RS-Chevy-SS

Update: The swap is mostly completed. If you read through this thread there are several posts by myself and RF including pictures that detailed the process as we went through it.

Nearly every question about a similar swap will have an answer in this thread.

Original Post starts here
Ok major post edit. Ive scraped plans for the LO5 in favor of the L30 vortec 305 long block below. Power increase will definitely be noticeable and the cost vs power ratio fits very nicely for my vision of the car. My goal has always been to get a new motor in that just has some more power than the LO3 but doesnt need to push 350hp. Car is babied for the most part.

L30
http://www.jegs.com/i/Chevrolet-Perf...30284/10002/-1

Update 2-12-14: All parts ordered and on the way!

Update 4/23/14: Vehicle is now road worthy. Engine swapped at Mileage 153963. Drove it 35 miles today.

Update: 6/29/14: Vehicle is driven nearly daily. 2k Mile mark. Tuning with EBL has begun.

Update: 8/28/14: Vehicle continues to serve as DD. Tuning is nearly finalized. Engine has much more power than the stock LO3.

Update 1/17/15: Running great 6k mile marker on engine, little less on transmission. Minor things to touch up.

Update 4/10/16: Running Strong. 14,500 miles on new engine and transmission. Had a major miss that ended up being a bad distributor cap(forgot to swap when swapped the engine) replaced that and all is well now.

Enlisted RFMasters assistance with the install!

jokerZ71

The 1st link (210HP) is the 1 you want.It is the 1/2 ton engine with 64cc heads & 9.4:1 CR.The 190HP version is for 3/4 & 1ton trucks.It has larger chambers & less (8.75:1)CR.They both should be roller blocks.They just use a flat tappet cam.For the money,I'd just buy the L31 instead of an L05.You will already have roller cam & better heads for not much more.

Fast355

iTrader: (2)

Between those two, I would pickup the 4-bolt main 1 ton truck engine. The lower compression ratio is from a deeper dished piston, not the cylinder head. The 1-ton truck engine has a better forged crankshaft, 4-bolt mains, and a single roller timing chain. While it is slightly lower in compression it is still a very strong runner. With headers, an edelbrock 3704 intake, and a matching tune I put down over 200 RWHP with one in my G20 van. Then I tore into it and put a production 1996 LT4 camshaft and 1.6:1 full roller rockers on it. I put down over 250 RWHP and it was a torque monster with over 350 ft/lbs. With ported vortec heads and a custom cam made over 350 RWHP.

That being said, SKIP the TBI engine and pickup a 4-bolt main Vortec engine. It is a cheap way to get vortec heads and all the roller cam stuff. Worst case you are needing a TBI Vortec intake. The 1-ton vortec engines had the same pistons as the 1/2 ton, but had the forged crankshaft, single roller chain, and the same HD goodies as the HD TBI.

http://www.jegs.com/i/GM+Performance...FZBj7AoduzwAJg

Either way with a 350 you are going to need a set of injectors, a knock sensor, knock module, and an ECM upgrade anyway. You might as well put headers on it while you are there as well and rid yourself of the horrible stock TBI intake manifold. If you don't open up the intake and exhaust, you might as well leave the stock L03.

I have the engine above in my 97 Express. With a mild cam upgrade, the MPFI L31 marine intake, and LT1 exhaust manifolds into the factory dual 2.75" to single 3" exhaust system I put down 330 RWHP through a 4L80E. It is a beast of an engine properly cammed and tuned.

RS-Chevy-SS

Wow, what a great response. I was checking out the L31 but thought it would be a major compatibility issue. Which intake mani would I run?

My goal is to put a new engine in it with some more power than the LO3 but I dont necessarily need it to push 350+ as its mostly a weekend car. Which would you suggest for that? Also in the interest of cost, the original tranny with 150k will remain as is until it blows.

jokerZ71

The L31 would serve you a lot better.If you need to pass emissions,you will need to use the GMPP TBI to Vortec intake to be able to retain your EGR.There are also carb intakes you can use with the TBI adapter.If retaining EGR you will need An exhaust manifold or headers w/ the EGR provision.If emmisions is not an issue,you can delete EGR in the tune.You will need some tuning either way,L05 or L31.It's not a bad swap.

