engine parts interchangability

[ctadams21]

Thinking about building a spare Sy shortblock to keep in the corner for a rainy day (sounds like I can count on needing it) Can I just rebuild a stock 4.3 (1990 TBI) with aftermarket pistons and camshaft.
Can I assume the crank, rods, balancer, block are the same as the turbo motors?

 

[myclone]

Main caps are nodular iron in a syty where the NA TBI is just reg cast iron. Rods are laughable at best on sytys/early TBIs so do yourself a favor and get at the least L35s. Do Eagle rods if the budget allows then you can just about forget about em for the most part.

Do TRW pistons if youre on a budget or J&Es if you have the bucks to spend.

Cams are the same between a syty and the NA TBI engines.

 

[ctadams21]

Cool...Thanks!

 

[Hu Ryde]

MyClone, if you don't mind going into more detail on the topic I would love to get it up on the website with credit to you of course. If anyone has pics of these syty parts and non syty parts that also would be great.

What's the best block, (year and info) to build on.

Also any extra info like a list for a budget build and a non budget build.

Basically everything that's different/same in syty motor compaired to same year tbi.

If anyone has the info and dont mind writing a small book please do, I'll put it on my site and giver proper credit. Thanks.

 

[myclone]

I dont need any credit as 99% of what I know about syty engines I learned off here. The other 1% is from building a few hi po NA 4.3s at one time.

I wish I had a decent camera to show you as the mains are different. I kinda took that with a grain of salt so to speak when I first heard it but I got my hands on some syty caps and compared them with reg NA caps. Deff a diff in color and the syty stuff that I had didnt have a part number on it compared to every other GM cap Ive ever seen had a part number on it.

I dunno if any one year block is really better than another. People on here say to stay away from the late block which has the balance shaft as its supposedly not as "meaty" as the earlier blocks. Dunno myself unless I have them x rayed or sonic checked. The balance shaft blocks are more work if you get rid of the balance shaft as you have to plug the oil supply holes to the now gone balance shaft.

Ive compared the stock rods, L35s, and SBC rods.. The stock ones are what Id call light duty on the big end. The L35s are slightly beefier . The beams looked the same to me. SBC rods are the wrong size on the big end and IMO once you have them machined to work you'll have as much $ in them if you just went out and bought Eagles.

Stock pistons are hyperutectic(sp?) which have a higher silicone content than forged which allows tighter piston to wall clearances to keep cold start noise to a minimum. Hypers wont tolerate much more detonation than reg cast pistons in my experience and we all know detonation is a huge prob with our application. I use TRW forged or J&Es myself. TRWs wrist pins are heavier than the J&Es and J&E seems to have a little better quality control than TRW. Both are durable and long lasting but J&Es are pricey.

Cranks are all the same for the TBI/syty stuff. All cast even fire. The general thinking here is the stocker is good for ~600hp if its prepped.

Budget build(my opinion)

Start with a syty block(gotta have those main caps IMO)
hot tanked
new cam bearings/freeze plugs
oil galley plugs "staked" in place or block peened around them
.030 over bore
ARP studs(2 bolt)
line bore checked and honed if needed
standard rod/main journal crank
chamfered oil holes(can be done at home)
removed casting parting line on crank(can be done at home)
Melling Z28 oil pump(standard volume with a higher pressure bypass spring)
Smoothed/chamfered oil galley in lower section of pump(done at home)
One piece oil pump drive(integral sleave)
Smoothed oil passage on rear main and chamfer(done at home)
TRW .030 pistons with spiro locks
L35 rods, checked. Resize only if needed
Balance rotating assembly.
Childs & Albert ZGS rings part# RS-40X4.035(pricey but worth every penny)
Double roller timing chain from Jegs/summit(part# escapes me right now)
stock cam(its a roller so it can be reused if journals are ok)

L35 heads, cleaned, new valve seals, valve job(3 angle), new guides if heads have high miles.
ARP Head bolts(6 point or 12 point doesnt matter)

Dirt cheap rebuild:

clean and reuse stock pistons with moly rings and stock rods(DIY)
hot tank block and new freeze plugs and cam bearings
block honed for new rings(DIY)
new main/rod bearings(DIY)
standard replacement timing chain(DIY)
same oil pump as above as its dirt cheap
disassemble heads and clean everything. install new seals(DIY)
ARP main cap bolts if you can or reuse stockers if your really poor
Reuse stock head bolts

Ultimate (IMO) build to follow as ms mycloe says its time for bed :wink: :wink:

 

[Hu Ryde]

Awesome! That's exactly what I was looking for. Does anyone have pics of the caps so I can include them in the write up? Thanks again bud.

