Hey guys! Ok, I have a 1987 Pontiac Grand Prix LE...I know, I know its not a third gen. however when I bought this I was looking for one. I just couldn't pass this one up. It had never seen snow and always garaged and only 30000 miles! Now I used to be a ford guy until I decided I couldn't stand the super high maintenance of a supercoupe So I'm finding myself a bit lost. I know very little about the 305. My Pontiac has the LG4 roller motor, and I am quite amazed the low end torque isn't too bad. However I would like some more power out of it. I have no plans to go to a 350 just yet b/c the motor is just like new. I am going to do the exhaust this winter (ie: headers etc). should I do the cam next? and if I do this, will Comp cams xe256 work with this motor being that its a roller motor with a CCC quad? I may be going about this all wrong...please let me know. I would be very greatful!

 

first off let me say
with that out of the way, your question is just in general of all cars, what can i do to make it faster? the internet has been around a while there is tons of info on this. and you are right this is a thirdgen site, but it does not prohibit you from search through the forum posts, but it makes it easier for other people searching to not have to see a post that is pointless.

 

I'm sorry, I was not my intention to inconvenience anyone. For me part of being a car enthusiast means talking to other dudes about things that worked well for them for example or get more personalzied answers based on my questions that I may have about their perticular setups and from there, decide what is right for me. Not to mention talking to other guys about their rides, having fun and making friends. I'm sorry but I don't agree with what you wrote in any way.

 

Your statement is not without merit, but I don't see too much wrong with what he said. Take a look at what is on this board and the carb board. They both have enough reading material to keep you busy for hours on end. Setups, dyno's, specs, results, time slips, head flow numbers and things like that. When you have done a little research, give us a more technical question. We will gladly answer it if we can.

That being said, I built a strong 305 using mostly stock GM components. 265 RWHP/320 RWTQ

 

you didnt see my point.. this info has already been covered, with a quick search on these boards, you will find all the info you need about your setup, without having to wait for people to reply back and such, if you want to make some friends here, you should post over in the regional boards. im not trying to be rude in anyway, just trying to help you find the info you need. no one has replied to this post because it has been covered before.

 

An exhaust change will help a lot. Even if it has the LG4, which was considered high output for that car (did I just say that? lol), the exhaust is only a single and if I remember right, its 2.25". Just replacing from the manifolds back with 2.5" Y and a 3" catback with a different muffler, larger cat (if you intend to keep one), and dual 3" out the back (just personal preference, a single will work fine) will make a big difference. Probably doing headers at the same time will be beneficial. The other item would be the cam, LG4 cams are tiny. It also probably has a 2.29 or 2.41 gear in the back, a very low stall converter, and a really soft shift... so just keep in mind the entire drivetrain was never intended for performance.

 

H.O.? lol...that is funny, I guess that would depend on ones definition of H.O! That aside thanks for the information Madmax. Now I have been reading some forums and have found that some guys say use compcams xe262 and some say xe256. Can either of these be used w/o changing much else in the valve train or are there other things I should consider like valve springs and such? What is a better cam for an everyday summer cruiser?
I agree with you on the exhaust setup 100%. It would compliment the motor rather nicely.

 

With stock heads, I'd say go with the xe256h. You will need to get better valve springs and a new set of lifters. Change the timing chain too.

Here's the whole kit at Summit for $350.

COMP Cams Xtreme Energy Cam and Lifter Kits: CCA-K12-256-4 - summitracing.com

 

Whoa, ho, cruiser granny car! I like it!
Buddy of mine had a supercoupe in highschool, torque peak was at like 1800RPM, that thing was a beast. It'd roast the tires like nothing, and it's a V6!

Anyway, all good info here. The thing is, that car is probably more condusive to dual exhaust then the 3rd gens, so I might recommend that, dual 2.5" with an X pipe or something.
I don't imagine there's a forum for that kind of car out there eh?

With the overdrive, and the sleepy gears, it'll probably have a theoretical top speed of like 300mph or something. 3.08 or 3.23 with the overdrive trans is still quite bearable on the highway (for a cruiser car, people here go for 3.73's usually...), and would give you more grunt. Maybe just use a spacer, since you probably aren't needing a posi unit right?

