S-10 Forum banner

1 - 20 of 32 Posts

·
Registered
Joined
·
164 Posts
Discussion Starter #1
So the forum ate my first thread on swapping parts and all the questions that get asked all the time here. I'll try again.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #2
Again...the forum ate my post. I'll try this again when it's not 1AM and I have the patience to deal with a 10 minute post timeout.

For now, we'll start with the basics: Valve covers.

The stock stamped steel valve covers on the S10 are notorious for developing oil leaks. The main reason this happens is the rubberized cork gaskets shrink over time and that starts the problem...people go out and "snug up" their valve covers, trying to stop the leak, but no amount of "snugging up" will stop an oil leak once it starts-you need to remove the covers and clean off all the oil, and replace the gasket. Unfortunately, repeated "snugging up" will cause the valve covers to warp in around the bolt holes and then no matter how tight you get them, they still leak. Bummer.

One solution to this is to replace them with the much more rigid cast aluminum units from the Fiero 2.8L V6...the same engine, but slightly fancier. The valve covers you want look like this:



They tend to command a high price on the forums and ebay...but at a junkyard they are generally 25-45$. The cast aluminum covers are not prone to leaking or warping from having the bolts over tightened-but they can be broken or cracked from over tightening. The oil filler will be on the driver's side, and the PCV system may need a little reworking of the hoses, but they are a direct bolt-on. You do need to make sure the PCV system is hooked up-without it you will have neverending oil leaks. Do NOT just block it off!

This swap is very simple, and takes about an hour to do-you want the tops of your cylinder heads and all the sealing surfaces to be spotlessly clean when you assemble it, or you can wind up with just as bad an oil leak as you had when you started.

When you're finished, it will look something like this:

 

·
Premium Member
Joined
·
438 Posts
Great thread. Thanks.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #4
Next on the list: TBI Upgrades. Upgrading the TBI won't make a massive difference on it's own, but with a heavily modified-or even a 3.4L bottom end under your 2.8L manifolds-it is beneficial.

I know that some of the early 2.8's were carburated. I'm not going to cover that here-I'm a EFI guy. But, there are some upgrades than can be done to the stock fuel injection system and that work OK. First, the biggest issue in getting these mods done correctly and making them functional is KNOWING WHAT YOU HAVE. These 2.8L trucks are all 26 years old at the newest. They've been modified, upgraded, engine swapped, hacked, chopped, restored, resto-modded, and driven into the dirt. You just have got to know what you have, before you can make an effective upgrade.

The Stock 2.8L throttle body has a pair of 35mm throttle bores, and 33lb/hr injectors. This is enough fuel-but you can make a *little* more power and make the truck much more responsive by upgrading to the 4.3L TBI unit. The 4.3L TBI unit has 43mm throttle bores, and 45lb/hr injectors. There are a few different models of this unit, but specific modifications are needed for automatic trucks to make sure the throttling cable for the transmission works properly-without this cable being properly adjusted, transmission damage WILL ensue.

The best solution to this issue is to get a TBI assembly from an early 4.3L Chevy Astro or GMC Safari van. Most commonly, a 1991 or 1990 van will have the correct throttle bracket. The throttle bracket and throttle pull arm are the same as the 2.8L S10 TBI assembly, so to install it on your 2.8L engine, all you need to do is swap the injectors for 2.8L injectors, and bore the intake manifold to the larger diameter throttle plates. You can do the intake boring with a carbide bur installed in a drill chuck OR using a milling machine-but you will need to remove the intake from the engine to make sure no aluminum filings or tools get dropped in. I've heard of people stuffing rags down the intake to catch shavings, and I've done it myself a few times over the years-but it's just not good practice.

This is what your intake manifold will look like when it's bored to fit the 4.3L TBI unit:



Keep in mind-YOU MUST swap the injectors! Not swapping them will cause a HUGE rich running problem, and the computer WILL NOT compensate for it.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #5
So let's talk about headers. What fits, what doesn't, and what's worthwhile and what's not.

Shorties versus long tubes...For a mild to moderate street truck, it does not matter. Shorties are easier to install, but are harder to tune to the correct length, while long tubes are harder to install and can be easier to get to the proper finished length. So what is the correct and proper length?