Fast355

iTrader: (2)

Definately not....All your accessories will bolt up, with the GMPP TBI intake everything else more or less bolts into place. I am not a big fan of keeping the AIR injection unless you need it for smog. Just puts too much clutter in the engine compartment. I also eliminate that stock pos heater diverter valve and metal tube that runs along the frame rail. With vortec heads and modern cats it will run just as clean if not cleaner than the stock L03. The last test it had to go through, my TBI swapped G20 blew almost 0s on the emissions dyno with the stock GM LT4 corvette cam in it. Had longtube tri-y headers and dual 2.5" exhaust with highflow cats even. I was literally putting down 100 hp more than the stock anemic 4bbl carbed 305, getting better fuel mileage, and running with a fraction of the emissions output of the stock engine.

jokerZ71

All 4 of the above engines use the exact same nodular iron crankshaft,not forged.The 190 HP HD L05 does have 76cc swirl port heads that lower the CR to 8.75:1 vs 9.4:1 for the 64cc heads in swirl port or Vortec.

Fast355

iTrader: (2)

:Well you better tell that to someone that has not had those engines apart. The 810 casting cylinder head used on the 20270 engine has a 65cc combustion chamber. I KNOW, I CC'd mine. It has a piston with a larger 18cc valve relief similar to the ones used in the Syclone/Typhoon 4.3.

Please correct your false information!!!

My personal 20270 crate engine and the 283 engine BOTH have a FORGED crankshaft. Not some bullshit nodular iron crank. I will make sure to take a picture of the crankshaft parting line when I pull it apart for the cam and head swap.

jokerZ71

The 283 most likely does have a forged crank.If you look @ the descriptions on all 4 engines either in the link or in the GMPP catalog it plainly states"nodular iron crankshaft". The HD L05 plainly states 76cc swirlport heads.Just click the links the OP provided or look it up @ GMPP.I'll correct any "wrong info" whenever you provide proof that it's wrong.Show me the specs on any of those 4 engines that backs up your claim.My proof is in the links provided by the OP.

Fast355

iTrader: (2)

I don't need to prove the head difference. Find someone that has cc'd an 810 swirl port head other than me. I have a picture of the piston I melted in that engine. Its unlike any 1/2 ton 350 or even the later vortec pistons. Those are 12cc worth of dish. The HD TBI has a piston difference that is it as far as compression ratio goes. The 810s do have larger valve stems and intake valve rotators.

The 20270 has a forged crank as well. (Atleast it did in 2005 when I bought mine)

The information on those engines is not correct. The cam specs are also not right for those engines. For one thing the cam info is not even right, they run the old 929 350 cam. 194/203 @ .050, .390/.410" lift

EDIT.....Piston from a 20270 after meltdown, what happens when you push an engine hard towing a trailer with 7x24# LT1 injectors and an identical looking 17# 3.4 V6 injector in #5 iirc.

jokerZ71

I know Jeg's descriptions can be wrong,but,GMPP should know.Look up the specs by the engine part# anywhere & post a link showing that either of the 4 engines has a forged crank.For 1 thing,look @ the prices.A forged 350 crank is more double the cost of a nodular yet there is only $50 difference between the 2 or 4 bolt L31 & only slightly more between the 2 L05's.None of the above 4 engines comes stock w/ a forged crank.If you can post a link or specs from somewhere that states your info is accurate,i'll gladly change mine.Otherwise I won't encourage someone to spend $2000 thinking they have an engine w/ a forged crank,when it's not.

RS-Chevy-SS

Deleted

Fast355

iTrader: (2)

I am telling your first hand that the 20270 that I bought in 2005 and the 283 I bought in 2006 have forged cranks. I have had the front covers off and cams out of BOTH of these engines. I know how to tell the difference between a cast and forged crank. The parting line on both cranks was a good 3/8" wide unlike the tiny little parting line that is on a cast crank. It is a very different looking material as well.

The cost difference just means that GM is gouging their bread and butter 350 customers. Lets see intake rotators, single roller chain, 4 bolt main, hardened valve seats, & larger stem valves in the 20270. Those things alone are more than $50.00 difference.