I thought part of the definition of LG4 was that it was flat tappet. If you're sure it's a roller, then look at roller cams. I think it's a flat tappet, so i'd highly recommend that cam madmax suggested, the xe256.

A dual snorkle air cleaner would also help.

 

Oh... I didn't read that you think it's a roller cam engine. I agree with Sonix, I think the LG4 is a flat tappet engine.

If the car still has the original engine, you can decode the VIN to find out for sure which model you have.

If you do have a roller engine, you can re-use the old lifters, but not so with a flat tappet.

 

oh yea, hehehe, ever do the spark plugs on the supercoupe? hahahaha!

 

Yeah I have changed the plugs on my SC...lets just say I had anger issues that day Sonix! Part of me really doesn't want to sell it b/c it is a fun car to drive..however the Grand Prix is such a nice car too, I love it and its good to back at GM needless to say.
Anyways, yes I am 100% sure its the LG4, as I found some sort of assembly option list sheet under the carpet when I was installing wiring for speakers...it list everything for options that went into the car. Kinda cool huh?
I was also under the impression that the engines that had the center bolt valve covers were the roller motors..I could be wrong, oh and it is a '87 and is that not the first year of roller motors?

Am I just waisting my time with a 305? or should I just get a 350 and be done with it? I guess I'm somewhat concerned about mileage in some sence. I have heard that a well tuned mild 350 will get just as good as a 305...is this true? And whats this I hear about 305's cracking down the middle? Why is that? Holy crap my questions are kinda everywere tonite guys...sorry 'bout that but I need to know! I only want to do this once.

 

305 blocks are every bit as tough as 350 blocks. It is the Ford 302 that you hear about cracking down the middle. That doesn't happen until somewhere around 500-600 HP on the 302 though. On a Chevy you will typically push the main caps out of the bottem of the pan before you hurt the block.

 

Duals isnt so easy, the trans crossmember isnt friendly to that sort of modification. Easier to just stay with a single.

 

he's talking about a Grand Prix actually, not a thirdgen. Perhaps those are easier to do dual exhaust on?

You're not wasting your time on the 305, just make sure to only add parts to it, that can be easily transferred over to a 350. Nothing "305 specific". Those parts are wasted when (not if) you eventually go to a 350. Hard to justify tossing a perfectly working 305 too. LG4 should be flat tappet, but I also thought it should have perimeter bolt valve covers as well.

Maybe someone else can chime in, but i'm pretty sure carbed motors got flat tappet cams. I don't think there were exceptions to that rule.

Yea, that ccc-carb will work fine on a 350, and give about the same mileage as the 305, while you're pussyfooting it around on the highway - the difference is felt when you stand on it...

 

I knew that, and the trans crossmember is an issue. You either need to replace it with an aftermarket piece of junk or run the pipe under it.

 

Thanks for the info guys..I think duals can be done no problem with an aftermarket crossmember, but I really like the Idea the exhaust being a 3" single to a Camaro style muffler tucked behind the axel and nice shinny duals out the back..It should be plenty for a 305. I've seen some g-bodys with true dual exhaust, and I always noticed mufflers hangining down from a distance. Its just not the look I'm going for.
I'm still convinced its a roller motor however......it also has the intake that has the bolts that go in on a different angle too now that I think about it, unlike say a '86 305 with the outer perimeter valve cover bolts.
I was so sure GM went to roller cams in all their small block motors in 87.
I know Olds put a roller cam in their 307 in 87, and thats a carbed motor. I'll do some more searching see what I come up with...I think this is something that I need to know before I start buying parts ( that are not 305 specific, makes sence and dually noted )

 

SEARCH!!!

 

In 1987 the LG4 was a roller block. I have a roller cam, one piece rear seal, and center bolt heads on my LG4.

 

So what's the difference between a 1987 LG4 and a 1987 LB9?

 

My LG4 has a CCC-Qjet sitting on top of it

 

So the LG4 has a Carb, and obviously a different intake manifold, and I suspect a different exhaust manifold too. Is the Cam the same one as in an LB9?

 

Carb and intake, check

Exhaust manifolds are the same as the L03

Cam is the same peanut roller grind that came in the 1987 up LB9 AND the L03

Heads can be either the 081s or the 187s, pull a valve cover to find out. You would be suprised what you can find 187s swirlies on. I have even found 187s and 193s on STOCK non-touched Marine engines.