For a 2.8L stock engine, the tuned length is 49" to the final merge collector for 1.5" primary tubes and a stock cam. This is NOT the length of the primary tubes! This is the total length until both the left and right side manifolds merge together. But wait, isn't true dual exhaust the "best" exhaust? No, not at all. It's neat and can give boosts in some applications, but more often than not, a single-piped engine with a properly tuned exhaust system will outperform a true dual exhaust system.

What if I have an aftermarket camshaft installed? The exhaust merge length changes with camshaft duration and lobe separation angle (we'll get to those in our next post.) Basically, as the camshaft's exhaust duration gets longer, the header tuned length gets shorter. As the exhaust valve closing point gets earlier, the header length gets longer.

Hedman 69370 headers will fit all years of the 2.8L S10. No provision for EGR or AIR injection, though. About 250$, nicely made, properly sized for iron-head and aluminum head engines-Aluminum head engines will require removing and replacing the header flanges.



Another option is Hedman 69376. This again will fit all years of S10, and is a shorty header. 1.5" primaries, no EGR or AIR injection, and nice to make mate up to the stock exhaust routing.



Seems to be that at the time of this post, those are the only header options I can find new. Used headers are a crap shoot-you really need to see them in person to see that they're not rusted through or seriously tweaked.

Another option is to build your own headers. This is the only option for the aluminum head swap, as the flanges will NOT fit-the bottom bolts are moved much lower on the head and many header flanges won't reach. Some flanges can be slotted and will have enough meat to fit the aluminum heads, but only the round-port heads.

Here's a shot of the stock iron 2.8L heads:



And here's a shot of the aluminum 2.8L GenII heads-these are an improvement on the iron heads, but not as good as the GenIII heads.



More info on next post.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #6
So let's talk about headers. What fits, what doesn't, and what's worthwhile and what's not.

Shorties versus long tubes...For a mild to moderate street truck, it does not matter. Shorties are easier to install, but are harder to tune to the correct length, while long tubes are harder to install and can be easier to get to the proper finished length. So what is the correct and proper length?

For a 2.8L stock engine, the tuned length is 49" to the final merge collector for 1.5" primary tubes and a stock cam. This is NOT the length of the primary tubes! This is the total length until both the left and right side manifolds merge together. But wait, isn't true dual exhaust the "best" exhaust? No, not at all. It's neat and can give boosts in some applications, but more often than not, a single-piped engine with a properly tuned exhaust system will outperform a true dual exhaust system.

What if I have an aftermarket camshaft installed? The exhaust merge length changes with camshaft duration and lobe separation angle (we'll get to those in our next post.) Basically, as the camshaft's exhaust duration gets longer, the header tuned length gets shorter. As the exhaust valve closing point gets earlier, the header length gets longer.

Hedman 69370 headers will fit all years of the 2.8L S10. No provision for EGR or AIR injection, though. About 250$, nicely made, properly sized for iron-head and aluminum head engines-Aluminum head engines will require removing and replacing the header flanges.



Another option is Hedman 69376. This again will fit all years of S10, and is a shorty header. 1.5" primaries, no EGR or AIR injection, and nice to make mate up to the stock exhaust routing.



Seems to be that at the time of this post, those are the only header options I can find new. Used headers are a crap shoot-you really need to see them in person to see that they're not rusted through or seriously tweaked.

Another option is to build your own headers. This is the only option for the aluminum head swap, as the flanges will NOT fit-the bottom bolts are moved much lower on the head and many header flanges won't reach. Some flanges can be slotted and will have enough meat to fit the aluminum heads, but only the round-port heads.

Here's a shot of the stock iron 2.8L heads:



And here's a shot of the aluminum 2.8L GenII heads-these are an improvement on the iron heads, but not as good as the GenIII heads. Se how the lower bolt hole is right down over the head gasket now?



More info on next post.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #7
Speaking of Aluminum heads and exhaust ports, this is a GenIII exhaust port, with a flange fitted over it. This is the flange you need to graft onto a factory-made header for these head swaps.

