what's up...i have an 85 Trans am, LG4 with a 5 speed. i'm the 3rd owner so i have now idea what internal mods the engine has, but after taking a few people for a ride in the car...they tell me it's not stock at all. for one the car has pulled up to 5500 rpm, i've been in other LG4 cars and valve float occured at around 4400 rpm. it does have the stock LG4 intake manifold however, and it totally runs outta breath after 4 grand, it also has weird looking green valve covers on it(i know our cars didn't come with green...silver and black i believe?). now my question is, could this be the original 305? it's pretty quick, i can hang with the earlier LT1 cars...i was thinking maybe it could be the GM goodwrench replacement 350, with the 305 intake and carb on there(which would be pretty bad right). because the car did have a few "GM Goodwrench" stickers on the windows and under the hood. can anyone help?? cause i don't wanna start modding the engine thinking it's an LG4 and later find out it's a 350. thanks a lot!

 

The only way you're going to find out is if you get the numbers off the block. Somebody could have swapped in the L69 305 or just did some mods to the LG4 to spice it up a bit.

 

yea thanks, i need to get a book with the casting numbers...it definetly sounds like a 305 at idle and low RPM, but when i get on it, it sounds pretty damn mean like a 350. i thought that may be cause of the poor intake, but who knows...have to get the numbers. thanks again

 

If you get the number, go to the link below:
http://www.mortec.com/castnum.htm

 

I am currently using the LG4 intake on my GM Goodwrench 350. I will tell you one thing though, there is no way my car can hang with an LT1. The stock cams in the Goodwrench are horrible, that's why I already have a new intake and am going to buy a cam that should put me right at 14 flat.

 

The LG4 and L69 intake manifolds were the same. Many have used them on 350s.

Stock, my LG4 would cut out at 5200 RPMs. I honestly don't know if the valves were floating or the ignition was the culprit - I did the ignition module at the same time as the other mods in the sig.

I do know that it will now rev to at least 6300 RPMs. Power drops off above 6000, though.

You really need casting #'s to determine if it's 305 or 350, though.

 

where exactly on the block are the numbers, I'm going to be junk yard hopping soon, any engine I want is about 120 bucks with accesorries. can someone post a pick with an arrow pointing to where I should look, thanks

 

Nice car man, How does it pull? would you say your at least in the 15 flat range right now? and at about what speed does the intake just fall on it's face, my car dies at about 95 or so, and 4th gear tops all the way out at about 110(this is why i think it's the stock 305, pretty sad) i'm going to the track sunday so i'll see what's up with mine...thanks again.

silentneko...if the motor is still in the car, i'd say just pull a valve cover off and look on the head and see if it's a 350 head or a 305 head(i haven't gotten around to doing this, but it wouldn't do me any good if the block was a 350 and the heads were from the LG4)and if the engine is out of the car i believe there is two castings on the back of the block...two on the passenger side and one on the driver side, maybe one in the front i'm not sure i could be wrong.

 

The only block no's i go by are on the driver side at the rear of the block ,right behind the head.I wouldn't go by head no's,people change heads all the time.I know the no's are hard to see when the motors in the car ,but it's the only way to be sure.I used a mirror to see them on my car because i couldn't get my head far enough to see them.As far as the intake goes,they pull well up to 5 grand or so,if your engine is more than alittle modded,(cam,exaust,converter,etc)you might do better with an aftermarket one rated for higher rpm play.See ya.

 

Things you should know about block hunting-

1- 55-67 Small blocks have small 2.30 journals, 68+ have 2.45 journals, and 70-80 400s have larger 2.60 journals to help the big stroke. A Micrometer is a good way to identify these.

2- 86+ have one piece rear main seals, so pre 86 cranks are incapatible.

3- Cream of the crop bow tie blocks have a HD in a chevy symbol on the right hand, passenger side. Buy this immediately if you see it!!! :hail:

4. The only way to see if you have a 4 bolt main block is cracking open the oil pan. Chevy factory 4 bolts are halh the strength of aftermarket 4 bolt mains.

Hope that helps!!!

 

Thanks, well I ran the car before the gear swap, cat-back and tune up, I pulled a 15.41 w/ a slipping tranny.

Now with the gears, cat-back, tune up and slightly better shifting tranny a horrible 15.32.

What happened was the cam in this motor sucks, and the power drops off @3500 rpms, which with these gears keeps me way out of my power range. So I'm ordering a new cam and I already have a new intake, I'll post the results when it's all done, should be late spring.

 

[. it does have the stock LG4 intake manifold however, and it [/QUOTE]

A friend of mine reused that intake for awhile when he put together his built 400 small block. It worked well with both a Q-jet and an edelbrock carb... Made much more torque with the q-jet though. The motor had a large cam, recond. stock chevy 400 heads, headers and a custom y-pipe hooked to the stock catback.

So as far as we can tell, the LG4 intake flowed pretty well, it didnt seem to hurt things at all even with bigger c.i.