Okay so i got a 87 tbi 350 block and heads for $80 in amazing condition, and it will be going into a race car over the winter. this is going to be a basement style build, im looking to use as many oem parts as possible and build a nasty frankenstien. i am very fimiliar with the building and machining process but im a little new to the gm carb game.

its a 87 tbi 350 truck block. im looking for the best heads, intake and carb setup to run. looking to shoot for the 300+ range

Also was told these blocks were 10:1 stock, is that true?

Thanks, nick

 

the heads are garbage, the pistons will be replaced by the correct overbore size during the machinework phase, so what the compression is on them is mostly irrelevant to pretty much everything.

Check the lifter valley and cam snout area for the bosses for OEM roller cam hardware. They are probably not drilled/tapped, but if they're there you can use them. Make sure the tops of the lifter bores are machined flat for the factory dogbones, if not they wont seat properly and you will have to pay $300+ for retrofit roller lifters to use a modern camshaft.

Which brings me to my next point, you are worried about heads, carb, and intake. The cam is just as important as heads and they need to fit each other. The factory heads on that engine need to be discarded right away if you want any power at all. They should be 193 heads. If you want to be cheap and severely limit your power potential, you can run 083 heads and a factory roller cam... but you're going to end up at 240hp. If you want to be even more cheap you can buy one of those house brand lumpity flat tappet cams and make around 200hp. This is flywheel horsepower, btw.

If you really want The Best, not many can argue with a combination of AFR195's, and maybe and XR276 cam. Should be north of 400hp.

If you're planning to just use the factory long block as is. the cam will prevent any cylinder head upgrade from making a real difference. It's truly terrible. You'll ened to pull the heads and then you can see what the pistons look like to determine the compression ratio. GM wasnt very consistent with that. Then you need to decide roller or flat tappet.

 

Is budget a large factor? If it is this has been done plenty of times on here, and i'm sure some people will say it's old technology now but i'm just going to throw out the vortec/hotcam/carb combo. Most people will tell you that the stock heads are garbage aswell. Take a look at this http://www.chevyhiperformance.com/te...cam_355_build/

 

Sure we can. Since 180 cc heads are enough for 525 HP and 6500 RPM on a 400 SBC, why suggest 195 cc heads for a lame 350? You lose average power, you don't offset it with peak power, you hurt driveability and gas mileage. So why consider the wrong thing?

 

see

https://www.thirdgen.org/forums/tech...er-tappet.html

 

Im just throwing things out there, man, we dont even know his budget. I just wanted to throw some parts out so he gets an idea of the costs involved. From there we can get a better idea of where to go, but it's way too open ended to start deciding things like port size when we dont even really know if it's gonna be a 350 or a 383 or not yet.

 

Thanks for the quick responses! budget is kind of the main factor if this build and why i have a 350 long block sitting in my shop. ill fill you guys in quick. this is for a drift car, i am highly knowledged in import engines and machining. im fimiliar with dometic motors but i dont much about making power with them, and this is why im here today. so im basically looking for a frankstien style build, my goal is 300-400 at the flywheel

 

But any self respecting 383 is a cake walk to 400 hp.And consider torque more so than a very old standard of HP.The "D" cup style .030 over stroker pistons decked block to a quench target of .035 to .040 is a start.The new GM performance Vortec,not the junk yard dog heads,of 195cc heads is also going to lead you to your target.Limit the SCR with Iron heads to 9.5 with a DCR of 8.5.Long tube headers and a solid ignition also play a major role.Which T/C injunction with a smooth broad torque to hp mated to choices of rear end ratios and tire size is also key players.
This all starts with a strip bare block,hot tanked at a machine shop and dial bore checked in multi locations in each bore.Something that old I'm about 80% sure you'll find bores that are oval from the thrust side.How bad that is will dictate how much over bore it needs.Limit that to .060 over.And even if it needs to go .060 over,it is a good time to stop and think that one over if you want to spend that on a block that would be only a one build foundation.If that is the case,I heavily suggest you get a L31 block from a truck yrs of 1996 to 2000.There are tons of them out there really cheap to get.Stay clear of cheap standard rebuild kits.Most have pistons with piston pin height's that are a turd for performance.

