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ClemSparks
ClemSparks UltimaDork
8/30/21 10:33 a.m.

Personally, I have a hard time back-dating a vehicle to a carburetor from Fuel Injection.  My limited experience with TBI is fantastic...in a stock application.  I think (like any high-performance build) getting TBI to run right on a built engine will be a labor of love.  I don't have experience with the aftermarket fuel injection but would be looking hard into it.

I mostly came here to post this thought that just occurred to me (specifically regarding your induction system):  It's all going to be antique in 10 years.  Most of the options are already antique.  Maybe that thought might help get past the wanting to optimize every aspect.  I know I tend to get bogged down in these details.

 

Regarding carburetors and drivability:  MOST of the toy cars/trucks I have around here are carbureted.  If you start them up regularly, they run great.  When a carbureted car starts acting up, it still usually gets you home (if it's a carburetor issue).  There are passages to plug up, gaskets to leak, and diaphragms to tear.  Those are the failure modes.    Even the fuel system on a carbureted vehicle is easier to diagnose and repair in a parking lot or on the shoulder of a highway.  

I'm not trying to talk you into a carburetor (it kind of looks like I am) but you don't have to "become a wizard" at carburetors to make them run right.  You just have to drive them.

Project822
Project822 New Reader
8/30/21 10:52 a.m.
ClemSparks said:

I'm not trying to talk you into a carburetor (it kind of looks like I am) but you don't have to "become a wizard" at carburetors to make them run right.  You just have to drive them.

The "becoming a wizard" comment was about taking a junkyard Rochester Quadrajet and tuning it for performance on a modified engine.  While I am still starting from practically zero, I would feel more confident starting with a carburetor that was intended to be tuned, jetted, etc. for performance.  I personally like the Quadrajet and would gladly have one on a stock engine (unless it was an injected vehicle, in which case I would be leaving well enough alone,) but I need to ensure success on this project because I am no longer the only person occupying my life--or the vehicle.  

I, too, like the TBI system as an OE system from its time and place.  It is durable and dependable.  If I wanted to swap in a stock TBI engine, I would surely leave it all alone and slip it in.  But I don't want to go through the effort and expense of a V8 swap without making some improvements.  The question is how many improvements.  I started this thread with bigger ideas, but am settling on an L31 Vortec around 350HP with stock 5.7L displacement with some head work and a decent cam.  That's a good place to stop spending money before it all starts to get expensive.  But 350 is well beyond what I want to attempt to squeeze out of TBI injection.  Maybe it could be done, but I would bet that the end result would be more costly and less depandable and driver-friendly than a well-selected and well-tuned carb.

03Panther
03Panther UltraDork
8/30/21 1:06 p.m.

No personal experience with the TBI (other than stock), but I hang read it's not a big problem, unless trying to squeeze huge numbers out of it. Should be well documented... somewhere!cheeky

The bolt on FI does not have all the knock sensors and other stuff that make modern FI so much better than carbs. So unless going LS ( and I HIGHLY recommend against it for this van) the only advantage to aftermarket FI that bolts to a carb intake is better unattended cold start/warm up, and extremely lean angles the carb fuel bowls have trouble with. So it's not really backdating it, unless he were to rip out the TBI on the stock 4.3 for a carb (a few did come with a Q jetsurprise) I've seen a total of one in a junk yard!

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) UberDork
8/30/21 2:10 p.m.

TBI is darn near bullet-proof.

I have re-tuned a 305 ecu to run on a 350 with cam, ported heads, headers, Holley TBI unit 350 injectors, and a vacuum-referenced fuel pressure regulator.  Takes time, but it can work.

The Rochester in my C10 is the one the truck came with. I followed Cliff Ruggles' book on Rochesters, and it totally runs like a champ, in 100° summers and -5° winters, never misses a beat.  My truck idles in gear at 8inHg with a very choppy idle; the Rochester works just fine.

I'd hack the TBI, since almost everything you need, you already have.

Project822
Project822 New Reader
8/30/21 3:11 p.m.
SkinnyG (Forum Supporter) said:

I have re-tuned a 305 ecu to run on a 350 with cam, ported heads, headers, Holley TBI unit 350 injectors, and a vacuum-referenced fuel pressure regulator.  Takes time, but it can work.

