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Project822
Project822 New Reader
8/26/21 2:37 p.m.

I am settling into fatherhood and have sold off my race car projects and dreams, but that doesn't mean that I can't still have some motoring enjoyment.  

I bought a 1987 Chevrolet Astro for a family vacation/road trip/going to see grandma vehicle, and would like to breathe some fire into it.  After joining the very useful astrosafari.com forum and learning more about the task ahead of me, I have decided that a Gen III/IV swap is more than I want to tackle; there are many fine details that would bog me down/add up cost and complexity/cause my wife to ask why the perfectly good van that we bought hasn't run in six months.  So gen I/II it is!

Before I get started asking my questions, I want to say for clarity that I don't want to deal with the LS type engines, regardless of how awesome and superior they are, because I need the swap project to be as straightforward as it can be with as few bends and turns as possible.  Even "straightforward" swap projects have their bends and turns.  I don't want to add any unnecessarily. I am father to a two month old baby and a husband to a kind and loving woman who I want to keep kind and loving and cannot spend hour after hour fabricating stuff like an accessory drive system when the SBC practically drops into place.  So that's why SBC and not 5.3 or 6.0.  

I am used to building engines that have practically no aftermarket support, and going to SBC is actually the opposite problem if you can call it that; there is so much information and so much support that making choices becomes difficult for the uninitiated.  

As much of an improvement as a TBI (to match the 1987 TBI Astro as exactly as possible to make the swap easier) would be, I don't want to go through the effort of the swap without a substantially better improvement.  I would like to build a 350-400HP under 6kRPM SBC with all the torques I can get to swap in when the engine is ready. 

I am not a cheapass, and I don't spend money like a sailor on leave.  I try to make wise compromises that allow me to have nice things that are well build but also eat better than a hobo and make the house payment on time.  

[b]Parameters:[/b]

Long-term factory-like durability is essential; this has to be a minimum 100k mile engine that wouldn't require any special attention that a factory engine wouldn't require.  If necessary, I will sacrifice power to meet this requirement.  

Budget: $5000-7000 (less than 5K if possible, but not necessary if it requires sacrifices in reliability or substantial sacrifices in power.)

Pump gas. 87 octane if physics allows, 93 if not.

Straight plugs for the sake of header selection.

ROLLER CAM AND LIFTERS MANDATORY.

Injection preferred for fuel economy and ease of operation.

Family truckster drivability, 15-20 freeway MPG.

[b]Questions:[/b]

Am I asking too much?

Which cylinder heads should I be looking at? I would like to have aluminum heads, as I am accustomed to that. (Bare heads are A-OK because I would prefer that my cylinder head guy have freedom to make his own valve and spring choices based on flow results after porting)

Which cams should I be looking at?

Which engine blocks should I be shopping for?  Four bolt mains?

What is a modest rod upgrade that allows floating wrist pins?

How much compression is safe for the parameters I have given?

Comparing Edelbrock Pro-Flo against Holley Sniper, is one better than the other in my application?

I realize that there are probably dozens of books on the subject of building SBC engines.  If you have one to recommend, I am happy to buy one.  

06HHR (Forum Supporter)
06HHR (Forum Supporter) Dork
8/26/21 3:00 p.m.

You sure you want to build one? For 5-7k you can get a stout crate SBC that will hit all your metrics and have some change left over.  GMPP will even give you a warranty..

ClemSparks
ClemSparks UltimaDork
8/26/21 3:03 p.m.

I have only rebuilt 1 SBC engine and I haven't fired it up (let alone driven it) to confirm my results.  I was not aiming quite a high as you for power.  Many of my requirements were similar, though.

I want it to be reliable like gravity, run on 87 octane if possible, and be built on a pretty tight budget.  I didn't want cranky hot rod issues like low vacuum (power brakes?), need for a high-stall torque converter, overheating in traffic, etc.  

I don't think it's realistic to aim for 400-450 HP in a small block chevy AND have it run on 87 octane and have street manners for the type of driving you are going to do.  Please remember this is coming from a guy who hasn't actually done it.  I will be so happy to be proven wrong here.