Going to stop here.Remember this.A well executed matched parts build sheet as a planned build doesn't have to be for a race car only nor expensive.

Get it checked out at a trusted machine shop and post what they found.

 

Whoever told you a stock 1987 350 truck motor has 10:1 compression is either on drugs or doesn't know a thing about engines!
Probably 8.5:1 at best!

 

Appreciate all the info! great to know but like i stated before, im not looking for any crazy build, i already have a inline 6 2.5 turbo out of a skyline from japan i have gone through, top to bottom, that is the primary motor we use in one of the cars. But i grabbed a 350 so i could make moderate power to go out and have fun and if **** breaks i can run down to pep boys and get any part, not have to worry about 1-3 week waits on parts. this is just going in our practice beater car, that is already 3 cars in one. so im looking for mostly "bolt ons" for lack of a better term. Heads, intake, carb, cam etc. Just asking for some advice on what combinations flow the best and i can make the best reasonable power out of it.

 

Well the problem you run into here is these smallblock chevys were designed in 1955. They are old, they are primitive. You can easily get power out of them, a LOT of power out of them, but that means spending money and being very careful of what parts you use.

It's not like an import where there's a new engine family born every 10 years and they're all heavily optimized and super efficient for their displacement. Where headers and intake will net you a few horsepower and it's hard to improve significantly on the factory parts. In the sbc world, the difference between a 150hp 350 and a 500hp 350 from a cost perspective is about $2000 worth of cylinder head and camshaft.

The 350's in the 70s made 150hp, the 350's in the 80s made 230hp, and the 350's in the 90s made 280hp all because of improvements in cylinder head design and camshaft design, but to hit your power levels there are 40 years of parts and country hot rodder "wisdom" you have to ignore to make sure you only use the modern stuff that's actually good. That truck block is a flat tappet camshaft block, which puts you behind from the start. You need to get a picture of the lifter valley to know whether it's easy to convert it or not.

You will never make more than 250hp with those cylinder heads. And you won't make much more with that cam either. They're pretty well matched to each other and are very good at towing, off-idle torque, and fuel mileage.

400fwhp out of a 350 is going be very, very difficult. It cant be done with any factory head Im aware of and be street practical with pump gas.

Roller cams will get you extra added reliability, durability, power, and efficiency. A retrofit roller setup will cost you about $400 for everything you need. The factory roller setup will cost you about half that much. A factory roller longblock is around that price range too and will have everything you need. Instant $400 savings.

The last iteration of the Gen I smallblock chevy was in the 96-98 Silverado/Sierra 1500 vehicles. The cylinder heads those came with are the best factory cylinder heads available. They require some important machinework to make them workable for a performance application, but you could always buy a $200 set of beehive valvesprings and their retainers to make them work stock... but it's up to you. These engines are also roller cam engines. These are what are referred to as the "Vortec" engines.

The Vortec cylinder heads were designed during the original LT1 program, and are special in several ways. But a 350 with an XR276 roller cam and Vortec heads can make around 350-380fwhp in the right conditions. If you really want to shoehorn something together on a budget, that's how you do it.

You may be tempted to keep the block you have because you have it, but go see how much a Vortec longblock costs you. It may be cheaper to buy a whole new block with a roller cam and vortec heads already than to buy Vortec heads AND retrofit a roller cam onto your TBI 350 block. You can reuse the factory roller lifters unless they're damaged, and they're cheap to replace anyway. So you dont even have to buy those. You will just need to address the valve lift limitations of the Vortec heads.

If you MUST cheap out and lose power and go flat tappet, be very sure of what you are getting into. It's a crapshoot to get those working without destroying your engine and modern oils just aren't designed with them in mind. The only reason so many are still around is because they're lazy, slow factory flat tappet cams. You go with a large, aggressive aftermarket flat tappet cam that needs really stiff valve springs and you have to be many times more careful to make sure it doesn't distribute powdered metal through all your bearings in the first 20 minutes of run time. Plus you leave at least 15-30hp on the table. Plus you have to be super careful what oils you run for the life of the engine.

But be aware, the secret is out on how good Vortec heads are, so if you go looking for one of those engines, it's just for a rusty work truck you're trying to keep running, not because it's some hot ticket to building a racecar.


