my 85 trans ams motor just went south last night and i knew it was on its way out but i have a 89 formula parts car with a LO3 305 tbi in it and i was wondering if i could just swap my 4 bbl carb and intake off my old motor and put it in place of the tbi please help!


thank you very much!

nick

 

Yes you can. I would really express my feelings against you using that l03 you should get a 350. If it all you got then yes it will work fine. Let me know if you have any more questions.

 

What went wrong with your LG4?

If it's bottom end only, then it would be highly advisable to just use the LO3 shortblock. For 2 reasons: 1) The intake mount bolt pattern is slightly different on the LO3 - not a big thing, but a hassle; 2) LO3 swirlport heads aren't very good.

If you just want something that runs, then yes, you can put the LO3 under the LG4 intake/carb/etc. The flexplate/flywheel is also different, so you'll have to use the one that goes with the engine.

 

awesome i was a lil afraid that it wouldnt bolt up but yeah thats all i got to work with for right now and the engine and trans are gonna be swapped b/c my 3rd and 4th clutch packs are smoked in the trans as well lol...i bought the car that way but for a rust free third gen i cant complain and its well worth it...but i plan on buliding a 383 or a 400 in the future and the LO3 is just a temp motor.

fun! fun! ill keep ya posted with pics and such!


nick

 

You never did mention what happen to the LG4

 

well it was knockin like crazy and well i still started it and took it just to the corner store for beer once in a while and i noticed it started runnin a lil rough and stallin out and then it stalled out 2 times last night at the gas station and just quit...and then when i went to go turn the key the 3rd time it just seemed like it was froze so i think thats what happend

 

I think as cheap as head gaskets are you should just use the L03 shortblock and re-use the LG4 heads. Those TBI heads just suck so bad...

Plus it's easier than grinding your intake holes for the four middle bolts to line up properly with the wrong intake to head combo...

 

I'm not sure which is more work, swapping heads or elongating intake manifold mount bolt holes. It's probably the former, but torquing head bolts is more straight forward.

 

so your saying if i swap the heads out i will have no problem bolting up my carb and intake

 

Yep... and the LG4 heads flow better.

 

my buddy said as long as the water jackets line up on the intake he wont have a problem but ill let him know about the head swap on monday

 

Trust us, the coolant passages will line up fine. The heads are interchangable, and the blocks are the same.

 

i trust you guys to the fullest thats why i been on this site with all three of the third gens i owned

 

even though it is annoying to have to enlarge those holes i still swapped my heads knowing if i did i would have to do it but if left the heads i wouldnt have to
trust me its worth it and it will only take an hour

 

Just FYI, the swirl ports flow better on the exhaust side than the LG4 heads do. The exhaust is where you gain the most in porting. The factory intake port in a TBI head can support around 300 flywheel HP.

I would personally run with the swirl ports.

 

Umm... no. This has been debated alot in the past. The swirlies ALWAYS come out short. If he was staying TBI it would work well in conjunction with the swirlies. Since he wants a carb, the 416's will be a MUCH better choice.

300 hp from a factory port TBI? I have had 416's much higher, and ask Sonix about 416's, he swears by them.

 

Debate it all you want, facts are facts. Take a look at Dewey316's, DynoDon, and my track/dyno numbers. Also another member ran a swirly headed L05 with a mild cam into the 13s.

Dewey316s car performed much better at all rpm's under 4,500 rpm with the swirlies than PORTED 416s.

The 416s are the ones that ALWAYS come up short.

 

Where is the proof? Show me please.

 

Lo-tec was the one that ran a 13.6 in his camaro with the cammed L05.

Here you go, Dewey's 305 had a Ultradyne roller camshaft in it with stock heads, headers, exhaust, and a weiand 7525 single plane intake manifold. Open element 14x3" air cleaner.Cam, UltraDyne 272/282(adv) 206/216 @.050 .447 .447 112 LSA (106 CL

Here is the thread for Dewey316s 187-416 swap. His built up 305 did not make signifigantly more power from the ported 416s until over 4,500 rpm and lost below 4,200.

https://www.thirdgen.org/forums/tbi/...light=TBI+dyno

Attached is the dyno chart.

EDIT- Want further proof, the 1987 and 1988 LG4/L03 was the same engine except for the heads and the intake setup. The TBI engine had a more restrictive intake manifold, with a smaller CFM throttle body, and made more HP/TQ than the LG4 did.