 

[myclone]

Ultimate (IMO) build to follow as ms mycloe says its time for bed :wink: :wink:

Welp, I thought a lot about the "ultimate" build and theres really no way to do it that would keep everyone happy. As in my ultimate build might be someone elses idea of a mid level build or vice versa. If money is no object then it just gets into too many one off/custom parts to list IMO. Besides who would want to read about my dream build anyway? :wink:

So, here is the build that Ive got in mind. Might take me a year or more to do it on my budget but its my basic plan(so far)

block converted to four bolt mains
hot tanked
new cam bearings/freeze plugs
oil galley plugs "staked" in place or block peened around them
.030 over bore
line bore checked and honed if needed
standard rod/main journal crank
crank indexed, x rayed, then cryo treated
chamfered oil holes
removed casting parting line on crank
Melling Z28 oil pumpSmoothed/chamfered oil galley in lower section of pump
One piece oil pump drive
Smoothed oil passage on rear main and chamfer
TRW .030 pistons with spiro locks
Eagle rods
Fluidamper harmonic damper
B&M or TCI flex plate(heavier duty than the stocker)
Balance rotating assembly
Childs & Albert ZGS rings part# RS-44.035
Double roller timing chain
comp cam(to be determined)
shimmed oil bypass in block
MSD pro billet distributor
stock syty head gaskets
ARP head bolts (pro series/6 point)

Vortec heads(unless I find a pair of brodix alum ones cheap) with 2.02 intake/1.60 exhaust valves with 5 angle valve job and my own special little back cut on em. The heads will be bowl blended, short side radius worked, chambers smoothed, chamber wall laid back away from valves some to unshroud the valves, straightened ports on intake(not hogged out though), screw in studs, 1.6 or 1.5 full roller rockers, guide plates, chromoly push rods, new valve springs(to be determined), 10 deg valve spring retainers/locks.

 

[canadian]

i didn't notice on your ultimate buildup two things that i would have done just to be on the safe side:

have the deck height checked
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make sure both sides of the motor are the same distance from the crank centerline so that there is less variation from cylinder to cylinder when it comes to volume/compressed size.

cc the heads
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production casting tolerances aren't always the same from combustion chamber to combustion chamber. this will make sure that they are all equal and you aren't starting with something that will ultimately be a problem (if the cc's are way off) when you get the motor together.

heck, i've seen a set of edelbrock heads that were advertised at 65cc with as much as 3cc difference from chamber to chamber. might be something to have checked if you are doing an all out build.

 

[TurboManiacal]

I wish I had a decent camera to show you as the mains are different. I kinda took that with a grain of salt so to speak when I first heard it but I got my hands on some syty caps and compared them with reg NA caps. Deff a diff in color and the syty stuff that I had didnt have a part number on it compared to every other GM cap Ive ever seen had a part number on it.

************************************************

Start with a syty block(gotta have those main caps IMO)

So say that I got the wrong block from GM in my Sy. You're saying here that the main caps would be wrong...(that and based on what I've seen elsewhere...) so could the wrong caps be replaced with the "right" caps? If they can be replaced why then would you need to start off with a SyTy block if the caps can be replaced and those are the only things that is stopping a normal block from bein a SyTy block? (Excluding the previously mentioned balance shaft blocks) Or is it not worth the hassle...if you're replacing main caps...to just go ahead and go 4 bolt? Is that what you're refering to?

 

[myclone]

The syty main caps being nodular iron instead of reg cast iron are stronger. The two types are demensionally interchangable and serve the exact same function. If you started with a NA block the main caps from it would actually function correctly but very possibly wouldnt hold the crank shaft in its proper position under boost which would kill the main bearings.

Cheapest option: IMO

If you start with a non syty block you should purchase some after market 2 bolt main caps and have them installed by a machine shop. Milodine makes some as well as another vendor I believe. IMO this would be as strong as a stock syty set up. On the other hand if you had a set of syty main caps then you could accomplish the same thing with whatever block you used

Next would be converting to 4 bolt mains using after market caps installed at a machine shop.

Lastly and IMO the strongest would be splayed 4 bolt caps.

HTH

 

[just a 6]

I don't know if you knew about this or if it's been explained already, but to put it in simple English.