The Holley TBI unit is a drop-in upgrade from the factory TBI unit?  I don't know what I don't know.  

bonylad
bonylad HalfDork
8/30/21 3:37 p.m.

Well.  The easy button is a late model 5.7 Vortec out of a Suburban or truck.  Can be made to run with your harness, can be be easliy modded from the stock 255 hp to mid 300s and are cheap. Pick up a engine, go through it and freshen it up. The Vortec heads are based on the LT1 without the reverse flow coolant (just learned that), set up with some nice headers etc.....voila!

You can drop it in as is with adapters and run the TBI unit, though it wont be ideal till you get a cheap Sniper EFI....then go nuts!

06HHR (Forum Supporter)
06HHR (Forum Supporter) Dork
8/30/21 4:01 p.m.
Project822 said:
SkinnyG (Forum Supporter) said:

I have re-tuned a 305 ecu to run on a 350 with cam, ported heads, headers, Holley TBI unit 350 injectors, and a vacuum-referenced fuel pressure regulator.  Takes time, but it can work.

The Holley TBI unit is a drop-in upgrade from the factory TBI unit?  I don't know what I don't know.  

Yes, it has the 2" throttle bores like the 454 spec factory TBI.  The 4.3, 5.0 and 5.7 spec has smaller throttle bores.

Project822
Project822 New Reader
8/31/21 9:50 a.m.

Well, hasn't this thread taken some turns?

Now it seems like pulling and rebuilding a junkyard L31, working the heads, mild cam with 110-112 degree LSA and an appropriately sized Edelbrock carb is going to be the ticket.  

I appreciate the feedback on using and upgrading the factory TBI, but I think a good carb makes more sense.  

Now to find a good-ish junkyard engine.  I hope to go scouting this weekend to see what is out there in central Ohio.  

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) UberDork
8/31/21 12:57 p.m.

You'll likely make more power with the carb than the TBI unit, too.

madmrak351
madmrak351 New Reader
8/31/21 8:27 p.m.

The SBC is the right way to go with your time constraints. The front accessory package is a direct bolt on as is the transmission. Don't disregard the benefits of a crate motor for time savings and the warranty aspect. Also the parts and machine work involved in a rebuild aren't inexpensive plus the inevitable surprises that always come up. The 383 stroker is a good choice for the type of usage you are looking at. Torque is much more of a factor in your application. Although I feel fuel injection is awesome, I favor OEM systems over aftermarket for reliability, drivability, and economy. I hate to say the C word but the carburetor may be you best choice for ease of set up. I knew a gentleman who did 4 of these Astro van swaps in the 90's. He stated they were relatively easy.  He had 2 as panel van work trucks, and he also swaped his wife's window van and then built another swaped work van. Best wishes on your project.

Project822
Project822 New Reader
9/1/21 6:48 a.m.

In reply to madmrak351 :

Yes, I am nearly 100% convinced to go carburetor.  Something momentous would have to come up to convince me otherwise.  And it would take something even greater to convince me to choose another engine over the SBC.  I would love a fully modern LS-type swap in there, but the gotchas would get me and drag me into a years-long project instead of weeks (well planned and executed) or months (how I do things.)  

 

Your point about saving time and possibly money with a crate engine or short block is well taken, especially considering my time constraints.  But I also like to understand what I drive, and I have never seen inside a SBC engine--well, not in a personal, intimate way.  

06HHR (Forum Supporter)
06HHR (Forum Supporter) Dork
9/1/21 8:58 a.m.

In reply to Project822 :

TBH, there's really not much to see.  It's really a case of if you've seen one non-rotary ICE you've seen them all.  Only difference with modern OHC 4 cylinders is the extra rods and pistons, and the cam is in the block instead of the head, so your valvetrain is pushrod actuated instead of shims or buckets like with OHC.  In terms of complexity it's a bit of a step backwards, but you still have to do things like make sure your ring gaps are correctly staggered and spaced, your bearings are correctly sized and clearances are within spec, etc...  So much of engine builder 101 that applies to a K24 will apply to a SBC.   

APEowner
APEowner SuperDork
9/1/21 9:34 a.m.

