Hi, normally I do not really like threads where people ask for advise regarding what parts to buy for use with particular setups.

I somehow however reached a point where my next purchases will determine the course I will take in building my LO3.

The reason I'm planning on rebuilding the engine is that it's roughly 120k miles old now. I would like to take a peak inside and determine which parts need replacement to keep it running another 100k miles without me worrying about it. I might as well take the oppertunity to improve the LO3 in some regards while I'm at it.

My main goal is a street driveable car with acceptable fuel economy and gaining some power. Anything bringing me closer to the 300 FWHP mark will make me happy. I do not intend to race the car.

One of my main concerns is low end power which might mean that some of the parts I am currently considering wouldn't appear to make a lot of sense. At this stage I'll gladly take any advise given .

So, what I have is a bone stock LO3 which I do not intend to replace or stroke due to taxes (about $1000 a year for 305 cid displacement)

I can either get my hands on a set of LB9 heads (081) or a set of LO5 heads (193). I'm tending to prefer the LB9 heads at the time.

To go with that I have a set of Hooker 2460 headers and Y pipe along with a 2,5" cat (required) to go with my 2,5" cat back exhaust. I'm not looking for big numbers, so the 2,5" should be free flowing enough.

On the intake side I'll organise a working cowl hood, and wish to top the engine off with an 7101 Edelbrock RPM intake, a TBI adapter plate and my stock TBI unit. I'll organise pressure to the injectors to make that part work. I guess 190 lph fuel pump and adjustable FPR should do the trick. I'll have the whole controlled by an EBL unit.

So, with these parts, and a stock bottom end, what would be the preferred specs for a cam that would give me some low end torque, and a usable powerband from 1500-4500rpm? Idle at 600-800 rpm is a plus. I'm not quite looking forward to having to idle the engine at 1000 rpm after fitting a cam.

Price for the cam is not really an issue. Living in Europe I'll have to order it, and since I have to order, anything from $100 to $300 goes.

Looking at the stickies the LT1 cam has approx:
duration 203/208, lift .450/.460 and 116 degrees lobe seperation.

Looking at some aftermarket hydraulic roller cams I see durations far longer at .450/.450 or similar lift and the advise not to exceed 115 degrees lobe seperation on EFI engines.

I guess understanding how these values would effect my TBI and which would be favourable would help me a lot in my decisionmaking, so as said, any help in this area is greatly appreciated.

 

If you make this step, I would suggest you download camquest6 and buy one of these to start with http://www.summitracing.com/search/?...no%20sim&dds=1

From the two heads you posted, I would go with the 081. Never heard about 197's.

The LT1 cam is good for the $, but for a project as yours, I would get something more performance related.

Could also stroke the 305 or go 350 383, nobody will notice, as they look identical.

 

So in Germany they tax you on your displacement? Thats interesting. I guess the bigger the engine the more fuel and more emissions is thier reasoning? I'd order one of those xfi cams. The 268 or the step below which is the 260 I believe....

 

The 081 heads are 58cc combustion chambers, that would boost your CR quite a bit. With bigger valves and a lot of porting, they would be good to about 400 hp, but for that kind of money you could probably get a good set of modern aftermarket heads and be better off. You probably mean the l05 heads were 193 heads, know as swirl ports. They make good torque down low, but run out of air above about 4800 rpm. I second the recommendation that you download and use camquest6 from compcams.

 

Meant 193 heads ideed.
I had a look at camquest and dsktop dyno is on it´s way. Hope that will shed some light on what kind of cam would make the engine do what I want it to do.

Some serious porting is already going on on the LB9 heads.
Not certain on fitting bgger valves though as that would mean additional machining (increase valve seat size etc.)

Does anyone know what kind of compression I´d be looking at with the LB9 heads?
I believe the combustion chamber has roughly the same size, right?

Camquest6 using the data found on this site seems to point to following cam profile:

Compcams 08-422-8 XR270HR grind (what´s up with the grind thing? Have to look into that I guess)
(I just found out the good part which is that they offer starter sets for dummies . Never swapped a cam before and for $750 for a set including all required parts it looks like a fair deal to me)

Duration int. 218 exh. 224
dur. seat to seat int. 270 exh. 276
Lift int. .495 exh. .502 w. standard (1.5?) rockers
Does anyone know if the LB9 heads support .502" lift?

Such a cam would, provided I stick with moderate values for intake CFM, somewhere around 300+ peak HP and 346 peak ft-lb
Torque would be pretty good from ~1500rpm upwards and performance goes down the drain from 5000 rpm onwards all according to plan .

 

Not sure if this is necessary, I decided to not go under 112 LSA for pollution tests, could check out what Cams the guys in CA use, that are pollution and performance friendly.

O81 (58cc, same as 187's) would at least require screw in rocker studs, probably the LT4 style retainer will clear the lift, valve springs and a clean up mill.

1.94/1.5 valves are not luxury for a mild performance head.

I remember going over that kind of build too, came to the conclusion that a set of TFS 175, in general, would make more power, weight less and would end up cheaper on this side of the pond.

 

Not quite sure on the cost factor.
The ported LB9 heads would cost me 150 for the pair

But lobe seperation over 112 = bonus in the smog test department?
That´s good to know.
Back to the drawing board I guess

 

Should refrase, you got extremely lucky and found a set for dirt cheap.

How much does a valve guide replacement, 1.94/1.5 valves upgrade, clean up mill and screw in studs run in your area?

 

That I´m not certain about.
Would have to inquire, but I think I know who best to ask.

Found a cam with another profile.
I downloaded desktop dyno as well as a set of cam profiles and head data.

