Hey, i have been looking into swapping a lsx motor into my thirdgen. Unlike most i would like to swap the intake and run a carb on it. Since doing this i was considering using my 700r4 (built of course). This would be a budget build so i have been looking mainly at the lq4 6.0l engine because they seem to be had very cheap at local yards.

Now my first question is what is the deal with the crank length and adaptor situations on the lq4s?
Does the early 6.0's use a normal crank that can bolt up to a 700r4 without adaptors?

How much improvement is the higher compression of swapping heads verses the stock compression? This motor would get either the edelbrock rpm or victor intake with conversion box, engine swap longtubes, a better cam (like a 232/234 or something) and possibly 150 shot. I was thinking the lower compression would help with the nitrous on pump fuel...obvious its a way overkill but i dont really want to pull the bottom end apart or heads off, cause the last "budget rebuild" ended up costing a fortune.

I dont know much about the lsx motors but i am use to a "slightly" modified pontiac 400 so im guessing its not going to have the low end torque im use to but will have more high rpm pull.

 

IMHO, those two are incompatible.

But, your car, your money.

 

these engines were designed around EFI

 

budget build compared to the 11+k pontiac 400 sitting in the 78...

I just want to make a good running street car without blueprinting a whole motor like the last.

I dont want the high price tag of getting a wire harness, buying the overpriced fast parts, spending all the extra time making electronics work, and then tuning. Not saying im not capable... just a holley 4150 street hp is much cheaper...

 

No, it isn't, really.

LQ4 stock has what, 300+ net flywheel HP? Sell the truck intake manifold, get an LS1 intake (I sold my LQ4 intake for more than I got out of the LS1 intake). You'll need different fuel rails, and if you play your cards right, you can get them and TB with the intake manifold. Of course, and LS6 intake would be better, but still not all that expensive.

You're already planning headers and cam. Regardless of what induction you use, you're going to have to get f-body oil pan/pick-up and front accessories.

The LQ4 harness and PCM will still run the engine fine, although a custom tune would always make it run better. To get the carb running properly you'd need either wideband O2 and/or dyno sessions, so I'd still call that a wash.

400 HP with good manners, easy.

The Victor carb intake makes peaky power, not good for a good running "street car".

My advice would be to reconsider the trade-offs.

 

that is not entirely true...considering i would have to purchase the pcm and lq4 harness and then have the harness modified for a third gen. That would be some money there.
A wideband is not a necessity to tuning a carb as its not a necessity to retune the pcm for efi...its called reading the plugs. I have tuned carbs on a 4-gas analyzer before but its not a necessity.
I know the victor would be a peaky style, given by its single plane design. I was leaning more towards the performer rpm for street.

 

If you get an LQ4 without the harness and PCM, that would be rare (and wouldn't save you significant money).

Attempting to tune a carb by reading the plugs will never give you the driveability of EFI. Simply ain't gonna happen. We are talking a street car here, right?

(Don't forget I moderate the Carburetor forum, so it's not like I don't appreciate carbs.)

But, hey, it's your car and your money (did I say that already?).

 

in an attempt to expand upon what five7kid said...


There are certain things you need regardless of what induction method you choose. That would be the f-body oil pan and accessories.

Now the differences in carb vs fuel injection boil down to fuel delivery, intake, computer control, and tuning. Let's hit them one by one.

If you've got a TPI car now, you'll have to rework the system to deliver low pressure for a carb. I'm not terribly familiar with your options here, but my guess is that the best method is to replace the in tank fuel pump with a sending unit from a carbed car and run an external fuel pump & new fuel lines. If you choose to stay FI, then you slap a corvette regulator in-line near the tank and can keep your fuel system largely intact. If your car is carbed already, then the balance may shift to the other side for fuel delivery.

On to intake. A carbed intake & carb will cost you more than a used ls1 intake complete with rails, injectors & throttle body. Used LS1 stuff is very affordable. You might luck out and find a used carbed intake & carb, but chances are you'll still pay more.

Lastly is computer control. Even with a carb you need a stand-alone box to control ignition timing, and that's not cheap. If you're smart enough to modify a stock LQ4 or LS1 harness, it'll be cheaper than the stand-alone box for the carb. If you've got to pay somebody to modify one for you, it'll probably still be cheaper, but not by a lot.

