Well fellas the old 89 L03 is old and tired and sick. Weve been waitin for her to blow for a couple years now but the only blowing shes doin is more oil out of the pipes. So my question is i want to remain stock the plain is to rebuild the L03 i know i know go 350 but its easier to just rebuild it. So question rebuild the stock heads or go aftermarket? If so which heads?

Well you're going to hear "build a 350" but if you want to do it then go for it. If you want to swap out the heads you have ALOT of heads to choose from. Instead of going into a whole schpeel about it just read this.

http://www.thirdgen.org/techboard/tb...-synopsis.html (TBI: Condensed Performance Synopsis)

For a 305, the best heads are the Trick Flow Super 23 305 aluminum heads. They have valves that fit the stock bore and a small chamber to keep the compression where it should be for a hotted up small block. I'd also argue they'd work well on a dish pistoned 350. The only problem is they're $1000 for an assembled set.

If you want to keep it on the cheap, L30 305 Vortec heads are pretty much the best there is.

And where can i get a set of the L30's? also flow?

L30 Vortec engine can be found in 1996 to 2003 C/K trucks and Express vans (and possibly others cargo applications).

As with any OE vortec head - it requires a vortec specific manifold. GM offers performance 12558060 Cylinder Head which can be purchased outright from usual speed part vendors.

On a side note I have tried to go with vortec heads for my 383 build, but after magnafluxing two sets of heads (both 906 from L31) I tossed the towel (and $300+ later). Both sets had cracks starting between middle adjacent chambers. My machinist told me that he sees a lot of 906's with this crack pattern - in his opinion OE casting is just to light, not enough metal to spread the heat out evenly. He does not see the same issue with offshore copies since the casting has more metal there. So, there is my 2c worth on Vortec subject. As another poster mentioned go with Trick Flow Super 23 (the 305 version). For My 383 build I chose to go with TFS-30410005 after wasting money and time with questionable OE castings.

//RF

so are these what i should be looking at or somethiing else? Also will the accomadate a small bore over? In case the block needs to be bored Also how would the stock heads ported run? The idea is to have something reliable. Something that runs smooth like stock but has a definate power increase so something a bump up from stock
http://www.summitracing.com/parts/TF...1/?image=large

If you are looking for power on the cheap get your self a set of Vortecs, used LT1 cam, and a vortec intake manifold. That is what I would do. You can also get the 062 casting and have them milled down to < 58cc's. The 059 or 520 Vortec (305) heads are harder to find and the 062's have the bigger 1.94 valves and are everywhere. I have heard that the 906 heads have more of a tendency to crack too.

There are no substantial physical differences between 062 and 906 Vortec castings. Both shared essentially the same casting mold when produced by GM. The 906 heads were fitted with hardened valve seats for use in HD truck applications - i.e. 2500 and 3500 trucks used for towing, heavy loads. In hind sight GM did not put enough metal into these castings. I can post photos of magnafluxed Vortecs heads showing cracks! I had spent $300 on two sets of 906 Vortecs only to find both sets (4x cylinder heads) worthless (and another $90 to magnaflux them both).

As for 059 or 520 Vortec heads - I have no first hand experience. I suspect that these used heads are 'less' prone to cracking since they were not subjected to extended high output operation.

Milling 062 heads down to achieve 58cc chamber would also reduce deck thickness which is marginal to begin with. I would suggest that you go through the numbers ($$$) and you may find that spending money on used Vortec casting does not make financial sense!

Do the math - all that machine work and a new intake manifold!

Trick Flows 175 on 305 have been extensively researched:

http://www.thirdgen.org/techboard/te...5cc-heads.html (Trick Flow 175cc heads on 3.766" bore - valve lifts)


//RF

Also don't be so quick to throw away the LO3 heads. Sure they aren't good by modern standards, but they aren't as bad as a lot of people think. Something with 165 cfm intake flow would have been pretty hot stuff in the 70's. Combine that with the modern roller cam and you can have quite the performer indeed. The biggest thing making your engine an boat anchor is the cam and exhaust!

Throw in a LT4 cam (#12551142), a good intake and exhaust and you should be able to do 250+ BHP even with the tiny stock throttle. At least that's what the maths program says, and that's my plan for my LO3. It's not exactly the massive 350 hp everyone seems to want, but it should scoot a light third gen pretty nicely. And it'll make that power without needing to be revved more than 5500 rpms.