Your budget sounds good in that you can buy good heads, hardware, rods, cam, etc.  My vortec-headed, carbureted 350 was built to get in and twist the key and go anywhere I wanted to.  I didn't have the budget for things like fancy heads, forged pistons, upgraded rods, or even good rod bolts, so I knew I wasn't building a high-power engine.  My budget also had me using parts that I could scrounge and get good deals on (Old, 2-piece rear main seal block, no roller cam, used-but-good vortec heads, second-hand-but-never-installed Intake for Vortec heads and Carburetor).

In your shoes, I'd start with a Vortec engine to build as they are already set up for roller cams.

I looked into a stroker build but there are a lot of details that result in quite a bit of work to be done.  That's fine if you're up for it.  I decided I wasn't up for it.  It's clearly a good way to go to get more power out of a small block.

With stock (iron) vortec heads and the pistons I used, my machine shop guys say I should probably be seeing 9.2-9.4:1 compression and they think it'll run on 87 octane.  My armchair research supports that but I'm a bit skeptical (well...I was until my machine shop said so).  Evidently the combustion chamber on the vortec head tolerates more compression than old-school heads.  Your head and cam choice will have an affect on what kind of compression you can "get away with."  I don't have enough experience in that realm to advise (but there are guys here who do!).

ClemSparks
ClemSparks UltimaDork
8/26/21 3:11 p.m.
06HHR (Forum Supporter) said:

You sure you want to build one? For 5-7k you can get a stout crate SBC that will hit all your metrics and have some change left over.  GMPP will even give you a warranty..

Not to mention the fact that there's that much less down time for the loving wife to start getting tired of an inoperable minivan.  I'm going to second the motion...look into crate engines hard.  Talk to your machine shop and see what the lead times are on their work if you build your own.   (though...I wouldn't be surprised to hear there are long lead times on crate engines right now either)

Edit:  I guess this point is moot since the vehicle is driving on its original engine until the new engine is ready to go anyway.

barefootskater (Shaun)
barefootskater (Shaun) PowerDork
8/26/21 4:38 p.m.

How much of that budget is for the engine and how much is for all the extra stuff. Bigger radiator, mounts, accessory drive, fuel system, exhaust... one can build a very respectable 350 for $5k, but swapping that into an Astro could easily swallow another $2-3k. 
My recipe for a reliable budget engine that likes cheap gas is aftermarket vortec heads, 280 degrees of cam w/ .480 lift, good dual plane intake, long ceramic headers, topped off with a q-jet. Should make 350/350 without any fuss, have a good idle exhaust note, and make good tq all the way around. And it'll happily run on 87. 
Add in about $1200 if you want to jump into a roller cam.

It doesn't sound like much power by today's standards, but it's nearly double what came in it. 
I'd worry about that baby 7.25" rear end too. 8.8 swap should be pretty cheap/easy but it all adds up. 
 

Im not sure I'd want to drive an Astro with 450 horses under the dash. After re-reading your stated goals, I'm not sure at all on the stated budget. Plan to keep AC? Cruise? Power steering? How are emissions laws where you are? Will you need to buy expensive catalytic converters? Upgrading brakes? Suspension? 
 

I don't mean to come off as negative! Far from it. But with stated goals (450hp, 15+mpg, durability, family hauling?) I think you may need to compromise on a thing or two. Or get a much bigger budget. 

AnthonyGS (Forum Supporter)
AnthonyGS (Forum Supporter) SuperDork
8/26/21 6:33 p.m.

I'd build a gen 2, LT1. I'd have Lloyd Elliott do the heads and custom make a cam for it.  I'd also do a 24x conversion with coil on plug and ditch the optispark system.  There are already a few of these on the road and it makes your power goals and will hit your mileage reliability goals too.  I think it'll be under budget too.

Congrats, I just gave you the long term upgrade plan for my 96 Camaro.  I'm slowly looking for a Corvette LT-1 core since they are 4 bolt main.  Of course the two bolt blocks can be bored and tapped for 4 bolt caps too.  
 

I may do the 24x conversion first just for reliability and some power gain.

mdshaw
mdshaw Reader
8/26/21 9:09 p.m.

What about turbo charging the 4.3 like the Cyclone? 

pres589 (djronnebaum)
pres589 (djronnebaum) UltimaDork
8/26/21 9:22 p.m.

In reply to mdshaw :

Syclone, Ford still had rights to the Cyclone name when that truck came out.

