of the LG4 are dished while the LB9’s are flat topped. That is where the majority of the power comes from.

If you want really good heads for a 305 you have 2 options, neither of which is too expensive. An aluminum option is the Trick Flow® Super 23® 175 Cylinder Heads for Small Block Chevrolet. These come in various configurations to meet your specific needs (maximum valve lift amounts, spring sizes and weights as well as early and late model intake bolt configuration) and have 56cc chambers which will boost your compression a touch. If you want the durability of cast iron go with World Products 042650-1 - World Products S/R Cylinder Heads (these match up with center bolt of the 1976 to 1986 intakes) or World Products 042750-1 - World Products S/R Cylinder Heads (these match up with 1987 to 1995 intakes). The World heads keep the stock 58cc chamber leaving your compression untouched. The only real difference between the two World Product heads is the angle of the middle bolts of the intake. I know of many folks that just drill out the holes as necessary to make older intakes fit on the newer heads.

Hope this helps.

87WS6

iTrader: (1)

That would have helped back then. I ended up selling that car and getting a different one. Now I've got a 1992 Formula Firebird with the LB9 engine and the T5 transmission. I'm currently in the process of building a 383 to drop in it.

Atilla the Fun

My reference info on the 'birds is vague, but in the Camaro, the fact is that ALL '85 LB9 had 3.23:1.

Doom86

Did they switch back to dish pistons on the LG4 in 87? I've torn down 2 different 86 LG4's and both had flattops and knock sensors.

Atilla the Fun

I've torn down an early '86 L69 and found flat-tops, but I've done at least a half-dozen '86 LG4s that were unmodified that were dished. ALL '87-up 305s were dished pistons.

five7kid

iTrader: (14)

Interesting. My unmodified '86 LG4 was flat top with reliefs.

87WS6

iTrader: (1)

I'm not sure what my 87 LG4 had piston wise. I never took it that far apart.

Zepher

iTrader: (1)

My 86 LG4 was flat top too.

Atilla the Fun

This is rediculous, but what if F-car LG4s had different pistons than Caprices and C-10s?

Doom86

AFAIK they started using flat tops in 86' in the LG4 and added a knock sensor. That's for F-body don't know about other cars or trucks.

Atilla the Fun

Flat tops first appeared in the '83 cross-fire and the '83.5 L69, ALL L69s had flat tops. Including Monte Carlo SS.

dpalacio1

What cam grind and exhaust did you use on there? Sounds nice! I have an 87 Trans Am 305, 5 speed, Carb, All stock, that I wanna change the cam out in ... I am also the original owner of the car ...