- to get more HP from stock LO3 iron will require a better intake manifold, improved camshaft, some minor (cleanup) port work, free flowing exhaust and ECM tuning to take advantage of new combination of parts. Stock TB flows 490 CFM and should be adequate for a street motor, which basically spends most of its life below 5000 RPM. In the future, once engine is back together I would also consider bumping FP a bit from 13 PSI to about 16-20PSI to make sure that you are not going lean at WOT. Stock 305 injectors can handle additional pressure, but keep an eye on idle injector pulse width. All of this will take time and effort.

//RF

Hey thanks a lot for the feedback! So to get this straight I can run the stock L03 Heads ported with the combination of an intake and a LT1 cam and my exhaust and make pretty decent power right? And suggestions on the rebuild kit for the motor? Also will that parts combo handle a small bore over if needed?

UPDATE: Went ahead and pulled the plugs today since she had been behaving really bad as of late missing and what not and noticed about 3 of the plugs where fouled out and one had literally oil on it along with fuel. The heads are getting really bad. The valve guides or seal were the culprit for the common smoking problem on our cars right? 148000 Miles never been rebuilt

I have about the same amount of miles and mine smokes a bit at startup as well. I'd seriously consider another set of heads since your doing a full rebuild.

I know others have you convinced to use the old heads but check this out. I found a nearly new set of 059 vortec castings in an ad here: http://wichita.craigslist.org/pts/1533696574.html
That along with the cost of an intake manifold could put you well into the 300hp range. The thing that would make it expensive is if you needed to keep your EGR and buy that really expensive GMPP TBI Intake. Your buying a new intake anyway right?

Seeing that you are in Southern California means you probably need to keep your EGR since they are pretty tough on smog issues. I know as I used to live there too.

Factor in the cost of rebuilding a set of 187 heads. Then, look around for heads that are already rebuilt or ready to go. Most people aren't ready to shell out $1000+ for the Trick Flows on a 305. BTW, in the summit catalog the ones setup for roller cams are around $1200 for a set. I also saw a nice set of 113 corvette heads go for $350 on here yesterday.

I agree. Do the math first before turning wrenches. It is all too easy spend money when a simpler (and less expensive) path is readily available. Regulator - since you are in CA you must keep all emission equipment fully functional and any replacement part must have CARB EO D number to avoid later headaches during smog check. Be very careful when selecting cam, heads, and headers!
Regarding head rebuilding - do the math. Cost of rebuilding 187's vs. getting cast iron S/R heads ready to bolt on with better flowing ports. From a long term perspective I would keep stock intake, but look into replacing stock cast iron heads, intake and exhaust for better performance.

//RF

RF AND RS Thanks for the replies heres the thing im from a small town in CA and my car is registered there which is exempt from smog so as long as i never sell this car it will never have to get smogged lucky me haha i already ripped out most the smog equipment and air tubes. So the cost of rebuilding the heads is more then buying new? Im new to rebuilding a motor so this is the first. I wont be doing the work one of my more experienced engine guys will while i watch and learn but im funding it so kinda wanna go the cheapest route and get a smooth running engine 300hp is nice but is the cost justifyable?

Here is a nice tread covering some important details.
http://www.thirdgen.org/techboard/tp...ggestions.html (305 rebuilt suggestions)

Thanks for the help so this is the kit im looking at tell me what you think.

http://www.summitracing.com/parts/FEM-CSMHP749-300/

Kit covers stock rebuild - just the bottom end, minus cam!

Need at add:

Oil pickup
Rods (reworked stock rods will cost more than brand new with better bolts)
Machine work

//RF

Im gonna add, there is not anough detailed information about that kit.

In order to start the machine work of the block, you need to find out the following of that kit:

-compressed thickness of the head gasket
-head gasket bore diameter
-piston volume
-piston copression distance

To chose the right pistons it is necessary to know the Combustion Chamber Volume of the heads.

Also I dont know why they include a high volume oil pump.

Sorry for the late response fellas. So that kit should be good? and just going back to heads, im probably going to be using the stock swirl ports after a rebuild to them

Bump!!!