There's no doubt that the LS is a great engine but the performance requirements laid out by the OP are not hard to meet with a traditional SBC.  I'd do a 383 stroker kit because they're plentiful and cheap and the extra displacement makes it easier to hit the performance goals with a milder cam.  Almost anyones ready to run aftermarket aluminum cylinder heads will work.  Pick a cam and go.  I'll try and pull together some specific recommendations later today.

As far as carb vs FI is concerned, FI is more expensive but provides more control and theoretically a more refined driving experience.  Carbs are cheaper but not quite as refined.  They also don't like operating over a wide range of elevations.  I suggest a carb to start with while collecting parts to put together a FI system down the road.  Yeah, you'll end up spending more money in the long run but it'll allow you to split the project into two major parts and minimize downtime.

03Panther
03Panther UltraDork
9/1/21 10:19 a.m.

In reply to APEowner :

Well stated advice. And I'll reiterate that he does not need the best, most expensive crank to go 383. A cast crank and 2 bolt mains (as long as it IS cheaper, these days) will meet the needs in that Van. If not less, then sure, get the better! Never hurtslaugh

madmrak351
madmrak351 New Reader
9/1/21 10:23 a.m.

In reply to Project822 :

I understand about wanting to be hands on in the engine rebuild. I am  very much a LS swap proponent, the stand alone harness is well documented or easily purchased. The thing that is most concerning to me in your application is the front accessory drive layout that would allow retention of the a/c compressor. The truck accessories generally require the frame to be notched and boxed to clear the compressor or an aftermarket accessory drive package. I am not a fan of most of the aftermarket drive packages I have worked with. The layout of the Astro van does not make frame mods nearly as simple as a truck where the dog house comes off easily. Once again the SBC is much simpler. 

03Panther
03Panther UltraDork
9/1/21 10:48 a.m.

Before I forget again, you do need adapter mount brackets, to move the sbc just a bit, so the trans does not have to move at all! Everything bolts right up, including stock rubber mounts, accessory drive, the 4.3 is just a hair shorter. 
mmusicman on that van forum is a great source. He writes a tad aggressive, being an arrogant azz, but he's smart, done it, and has great how to write ups!! He's actually a real nice guy; you just need thick skin, sometimes. 

Project822
Project822 New Reader
9/1/21 11:05 a.m.
madmrak351 said:

In reply to Project822 :

I understand about wanting to be hands on in the engine rebuild. I am  very much a LS swap proponent, the stand alone harness is well documented or easily purchased. The thing that is most concerning to me in your application is the front accessory drive layout that would allow retention of the a/c compressor. The truck accessories generally require the frame to be notched and boxed to clear the compressor or an aftermarket accessory drive package. I am not a fan of most of the aftermarket drive packages I have worked with. The layout of the Astro van does not make frame mods nearly as simple as a truck where the dog house comes off easily. Once again the SBC is much simpler. 

Right, and a stipulation that I did not mention is that I do not want to cut this van.  I have cut a lot of cars, sometimes deeply, sometimes VERY deeply, and this van is too clean to cut.  So that's another way in which SBC wins for this build.

Project822
Project822 New Reader
9/1/21 11:07 a.m.
03Panther said:

Before I forget again, you do need adapter mount brackets, to move the sbc just a bit, so the trans does not have to move at all! Everything bolts right up, including stock rubber mounts, accessory drive, the 4.3 is just a hair shorter. 
mmusicman on that van forum is a great source. He writes a tad aggressive, being an arrogant azz, but he's smart, done it, and has great how to write ups!! He's actually a real nice guy; you just need this skin, sometimes. 

mmusicman is a wealth of information.  My first thought was to modify the subframe for the new mount position, but I might buy/make the adapters instead.  As I said above, I just don't want to cut this van.  Maybe if I were to find a clean second subframe, but then I'd have to store a subframe--and the Astro's subframe is not unlarge.  

03Panther
03Panther UltraDork
9/1/21 8:31 p.m.

If I dig deep enough, I could prolly find the patterns I downloaded to make your own... but you might could find 'em online just as easy. They are available. after ya fab them, it a bolt in affair.

I'm TowVan on there, but never did much. Chevymayer (sp.) is another fave of mine. He went with a marine crate long block in his! And someone started a well pictured thread on the exact 4.3 build I would do if I didn't V8 one... but left us hanging 3/4s of the way through.angry He used a 95 cam in his 99, with 1.6 rockers, just for a crisp mild bump in power. But never gave feed back as to results.