Oh and further proving my point.

http://www.hotrodders.com/forum/stoc...-a-170521.html

RS-Chevy-SS

Leaned out? Overheated and melted down?

jokerZ71

Other than the ZZ4 & the 383 engines,no crate or production 350 is made with a forged crank & haven't been for yrs.Like I said,simply post up a link proving your point stating that any of the 4 engines being discussed have a forged crank.

jokerZ71

The L31 is an easy swap & has many benefits over the L05 such as a roller cam,better heads.If don't have to pass emmisions,you can use a vortec carb intake w/ a TBI adaptor plate instaed of the hi price GMPP intake.As far as tuning goes,your gonna have to retune either way you go.The L05 or L31 will not run very well with the L03 tune.

jokerZ71

You do not want the 4 bolt HD L05.It has lower CR,crappy heads.Since you have 2 different opinions here,just call Jeg's,Summit,GMPP'or even your local GM dealer & get the correct info from the horse's mouth.

jokerZ71

There wre instances due to production shortages that the smaller chamber heads were used in the L05 HD w/ a larger dish piston,but,this was not the norm & would only occur most likely in a production engine.If you order a crate,there's a 99% chance that it will have 76cc chambers & less efficient valves.Fast355 I've been around reading on here for some time now & have had the occasion to read a lot of the info you provide & for the most part respect your knowledge & input here.I just think you may be honestly mistaken in this case.It's not a big deal.If I'm wrong,i'll be the 1st to admit it & correct my info.I've put my foot in my mouth more than once,but,I feel pretty sure about this 1.Sry for any misunderstanding.I mean no disrespect.I just don't want someone spending that kinda money thinkin they are gettin somethin that they're not.

RS-Chevy-SS

Thanks for this. Which intake manifold and adapter could I mate to the L31? So If I decide LO5 then definitely go with the 2 bolt correct? Im tempted to go L31 but need to see cost difference as that is definitely a factor. Local shop wants 1K to install motor and swap all accesories. They will also bolt the intake mani etc

jokerZ71

I'll get you some part #'s for an intake & post back.I gotta run for now.By the way if ya wanna ck it out,the L05 2 bolt will have 193 heads which are 64cc.The HD version uses 191 heads which are 76cc if ya wanna verify. Also do some reading on the L31 swap.It's not a bad deal & with todays oils,flat tappet cams are not a very wise choice.The L31 is rated @ 40 more HP than the L05 & is a much more efficent engine.

jokerZ71

I am a member @ HOUR.com & post regularly there.The link you provided is no more than a forum post.it is not valid proof.Can you not find the specs on what you claim & post them in link to verify?

Fast355

iTrader: (2)

There are ZERO 76cc swirl port heads in existance. The 191s are even 65cc. It is a deep dish piston period. They even did this on the turbo 4.3s with 65cc chambers.

That being said there are plenty of 1-piece rear main seal, forged crank engines out there. My brother actually has a 99 Express 3500 4-bolt main engine in his garage. I will try to get a picture of the crank this weekend.

Fast355

iTrader: (2)

You will not get a 76cc TBI head....PERIOD....They don't exist!!! TBI heads are actually very efficient in the rpm range GM intended them to work well within. My Vortec 350 will not touch the mileage or make the low-end grunt my TBI made. The port velocity is just not there at lower rpm.

RS-Chevy-SS

Great posts again Fast. So ive narrowed it down to either the stock LO3 from Jegs for $17xx or the LO5 from summit. So my question now goes back to the original. Given it appears both LO5s have the same internals minus the 2 and 4 bolt mains, would it be wise to go with the two bolt for the extra 20HP? And you wouldn't happen to have any part numbers for the esc, knock or prom would you?

jokerZ71

I agree the TBI heads do offer better low RPM grunt up to 3500 rpm or so,but,you are dead wrong about the 191.They are 76cc chamber heads.Source after source plainly states this.If you are so sure of what you are saying,simply supply 1 source or link that backs you up & proves your point.A reliable link or source.Not a post from another forum.193's are 64 cc TBI swirl port heads.191's are 76cc TBI swirl port heads.The L05 HD/4 bolt crate will arrive w/ 76cc 191 heads.Provide just 1 realiable source that proves otherwise.

RS-Chevy-SS

So in the interest of cost and simplicity. I have decided to go with the LO5. No that being said, I found the knock sensor on rock auto for an 89 C1500 with the 5.7 I cant find an eprom. What else do I need?