Also, for the record, unless they used dished pistons (very possible) it should be in the low 9's in compression. The 193 heads had 64cc chambers which traditionally is mid 9's. But those heads are garbage, so whatever compression ratio the factory setup is, it's pretty irrelevant to you.

 

Here is my lifter valley:


the vortec heads and xr276 sounds like its going to be my best bet if do able. i have already found a few sets of 906 heads. what would be the best carb/intake setup on for that?

 

Okay so you dont have the pedestals drilled, but they are there, and you DO have the tops of the lifter bores set up for dog bones.

You will need to drill and tap the pedestals and drill and tap near the front snout of the camshaft for the cam retainer plate. You drill and tap the pedestals to fit this setup in there:



The central plate is called the spider, the things around each pair of lifters to keep the from rotating around the vertical axis (to keep the roller in line with the cam lobe) are called dog bones. You can probably surmise why. Your block is machined to seat the dog bones, so you're lucky there.

This is the dogbone held in place by the leg of the spider:


This is the camshaft retainer, and you can see the two bolt holes in it, and how they line up with the two holes on the block. The upper 3 will have plugs in them.



It goes together like this:


http://www.crankshaftcoalition.com/w...ying_camshafts

You may find that interesting. I know a lot of this is peripheral to what you already know, but as it's more relevant to domestic pushrod engines, I figure more resources cant hurt you.

This is the kit you need, or one like it:

http://www.summitracing.com/parts/edl-97386

And the retainer:
http://www.summitracing.com/parts/na...8501/overview/

And these are the lifter types you'll want. I dont care about brands, I dont know, but just for the sake of budgeting to get an idea, here you go. I suggest you do your research, but for the most part the OEM lifters are just fine for the vast majority of this stuff so tht should give you an idea.

http://www.summitracing.com/parts/na...make/chevrolet

This is actually an interesting kit... seems more expensive than the other stuff separate... weird. But the roller lifters from 87+ are mostly all the same. I beleive LS lifters actually interchange with gen I lifters.
http://www.summitracing.com/parts/na...1042/overview/

And for the sake of comparison... these are the retrofit lifters if you didnt want to go that route:
http://www.summitracing.com/parts/cc...make/chevrolet

http://www.summitracing.com/parts/tf...make/chevrolet


But considering the OE type lifters and retainers are going to cost $200+, and the retrofit setup $300-$500, that's why I say you may want to just start with another long block. The cost of the long block is almost nothing in the big picture, because chevy's are a dime a dozen and fast chevy's cost 5-10 long blocks worth money to build when you ignore machinework.

If you were willing to sacrifice reliability, durability, and performance for the sake of cost, you could always run a flat tappet cam and lifters for $200 or so for a set. You should at least be aware that's an option. Just make sure you do your research on break in oils, and the last 10 years of history of flat tappet cam and lifter lobe failure, ZDDP, etc. Even on cams with teh same measurements, rollers are going to have far more aggressive ramp rates and will always make more power, but you can go bigger on a flat tappet and compensate in some ways. But you sacrifice some of your streetability and your power band to do it.

If you get Vortecs, thier main drawbacks are they cant handle lift above .470". This can be compensated by using beehive springs ($200 a set) or by having a machine shop mill down the valve guides so there's more room between the retainer and the guide at max lift. That SHOULD be cheap. They also need special intake manifolds. You dont have a standard one so the lack of interchangability isnt a huge problem.

Vortecs also don't see much, if any flow increase beyond .480-.500" lift, so massive lift cams are not going to help you, you just want to bump them open soon and leave them open a while. But cams with lifts up into the mid .500's are going to cause you frustration with valve guide to retainer clearance and they wont get you much performance benefit. The two main theories are you get the biggest cam and dont worry about lift, just get it open and let the fact that the valve is open longer compensate for the lack of extra flow above the high .400's in lift, or you find a cam that doesnt open past .500 or so. For the most part your hands are tied because what's available is what's available, just know that if you have an option to buy two different cams of the same basic measuremetns, and they're both the same major product line, get the one with the lower lift numbers. You wont see the benefits. Stick with something at least in the mid 220's in duration. The XR276 is around the point of diminishing returns for Vortecs in terms of streetability, wide power band, and good peak power. You get a little more power by going bigger but you start losing more in other areas.