What's the your head's CC??? CSMHP749-300 states that approximate compression ratio 8.39:1 with a 64cc head. With 55cc heads you are going to be closer to 9.0:1 SCR. That's good enough for DD running on 87 octane gas.

//RF

RF, So here is what needs to happen. I want the motor to be rebuilt meaning new pistons and rings and such. The heads also need a valve job because the guides or seals are leaking oil. So can you please tell me what i need to buy and take to a shop and have them install? I cant find the right kit and cant find any head rebuild kits. I got qouted a price of 600 to rebuild it but i have to buy all the parts. They said they wont bore it but just hone it how does that sound?

Regulator

Summit kit CSMHP749-300 comes with 0.030 overbore pistons and rings. So the shop must bore and finish hone to accommodate oversize pistons and new rings. There is standard sized kit there as well, but IMHO I would consider looking for another machine shop to do work on your engine.

There are couple of reasons -

1) any shop that suggest that a high mileage engine can be rebuilt by just honing bores is not telling you a complete story. Before honing of the cylinder can be performed cylinder must be true - i.e. perfect circle bored to a diameter to accommodate new pistons clearance requirements. This part is critical to engine longevity - you do not want your newly rebuilt engine to consume 1 qt of oil every 500mi and be smoky dragon!
Over time, in a high mileage engine, piston travel tends to thrust against one side wall of the cylinder. Cylinder perimeter begins to resemble oval (exaggerated), but you get the drift, right? Honing will enlarge bore diameter (and will not correct oval bore shape) and you may get too much piston to wall clearance - resulting in piston slap

(http://www.pistonslap.com/whatisit.htm ).

2) My recommendation is to get second opinion and pricing.
You'll need to have your block (rods, crank) measured - bore and hone for hypereutectic pistons. Deck should be checked for flatness and true. Deck should be established.
Have your rods and rod bolts checked, before pistons are installed.
Crank shaft must be measured - both mains and rods bearings surfaces before new bearings can be ordered. If required crankshaft must be turned down - 0.010/0.010 is very common.

3) Heads will require:
cleaning and disassembled
magnaflaxing (say a prayer)
inspection of valves for possible reconditioning or new valves - compare to new valve cost.
valve guide inspection and measurement (bronze guides are about $7 + labor)
new viton seals
new valve locks
new springs
new spring retainer

Did you consider purchasing new heads??

4) Invest into SBC engine rebuilding bible! My dates back to 1979 - How to rebuild your Small Block Chevy by David Vizard.

5) 1-3 is a small snippet of steps required.

As you can see it is a bit more involved - so I strongly suggest (and recommend) to a get a notebook and write down all parts, costs, steps required to do the overhaul. #4 is very helpful.


//RF

I would not cosider that kit if you cant find out what is listed in post #19.
http://www.thirdgen.org/techboard/po...88-post19.html

The chance that kit has what you need is tiny. No big deal as we can help you put togheter a kit.
Check at some machine shops, for what size overbore they are equiped, to know what size pistons + rings to look for, so you can check availability and can compare prices.

Thanks RF. So would it be cheaper for me to buy new heads? Im kinda against it due to the whole retuning the computer thing. What do you think would be a reasonable price for a complete rebuild with everything you said? Im just gonna drive to the OC and take it to you and you can do it haha. Also with the bore am i going to have to change fuel pump or injectors? what about ecm? Thanks alot! Also i currently have piston slap under load but not when idling, and the motor will burn 4 quarts of oil on a 400 mile highway trip. What is magnaflaxing?

I think thats the best route is helping me put a kit together as im not to knowledgeable about rebuilding engines

It would probably be cheaper to buy a rebuilt set of 187 heads for sure. You could probably find a set off ebay pretty cheap. If you keep all the stock stuff (cam and heads) you could use the same ECM and chip.

I would personally use a different casting head and a little better camshaft but of course that would require ECM tuning for optimal performance.

Regulator

This is a very good thread. My general comment when it comes to engine building is that haste makes waste! So lets step through it step by step.