 

·
Boozebag
Joined
·
8,997 Posts
Xnke...
I'm not going to jack, but how about some info on the earlier and later cranks, balancing, block info and the 2.8. 3.1, 3.4 and the double cam engine?
Good start to this thread...
 

·
Registered
Joined
·
164 Posts
Discussion Starter #11
All of the following engine data is for Generation I and Generation II engine blocks-the Generation I engines being the iron head engines, and the Generation II engines having the Generation II aluminum heads. None of these engines have roller lifters, or the provisions for them.

The 1980 to 1985 60*V6 engines were built initially with small crankshaft main bearings and external engine balance-meaning that the crankshaft does not have enough mass in it to fully balance itself without having an extra weight on the flywheel. These engines are junk for any kind of performance-the crankshafts crack and break through the main bearing journals frequently. There are no definitive external identifying marks.

1986 to 1988 engines have the bigger main journals and stronger crankshafts-but are still externally balanced. These are "usable" but not ideal-the flywheels are getting harder to get, and you MUST use a pre-1988 flywheel. It MUST have the balance weight cast in to the back of it.

The 1988 and newer engines all have the larger main journals and internally balanced crankshafts-meaning the flywheel is neutral balanced. All 2.8L iron head engines from 1988 and up are internally identical, the only changes being the camshaft profile. All the longitudinal mounted (rear wheel drive) 2.8L iron head engines from 1988 and up will have a big "L" cast into the driver's side of the engine block, and are smooth cast-no ribbing. This block casting does not have the provision for the crankshaft position sensor or the camshaft position sensor, but it does have the redesigned main bearing webs for the larger crankshaft bearings.

This is a poor picture-I hope to update this with a better one that shows the side of the block in more detail later. This is a smooth cast block.



Now, you'll note I mentioned all the RWD 2.8L IRON headed engines are identical...and they are. However, there are Transverse-mounted engines as well...and they have blocks cast with a "T" into them. This includes the Fiero and the aluminum headed front-wheel drive engines. Some of these blocks are ribbed, and aluminum head blocks have provision for the crankshaft position sensor in the passenger side of the block. All the "T" blocks have the starter mounted to the opposite side of the engine from the "L" and "F" block castings, and the bolt bosses for the accessory drive and engine mounts are not the same-a transverse mount engine block will NOT bolt up to longitudinal engine mounts!



Remember I said that only some "T" blocks are ribbed?



None of the previously mentioned blocks have had any internal reinforcing, only some of them have external ribbing, and all of them have the same cylinder bore, be they 2.8L or 3.1L. Now, we'll talk about the "F" casting blocks-the 3.4L F-body engine. There are some significant differences in the casting, namely the provision for both a camshaft position sensor and a crankshaft position sensor, the blocks are thicker cast in the main webbing and they have external ribbing cast into them to stiffen and reinforce the block. The ribbing on these is quite a bit thicker than the older ribbed "T" blocks. The bore is larger diameter as well.



There is one more engine block casting out there for these engines-the GMPP "Bowtie" part number 10051141 aluminum block. These blocks are not worth the effort or cost to bother with-they are just too expensive to work with. They DO weigh only 59lbs, though! They're not produced or available anymore from GM, and with total production under 1000 units, you're just not likely to find one out there. However, I'll hit the highlights for completeness.



The Bowtie block is cast in aluminum, the main webs are solid cast, and the external ribbing is similar to the "F" casting 3.4L block. It is fitted with cast-in-place iron liners that are too thin to bore to the 3.4L bore size, so without replacing the iron liners the maximum displacement is 3.25 liters. MANY of these blocks are cracked through the lifter gallery, just like the iron blocks, and these blocks do not have provisions for roller cam followers. These blocks are all machined for steel four-bolt main journal caps, and the caps are still available from GMPP. The front and rear cap are both cast iron 2-bolt caps, but the middle two caps are billet steel 4-bolt units. The aluminum block is drilled for both starter patterns, and it has the provision for the crankshaft position sensor but NOT the camshaft position sensor. This block is drilled for priority main oiling, but is also only machined for the two-piece rear main seal-it will need to be remachined for a one-piece seal to use any of the common 60*V6 cranks. The aluminum block has bosses on it for both rear-wheel drive and front-wheel drive engine mounts and accessory drives.

