383 Vortec/TBI Build Thread

[Daveo91Burb]

http://www.gearhead-efi.com/Fuel-Injection/forum.php Check out the TBI section. These guys have forgotten more about TBI tuning and specs then I could ever learn. The guys on there are a great resource for tuning. There are aftermarket computers available. The Dynamic EFI and moates.net are both great providers of tuning products. I have been torn between modding a TBI motor or swap in a LQ4 6.0 i have sitting around. Im well versed in TBI and TPI systems.

Yep, that's a great site, tons of info there. Earlier in this thread I mention Old School EFI, Vancouver, WA - notice his logo at the top of the page. He's one of the main moderators/sponsers and has a lot of posts there. He's been great to work with so far, and I haven't even paid him for anything yet! (I actually feel guilty emailing him because of that, but I'll eventually get this engine put together and need a chip burned for it).

 

[Daveo91Burb]

Sounds to me like the first machinist ordered the wrong crank and was covering his ass. IIRC only the 400 SBC and all BBC were externally balanced and use weighted flex plates/fly wheels as part of the balancing. You should be able to order a ext. balance flex plate for and 88-95 350/4l80e combo. Think the 96-99 use different tooth # flex plates

Yeah, he kind of admitted that - he said he usually does order the internal balance ones, but thought he could internal balance this one and save a few bucks (not sure if those were my $$ or his, probably his from the way things turned out). He messed around with it for a while and then decided it would need to be external.

You're correct that the 400 originally was the only SBC that had external balance, but that's pre- one piece rear main seal only. When GM did the redesign in '86 and went to one piece RMS, they also went to external balance but on the rear only - balancer was normal, but flex plate was weighted. (This is true for 350s, not 100% sure about 305s) I've done a lot of research in the past few weeks on this, didn't know that little factoid until then, but it's supported by the one piece RMS motors I've taken apart lately. I'm pretty sure I got it figured out: I need a 168-tooth (most of the later ones are), SBC crank bolt circle, 11.5" torque converter bolt circle, external balanced with counterweight. Pretty sure the ATP Z-167 fits the bill. The 11.5" bolt circle part is important for me. A lot of the plates available have 3 bolts at 11.5" BC and 3 at 10.5" BC - for multiple sizes of trannies/torque converters. AFAIK 4L80e uses all six bolts at 11.5" BC.

 

[4WDKC]

I know the pre 86 used a different tooth flex plate did not know it had weights on it, that throws a wrench into my thoughts of swapping to a 4l80 when my 700r4 goes kaput.

 

[Daveo91Burb]

I'm pretty sure I got it figured out: I need a 168-tooth (most of the later ones are), SBC crank bolt circle, 11.5" torque converter bolt circle, external balanced with counterweight. Pretty sure the ATP Z-167 fits the bill. The 11.5" bolt circle part is important for me. A lot of the plates available have 3 bolts at 11.5" BC and 3 at 10.5" BC - for multiple sizes of trannies/torque converters. AFAIK 4L80e uses all six bolts at 11.5" BC.

Update: The ATP Z-167 flex plate arrived yesterday. I think it's the right part. It's got the SBC crank bolt circle and it's got all six TC bolts at the 11.5 bolt circle - correct for 4L80e. 168 tooth, counterweighted, yep, think I should be in business. Both the Pioneer and ATP units are made in Mexico (same factory???) I was disappointed in the weld quality of the Pioneer, but the ATP actually seems to be a little bit better. I'd recommend the ATP Z-167 for anyone with SBC and 4L80e. Probably would work for TH400 too.

 

[Daveo91Burb]

I know the pre 86 used a different tooth flex plate did not know it had weights on it, that throws a wrench into my thoughts of swapping to a 4l80 when my 700r4 goes kaput.

I believe there has always been the different options of 153 vs 168 tooth, regardless of pre or post '86. From what I've read, if the two bolts securing your starter to the block are perpendicular to the drive train, your flex plate is 153, if they're at at angle (45 ish?), it's 168 tooth. If you have a starter for 168 tooth (or don't mind getting one) you'll want to use the same flex plate as I am, ATP Z-167, when you switch to 4L80e. You MAY be able to use existing plate, but pretty sure it would only allow a 3-bolt connection to the torque converter.

 

[Daveo91Burb]

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Final batch of parts ready to go to machine shop: kb 135 pistons, 8" counter weighted balancer, flex plate described earlier, and crank gear from a new cloyes true roller timing set. He already has block, rods, crank, and bearings. He's going to balance rotating assy, install cam bearings, install new freeze plugs, and final wash.


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[Daveo91Burb]

Brought everything home from machine shop today, hopefully for good! Fully prepped block, washed and ready for paint, fully balanced rotating assembly. All that's left: paint, short block assembly, long block assembly, remove old motor, put this one in, get a chip burned, get it running, tune, etc. etc. OK, I guess it's a lot to do, but at least some progress!

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[74 Shortbed]

Progress is always good..

 

[4WDKC]

Brought everything home from machine shop today, hopefully for good! Fully prepped block, washed and ready for paint, fully balanced rotating assembly. All that's left: paint, short block assembly, long block assembly, remove old motor, put this one in, get a chip burned, get it running, tune, etc. etc. OK, I guess it's a lot to do, but at least some progress!

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Everyone thinks Im crazy for having 2 money pits, glad to see Im not the only one.

 

[Daveo91Burb]

Everyone thinks Im crazy for having 2 money pits, glad to see Im not the only one.

Yeah, that's for sure! My Vette doesn't need a huge amount of stuff right now, but there's always something. Drove it to work today and on the way home a heater hose split, and drained the radiator. Glad I caught it in time - I have vortecs on that too and they're prone to cracking. I got it back home, but had to fill the rad with straight water to do so. so now I get to do a drain and flush I guess.

 

[4WDKC]

Yeah, that's for sure! My Vette doesn't need a huge amount of stuff right now, but there's always something. Drove it to work today and on the way home a heater hose split, and drained the radiator. Glad I caught it in time - I have vortecs on that too and they're prone to cracking. I got it back home, but had to fill the rad with straight water to do so. so now I get to do a drain and flush I guess.

Here's my money pits

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[Daveo91Burb]

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And here's my two! I need to get some better pics that show more of both.

 

[4WDKC]

Nice, any updates on the build?

 

[Daveo91Burb]

Actually yes but it's only that I'm ready to start assembling. Only succeeded in getting it painted and on the engine stand. And ordering more parts: gaskets seals and cylinder head bolts.

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[Daveo91Burb]

So anyone have experience with these head gaskets? They're copies of Fel Pro 1003 hi po gaskets, but price is a bit less. Leaning towards just going with fel pro but if these were trustworthy......
https://www.ebay.com/itm/311645244663


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