carb and intake... given your stated goals... and the setup I jsut described, I think the obvious intake/carb setup is an Edelbrock Performer RPM and a Holley 650DP or equivalent from another company (Quickfuel, etc). If you want to pay extra money for something that looks cool but doesnt really do anything, you can buy the Air Gap. But it has the same ports and the same flow numbers as the regular Performer RPM intake.

http://www.summitracing.com/parts/ed...Faxr7AodORcAuw

http://www.summitracing.com/parts/hly-0-4777c/overview/

http://www.summitracing.com/parts/qft-hr-650/overview/

The lighter your car the better that setup will work. It also works better for a manual, which you say drift car, so I hope it's a manual. I will also say for drift, you CAN use a T5, but any kind of repeated clutch kicks and drops on sticky tires WILL blow it up. ESPECIALLY in 3rd gear. But if you use regular street tires and arent doing hard drag strip launches on it all the time, it may hold a while. It's an interesting conundrum. It just might hold.

The thing is that T5's are $250 per. So you can almost afford to change it out every year. They're almost cheaper than their clutches. They're also pretty lightweight which will be nice too. But you may want to be prepared for a T56 swap at some point in the future. But if you can baby hte T5 and get by without beating it too much, you may be all right. Just be aware even the penny pincher setup listed above is MORE than enough power to destroy it in the right circumstances. Ive heard of them being killed behind v6's. They're just not very tough, but they're common and cheap and some of them will keep on ticking for a while, you just cant count on it.

An LT1 T56 isnt a straight bolt on, but it's not far from it. All the parts to convert it are available from various resellers and no fabrication is required. A new crossmember is really the main conversion part needed. The T56's are built like tanks. I've put mine through hell and it makes all kinds of horrendous noises but they're just hard to kill. They were factory rated for 450 ft lbs. The T5 is factory rated for 300 I think? An LT1 T56 setup sells for $800-$1500


Yet another option I think you MIGHT be wise to consider since there's not much money spent yet... just feel it out. Get an LT1, aside from the optispark issues they tend to have, they are very good engines. They're the same as a regular 350 internally, but they run ridiculously high compression an therefore can handle MASSIVE camshafts. The intake is good, teh computer is adequate and is worth keeping to tune. To make a 400hp LT1 takes nothing more than a cam swap and a tune. 400hp is the upper limit with their factory heads, but it can easily be done. An LT1 with a cc503 (about the same as the XR276) can hit about the same power levels of what we're talking about, more actually, and you can get a healthy pullout LT1 for $400-$1000 with computer. Just throw a cam and valve springs in it (it already has all that roller stuff I was talking about) and you have a 400hp 350. You can bolt a T5 to it, it bolts in place of the factory mounts. Stock thirdgen headers will bolt up, but D-port headers are preferred. The only complication I can think of is you will need all the accessories from the donor car, as your factory accessories and brackest wont bolt up. ANd then you'll need to do something about one of the power steering lines, but if you do a search that was figured out a long time ago. You buy a line from a specific car and it will fit just fine. Engine swap forum should have it.

If you want 375-400hp for $1500 or less, the LT1 swap is very, very hard to beat for the money. Add up the costs involved, the costs invested, and figure out your goals.

 

.

 

i was doing some reading and read that with just oem roller lifters, a dogbone/spider and roller cam and retainer and ill have a roller block, is this true? the retro fit got me a little confused if i must say. also i like the idea of the lt1 and will look into it, but i was going to try and stay carbed if i could.

 

235's are pretty narrow... you sure? A more typical size for a 17x9 is 275/40/17.

The dog bone setup keeps the lifters from rotating, so the roller wheels stay pointed the right direction. IF you cant use the OEM setup like I told you to install, like everyone else who has a 1956-1986 block, then you have to use the really expensive ones with the link bars. They serve the same purpose, but cost much more money. So basically, yes. The retrofit lifters that are $400 a set are for old blocks that do not have the pedestals and machining that yours has. Unfortunately the truck blocks were one of the rare exceptions of 87+ blocks that didnt get roller camshafts. They were casted in the same assembly line for the most part, but they just didnt get the holes drilled and tapped because they didnt need it. You basically have the option of going the retrofit roller route, or going with the OEM roller route.