1) Typical valve job consists of the following steps:

a) Disassemble and clean heads, clean valves, etc. Check valve guide for wear, head flatness for estimate. That runs about $120. Guides and flat fly cutting is extra.

b) magnaflux - check for cracks $45 for a pair.
http://en.wikipedia.org/wiki/Magnaflux

c) Cut valves and machine seats (basic 3 angle valve job) That runs about $150

d)Final assembly and check - verify compressed height clearances, etc that runs another $150.

e) parts needed (see jegs or summit for best prices)
springs 16x ~$60 for LS6 springs
valve locks 16x (kit) ~$20
seals 16x ~$30
shields 16x. ~$20
valve guides and new valves are extra if needed!

below is an estimate - your prices will be different!
(a-d) $120+$45+$150+$150 = $475 in machine work alone
(e) $60 + $20 +$30 +$20 = $130

(a-e) $605 (Let me check with my machinist regarding 58cc cast iron SR heads availability and confirm valve job pricing)

2) ECM retuning is only required if you dramatically alter engine (heads, cam, intake and exhaust). For example = wild camshaft, 12:1 CR, etc. From your descriptions it appears that you want to rebuild your 305 with a bit of performance improvement. As long as you stick with a 'sane, middle of the page' camshaft ECM, injectors & fuel pump should be capable of handling new engine. Increased bore size does not present significant fuel demands. Even though tuning will help extracting additional performance that otherwise left on the table.

3) You will not like OC traffic - 405 can be royal PITA!

Sooooo - make a list, get estimates - you better promise me that, right????

//RF

Double post

Thanks! Wow thats alot for just the heads. I found a set of stock rebuilt heads off of napa for about 289 a piece. Hows that sound? Also oc traffic isnt that bad ive made the trip many times. but would you be up to it? So which cam would fit into the mild cam description? also would stock heads be compatible with that cam? So to recap with a cam change and exhaust ill be able to keep stock ECM and prom?

You can get a rebuilt 187 or 081 head off ebay for $99+shipping right now. You could use a used L98 or LT1 cam which fits the mild description. They can be had very cheap < $50. You just wouldn't want a cam with too much duration.

so what do you think about these 2 cams
http://cgi.ebay.com/ebaymotors/5-7-3...Q5fAccessories

http://cgi.ebay.com/ebaymotors/ws/eB...AQ:MOTORS:1123

Yes, I am up for it but I have an engine project of my own cooking in my garage (383 TBI)

I've asked my machinist and he just shook his head - he does not do too many valve jobs on 305 heads due to factory induction hardened seats. It is a very thin layer of hardened metal around the valve perimeter. For valve job to work seat and valve must matched and lapped. If seat material is machined to far the valve over time will sink into the bowl. Replacing hardened seats is expensive and is not worth it. Large head rebuilding outfits simply mix & match valves without going through the trouble of doing performance 3 angle valve which requires seat work. Valve, springs, keepers, etc are dirt cheap and this is why you see a plethora of $100-150 305 heads on ebay and elsewhere. These are probably good for 50 to 75k miles.

Regarding TBI LO3 compatible camshaft - I would hold off on slecting one right now until I know what my pistons and heads are going to be. The LT1 cam has narrow LSA (111 deg) which moves torque peak higher in RPM. while the second cam (L98) 14093643 Lift 0.404/0.415 duration@0.050 202/207 LSA = 114.5 might be a good candidate -but expect some tuning work to be done!

So then your machinist doesnt want to touch them? Also i should stay away from the ebayers then? What about a store like napa? Dude im swamped right now Since im new to this engine building thing its tough for my to try and find the right combo of things to make it work some im like jumping around heads and exhaust and cam and motor.

Have u considered something like this, http://www.thirdgen.org/techboard/en...-98-350-a.html New piston rings and new bearings while its out, would turn it in to almost new. That may spare some $ to buy a cam and set of aluminium heads.

Yeah but the fact that i would have to change injectors and the ecm and fueling wouldnt that bridge the gaps?

Just an FYI,, we were able to upload an injector pulse width calculator on our website. It is located under the category "calculators" Feel free to use it....hope that it will be helpful !!!

www.southbayfuelinjectors.com

Full fueling upgrade would include, highflow fuel pump, VAFPR and EBL. Your 55# injectors with 26-28psi FP should be ok for close to 300fwhp.

Yes in the end it will probably cost the same as what you are projecting with the LO3. Though it would be no mach even if you leave the stock L98 cam in the 350.

Gimme numbers here haha what can i see with that money spent on 305 versus 350