Next up is crankshafts...and keep in mind we're not even to the aluminum head blocks yet!
 

·
Registered
Joined
·
164 Posts
Discussion Starter #12
So, Crankshafts, Connecting Rods, and Stuff.

There are several crankshafts available for these engines, and lots of little details that will make a crank suitable or not suitable for different engine applications. All but one model of the stock GM crank for the 60*V6 are cast iron, with the exception being SOME of the 3.5L LX9 crankshafts. The forged crankshaft will be marked with a 7484 on the nose of the crankshaft, right behind the front crank damper. If it's not marked there, it is NOT forged. More on the forged crank in a minute...it's not a direct swap.

First off, we have the old small-main-journal 2.8L crankshaft...Don't use this crank. They have a poor reliability record and are just not a good starting point.



All the crankshafts are marked-there are two different markings for the cast iron crankshafts, for ALL years. FWD, RWD, there are only two cast iron crank markings-the 2.8L and 3.1L. Even the 3.4L and 3400 engines use cranks marked 3.1L.

The 2.8L will look like this:



And here's a photo of a 3.1L crank:



2.8L crankshafts have a 76mm crankshaft stroke, while 3.1L and 3.4L engines have a 84mm stroke.

Now, remember I said we wanted the internally balanced crankshaft? This is an internally balanced crank. Contrast it with the externally balanced crank in the first picture above?...see the difference?



You might notice that the 3.1L crank above has some notches cut into that center round ring on the internally balanced crank. Those notches are for the crankshaft position sensor used on the distributorless ignitions, and are found on most FWD and the 3.4L RWD engines. It is a standard GM 7X pattern, meaning that there are 6 equally spaced notches, and one extra notch 10* from the notch signifying Cylinder #1.

Here's one in the block:



Those are the cast iron cranks available. Remember I mentioned a forged crank out there? It's for the LX9 3500V6, and only SOME of those engines got forged crankshafts. Only cranks stamped 7484 on the nose are forged. They'll have wide, flat parting lines, smooth, rounded corners and have undercut radii on the bearing journals, similar to the 2.8L and 3.1L cast cranks above.

This is a forged 3500 crank:



Notice a few things? First, it's internally balanced, and the reluctor ring is a 58X ring...just like the later GenIV LS engines. Also, the connecting rod pins are 2.5" instead of 2"...much too large for the stock 2.8, 3.1, or 3.4L connecting rods.

So, the rod pins are too big, and the reluctor ring is wrong...both are fixable. The reluctor ring is press-fit onto the crankshaft-and the surface it fits on is the same diameter as the old 7X ring. But wait...there's little punch marks in the face of the ring?



Those little punch marks are exactly the old 7X pattern, and it's clocked properly! From here, it's a simple matter to have the old 7X pattern milled into the reluctor ring, and then you can use the crank with the older 7X computer systems. Or, if you're carburated/distributor timed, you can use this crank as-is if you use the matching rods.

Matching rods? Yes. Remember how I said that all the connecting rods were the same forged steel rod in the 2.8, 3.1, and 3.4L engines? They all look like this:



All the rods for these engines, both rear wheel and front wheel drive, are the same...2.00" crankshaft pin, 5.7" length, with a 0.906" diameter wrist pin.

But then we get to the 3.5L engine...and the rods change. The rods are now powder metal, and have cracked caps...meaning they can not be resized. The bigger issue is that now the rod journals are 2.250" diameter...a full quarter-inch bigger than the older engines!



Now, this DOES make for a stronger crankshaft! But it also allows us to use that forged steel crank to offset grind for more displacement. The 3500V6 forged crank is still 84mm stroke-same as the 3.1L and 3.4L cranks...but we can push that out to 90mm with offset grinding. That takes our engine from 207 cubic inches for a stock 3.4L, to 219 cubic inches. Boring the block, we can pick up more displacement, and staying with commonly available oversize pistons we can get to 226 cubic inches.

This all uses the 3.4L RWD engine block, by the way. There are STRONGER blocks out there!
 