Project822
Project822 New Reader
9/2/21 6:47 a.m.
03Panther said:

If I dig deep enough, I could prolly find the patterns I downloaded to make your own... but you might could find 'em online just as easy. They are available. after ya fab them, it a bolt in affair.

I'm TowVan on there, but never did much. Chevymayer (sp.) is another fave of mine. He went with a marine crate long block in his! And someone started a well pictured thread on the exact 4.3 build I would do if I didn't V8 one... but left us hanging 3/4s of the way through.angry He used a 95 cam in his 99, with 1.6 rockers, just for a crisp mild bump in power. But never gave feed back as to results.

I will look out for you.  I am GasTungstenArc.  I probably should have used that handle here, but I was into a different project at the time and chose my name accordingly.  

The 4.3 is a really nice engine, but I just can't see investing in it considering how inexpensive (cross fingers) and easy (cross fingers again) and how 33% more a V8 swap would be.  

GCrites80s
GCrites80s HalfDork
9/2/21 9:00 p.m.

In reply to Project822 :

As far as Q-jets go, Cliff Ruggles in Mt. Vernon is the guru. He has tons of resources available on his website such as books and parts. https://cliffshighperformance.com/ No need to be scared of the Q-jet.

SkinnyG (Forum Supporter)
SkinnyG (Forum Supporter) UberDork
9/2/21 10:41 p.m.

His Rochester Quadrajet book is awesome.  I highly recommend it.

Project822
Project822 New Reader
9/3/21 6:38 a.m.
GCrites80s said:

In reply to Project822 :

As far as Q-jets go, Cliff Ruggles in Mt. Vernon is the guru. He has tons of resources available on his website such as books and parts. https://cliffshighperformance.com/ No need to be scared of the Q-jet.

Very interesting!  I will check him out.  Who would have thought that a Q-jet Dahar Master would have lived 45 minutes from me?

03Panther
03Panther UltraDork
9/3/21 7:14 p.m.
 

I will look out for you.  I am GasTungstenArc.  I probably should have used that handle here, but I was into a different project at the time and chose my name accordingly.  

The 4.3 is a really nice engine, but I just can't see investing in it considering how inexpensive (cross fingers) and easy (cross fingers again) and how 33% more a V8 swap would be.  

Same for my handle here. After becoming a forum user here, and a dislike of keyboard commandos, I just use me name (part, anyway) on the Beemer forums I have joined since! (Dan/pete) 

I'd love to do a mild build on a 4.3 V6 in an astro, but would be hard to spend more on that, than a comparable V8 for way less. especially when the V* can do MORE than the built V6, and still cost less!

Likely, I'll never do either, with the current finances.

And, although I've never read Cliff's book, I have never heard anyone say its not THE go to for a Q-jet.

Project822
Project822 New Reader
9/7/21 7:25 a.m.
03Panther said:
 

I will look out for you.  I am GasTungstenArc.  I probably should have used that handle here, but I was into a different project at the time and chose my name accordingly.  

The 4.3 is a really nice engine, but I just can't see investing in it considering how inexpensive (cross fingers) and easy (cross fingers again) and how 33% more a V8 swap would be.  

Same for my handle here. After becoming a forum user here, and a dislike of keyboard commandos, I just use me name (part, anyway) on the Beemer forums I have joined since! (Dan/pete) 

I'd love to do a mild build on a 4.3 V6 in an astro, but would be hard to spend more on that, than a comparable V8 for way less. especially when the V* can do MORE than the built V6, and still cost less!

Likely, I'll never do either, with the current finances.

And, although I've never read Cliff's book, I have never heard anyone say its not THE go to for a Q-jet.

Right.  The 4.3 is an excellent engine for its time, but working with it gets you 3/4 of a SBC for 4/3 of the money (or more, but it looks more clever this way.)  I know that the 4.3 was used as a Winston Cup engine for a while, so there might be some cool NASCARy stuff out there for it, but even then it's nowhere near the bang for buck of a SBC.

Aside from that, I have built plenty enough high stress small engines, particularly those that everything has to be made/adapted for.  I am ready for some big dumb easy torque.  

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