I think if I were thinking about a project like this I'd go looking for an early-90's 350 truck motor and just figure out what it needs. Quadrajet and an HEI ignition to start.  Getting that far would be a whole pile of work.

warpedredneck
warpedredneck Reader
8/27/21 5:20 a.m.

i think its a 2001 or 2002, gmc 2500 have one of the very last Vortec 5.7's with all the refinements,

If I was going to small block something now, thats the donor i would go for

Project822
Project822 New Reader
8/27/21 7:07 a.m.
06HHR (Forum Supporter) said:

You sure you want to build one? For 5-7k you can get a stout crate SBC that will hit all your metrics and have some change left over.  GMPP will even give you a warranty..

You're making a very good point there.  What I hold against a crate engine is: 1) I lose control over workmanship and quality/selection of parts, and 2) I don't get to understand the engine the way I would by building it.  I have spent almost my whole automotive life in four cylinder imports, and have never even owned a SBC anything.  

Project822
Project822 New Reader
8/27/21 7:08 a.m.
warpedredneck said:

i think its a 2001 or 2002, gmc 2500 have one of the very last Vortec 5.7's with all the refinements,

If I was going to small block something now, thats the donor i would go for

What I have read is that the blocks aren't very strong with those engines compared to the earlier Vortec engines.  Better heads, weak block. 

Project822
Project822 New Reader
8/27/21 7:11 a.m.
mdshaw said:

What about turbo charging the 4.3 like the Cyclone? 

The Syclone was a neat truck, but setting up the 4.3 for turbo and building the setup would be a longer and more costly endeavor than swapping in a mild SBC, and "'80s turbo car" and "reliable family truckster" don't belong in the same sentence for me. 

PS: It's not because I don't love the 4.3.  I do.  I just really want some big dumb horsepower for this van.

pres589 (djronnebaum)
pres589 (djronnebaum) UltimaDork
8/27/21 8:02 a.m.

I remember when these vans got the Vortec 4.3 and they weren't exactly slouches.  A mild 350 will be plenty of motor.  An L98 350 Corvette motor rebuilt to stock specs with just a bit more cam would probably be well more than enough.  You also get to start thinking about rear axle strength at some point.

Project822
Project822 New Reader
8/27/21 9:03 a.m.
ClemSparks said:
06HHR (Forum Supporter) said:

You sure you want to build one? For 5-7k you can get a stout crate SBC that will hit all your metrics and have some change left over.  GMPP will even give you a warranty..

Not to mention the fact that there's that much less down time for the loving wife to start getting tired of an inoperable minivan.  I'm going to second the motion...look into crate engines hard.  Talk to your machine shop and see what the lead times are on their work if you build your own.   (though...I wouldn't be surprised to hear there are long lead times on crate engines right now either)

Edit:  I guess this point is moot since the vehicle is driving on its original engine until the new engine is ready to go anyway.

Your second thought is correct: the crate engine won't save on down time because the replacement engine will be built and ready before I take out the 4.3.  The down time will be up to me to (mis)manage.  

eastsideTim
eastsideTim PowerDork
8/27/21 9:06 a.m.

I can definitely understand the preference for a non-LS solution.  I've run into a lot more problems getting the LS into my S10 than I did with its prior 305.  I don't really have any specific advice, but just to say to get anywhere near the power you want with durability and drivability, I think the main hit to your budget is going to be a good set of aftermarket heads. I suspect modified Vortec heads could get you to your target, but by time you pay to have them worked over, it will have been cheaper to go aftermarket.

tuna55
tuna55 MegaDork
8/27/21 9:13 a.m.

OP:

 

These are all bad answers, and I am sad.

 

You can get there. My information is pretty stale. My recommendation is to check HotRod or Car Craft or Engine Masters (if you have Motor Trend On Demand sub) 

 

https://www.motortrend.com/how-to/how-to-build-a-cheap-small-block-chevy/

 

https://www.motortrend.com/how-to/hrdp-0906-small-block-chevy-build/

 

https://www.onallcylinders.com/2020/06/05/ask-away-with-jeff-smith-getting-400-hp-from-an-old-small-block-chevy/

Project822
Project822 New Reader
8/27/21 9:17 a.m.
pres589 (djronnebaum) said:

I remember when these vans got the Vortec 4.3 and they weren't exactly slouches.  A mild 350 will be plenty of motor.  An L98 350 Corvette motor rebuilt to stock specs with just a bit more cam would probably be well more than enough.  You also get to start thinking about rear axle strength at some point.

