Slightly off topic here since vehicle is am 89 GMC K5 Jimmy. I am upgrading from stock TBI 350 to Vortec 350 TBI block out of a 98 GMC Sierra. I have a 400 crank lying around, so mine as well stroke it. My question is if I keep everything else the same, will stroking it to 383 make it flunk the sniff test.

 

Just going to 383 with no other changes probably wouldn't hurt as far as emissions goes, but keep in mind that a stock 400 crank would be set up for the old style two piece rear main seal, whereas all post 86 factory blocks have the one piece rear main seal. You could use an adapter, but if it were me, I'd sell the 400 crank (hard to find, and someone building a 400/406 would probably love to have it) and buy an internally balanced, 1 piece rear main style 3.75 stroke crank from Eagle or Scat. This way you won't run into any balancing issues (you'd need the 400's externally balanced flywheel and harmonic balancer wit hthe stock 400 crank anyway). The aftermarket crank is in the $200-250 range, and you should be able to get that or close to it for your existing crank.

 

Good catch, I forgot that the crank won't work with the newer block.

 

Having trouble finding an internally balanced 1 piece rear main 3.75 stroke crank...does one exist? I see 3.48 all day long. Know where I can find one? Thanks

 

Both eagle & scat offer 3.75" 1prms internal in cast ... eagle has 3.75" cast that'll go internal W/ OE 5.7 rod ... i think eagle site is www.eaglerod.com ... look at both 10352375057I & 10352375057E There are more cast 3.75 internal choices if you're willing to go w/ longer 6" rod. Even more choices if willing to buy $ pricey $ forged crank.

I disagree on value of used OE 400 or OE 89 350 or OE 98 350 sbc cranks ... lucky to get $75-100.

To get some ides on 383 & FI emissions ... look here about GM 17800393 383 crate HT383E for OE '96-'99 VORTEC FI emissions (no not tbi but get some FI ideas) ... also look at where one of these is installed http://www.maxchevy.com/tech/2007/ii_1-swap-1.html

BTW ... '96-'99 vortec is Not TBI ... IIRC it's something like CSFI ... central sequential ... it actually has separate injector for each cylinder ... but they're grouped in to a block with tubes running down inside of intake runners ... it also take a different computer than TBI. I have much of this stuff & am cloning a GM 17800393 383 crate HT383E for install into '97 GMC pu. I know where there's another brand new takeout spare roller cam like HT383E has for under $100.

 

I agree with you on the value of my used 400 crank,I might get $70-80 for it. But I have to respectfully disagree, multiport fi didn't start on the gm vortecs until 2000. The new body style trucks debuted as a 99 1/2 model but style retained the same tbi that was on 96-98 truck. In 2000 they started with the 5.3 vortec motor which had the cfsi that you are speaking of. Maybe you've come across a motor that someone retrofitted the later system on. My 97 Z71 had the vortec 350 with the tbi, and a guy at work had a 99 had z71 with the same motor. Another guy at work bought a 2000 tahoe, and it had the 5.3 with the multi port inj.

Thanks for the info on the cranks.

 

I read the article in your post and I guess you are right, the vortec 96-99 does have some kind of different FI system the the older ones. I stand corrected thanks for the info. I should have read your article before I popped my mouth off.

 

That's OK ... no prob ... I just wanna make sure you're armed w/ some info before you make decisions that might waste your time&$ ... & lotsa aggravation.

There's at least two (2) distinctly different families of small V8 motor that're both called VORTEC by GM. They're both emblazoned VORTEC right on air cleaner or valve cover

(1) The iron head one is what I speak of above and it a 5.7/350 ONLY displacement production motor in many '96-'99 gm lite duty pickups vans tahoes etc ... I think but dunno for sure that motor actually extended its production use till about 2002 in a very few savana vans. .. ... the '96-'99 run is the typical std though. All have roller lifters. All of this first type have ONLY cast iron heads & only cast iron blocks and they all have a distributor located at rear of block and a single coil. As above, it has a centrally located block of 8 injectors w/ hidden tubes ... NOT TBI. AFAIK, this motor is no longer found in new production vehicles sold in USA. BTW, this motor's iron vortec heads are the very ones that've become so popular to retrofit old 350 including C3 vettes.

(2) Then ... about 2000 gm & chevy lite trucks began using an entirely different (virtually no interchange parts) family of small V8 motors that're also called vortec by gm ... but they ALL have aluminum heads. All have roller lifters too. They all have ignition called coil-near-plug (separate coil (8) for each cylinder screwed onto valve cover) and they have NO distributor at all. Their block is quite different too & available in both iron & aluminum. Typical displacements are 4.8, 5.3, 5.7, 6.0, 6.2. BTW ... the most recent GM motor approved for nascar CUP is based on this family aka LSX. Most if not all vettes since about '96 have motor from same LSX family. The newer & much vaunted 500+hp 427" vette LS7 also same family.

 

Thanks for the info. I have a complete Vortec 350 from a 98 GMC Sierra PU. I want to soup up my 89 GMC Jimmy, which has the 200 hp 350 with TBI. This engine only has 30K mi and runs great. The Vortec motor has 60K miles and ran fine when pulled. Was going stroke the Vortec motor and put it in the there, but I don't have the computer, and you sd earlier I can't just use the existing computer for the tbi 350. I guess I could just take the vortec heads off and put them on the tbi engine and try to find a vortec intake for tbi...Do you they have one?

 

Yes ... here's a TBI-to-Vortec head manifold:
http://store.summitracing.com/partde...0&autoview=sku
Or if you have carb Vortec manifold but need a TBI adapter ... here's the adapter:
http://store.summitracing.com/partde...5&autoview=sku
and here's a carb vortec intake manifold:
http://store.summitracing.com/partde...6&autoview=sku