This stuff is really fun to play with, but I have to convert quite a bit and actually had to read the desktop dyno user manual
Still haven´t figured everything out however.

Camquest6 is a load of fun as well. And informative on top.

The cam I like at the time is another compcams, which will, in no small part, have something to do with Camquest. As soon as I start buying I will look into similar profile cams before ordering however.

Part number 08-302-8, Grind 264HR-12
Duration @ .050" 210° int. 220° exh.
Duration seat/seat 264° int. 274° exh.
Lift .480 int. .480 exh.
Lobe centerline 112°
Overlap 45°

Alternative for more performance, more lope in idle:

Part number 08-501-8, Grind XR264HR
Duration @ .050" 212° int. 218° exh.
Duration seat/seat 264° int. 269° exh.
Lift .488 int. .495 exh.
Lobe centerline 112°
Overlap °

Alternative for less performance but lower idle

Part number 08-500-8, Grind XR258HR
Duration @ .050" 206° int. 212° exh.
Duration seat/seat 258° int. 264° exh.
Lift .480 int. .488 exh.
Lobe centerline 112°
Overlap °

Might be a silly question, but where would the studs be screwed in?

 

Screw in studs conversion http://www.maxchevy.com/tech/2007/ii_12-stud-1.html

btw 8-302-8 does show up as a good fit cam.
Made me wonder what flow # u found for ported 081's.

 

Screw in studs are studs that screw into the block, then you slide the heads on them and nut the heads down, a more positive method for sealing heads in high compression engines. I believe that stock 305 heads are 58cc heads, so unless you are planning to put different pistons in, you won't be changing the compression ratio with the LB9 heads.

this discussion I had earlier on this board may help you somewhat with you cam questions, it did for me.

https://www.thirdgen.org/forums/tbi/...ideration.html

There is a sticky related to head flow on this board IIRC that will answer that question

 

I figured I´d just use these values:

https://www.thirdgen.org/forums/post...555-post6.html

to be a bit on the conservative side.
I guess porting, when done good, could get an additional 10% that I then lose in my 20 year old drivetrain so no worries in being too precise I guess.

 

You are right, sorry for the confusion, should have specified rocker studs.

 

Not much cost involved in that rocker stud-story.
I guess if I´d purchase the thread cutter (3/8th NPT?) I´d be able to fabricate a guider and thread wire in the heads in about an hours time.

Depends pretty much on how willingly the existing pressed in rocker studs come out.

 

OK for the umteenth time, go to page 3 on my cardomain and read. nuff said.

 

Your cardomain is what started me getting motivated to stick with the LO3. It has a lot of useful information on some of the basics.

(It also has the specs on the stock cam, which I only noticed today)

If I wanted to carboncopy your build, that would be fine.
Having the car where I have it however the ZZ4 heads and hot cam will be pretty difficult to find, so I will try to work with what I can find, and order the remaining parts new.

Do you by any chance know what the maximum valve lift is for the LB9 heads?

 

I figured it might be time to bring this one back from the dead for some more questions.

At this time I have the cam questions pretty much sorted out.

Either a 08-302-8 or 08-501-8 cam would get me where I'd want to go I think.

Playing around with Desktop Dyno a bit I started wondering about the intake however.
Desktop dyno keeps telling me that the stock TBI intake would produce about 10% more HP and torque then the Edelbrock RPM intake.
Of course, the program does not allow for the TBI adapter to be added.

Can anyone help explaining why I see a 10% loss in HP and TQ as soon as I swap away from the GM stock TBI intake? I kind of want to get rid of it, but if indeed it provides better numbers for my sub 300 HP setup I might be better off picking up the Edelbrock TBI intake?

 

If smog has no factor in your build. screw what desktop dyno says and get the performer RPM NON air gap with an adapter plate. It's proven to be better on here. Simple as that. If smog is against you then the TBI perfomer intake would have to do. If it were me in that 2nd scenario i'd just keep running the stocker

 

Smog is a factor in that the CO2 emissions will be checked.

There is no visual inspection like in some US states. If I go to a technical inspection the inspecting personell will expect to see an alien under the hood. US V8. They generally have no clue about what the engine should look like. Just that it has 8 sparkplugs and a lot of junk hardly ever found on european cars.

So as long as the EGR mounts up to the RPM, and I think there was an EGR version of the RPM non-airgap intake, all is good.

I think I could even get away with discarding my smogpump and most of the AIR setup.

EDIT: I apologise for all the typos. One of my pet rats stole the O and B keys and after putting them back they do not always respond.

 

Then I would get the RPM intake and an adapter plate. you'd be MUCH happier with it believe me. I have one and it works great.

 

they have an rpm with egr intake? hmmm. did not know that. ill have to take a look at that someday

 

Nope, my bad, no EGR versions of the Performer RPM. nly of the performer intake

I already had some difficulties believing what desktop dyno tried to tell me.

Not sure why it´s doing that though. It would be interesting t find out where the difference comes from.

Just out of curiosity, does the RPM intake with TBI adapter plus TBI plus 3" aircleaner still clear the stock hood?

 

I'm not running the EGR on my set up but I believe it will clear just fine. I have a small scoop on my hood but that was when I had the ! inch spacer. I haven't checked to see if it sits lower since the swap.

 

I would tend to think that it will not clear but I do now know for sure. sorry.

 

Ok, I'm just trying to figure out if 2" cowl would be enough.
As things seem at the time I'll be building the cowl hood myself, so it would be just as easy to make it 2 1/2" instead.

It would just be silly if I cut and weld a cowl, only to find it will not clear the setup when I'm done, so having at least an inch or maybe even two of air towards the top of the cowl would be comfortable.

 

yup make it a 3 inch and you'll be set