It might be enough with some modern engine management, cams (as you said) and porting.  I do like the L98 intake manifold, but I would seldom get to see it once installed in the van.  

You are correct about the differential, and the 700R4 might check out at some point also.  Unlike my many past projects, I want to do this one in stages.  Get the engine in and sorted, then address drivetrain.  I would like to think that something is already offered for the S10 that would slide right into place in the Astro, but I don't know if the Astro and S10 shared rear ends.  I really am practically brand new to GM; my last GM was a 1985 Cavalier circa 1993-4.  

eastsideTim
eastsideTim PowerDork
8/27/21 9:31 a.m.

The S10 and the Astro both use the 7.5" 10 bolt, but unfortunately, the Astro uses an offset differential, so almost nothing matches up directly.  I think there may be a Ford 9" from something that can be made to fit once the brackets are welded on.

The L98 intake is  really cool looking, but yeah, when would you actually see it.

bobzilla
bobzilla MegaDork
8/27/21 10:04 a.m.

You can get an easy 300-350 with Vortec heads, decent pistons and cam for under $2k. You can roll the dice on Chinesium heads like I did for the truck, and you'll need more cam than I have for sure. 

If it was me.... I'd do a nice clean roller block vortec headed 350 with a .480 lift cam and enjoy doubling the power ofthat Astro. 

bobzilla
bobzilla MegaDork
8/27/21 10:04 a.m.

In reply to eastsideTim :

that L98 intake is a torque monster and not very good for revving. 

Project822
Project822 New Reader
8/27/21 10:04 a.m.
tuna55 said:

OP:

 

These are all bad answers, and I am sad.

 

You can get there. My information is pretty stale. My recommendation is to check HotRod or Car Craft or Engine Masters (if you have Motor Trend On Demand sub) 

 

https://www.motortrend.com/how-to/how-to-build-a-cheap-small-block-chevy/

 

https://www.motortrend.com/how-to/hrdp-0906-small-block-chevy-build/

 

https://www.onallcylinders.com/2020/06/05/ask-away-with-jeff-smith-getting-400-hp-from-an-old-small-block-chevy/

You have offered some good information that might convince me to trim back a bit.  I have been liking the L31 as a swap candidate.  Maybe keeping a stock bottom end and working on the injection, heads, and cam would be a better way to go.  

Project822
Project822 New Reader
8/27/21 10:23 a.m.
bobzilla said:

In reply to eastsideTim :

that L98 intake is a torque monster and not very good for revving. 

That's more than I know about the L98, but 5000-5500 is about as high as I should try to rev in this application.  "Hand of God"-like torque makes more sense for me.  

 

bobzilla
bobzilla MegaDork
8/27/21 11:03 a.m.

4500-5000 Was about it for them. The Shortram intake replacement for them helped moved that up a bit. I want to say Cotton ran ito fueling issues with the L98/shortram I did in the 88 C4 around 5k. That thing made STOOPID amounts of torque. like everywhere.... idle to redline.

Project822
Project822 New Reader
8/27/21 12:51 p.m.
bobzilla said:

4500-5000 Was about it for them. The Shortram intake replacement for them helped moved that up a bit. I want to say Cotton ran ito fueling issues with the L98/shortram I did in the 88 C4 around 5k. That thing made STOOPID amounts of torque. like everywhere.... idle to redline.

I am inclined toward the L31 if for no other reason than the fact that it is already roller valvetrain.  I don't know when/if GM ever fixed the cam wiping problems on SBC engines before switching to roller lifters, but I know that roller lifters address the problem. 

Project822
Project822 New Reader
8/27/21 1:38 p.m.
eastsideTim said:

I suspect modified Vortec heads could get you to your target, but by time you pay to have them worked over, it will have been cheaper to go aftermarket.

Worked Vortec heads are definitely capable.  Worked any SBC head could do it with good port work.  But I prefer to get good aftermarket heads and have those worked.  Start higher, finish higher--right?  

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