One more thing, you can carb an LT1 using all the same parts you use to carb an SBC. They require a special intake, but beyond that, everything else bolts up just fine.

http://www.summitracing.com/parts/nal-24502592

You lose some of the major advantages of the LT1 that way. The LT1 EFI intake is one of the very few really good ones, as it can breathe to VERY high RPMs. The extra parts investment make it not quite as attractive as a budget option also.

 

alright, sounds good. i think i am going to look into oem roller route. I have a set of 906 heads i can pick up. and then ill get a decent cam.

What how bad are the downfalls of staying flat tappet and just getting a kit like this:
http://www.summitracing.com/parts/cc...make/chevrolet

 

That cam will only make 300hp. It will need special care taken make sure it doesnt destroy itself and put powdered metal through your bearings. It will make less power. It will need very close attention to valve springs. Too soft and you'll have valve float, too stiff and you'll flatten your lobes. This is not stuff peculiar to that cam, it's stuff you have to address with ALL flat tappet cams. That particular cam, being on the smaller side will be easier.

Flat tappet is less reliable, makes less power, is less efficient, and is less durable. The bigger the flat tappet cam, the more true that is. That is a pretty mild one. It's actually the one that I have and the car is GREAT fun, but I wish every day I had gone larger with the cam. In fact I wish I had gone with a roller cam all the time now. I always worry about wiping lobes when I push it hard.

But it's been in the car running well for about 4 years now. Vortec heads 350 just like what you're talking about. With the very cam you listed.

 

Well you said what i wanted to hear, and what ive been reading. That cam, vortec heads, intake and carb will fit my budget amazing!

would this cam be a bit better?
http://www.summitracing.com/parts/cc...make/chevrolet

 

I wouldn't go for that kind of "thumpr" cam. They're just set up to sound cool, and that's about it. If you're not upgrading valve springs on a vortec set of heads, I wouldn't go above .420, either, due to "'The limitation is the clearance between the bottom of the retainer and the top of the valve-guide seal. total 0.450” retainer-to-seal clearance. Max. Valve Lift: 0.420” which allows 0.030” retainer-to-seal.'" (http://www.hotrodders.com/forum/vort...ift-32857.html)

I got bored, so I got you a ballpark estimate on what you're wanting to do from Engine Analyzer, assuming 10:1 compression, thumpr cam, stock clutch fan and water pump.



Happy building!

 

I am going with the xtreme energy cam linked above. from the past 4 hours i spent straining my eyes most atricles and forums i read say .488 is max lift for vortec heads, so im going with a .469 on ex. also these heads will be going to my machine shop so i will have the guide bosses machined, and i believe the springs in the kit are upgraded, but im not sure. a call to summit can answer that.

 

Wel, more power to ya, bud. I used the same specs and changed the cam in the program to the "xtreme energy" cam, so you can get an idea of the difference. If I were you, I'd go with more duration, though, especially for a "racecar" build. Something like this.
http://www.summitracing.com/parts/sum-1106

Maybe even the next step up, if you can get your cylinder guy to machine/work the heads to take it.

http://www.summitracing.com/parts/sum-1107

Also, I hear some people complain about these cams being of "inferior metal", but I also see lots of success with these cams. Take it as you will.

 

99olo, that's fascinating....

i agree the thumpr cam is sort of a gimmick. If you want a bigger cam, go a step up in the xe series.

I also find it interesting that my car is 3550 lbs with me in it and normally traps at 102mph. That is, according to the online calculators I use, 309hp. Interesting how close it came to your program. Probably more of an interesting coincidence and the margins of error for both are probably on the order of 10-20hp, but still it's a good sign. Your chart says peak hp is 313, my estimated peak is 309. That's close.

I dont know about using a summit brand cam. Those are usually mainstream manufacturer hand me down old school grinds most of the time. You can get the same power with much better street manners from a much more reasonable cam if you buy a more modern grind. Vortecs have terrible exhaust port flow, so a longer duration on the exhaust is helpful, and with a stock bottom end (that seems to be what you want to do) you probably dont want to go past 5500 RPM very often. 6000 is fine with good rod bolts but even then I'd be a little wary about it. I'd aim for something that's 2000-6000 RPM range at most, which is usually about 230/230.