Every time you replace a main cap or a rod cap you have to line bored the block or rod. Dosen't matter if it's a used part or a new part, a Sy/Ty blocks main caps are line bored from the factory on that block. The NT 4.3 caps are line bored from the factory on that block, if you install a main or rod cap from a different block most likely the hole where the bearing are is going to be egg shape not round. = Primature bearing failure.

Same thing with cam caps for overhead cams.



[quote="Sigo
So say that I got the wrong block from GM in my Sy. You're saying here that the main caps would be wrong...(that and based on what I've seen elsewhere...) so could the wrong caps be replaced with the "right" caps? If they can be replaced why then would you need to start off with a SyTy block if the caps can be replaced and those are the only things that is stopping a normal block from bein a SyTy block? (Excluding the previously mentioned balance shaft blocks) Or is it not worth the hassle...if you're replacing main caps...to just go ahead and go 4 bolt? Is that what you're refering to?[/quote]

 

[Hu Ryde]

So does anyone have the PN for these caps?

Can 4 bolt splayed main caps be put on a N/T LB4 block? From what I'm reading it can but just want to be sure.

So basically bare block to block there is no difference at all?

Lastly, is there an easy way to identify the motor when it's assembled sitting out of the car in a junkyard?

Good stuff guys!

 

[myclone]

just a 6 is correct. Im was assuming everyone knew that if you change main caps the block needs to be line honed/bored.

Hu Ryde,

I dont have a part#... wish I did to see if they were still available(not likely IMO)

Whats a "N/T block" Do you mean N/A or Non Turbo? If so I believe the answer is yes. I know it can be done on N/A production SBC.

Block to block there is no difference other than late blocks with the balance shaft. Late balance shaft blocks are supposedly lighter duty but I cant confirm that myself as Ive never compaired the two.

Are you looking for differences to identify a non balance shaft vs balance shaft engine or syty engine vs N/A engine?

 

[Hu Ryde]

Yeah, N/T = Non Turbo, sorry for the confusion.

Yes, I was looking to ways to correctly identify the right block. Are there any markings between the years or specific casting # on the block?

I know how to identify a L-35 block by the manifold and such and those have the balance shaft and we dont want that block. But as for a LB4 block identification is there a engine code or casting # anywhere on the outside of the block that will set it apart from the other motors?

Thanks again!

 

[jwaller]

I have never seen a part number from GM to actually order the correct main caps. as dave said just get some steel caps and use those instead...they will be even stronger....and anything you change caps you must have it line bored anyway.

 

[Hu Ryde]

Makes sense, who's a good source for steel caps? Website? John, how much do you think Mike Hood can get them for us?

 

[myclone]

Makes sense, who's a good source for steel caps? Website? John, how much do you think Mike Hood can get them for us?

Turbo Tony provided this link a while back. I believe these are the ppl that he used for mains in his build up.
http://pro-gram.com/catalog/catalog...N_CAPS&cart_id=22196.9498&store=program.setup

As for part #s for the stockers..... I tried to look it up in my parts book but there is no part # for the main caps or block. It says "NS" for both which Id guess means "non servicable"(as in you cant get em).

 

[TurboTony]

FWIW,

I used the steel caps that gm sells. A 2 bolt in the front and 4 bolt splayed in the two middle positions. I reusued the stock rear cap. The block is just a regular LB4 tbi block.

If i had to do it over again, I'd prolly spend the money on a steel rear cap as well. Just wasn't in the budget at the time.

Also, the camshafts are different on the L-35 balance shaft blocks. The nose of the cam is different to accept the gear to drive the balance shaft. That will limit the cam choices you have, AFAIK nobody makes an upgrade cam for the balance shaft motor.

Be aware that the later TBI motors came with the balance shaft block. It's pretty obvious to indentify them by the timing cover.



HTH

Tony

 

[myclone]

FWIW,

I used the steel caps that gm sells. A 2 bolt in the front and 4 bolt splayed in the two middle positions. I reusued the stock rear cap. The block is just a regular LB4 tbi block.


Tony

I thought you posted that link when I was doing main cap research a month or so ago?? If not then my apologies for blaming you for providing ithe link :wink: .

Eh?

 

[TurboTony]

Hey Dave,

Yeah I posted that link, program machine is the only company I'm aware of that makes the steel rear cap.

I used the GM caps because they are easier to buy, just go to yer local dealer and order em up.


Tony