I've got an L03 right now, and I plan to take that POS out.
But I'm going to keep the next engine TBI'ed.
It will be a 350 with vortec heads, an XE268H cam, Edelbrock RPM Air Gap intake, a Holley 670cfm, and a few things here and there.
Would it be a bad idea to stay TBI?
I already have all these parts.

 

You'll need a lot of tuning, but i don't see why tbi isn't a good choice. I say go for it.

 

Well your gonna need to get some work done on your heads so that they can handle .490 lift. Also I am running the XE256H in my new motor and after some research I decided to go carbed because its very hard to tune a cam with a tight lobe seperation angle. I think that all the XE cams have tight lobe seperation angles. You probably want to get something with about 114 degrees for easy tunability. I am not saying you cant tune an engine with a smaller LSA but I wouldnt reccomend it if your not an experienced prom tuner. Also the RPM air gap intake wont fit under your stock hood. All in all it sounds like a great setup, especially if it was a carbed setup. If you want to keep the tbi you might want a cam thats easier to tune. I am sure someone on this board will suggest a good one for you because I cant think of one off the top of my head. Good Luck.

 

what kind of work do i need done to my heads? I have new springs for them. What's the price to swap to carb from here?

 

I'm really not an authority on TBI engine swaps, but here is a liitle of the conventional wisdom I've picked up:

1) Yes, prom tuning is highly recommended to optimize the power/driveability/mileage potential of this setup.
2) As is normally true, cam selection is crucial to parts compatability (i.e., heads, valvesprings, pushrods, injection or carb, etc.) as well as being compatable to your intended use of your car. Is it a driver, weekend cruiser, bracket racer, etc.
3) Some say that TBI is only capable of delivering enough fuel through two injectors to reliably support 330-340 HP, with the correct parts combination and tuning. If you want to exceed these numbers, you may want to think about other options.

Please bear in mind, these are opinions that I have read in the recent past, and I am generally in agreement with them. Also, I am in the process of researching the same kind of swap that you are considering.

Finally, if you do choose to keep your TBI, you won't be the first, and you have the valuable experience of others to draw upon.
Hope this helps.

 

from what i've gathered you either want carb or EFI. If you want EFI TBI is the cheapest and easiest to tune with. as far as cams and tuning go, listen for jprevost, dewey (is having good luck w/ tuning but no cam swap yet), and i think Rbob might be able to help.

-chuck

 

The tbi will be fine but id go with an XE 256 -12 on a 350. Plan on tuning. The calibration in the ecm will need to be almost completly overhauled to work well with the engine.

 

I already have all the aforementioned parts though.

 

If you already have all the parts there is definitely potential for a good setup there, but I would suggest that you start Prom tuning NOW. Start on your stock car and get the feel of it because that combo is going to need a lot of tuning and will be difficult for you to just jump into with no experience. What are the specs on that cam though?

 

I think this is the right cam http://www.compcams.com/Technical/Se...umber=12-268-4 .479/.480 lift, 224/230 duration, 114 LSA.

If those are the right specs, it should work just fine with tbi. If the block is an '87-up, it should be setup for a hydraulic roller cam, which is something you may want to consider. A little more pricey, but well worth it imo.

 

Isnt 224/230 a lot of duration for tbi? The hot cam has less duration and its powerband goes up to 6000 rpm. I dont know if the tbi would allow for enough airflow to get close to that.
Maybe im wrong.

 

Well I thought that it had 110 LSA, you should be fine with 114 LSA. That sounds like a great combo then. I have a friend with an el camino who has the same setup(carborated though of course) and he runs low 13's with 3.23 gears and a 2400 stall. So that should be a great setup if you get it tuned well.Good Luck.

 

That was my confusion too, but I think its the flat tappet 268h that has the 110 lsa and the roller has a 114. That cam is still going to require a LOT of tuning from a stock chip. You may want to look into a new fuel pump to be able to up the fuel pressure on those injectors.

 

In addition to 3.73 gearset and a higher stall TC youll also need prom burning equpment and some time to tune it. If your not knowledgable in ecm tuning, youll need to learn, or get a carb. While theres nothing wrong with running some duration, youll definatly need to do some tuning. I know the stock calibration didnt even come close to what my engine needed. I can only imagine what a healthy 350 will be like. Youll probably need to allow for some downtime while you tune the car, since it probably wont run the greatest when you first start out. Probably you should go over to the DIY-Prom board and familiarize yourself with tuning before you do the swap. Knowing what I know now, I would have never swapped over before learning how to tune the engine.

 

Those are the wrong cam specs. That's for the roller, I have the flat tappet.

:-/ looks like I'm going carb.

 

http://www.compcams.com/Technical/Se...umber=12-242-2
That's my cam's specs

My engine is from a 70's truck so it's flat tappet.
I have no idea about PROM burning, nor do I have the tools.
I don't even have a laptop to record data with.

What do I do?

 

What kind of work do I need done? I have Comp Cams valvesprings, do I need anything else?

 

If you're stuck on keeping that cam I wouldn't even bother trying to keep TBI with that 110 lsa it'll be real tough to tune. That'd be a task for someone with quite a bit of experience, so for someone who has no idea on that stuff yet...

 

my cam is still in the box, unopened/unwrapped. Any way that Jegs will take it back? I bought it a long time ago (a year?). Or maybe possible sale on TGO for roughly the same price I bought it for? Then I could get a cam better suited for TBI...

 

At the minimum youll probably need to have the guides machined down to give the necesary clearence with the heads if your using that cam. While your there, screw in studs would also be nice. Search. It seems like the topic comes up at least once a month on the Tech/General Engine board.