BUT.... I've always wondered if comp was blowing smoke up our butts about the thumpr series having a wider, flatter torque curve (The xe262 has a massive table top torque curve by itself... so...) which I figure might be better for a road race/autocross style car. They specifically mention endurance racing cams as inspirations for those grinds. But at the end of the day they're still just designed to get the most lope possible while having the torque curve come in as early as possible. I dont think power or performance was their goal there. They make power but I think something designed to 1. Make power 2. be reliable is going to probably outperform somethign designed to 1. sound good 2. be drivable.

99olo, can you throw in an xe268 and a 280H in that program and show us how the power curves look? A lot of guys here run vortec heads and Im pretty impressed at how close it is to my estimated numbers on my build, so I'm curious, and maybe it will help some other people too.

 

well i like those numbers, and im not looking to get crazy at the machine shop. this is just a slap together build to go out and beat the snot out of.

 

Alright bud, depending on what you wanna do, do whatever. I'll throw you a different graph with the 1106 camshaft, which is the best looking set of numbers, and should work with your heads.

Happy HP hunting.

 

Sure thing. Remember, I don't know the exact specs on the heads, so these specs are for comparison to eachother. If I knew all the head specs, what kind of accessories he's running on his car, I could give you much more exact numbers.

The first is the 268, the other is the 280h, which has a surprisingly large amount of lift for it's 230 duration.

 

Like I said... your ballpark estimate was within 4 hp of my estimate, and I've always heard the trap speed + weight estimates are far more accurate than even dynos... so whatever assumptions you're running seem to match pretty well to my setup, so that's why Im so curious. I've been wondering if a 280H could net me another 20hp. Looks like it wont... but yeah we all know these are just ballpark numbers. Fascinating exercise. Im actually kind of surprised these are all so close to each other. Makes you realize how important cylinder heads really are.

 

those numbers are nice. my build might have just gotten a little bigger (budget all depends on what i can get rid of from my import parts collection) so we will see. but i plan on going elec water pump and fan. just running a alt and ps pump. but i am also going to be looking into going roller possibly. and for up top it will be single plane intake, 650-750 carb. but i might look into bigger valves and getting more into the heads

 

Hey, let's hope the numbers I get when I actually know what my heads will do are correct.

This should actually be the minimum numbers, as I made what had to be estimated on the low end of the spectrum. You'd be surprised what kind of high rpm power you gain when eliminating clutch fan and mechanical water pump.

 

Remember, to make power, you have a couple basic options.

Rev it up, or give it more displacement.

If you're gonna rev it up, I don't recommend going over six grand with the stock rotating assembly. Replace the rod bolts, which is the weakest stock part, and I'd go to 6500. Balanced and whatnot will net you more, but I'd try keep it to the low end of the spectrum. Roller's good, but don't overestimate it. There are better things to spend your cash on, like fancy rocker arms, lighweight valves, and porting.

 

on other motors, ive noticed the difference after deleting the two.

on another note, can someone direct me to a good valve/spring setup for the vortec heads if i wanted to do new valves and heavier springs. i want to build this motor for high rpms is i can. and if im doing that then i can also shop around for a bigger cam, tappet or roller. i want to price out both builds to see what im up against

 

"The Sallee Chevrolet solution is to use Crane Cam’s 10309-1 drop-in valve spring and retainer kit which is good for .550” lift with no machining. The installed height for this Crane Cams kit is taller and the lower part of the retainer is shorter. The “AVERAGE” clearance between the retainer and seal is .575” for this kit. We have found that some of the Vortec heads, coming from the factory, do not have the valve seals driven on all the way. You need to check that they are before installing this kit. If they need to be driven on all the way, we have found that a 3/8” drive - 1/2” socket fits the valve seal just about perfect.As with all modifications to performance engines though, you should always measure to assure that there is proper clearance and fit.

Comp Cams sells a tool that will cut down the size of the Vortec valve guide and is around $50 or so.