·
Registered
Joined
·
2,132 Posts
Couple corrections:

Balancing: The change from external to internal balance was in the 1987 model year, the same year the genII 60* V6 was introduced. It's possible that some left over externally balanced engines made it into some of the longitudinally mounted applications, but the official change was 1987 MY. There were no genII 60* V6 engines that were externally balanced.

The LX9 crankshaft: There's rumors of non forged cranks in these engines, but no one has found one yet, that I've seen or read about. I've had 3 of them personally, plus a few that belong to friends and all were forged 7484 cranks. This crank will also not directly work in the earlier blocks, especially genI/II, due to the rods interfering with the pan rail, and I believe the pan rail was pushed out slightly for the LX9 block AND it's also clearanced where the rods get close to the pan rail, along with the pan being cleranced in the same way. The crank by itself will slide into teh older blocks, the mains are the same and spacing is the same, but the larger journals take up quite a bit more space.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #15
I've got two LX9 cranks, one forged, and one cast-and soon I'll have a 2.8L "L" block available to do some fitting work. I plan to have a few fitting sessions, and grind a crank out to a nice 3.7L stroker unit early next year.
 

·
Boozebag
Joined
·
8,997 Posts
I thought I knew a little about these engines...


Subd
 

·
Registered
Joined
·
164 Posts
Discussion Starter #17
So we've done cranks, rear-wheel-drive blocks, and connecting rods...time for some head info.

We'll start with the iron heads, that came stock on all RWD 60*V6 engines. These heads are OK for their original application, but for real performance applications they're just not a good starting point.



The iron heads have 52cc combustion chambers, and come in both the small-valve and large valve configurations. The small valve heads have 1.6" intake valves, and 1.30" exhaust valves, while the large valve heads have 1.72" intake valves and 1.42" exhaust valves. Another problem with the small-valve heads is inside the intake ports. The small valve ports are conventional in shape, flat floors and inline-valves. This changes with the large-port heads-There is a wing shape cast into the floor to help direct air and keep the airflow attached over the short-side radius of the intake port. This wing actually *helps* flow-do NOT remove it thinking you're helping airflow!



The iron head exhaust port is not too bad-the valve is shrouded and the valve guide boss is very much in the way-but the basic shape is pretty sound. The small port size works well for low-RPM street engines, but rapidly chokes the engine as RPM's climb.

Iron heads are either small-port, or large port. Other than that-they're all the same. On my flowbench, the factory large port iron heads maxed out at 139CFM on the intake port, and 118CFM on the exhaust port. They can be improved, and it is possible to get a 300HP iron head engine-but there is more to it than just port flow. A very good port job on the large-port iron heads will net approximately 150-160CFM intake flow, and 135CFM exhaust flow. All of the gains are found by controlling the cross-sectional area, and the bowl/valve guide area. The combustion chamber can be cleaned up but the shape of the combustion chamber is simply not conducive to port flow.

This is a comparison of the iron head intake port on the right side, and an aluminum head intake port on the left side.



This is a GenII aluminum head exhaust port on the right, with an iron head exhaust port on the left.



The aluminum heads, on the other hand, come in several types. All of the aluminum heads flow better and are superior to the iron heads for making power, and being quite a LOT lighter. There are Gen II heads, that have round exhaust ports, just like the ones in the comparison photos above. The intake ports are raised higher than the iron-head ports, and the total height of the head is taller. The aluminum intake ports are significantly better, stock Gen II intake ports flow 150-155CFM, and with minimal port work 170FCM is attained. The exhaust port flows considerably better than the iron head-140CFM-even though the exhaust port is extremely similar. The gains come mostly from the canted valves-as the valve opens, it moves away from the bore walls and so the bore does not shroud the valve-this is a BIG advantage.

This is a GenII head, bolted up. (picture reuse, alright!)



The GenIII cylinder heads have D-Shaped exhaust ports, and the intake port has been raised even further up, as well as being enlarged and refined. There are both an early 3100 head, and the later 3400 head. The 3400 model heads have bigger intake ports than the early 3100 heads. The exhaust ports benefit from the canted valves as well as the wide, flat port floor, and the late GenIII intake port flows are a little better still than the GenII heads at 180CFM. The exhaust port is better still than the GenII head, moving 160CFM with ease.