1987 LG4 = 165HP @ 4,400, 245 TQ @ 2,800
1988 L03 = 170HP @ 4,000, 255 TQ @ 2,400

 

LOL, look at post #123 on that thread, your boy "dewey" just proved you wrong.

 

Proved wrong, HA. Looks like Ken just proved you wrong on #127.

He never has given track numbers with the 416s, but the HP/TQ numbers don't look promising for the ported 416s. We drive on the street and track, not the dyno.

He gave up more like 20 ft/lbs below 3,000 rpm with the ported 416s. Keep in mind this is with a cam, headers, exhaust, and a single plane intake manifold. On a stock engine it won't even give a HP benifit. Been there, done that.

 

So let me get this straight.

You said look at one guys setup, I did, and you were proved wrong. So you tell me to look at another guys setup instead.

You said that the dyno gains mean nothing, and only track times matter.

So... We are talking about horsepower/ torque here. You talk about track then you bring in the factors of suspensions, tires, and drivers abilities.
Which all would make your point flawed.

Dyno proof is solid proof. Track proves that someone has a better car. Horsepower and torque is one of many variables.

 

I want some of whatever you are on if you think I was proved wrong. I stated under 4,500 where the original posters car is going to spend 95% of its life, the swirl ports are a better choice than the 416s. Which they are, proven on a dyno to be so.

Its dyno proof and its the same setup (DEWEY316s car). Exactly the same except the heads swapped. Its not even a straight comparison of stock 187s vs. stock 416s. The 416s in his case had been pretty heavily ported. It is just not worth the effort to swap from stock 187s to stock 416s on a stock cammed 305, PERIOD, end of story. I've done it and gained nothing.

By dyno gains, I mean peak HP gains, you know the 16-18 HP @ 5,000+ rpm. That just does not move the car as well as the 10-20 ft/lbs he gave up across the board under 4,000 rpm.

Post 127 is Ken talking about Dewey316s car.

Quite honestly you better tell my 350 in the van that it is supposed to kill over at 3,500. I would not think twice of running swirl ports on a street driven 305. This is how my swirly headed 350 ran (0-55 MPH)with nothing more than a ZZ4 roller cam, headers, and chip tuning. Stock TBI intake and stock TBI unit with ultimate TBI mods. I've got 3.08 gears and 29" tall tires lugging around a 5,400 lbs G-series van. I run vortecs now, but I shift at 6,500 with a larger cam than the ZZ4 cam.

http://youtube.com/watch?v=koWaPeAu3hg

 

To save me time from reading that silly thread again, before I go any further... what induction system was the comparison using? Carb or TBI?

 

TBI but it really does not matter. The TBI meters fuel a little better than the carb does.

 

I think it makes the world of difference. What is the standard CFM of TBI?

What I am getting at is that the swirlies were designed only for TBI, so obviously TBI will work well.

The LG4 came with the rochester carb which can be easily upgraded, more intakes available etc.

You put a TBI on 416's it will suffer. Put an Rochester on swirlies it will suffer. Due to aftermarket and what the original author wants anyways, 416's will be a much better choice. Besides, swirlies have what 76cc chambers?

 

Standard TBI is about 460-470 CFM @ 1.5 in/hg, if you convert it from the 590 CFM @ 28 in/h20 that a stock TBI will flow.

The swirlies were not designed just for TBI, in fact the LG4 ran with them in 1988 B-body cars.

The 416s were also put on TPI cars, so there goes your carb designed theory.

TBI 187 swirl ports are 56cc chambers, 193 casting 350 heads are 65cc chambers.

The 187s are still a better choice, any intake that will fit pre 87 heads will fit the swirlies or even later TPI heads for that matter, by elongating the 4 center bolt holes.

 

How so? How can you compare TPI and Carb design. I am comparing TBI and carb, and from your previous posts you believe TBI is superior. You can convert a standard rochester to 800-900 CFM So with that said, You should try testing out your head theory with the carbs instead of TBI. I am sure you will be surprised. The 416's will come out on top with the carbs.

You showed me TBI proof. As much as it hurts you to believe that TBI and carbs are very similar, they are much different.

A good example is .... put a high duration cam in a stock TPI and the gains are minimum.... put the same cam in a HSR and the gains are much much better.

Those swirlies are perfect mates for the TBI it is like their soul mates. Put anything better on a TBI like 416's and they do not match therefore the combination loses effectiveness. Just like the cam analogy.

 

I've got 366 RWHP from my TBI 350 with Vortec heads and the custom ground roller cam I am running. I have layed down 279 RWHP with a stock GM TBI intake and stock smallblock TBI unit. The TBI is not the restriction, PERIOD, end of story.