Another method is the infamous Vortec retainer "ghetto grind". If the camshaft being used only requires a stock 1.25" diameter single-wound valvespring, it is possible to only need to grind off approximately 3/32" off the bottoms of the stock Vortec retainers with a grinder or on a grinding wheel to achieve enough R-G clearance to run up to approximately .530" -.540" safely. I must caution here that R-G clearance must ALWAYS be checked to verify that there is in fact enough clearance - also include allowing for coil bind. One other thing - you must remove the dampner in this modification. Don't worry -- the stock Vortec valveguide being much larger in diameter than other SB heads will act as sort of a dampner and I never noticed any RPM issues related to lack of running one when I did this mod. Although myself and others who have done it this way have had no problems, I must caution this basically for those on a strict budget and cutting down the guides either with the Comp tool or at a machine shop is the best way to go. However, I'm of the opinion that since it works well within the noted constraints, then you're really only out your time to grind down the retainers. The choice is yours."

I found this here: http://www.nastyz28.com/forum/showthread.php?t=56505

I'm no vortec guy, but this guy seems to be.

 

Bigger valves wont help much with Vortecs. They're a really special head with a lot of very advanced air flow research into them. Thats why they work so well. The less you mess with the ports and the valves the better. The only thing I woudl recommend is going a little larger on the exh valves, but that wont help unless they're ported. But after the burn all the fancy air flow port velocity swirl blah blah blah that the vortecs are so good at dont matter anymore. Just trying to get the air out of there. I remember reading that the gains with alrger valves are almost nonexistent unless you do the exhaust and the exhaust ports. IF you only put in larger valves your exh flow actually decreases.

I obviously am a huge proponent of roller cams... but it's becoming more and more clear this is not a street car nd it's not a street engine. You dont need it to last for hours and hours idling at traffic lights and you dont need to drive down the interstate with it and you dont need to get good gas mileage out of it. Big roller cams make big power, but vortec heads are not going to see as much of a benefit at that end of the scale as you'd like due to their lift characteristics.

Plus you told me via PM you dont mind running weirdo Rotella oils all the time. So flat tappet actually makes a little more sense now than most. you can make power with flat tappets, it's just not as guaranteed to live a long time.

Now we are getting itno a situation where we are clearly pushing the factory rotating assembly far beyond what it was designed to do. With more power from the same displacement comes more RPM's (assuming heads stay the same). When you go up in cam size you're shifting that power band up and up and up. Thats one of hte advantages of rollers, they're so much more aggressive at getting the valves way open that you get the benefits of the next size cam as far as airflow, but you dont have to push up the RPMs any farther to do it.

But if you want the power, I think you should go ahead and get a big flat tappet, xe274, 280H, something like that, and get some ARP waveloc rod bolts put into your connecting rods. I cant guarantee it will last forever, it probably wont, but you're at least giving it a fighting chance if you do that.

If thats how you want to do it, I would also suggest you NOT do any significant work to your cylinder heads. BEcause when a rod lets go, it's going to take out one of your heads in the process most likely. If that's the case and you go flat tappet, you can actually get by with beehive springs. They're better and more high tech, but cost a lot more.

Do some research into the GM yellow (now blue) springs. They are designed for the Gen III/IV family. They have less mass and can control the valvesprings better. The smaller top the spring allows for a smaller retainer. The difference in retainer thickness gives you an extra .050" of valve lift clearance. With something like an xe274 flat tappet cam, that's plenty. They go to .490 lift whereas the beehive retainers generally give you up to .530 or so. As olo said, you ALWAYS have to check, ESPECIALLY with Vortecs. This is their main achilles' heel.

BTW, the retainer you need to run the GM springs i mentioned, are part number 787-16. These are the springs: https://sdparts.com/details/gm-perfo...parts/12499224

Their seat load at 1.8" installed is a little low, but that might be perfect for break in, but not at high RPMs. I would run them at 1.8 for break in. And then shim them up to 1.75. That should get you into the 110s or so seat pressure which is in line with what comp recommends, and you will lose .050 off your coil bind height, which is generally regarded as .550 for those springs, regardless of what GM claims. So you still have a .010 safety margin between max lift and coil bind that way. Maybe shim a little less than .050. It's not super complicated, just look into it a little. The heads will require machienwork to fit comp's recommended 986-16 springs in there. But these will drop right in place. Not ideal, but if you can have a machine shop check out the spring pressures at various heights you can figure out if they're adequate or not. Just buy 1 and have em check it for ya.

I suggest it so that when/if a piston lets go, you can buy another junkyard short block and throw more vortec heads on them with just throw on parts from your old heads.