As for the cam, if your keeping it, youll want to get a carb. The changes that would be needed to the computer to get it to do something resembling running well are way out of the scope of the average DIY'er. If you get a lesser cam, the efi would be fine. Youd also be able to skirt around the need for machine work ot the heads. But doing that before install is still recommended.As for returning it, its been too long, youd have to sell it in the classifieds. Its a very popular grind, so I imagine you wouldnt have much trouble selling it.

 

I also have an LT4 standard cam, obviously roller. Should I:

A) Build and swap in the 350 with carb (swapping to carb would mean I'd need to purchase a carb, distributor, and AFPR and/or carb fuel pump. Also I need a new flexplate to fit the damn thing.) with my parts and the XE268H

B) Keep my 305 in the car, keep it TBI (holley), and build it using my parts and the LT4 cam, then tune it from there.

Parts List
Vortec L31 Heads
Edelbrock RPM Air Gap
Comp Cams XE268H (brand new)
Comp Cams springs and hydraulic lifters (for flat tappet)
LT4 Standard Cam (96 Vette GS?)
Holley 670cfm TBI with adapter


Do you think the 305 will have at least 300 horsepower if I take that route?

 

I was told you need to have them pocket ported for anything above .470 lift, but the guy who told me may be wrong. All I know is everytime I see someone with vortecs that has more than .470 lift they always have them pocket ported and have bigger valve springs. If you do a search you should find what you need to know.Oh and also I would definetly just slap a carb on that sucker and go. Youll be running great times with that setup and like a holley 670 carb. Good Luck man.

 

It' going to need a lot of tuning, that's ONE of the reasons I like carbs....
No problems running my XE284 cam....

 

Token,

I would also recommend sticking with the 350 and going carb, namely because of the parts you already have.

Or if you are interested, you could try to find a newer block and could make use of the 670 tbi, lt4 cam, and vortec heads. But as it is now, I think you'll make good power with the block you have now with a carb.

 

Put the engine swap on hold, and get the prom stuff, to do your own tuning. Tuning is the name of the game carb or TBI. If you like splashing around in gasoline on a hot engine then carbs are your best answer. Got a distributor machine for getting the curve right on the distributor, then have at R+R'ing the dissy often to get it close.

I went 13s with a Comp Cam 270, 224 @ 050, 110d LS, with a cross fire.

Like I said it's about tuning.

 

How much vacuum does that xe-270 pull at idle? Ive read a few posts that the XE-268 pulls around 14-16 inHg of vacuum at idle, which would be very doable as far as the ecms resolution is concerned. I figure that if my engine could run for a year and a half (prior to tuning and fixing some stuff) only pulling 12 inHg at idle, it would probably do ok pulling 15 or 16 inHg.

 

I wont be doing the tuning, hell no. I dont have time or money or a laptop to learn how. Yeah, I'd like to, but it seems way too time consuming for me.

 

Then an engine swap keeping fuel injection isn't your thing. Carb is probably better for you.

 

I think I've made up my mind.
I'm keeping the 305, and I'm keeping the TBI.
Brian from TBIChips is burning me a custom PROM for my specs.
He says 280-300 horsepower from my setup, which is definitely respectable.
This leaves me more money for future additions, such as 3xx posi, which I hope is the next mod after engine work.

I have a few questions though.
1. I'll be using Vortec heads, so I need them milled to maintain good compression, correct?
2. How much does this cost?
3. While I'm at it, should I get screw-in studs?
4. Do I need any other machine work to get these heads to function properly with my LT4 cam?
5. Should I put my new valvesprings on or will the Vortec springs work fine?
6. Will I see a minimum of low 13s when properly tuned? (2.73 open)


Thanks a lot for all the input, guys.

 

You will need the heads milled to keep your compression, but I'm not sure how much that runs.

As far as the cam goes, as long as the lift is at or under .470", the heads and springs should be fine, though considering different springs may not be a bad thing. Some people say .480" is the max lift for the vortecs, some say .470". I just say .470 to be on the safe side.

Properly tuned, I think you will see 13s, espesially with that intake. But the open 2.73 may hold you back a lot, as well as the stock torque converter.

One other thing to keep into consideration. Brian is very good at what he does and will make you a chip that will work much better than the stock one. However, there will still be room for improvement (no matter who burns the chip for you), and you are going to want to send him data after you get you combo up and running so he can start to fine tune. You can find a cheap labtop on ebay, or use a friend's if they are willing. winALDL is freeware, and you can make the cable for $10

 

I think youll be lucky to hit 13's with those 2.73 gears your gonna need better gears and maybe a better stall. What are the specs on that cam isnt the lift like .492 with 1.6 roller rockers? If the cam is that big youll definetly need a bigger stall and lower (though numerically higher) gears.

 

I agree, the stock rear has got to go. Crappy ratio and theyre not too strong. With the trans, id pull it and put in a nice higher stall TC and, if the trans is in good shape with relativly few miles on it, id speak to Dana@Pro-Built and get some stuff like a new front pump, shift kit, and what not to help the performance of the transmission.

 

Why does everyone always say to go with atleast 112-114 LSA for tuning reasons, yet the stock L03 cam has 109 LSA?

 

109? damn.

Should I look for 1.6" rockers to benefit from my cam also?
I could pick up a set of stamped 1.6s for pretty cheap.

How much does head milling cost? Like $50?
What should I look for in the yellow pages when looking for head milling?

I have no clue where to start

 

One thing is I dont think the L03 cam had that much overlap because it was so puny. Probably not much worse then my cam, overlap wise.

 

yeap it had a 109 LSA. I think all the peanut cam cars did. I don't really know how lift and duration play into the scheme of things, but if someone would like to tell me that would be cool. I would think that if it had 109 to begin with then you wouldn't need to go as large as 112 and bigger to get it tuned right, but I might be wrong.

 

cuz the cams are so damn small it dont matter