This is a GenIII head, the 3400 version.

Intake Port:



Exhaust port:



Combustion Chamber:



Both GenII and GenIII cylinder heads have much smaller combustion chambers than the iron heads at 28cc's. The combustion chamber design does not change through the GenII/GenIII run, only the ports.

The 3500 V6 "LX9" cylinder heads are a little different still, with larger intake ports and a refined exhaust port, and a larger combustion chamber at 32-34cc's. These heads are great for both their awesome port flow, and the larger combustion chamber-they allow for much easier mix-and-match combinations for the 3.4L engine blocks. Now here's the rub-the 3500 heads will NOT fit on a 2.8L or 3.1L engine block! The bore is too small in the 3.1 and 2.8L engine blocks and the heads can not be made to fit. The 3500 cylinder heads can move a LOT of air, upwards of 200CFM of intake flow and 175CFM exhaust flow-Very Nice for factory castings! These intake ports are taller still than the GenIII offerings, but are otherwise similarly shaped.

Aluminum cylinder heads REQUIRE aluminum head intake manifolds. The iron head manifolds will not in any way bolt up. Also, early and late heads use different intake manifolds as well-and within the manifolds that will interchange on specific heads, there are both big-port and small-port manifolds! A lot to cover there...so we'll leave intakes to the next post...and we haven't even gotten to valvetrain parts yet.

More another night.
 

·
Registered
Joined
·
164 Posts
Discussion Starter #18
So here's a little bit about intake manifolds.

Basically, there are carburated intakes for the 2.8L iron heads, TBI intake manifolds for the iron heads, and MPFI intakes for the iron heads. I'll touch on these and show some examples, but as none of these intakes are really high performers, we'll only talk a little about them.

First up, the factory carburated manifold. As far as carburated manifolds go, this one isn't *terrible*, but it's definitely not a performance piece. Lots of people try, though.



I actually had trouble finding a stock unmodified manifold picture for this one-but here are some modified manifolds, mostly to get holley 2-barrel circle track or ford Motorcraft 2100 carburators to fit.







Next up, an Offenhouser Dual-Plane intake for the 60*V6:







Edelbrock makes a dual-plane intake as well, the lower base being universal and the top part being interchangable for the stock 2-barrel carb or a 4-barrel carburator.

Complete assembly:



Just the base manifold...could be a decent start on a carburated blower manifold, actually:



Stock 2-barrel upper:



And the 4-barrel upper:



There are some crazy intakes out there too, aftermarket racing parts, some GM factory racing parts...Falconer, GMPP, and others made these in limited numbers.

This appears to be an iron head Falconer:



This is a GMPP intake, although I suspect it too, was cast by Falconer:



Hilborne also built intakes similar to the falconer one, but machined for mechanical fuel injection only...they look just like a falconer intake, but the injector bosses are machined differently. Probably the same casting.

Then we have the Faegol Supercharger intake for the iron-head V6...This one isn't made anymore and parts for the blower are getting harder to obtain, however some people still value this quite highly:





We'll get into the factory injection manifolds next.
 

·
Boozebag
Joined
·
8,997 Posts
BTW, I have one of those Weber IDA intakes for a 60* V6 also...



How about this one?
 

·
Registered
Joined
·
164 Posts
Discussion Starter #20
Max, I could be posting pictures of every modified fiero/camaro intake I see, but we'd have photos of literally thousands of junk intakes...I've yet to see one that performed as well as the factory piece it was made from. I haven't quite got my post of fuel injection intakes ready yet, there are so many factory offerings it'll take several posts.

That modified 2.8L camaro intake looks like it'd be hellishly bad to drive-the large, flat plenum area is not conducive to power production at all the way it's shaped, and it would puddle fuel like a pothole in a rainstorm. Lots of folks forget that dry-runner intake manifolds just aren't designed to handle wet-flow duties...port fuel injection manifolds don't work the same way plenum fed carburator manifolds do and they don't cross-over well.
 
1 - 20 of 32 Posts
Top