The 305 is lucky to pull 450 CFM @ 5,500 rpm.

 

I would like to see that same setup with a carb. I bet the power would be much more.

 

I bet it wouldn't be. I am seeing 97-98 KPA on the MAP sensor at 5,500-6,000 rpm and WOT on a 99-101 KPA baro reading. That means that I have at most 1 in/hg of vacuum. The wideband is sitting at 12.4:1 and the MAF sensor is reading around 315 gms/sec of air flow. Please inform me as to why a carb would make better power. I have plenty of airflow left and plenty of injector duty cycle (70%).

 

Man, this is an argumentative thread guys. Stop the hate child!
Yea, the swirl port heads do provide better, *cough* SWIRL. Hence good low end torque. They have iddy bitty intake ports, which is part of that reason as well IIRC. Again the superior low end torque. Yes, low end means below 4500RPM. If you're only driving around town, low end torque makes things fun. Burning rubber at stop lights, etc. Driving a truck, big heavy caprice, van etc.

A light(ish) sports car (yea, I think these 3rd gens are sports cars) do well revving higher. I think in OUR APPLICATION (3rd gens) some ported 416's would beat out ported 187s at the dragstrip. I'm assuming a decent sized cam with some duration, and a 3000-6000RPM powerband sorta deal. "hot street" sorta thing. My low end may suffer a bit, compared to what it would be if I had used swirl ports, but the feeling of going 5000RPM and powershifting it into 3rd and chirping the 275s out back is kinda cool.

If I was using an L05 in a caprice or Delta 88, which I one day will do, I like the floaty boat type cars, i'd probably use swirl ports. Actually probably Vortecs. But low end torque and highway gears are a good match to that type of vehicle. I don't think they are well suited to the 3rd gens, unless they aren't going to be raced much. I can't really keep a straight face when someone tells me they "aren't planning on racing it". Yea, you bought the V8 sports car to drive to the corner store to get milk and drive to church right? mmm hmm.

I don't know anything about TBI injection, but FI in general scares me. Too many variables to keep track of, and expensive sensors. I think TBI has too many hassles to be worth it, since it's not THAT much better than a carb. I wouldn't go out of my way to upgrade to it. If one was going to upgrade a carb to FI, i'd want port injection, if I was going to the trouble of tuning it with a laptop and all - i'd want all the benefits. Also the way the CFM is measured with TBI throws me off, and lends itself to people miscalculating it. But if Fast355 can crank out that much power with a seemingly small TBI setup, there must be something written inbetween the lines eh?

My cousin told me the early '90's Chev Truck SS, with the 454 SS was rated at a scalding 225HP (or something shamefully abysmal) due mostly to the embarrassing TBI setup. But I only know that, so I shouldn't judge.
But then again, this thread wasn't an induction post, so I should digress with my various misinformation...

I think the original poster should stick with his carb, since his car has the ECM setup for that already. No need to swap in all the TBI stuff, for a minimal gain. Since it's a seemingly temporary swap anyway, just use the LO3 shortblock (cough, maybe with a new roller cam), and the 416 heads and carb intake and Q-jet. Then down the line a nice 350 roller block can be swapped in, preferably while keeping the cam bought before....

 

very intresting stuff guys but im gettin 2 sides here... swirlies or no swirlies that is the question

 

If you're gonna be hard on it, go with your LG4 heads, please. They are really better for the guy doing things in stages and on a budget, as you obviously are. Those LG4 heads can be made to work extremely well, they have lots of "meat" in them for port work and such, and apparently work great when you upgrade to a 350 later on. Add to that the fact that all of the 86 and older style carburetor intakes bolt right on and I'd say you have yourself a winner.

 

I still disagree, save the $50.00 on head gaskets and buy yourself a used LT1 cam, it will make alot more difference than switching to LG4 416 heads. The 187s can be ported to flow very well too, especially the exhaust side. Making power is not all about flow. You need swirl and tumble as well to get the fuel burning efficiently.

So far I see dyno proof proving the stock 187s can handle ported 416s below 4,500 rpm, but nothing to prove otherwise.

 

Isn't it also true that the 416s have the less efficient 70s chamber design that chevy stopped using on all their heads in 1987?

 

No, they don't quite have the bathtub style chamber. Most obviously the 416's had a smaller chamber, 58cc's. They did go to the 081 style head in 1987ish, but that's the exact same chamber. GM went to a more efficient fast burn with the vortecs (and the swirls for that matter). But it wasn't an "across the board in one year" sorta thing.