For tuning, you can get close-ish on a carb doing it the old fashioned way, but the only way for modern drivability & manners out of a carb is to have it tuned by somebody using a wideband o2 sensor. Likewise, having an EFI system tuned for your specific application really should be considered a necessity. For tuning, total cost between carb & EFI will probably be a wash.

Overall, without running an inventory & getting actual prices, I'd expect an EFI installation to be less expensive and also will produce better results for a street car.

 

Wiring harnesses aren't really that expensive... for instance, my LQ4 came with the computer and harness, both of which I sold and bought an Fbody ECM and Fbody harness because the harness fits better than the truck one with Fbody accessories (which you're going to need anyways). So it's a no-brainer to get the correct harness.

I paid $200 for the wiring harness, sent it to a member of TGO to have it re-pinned, spent a relatively small amount of money there, and came out with an affordable, pre-modified plug and play harness for hundreds of dollars less than a Speartech or Painless harness. It's sitting in my car ready to start up on Saturday, all I had to do was connect the dots.

 

If you get your engine from LKQ, it won't include ANY of the harness, which they cut every wire about 1/2" from it's sensor or whatever, and the computer is another $90. Even so, staying injected is still way cheaper than all the stuff to convert to carburetion. And carbureted, you'll spend 20% more on fuel, your cylinders will wear 4 times as fast, and so on.

 

On the fuel side, a simple return style fuel pressure regulator would work to lower the pressure for a carb. On the efi wouldnt a ls1 fuel pump, fuel line conversion, and possibly a fpr also be needed? I will do a little more research on the efi side of things and consider that instead.

Does anyone know the answer to my question on the crank deal?

 

It doesn't matter if you get the short crank because if you use the truck 5.3 flexplate then you don't need the .400"-thick spacer. But if you use a 700R-4, you still need a 4L60E converter because the nub on the engine side is different.

 

wait a minute...first, which years had the different crank and what was different about it?
Would i be better off getting a 4l60e and converting it to full manual control?

also i found this for the oilpan... http://paceperformance.com/index.asp...&ProdID=245308

 

The early LQ4's with cast iron heads had the crank stick out a little longer like the '87-up SBC's (relative to the bellhousing mount). If you get one of those, the distance for the converter in the front pump is correct for a TH700 or 4L60E up through '97. The later years LQ4 (starting with 2001, I believe), have the same crank dimensions as the LS1 engines, meaning mounting the TH700 or non-LS1 4L60E requires a spacer behind the flexplate. Using an f-body LS1 4L60E with the later LQ4 solves those issues.

That isn't the pan you want. That's the H8 pan, and although they state "Camaro", it's up to '81 only. The LS1 f-body pan/pickup/tray is the right way to go.

(FWIW, at one time I had two LQ4's sitting in my storage unit - I originally bought a 2003 LQ4/4L80E w/harness & PCM for the '57. I found out it had water inside the engine, and when I told the seller, they sent me another LQ4, this time 2004, with intake/front accessories/manifolds but no PCM and clipped harness. I was planning on a stroker kit for the '57, so disassembling and rebuilding the 2003 engine wasn't a problem, they compensated for the damaged engine by sending me another. I researched putting the 2004 engine into Berlinetta #1 with 4L60E, and looked into doing carb since it's an originally carb'd car. I concluded sticking with EFI was the right way to go, even though I needed to come up with harness & PCM for it and up the fuel pressure. I finally decided not to put the LQ4 into Berlinetta #1 because of the total expense involved, and that I already have two uncompleted LSx projects in the works.)

 

Early 6.0L's were equipped only with 4L80E's which required the spacer so their cranks were cast slightly longer

Later things changed and a more universal crank was necessary so the separate spacer was designed

Do a search on LS1 tech about older transmissions on LSx engines

That pan will drag on the ground. Use a Fbody or LS2/3 Corvette pan(non batwing)

The electronics are well covered and pretty much spoon fed as far as operations and installation

Fuel system is simple going EFI and can be built for under $200. A AFPR would be nice for higher end applications, but it not necessary for simple street use. The stock vette filer/regulator cost 1/3 of a normal AFPR and is simple to install

A FMVB 4L60E would work, but do you really want to drive that for an extended period?