Im still torn between the 2 bolt and 4 bolt. I would want the higher hp but is it worth the sacrifice for strength? Keep in mind this will be a street engine mostly for cruising and maybe a work commute every now and then. She wont be redlined from stoplight to stoplight but I may do an occasional pull getting onto the freeway. I have to be easy on the trans though at 150k, I don't know how much it will survive with a fresh motor

Schurkey

Your intended application is so mild that the nodular crank and 2-bolt mains are not a concern.

jokerZ71

I agree.The 2 bolt main 210 HP will be fine for your application & intended use.If you go with the 4 bolt,you will be giving up power & compression. If you google engine #12520270 & look at the engine specs @ Pace Performance,Summit,Jeg's,GMParts Depot,along with any other seller of this engine,the descriptions of evry single place states....#12520270 is an L05 HD for 3/4 & 1 ton trucks/vans.It will arrive @ your door with a nodular iron crankshaft,cylinder head #14102191/76cc TBI swirl port head.8.75:1 CR. Camshaft specs of 382/402 lift...165.9/174.9 @ .050 duration.Not the 300 HP/350 camshaft.It does use valve springs from the 300HP/350 tho. If you want this engine,it will work for your app,but,it will not have a forged crank.It will not have a 300HP/350 cam.It will have 191 TBI heads w/ 76cc chamber.Check any of the reliable sources above to confirm.Unless Fast can provide some reliable data to prove otherwise,besides an old forum post from another site,those are the specs on the engine.Very easy to confirm the above info.It doesn't really matter to me which one you choose.I just didn't want you to think you were getting a forged crank,etc if you buy this engine.

RS-Chevy-SS

I appreciate that. So the two bolt should work? Any ideas and where to get the prom? Trying to confirm part numbers right now. Is there ANYTHING else I need besides the prom, knock sensor, amd injectors?

jokerZ71

If you keeping everything stock,the prom from most any L05 equipped vehicle should work.Even possibly 1 of the aftermarket chips for an L05 equipped vehicle.I'm really not even sure about the knock sensor.IIRC,they are same for the L03 & L05.I would double ck the part #'s between the 2 to be sure.Look around in the DIY/PROM section here & you can get the info you need.By the way,the L31 is pretty much the same price as the L05.You can use pretty much any carb intake w/ Tbi adaptor plate,swith over timing covers from your L03,& everything else is pretty much the same as the L05 swap.Proper tuning for the better flowing heads & the higher dur/lift roller cam will be needed tho.The carb intakes can be had from $100 to $200,just depending on what you want.IMO,I would use the 7116 Performer w/ TBI adaptor plate if you don't need EGR.

RS-Chevy-SS

I see the deciding factor was the added cost of intake mani along with the cost of tuning. I can reuse the 305 intake with the lo5 right?

jokerZ71

Yes,the intake should swap without trouble.

jokerZ71

I'm not sure what you're expecting from the swap,but,honestly,an L03 to L05 swap,stock to stock,is not gonna net you very much of a performance increase,especially considering the $3000 you're puttin into it.If your L03 is is about to crap out on ya,it mite make sense.Otherwise,if it's in decent shape,you could invest about half of that amount in the L03 & still have better performance.Granted,if you are considering other mods,the 350 will respond better & show a better increase in power for $'s spent.The L31 on the other hand will give you almost double the performance gains for just a few bucks more.It will be a much more efficient & realiable platform to build from as well.Stock for stock,the L05 is gonna gain you maybe 30/35 HP over the L03, while the L31 will net you prolly 50/60 HP & still be much more realiable & efficent.That's not to mention the problems with flat tappet cams wearing from todays oils & in 2016,it's gonna be even worse due to upcoming changes in the additives in oil.

Fast355

iTrader: (2)

191s are 64cc and that is beside the point. The replacement hecho en mexico HD TBI engine uses 64cc 810 heads and 18cc dished pistons. I know i had the damn engine and my first vortec head swap on it was right at 9:1 compression with shim style head gaskets and it would run 87 octane fuel with a full 34* of timing advance all day long.

The engine also had a 300 hp 350 camshaft in it. The cam that I have seen repeated 100 times over is smaller than a 305 camshaft in duration and more lift. Those specifications match NOTHING from GM.

Not to mention I have already stated the HD Vortec engine is the way I would go if performance is of interst.