 

Not that it pertains to this discussion comparing 416s t0 187s, but are you saying that the 416s and the 081s have the exact same chamber? Here's two threads that claim to have pictures of 081 heads. The chambers do not resemble the 416s I'm familiar with. Would you agree? Or have I misread something?

https://www.thirdgen.org/forums/engi...?highlight=081

https://www.thirdgen.org/forums/tech...?highlight=081

 

I think my point is being lost.

While the TBI heads can be made to run well below 4500 rpms on a warmed over 305, how do they do on an extremely warm 350?

The proof is in the pudding for the LG4 heads because on a budget they can be moved to the larger displacement small blocks and still preserve the budget theme while accepting more mods than the TBI heads can handle in the future.

My view is for the long run. Isn't there a 350 or budget 383 engine in the future SOMEWHERE down the line or are you a dedicated 305 man?

THAT is the question.

 

I've already done that testing for you.

https://www.thirdgen.org/forums/tbi/...ght=garage+193

Hot Rod magazine also did some testing for you, the 3/4 350 that they built (their 4.3 V6 that they made 300 HP from) had swirl ports. It pulled well all the way up to over 6,000 rpm with only 224/224* @ .050 of cam.

 

i plan on going with a 383 or stroking out a 400 but i want about 500 N/A streetable hp.

 

You will be able to do more with the 416's if you want to just use what you have then use 416's, if you want to upgrade later that is always an option.

 

Chesterfield - i've only heard talk that the 081's had a "very similar" chamber as 416's - I can't honestly say i've held them in hand.
But those two threads showed pics of the chambers of 081's, and they looked identical to the 416's I used.

1985_T/A - Well you've got lots of info here to chew on. Whichever heads you use, and heck, the rest of that motor - won't have any transferable parts to a 500HP small block. So don't bother buying anything that you plan on reusing. Many people from all kinds of sources despise the swirl port heads, Fast355 and a few others on this board tout them as being good. There are a few magazine articles on them performing well (not too many though right?). You can take that as you would like, but they don't have a large following in the aftermarket community. I've never though Fast355 as a liar, but he seems to get results that very few people can follow, or are willing to follow - for whatever reason. :shrug: Your call I guess, this argument can go on forever...

 

Are you implying that he should build a 500hp 383 or 400 with 416's?

Guys i think we are getting a little carried away here. He isnt looking for a 400hp monster here, in fact he isnt even planning on porting the heads. I have to agree with fast355 here and say that he would gain a lot more by geting a used lt1 cam than he would by swapping the heads.

 

Sonix,
Here's what I'm talking about. The 081 left, the 416 right. See the spark plug boss that optimizes the spark plug location on the 081? This is what the vortecs, swirlports and fastburn have adopted. The 416 is visually the same as the heads found on 70s LG3 305s. I don't know if it means much, but the 416s use the same casting mark as the 70s head. It may have been innacurate for me to say that Chevy stopped using the older style on all their heads in 1987.
You say many people dispise swirlports. That seems a bit irrational. Any of them ever port them and post results?

 

Well i'll be damned, now you have me doubting myself. I could have sworn my heads have the square boss sticking out with the spark plug like that, (similar to 081's) ??

Perhaps irrational, maybe from many times being burned from poor results? I can't speak for the masses, I just know that it's rather uncommon to hear of someone porting swirl port heads - not just on this forum either, I remember reading some threads on fullsizechevy.com and was hearing the same type of negative opinions on swirlports. Maybe it's just wrong old negative stereotypes that keep getting passed around, who knows. I'm just pointing out that it's very uncommon to port swirl port heads - they seem to have a very bad rap.

 

I found the 416 pic linked in this thread. I can't say positively that any of these pics are correct. I seem to recall it being said that 081s are the centerbolt version of 416s. If these pics are correct I don't see the similarity. The pics of the ports don't look all too similar either.

https://www.thirdgen.org/forums/tech...highlight=416s

 

Yea, that's exactly what i've heard as well, 081's are simply the centerbolt version of the 416 casting. Anyone on here have a set of both on hand to compare?? I'm starting to think you're on to something chesterfield (hey, I thought that was a canuck saying?), maybe they do have some distinct differences...

 

If I was aiming for 500 HP I would not use either heads. Since he only has two choices then in my opinion the better choice is the 416's

 

yup this is just a temp motor... im trying to build it to spank my dads new corvette