 

It's hard to make that type of a blanket statement, though it's probably true in most cases. LKQ owns a LOT of salvage yards that are more or less independently run. I was told over the phone when buying my LQ9 that the harness would be cut. When I received the motor it had a fully intact harness on it.

 

A stock TPI car's fuel pump & fuel line(s) should be adequate for stock LS1 power levels. Depending on how much power you plan to produce, you may need to make upgrades.

There are a couple ways to approach the fuel system, both of which will retain a certain amount of the factory TPI stuff, as long as it's capable of supporting your intended horsepower levels. The first method is to keep a system similar to what your TPI uses... a send line from the tank to the rails. The rail will need a crossover line to the other rail. A fuel pressure regulator will be attached to that other rail, and from that will be your return line to the tank. This is the simplest method from in installation standpoint because you don't have to mess with any of the existing stuff... you can tap into the hard lines in the engine bay.

The second option is to use a corvette style FPR that you mount near the tank. This requires you to cut the send line and feed it into the FPR, and cut the return line and connect it to the FPR as well. You then connect the remainder of the "send" line to the output of the FPR, and make a Y-connection to feed both rails. The benefit of this system is that it winds up costing less... the Corvette FPR is only $30-40. A rail mounted FPR is considerably more expensive.

 

Mounting the corvette filter in the engine bay will reduce cost and simplify installation at the cost of neatness

 

Here's an article which may be of interest to you.

Also, regarding the oil pan, I think the general consensus was that that pan is still too deep. It says "Camaro" in the product description on that site you linked to, but that is more for the older ones 1st gen 2nd gen... It is 7 1/2" deep which is only 3/4" shorter than the stock LQ4 pan. An F-body LSx pan is only 5" deep, by comparison. Here's a link to where I'm getting my numbers. Note: the part number for the pan you linked is: 12614821 (on the sticker on the pan in the picture) . It is the "Hummer H3 5.3 Alpha" pan in my link.

 

That is the first article i looked at but i always doubt some of the things said in these magazines....

Heres another article where the carbed version made more hp than the efi with every cam...(granted they dont mention streetability):
http://www.hotrod.com/techarticles/e...est/index.html

That makes sense about the oil pan...i figured there was a catch to that deal, seemed too cheap.

 

Actually, you need to upgrade the fuel pump with an LS1 swap. LS1's use more pressure or something like that. Everyone I ever talked to said that my stock fuel pump wouldn't do the job at all, so I swapped in the Walbro 255, which is what a lot of people do.




I did this after consulting with Pocket. It's a very nice, factory looking (albeit nicer than factory) fuel system that cost me right around $180 from the tank to the fuel rails. I got some -6AN stainless line, a bunch of Russel fittings, and a Corvette filter with the built in regulator and put it all together myself.

 

Were you planning on the rectangular port heads?

Using their numbers, they spent almost $1300 on induction and ignition. If you can't find PCM, intake, and harness (even custom) for that, you aren't trying hard enough. If you go with a 90mm intake, then you'll need a different TB, so that will bump the price right up to what they spent (unless you modify a stock harness yourself). Of course, that's before you sell off the stock LQ4 stuff you won't be using. And, obviously, a FAST EFI intake will be much more expensive than factory intakes.

They also admitted the carb traded off peak torque for horsepower.

 

if I **** anyone off for reserecting a 7 year thread forgive me lol... these people seem quite knowledgable though!... anyways couple questions thinking on doing this in my 87 iroc-z it was originally tpi but believe someone converted to carb... now my question is, do I need the pcm from the truck and the wiring harness or should I buy the pcm and harness from a 4th gen fbody??? I already know i'll need to swap to all 4th gen accessories... ohhhh and what about underhood fuse box will I need that also??? who makes up plug and play harnesses compatible to the 3rd gen?

 

The truck PCM and harness are fine. You can even use the fusebox from the truck if you like (but it won't have cooling fan relays).