Otherwise, you can go check this out... Same basic idea as the beehives but Im thinking this guy has some kind of setup where he buys retainers that are already "ghetto grinded" in a professional way. For flat tappet spring pressures, it should be fine.

http://www.alexsparts.com/valve-spri...d-flat-tappet/

Vortec heads are popular and there are lots of different available methods for making them work. In your case since they're more or less expendable heads... you may want to avoid investing machine work into them.

 

He's right.

If I were to do machine work to heads, they'd be some cheap 882 smogger heads and I'd do it myself (At least the porting). They can flow a lot, but there's no guaruntee they'll last for a long time. Perfect for a race motor of sorts.

 

Well... those would really kill the compression ratio, so he'd need to mill them. It starts adding up. But he does have the swirl port 193's on his long block... Maybe he could port the hell out of those and make them work? I think after you grind out the ramp you're really getting into some mismatched port volume/cross section territory, though.

 

Hey, didn't he say he was gonna...

Oh, you said that. "the heads are garbage, the pistons will be replaced by the correct overbore size during the machinework phase, so what the compression is on them is mostly irrelevant to pretty much everything."

Well, if he does replace the pistons and do the machine work, he can get a piston with some dome to it.

 

My plan from the start is arp head studs and rod bolts to help the durability. i have yet to look into pistons/rods, but if im not doing much to the heads then it might be an option. any good suggestions on the cheaper side? taking the short block apart i was on the fence about because i do have a feel this motor will be short lived.

And this car will hit the streets but no worries about that

 

Rocker studs are a good idea, but I'd recommend you look into pinning the studs, cheaper alternative. regular head bolts are fine, no need for studs there.

Id leave the pistons alone unless you bore it. Costs escalate very very quickly from there. Just a ball hone and new rings will suffice for you.

 

okay, ill look into everything. should i just run oem head gaskets?

 

Felpro will be fine.

 

You may want to look into quench distance articles. Ideally you want .040" between the top of the piston lands and the quench pad on the cylinder head (the flat part). This gives you a lot of extra power and detonation resistance. You can just throw some feeler gauges in there and take a conservative estimate, and get a head gasket to keep that distance at .040. From the factory it should be .025 so even the thinnest normal gasket, a .026ish is available I think, would get you at .050. But it keeps things closer to ideal than if you get a normal. 040 head gasket. You can figure that out when the time comes, but just a regular fel pro is fine too if you just want to slap it together.

Here is a rocker stud pin kit:

http://www.summitracing.com/parts/mrg-806g

As you can see, almost nothing to it. You'll need to drill through each boss into the stud and put the roll pin in there to keep it from pulling out. For a big flat tappet, that's more than enough. Going flat tappet does allow you to take several liberties as the spring rates they need are much milder.

Read here for a much more in depth discussion of it:

http://www.hotrodders.com/forum/how-...ec-154788.html

 

Hey Infernal. For what it's worth, my (old) unported Vortec headed 350, with an XR276HR and 10:1 SCR/8.03 DCR, 700R4, 3.27 rear gear and 3750 lbs (staged) trapped at 107 mph. 20+ mpg too.

 

Why is your car so heavy?

 

It seems to be about the going rate for an 86 IROC.
Iron heads, T-tops, full interior, power everything (except seats), Dana 44, IROC rims, 700R4. Plus me at 230.

 

I do think "pinned" studs have a time and place.I have seen drilling the boss create stress on the boss leading to it cracking where a conversion to screw-in studs would not have.A threaded hole is by far stronger.

 

a 6500 rpm factory shortblock and factory heads with flat tappet cam valvesprings is about as clearly the place for pinned studs as youre gonna find. Just my opinion.

 

Be sure to let us know how everything goes on this build. I'm curious to see what happens and what you do.

 

The thing is guys that run over just abit over redline and bounce off the rev limiter are more people than I care to count.

 

Depending on what cam he runs, I'm not sure pulling studs out would be a problem for him. But it's always nice to have the extra insurance. Maybe if he gets screw in studs, he can re-use them if/when something so south.

 

I'm thinking a xe274 or 280h, beehive springs or those other ones linked, and I will be doing upgraded studs, this motor will see rev limiter, most likely a msd setup of sorts