Fast355

iTrader: (2)

In 2005 the 20270 had 4 bolt mains, a single roller chain, a forged crankshaft, 18cc dished pistons, 810 64cc heads, and the 929" camshaft. Just because someone put the wrong specifications on the net does not make them accurate.

jokerZ71

Fast,maybe the engine you bought in 2005 is as you desribe.IDK,but if he orders an L05 crate today,it will have the specs I listed.It's rite there in black & white from several realiable sources & ppl who sell this engine.Have you even looked @ the engine specs in the links?I have provided realiable data from several realiable sources to prove my point.You on the other hand have provided a post from another forum from ppl obviously as confused as you are & your own limited knowledge of 1 engine that worked on.The 810 heads have not been used for sometime now.Can you not provide 1 single ad or link that backs up your inaccurate info?If not,i'm done arguing about it with you.My point is proved & my info is correct.If he orders any new L05 or L31,it will have a nodular crank.Not forged.If he orders an HD L05,it will 191 76cc chamber heads.Look @ Pace Performance's description of the engine.It's rite there in black & white if you will simply read it.Idk what you may have bought in 2005,but,it's not what is being sold today.If no have no other validation to your claims other than your own opinion based on the 1 engine you looked @,then I'm done discussing this with you.

jokerZ71

Just becuz you tore 1 engine down that was bought 9 yrs ago doesn't make you accurate either.These specs I'm listing are from dealers in the ads they use to sell these engines TODAY.They are not internet legend or an opinion based on 1 engine that you worked on.You provide absolutely nothing to back up your inaccurate info.NOTHING except your own inflated opinion.

RS-Chevy-SS

Im looking for a otherwise stock GM crate that requires the least amount of work possible yet makes a little more power than the stock 170HP lo3. The L31 would be a great choice if it wasn't for the added cost of the intake mani along with an unknown cost of tuning. LO5 looked liked the next best choice, however you stated the flat tappet cam will have issues with todays oil which I don't feel like taking a risk on.

The more we explore this the closer I get to just throwing a new LO3 in it which is not what I really wanted to do.

jokerZ71

The flat tappet cam thing is not as much of a deal on stock low lift cams w/ stock spring psi as it would be in a performance cam/spring situation,but,it is a risk.A risk that will be there in the L03 as well.You can use zinc additives to the oil,but,they will damage catalytic convertors,which is the main reason for their removal from oil.By the time you buy the engine,pay for the install,buy gaskets,oil,antifreeze,plugs,etc,you will be well over $3000 into this thing,either way you go.That's over $100 per HP gain if you look @ it that way.LOL.I'm pretty sure that as many ppl that have done the Vortec/TBI swap,a good tune should be able to be had very reasonable.When you're $3000 into it,another $300 isn't a far stretch & would be well worth the added cost in the scheme of it all.$3000 for very little improvement vs $3300 for a great improvement.

jokerZ71

Fast355,are you absolutely sure that you have #1252072/L05 engine?The reson I ask is becuz #12569068 is also an L05 engine,tho not a an RPO.It is designed & sold for LPG conversions.It has special valves/springs,forged crank & other internals suited for propane use.If thru some mix up,you actually received this engine by mistake,you made out good becuz it sells for $3600 to over $4000 depending on where you buy it.IDK the actual head,or,cam specs,but,they very well may be different for LPG use vs gasoline.

Schurkey

When I popped the original LO5 in my '88 K1500, I wanted a crate engine because I figured it would take too long to rebuild an engine; and I needed the truck back in service as soon as practical.

The "GM Replacement" engine for my truck would be the 12568758 listed in your first post--the 210 HP solution. When I called my parts supplier, they recommended I buy the 12513151 - 5.7L (L05) as installed in 1991-1993 Chevy Caprice (Exc. 9C1 Police Package), 1991-1993 Buick Roadmaster, and 1991-1993 Cadillac Fleetwood Brougham.

The '151 is essentially the same as what GMPP was selling as the 300 hp crate 350 for many years, with a few differences: More-mild roller camshaft and 2-bolt mains instead of 4-bolt mains. I think everything else was the same--heads, flat-top pistons, PM rods, nodular crank, high-volume oil pump, windage tray, etc.

It's a crying shame that GM kept the crappy 12568758 but discontinued the 12513151. The '151 has given me excellent service in my pickup--about 80K miles (so far...) and it runs like a top on the original ECM and tune despite the additional half-point of compression. I did NOTHING to the computer programming (but I had the LO5 to begin with.)

IF (big IF) you'd be interested in a used or rebuilt engine--and you wanted the swirl-port heads rather than the far-superior L-31 Vortec heads--then consider grabbing one from a '91--'93 "B" or "D" body. It may be that GM or the aftermarket can supply a rebuilt with warranty for less than the "new" GM crate engine. (Or maybe not...the GM crate engines are attractively priced) Or you could select a "good used" engine and run it "as is", or buy the core and rebuild the engine yourself, if you have the time, skill, and tools. You'd keep the simplicity of your original TBI intake manifold, but gain the roller camshaft and additional compression.

jokerZ71

I bought my Z71 new in 97.I pulled the original L31 @ 250,000 becuz of low oil psi.It was running great.I replaced it with a Goodwrench crate L31 in 2006.That engine now has over 300,000 & it is still running great.They were both still quiet,no smoke,use about 1/2 a quart between changes.I'm currently rebuilding the original engine.I was amazed @ how clean & how little wear there is for 250,000 miles.The cylinders didn't even have a noticeable rudge cap & you could still see hints of the original crosshatch on the walls.Truck has a total of 552,000 on it today & is still a good truck.

RS-Chevy-SS

Man this choice is tough. I can get the LO3 for about 18 and install for 1k minus gaskets etc. LO5 I can get for 17 and same install but im weary of the cam now. L31 is nice but the intake mani and tb adapter put the cost of motor to around 2300 then same install and gaskets

jokerZ71

I see rebuilt L31 long blocks w/ 3 yr/36000 mile warranty anywhere from $1250 to $1750.GM Parts depot did have new L31's for $1850 & free shipping recently.IDK if they still do.Shop around.You can prolly find a better deal.

jokerZ71

You can also find good used intakes pretty cheap as well.Even some of the new intakes are reasonably priced.They can be found anywhere from $100 to $200.

Fast355

iTrader: (2)

Those specs have been around well before I bought the engine. That being said 810s are the later version of the 191 heads. I am not going to argue with you either. The 20270 and 283 both had forged crankshafts. You can argue all you want, I don't care. The 8,800+ GVW engines were designed to run at wide open throttle pulling a heavy loaded truck and trailer. They are overbuilt for what they are doing for a reason. 4 bolt mains and forged crank. The 99 2500 Express 4 bolt main short block in my brothers garage has a forged crank too.

Oh and here is another link stating the 191s are 64cc, more like 65.3 that EVERY 350 TBI head is. 193/191/810 they all have the same chamber.

http://www.hotrodders.com/forum/sbc-...ccs-22481.html

Then factor in that cam matches NOTHING GM ever built, it just tells me that information is flat WRONG.

Or here maybe you will believe a machine shop....

http://www.ebay.com/itm/14102191-Sto...-/261353790882

I ask you again to please take down atleast your wrong cylinder head information. I have seen the wrong information get a racer disqualified and accused of cheating. Only to find out he had done NOTHING wrong. Mortec used to list the 14022601 305 HO heads as being 58cc when in reality they are 53cc. A dirt track racer I know was challenged and had to tear down his engine. I took the numbers on paper that a machine shop had given me when they cc'd my stock 601 heads prior to milling the heads and save his reputation. So once again, be careful posting WRONG information.

jokerZ71

Can you not come up with anything other than a forum post to prove your point?i MEAN REALLY,IS THAT ALL YOU CAN COME UP WITH TO PROVE SOMETHING YOU SO STRONGLY FEEL IS CORRECT???LOL.Your engine may very well be the way you state,but,if the OP orders an L05 HD today,IT WILL NOT HAVE A FORGED CRANK !!! You can't come up with anything to show otherwise becuz it's BS.Some buses & larger vehicles did in fact have forged cranks,but,they were not sold under the #12520270 part #.

jokerZ71

I just talked to Pace Performance & Chuck Hutton Chevrolet here in Memphis.Engine # 12520270 is an L05 HD.It has a NODULAR IRON crank.It has #14102191 cylinder heads w/ 76 cc chamber.

Schurkey

You're WARY of the cam, not weary.

You'd have to be nuts to put another 305 back in. Both engines use flat-tapppet cams. There is some cause for concern, but don't obsess: the valve springs aren't stiff enough to make cam wear a deal-breaker.

But the power and roller cam are both long-term joys that will remain long after you've paid off the engine.

Fast355

iTrader: (2)

BOTH come from the wrong listing. PERIOD...NO 76cc 350 TBI head, PERIOD The HD engines have 18cc dished pistons to get the lower 8.75:1 compression while the LD engines have 12cc dished pistons and 9.3:1 compression.

They may have changed the crankshaft, but in 2005 you got a FORGED STEEL crankshaft. GM even states they built these engines to the 1993 production specifications. 191 heads were not made later than about 1991. 810s are the heads you will get with a 20270.

Finally the factory TBI hydraulic flat tappet camshaft is equivalent to the CS-274 and even the GM service manual list it as being .390/.410" lift.

http://www.summitracing.com/parts/slp-cs-274