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TBI re-build advice

AlphaVictorTango

AlphaVictorTango

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So I picked up a '90 V2500 Suburban about 6 months ago. Ran great for about 4 months but started to develop a nasty ping at part throttle. I've run through everything I can think of. Tank full of 93, check EGR function, temp sensor, knock sensor, full tune up. No codes stored. I did a compression test and found cylinders 3 and 4 with about 30 psi. so... time for a new motor. Truck has 180,000 on the clock. I've got a motor from a '89 1/2 ton that I've pulled apart and sent heads, block and crank to machine shop. I'm thinking a mild roller cam with roller rockers and a tune from TBI chips.
Anyone have any thoughts on where to spend a "little" :wink1: extra cash in this re-build? I'm only going to do this once and don't want to read about some bad ass set-up I should have done. Sorry for the long post but I've been watching this forum for awhile and am very impressed with the amount of technical knowledge out there. I'm a tech at a european shop and it's been 15 years since I was elbows deep in a SBC. Thanks for the help and ideas guys!:bow:

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Being a tech i'm assuming that by saying cylinders 3 and 4 you're talking about the 2nd cylinder back on each bank?
 
LOL, nope I said European Tech. Does Chevrolet identify cylinders from right to left across cylinder banks? Looking at motor, 1 is first on left and 2 is first on right?
I understand I have a lot to learn about GM motors but what does me misidentifying cylinders have to do with my post? Were you thinking intake leak or something? I was looking for people with experience modifying TBI motors to maybe give me some insight. Like British Slave's recommendation. This will be a perfect time to send out my injectors to be cleaned.
 
Thats one sweet lookin burb.

I would definitly go roller cam, maybe even vortec heads.

depends on the budget and how crazy you want to get with it.
 
no body want to talk TBI i will.
You are putting a roller cam in good! have the machine shop mildly port your heads.
Gasket match the the intake to the heads. Clean up the casting flash and bumps in the intake runners. Smooth out the swirl ramps, unshroud the valves. Simple cheap porting.
Exhaust: Best i know of is edelbrock TES system. Mine is 10 years old and never a leak. Stainless steel headers= so no rust! Wont build top end power but work great for low end torque. which is good for a Sub
Intake: unles you are going wild. The stock manifold will support HP to around 350.
I would get a bored TB and other parts on this page from:http://marine-performance-parts.com/gmtbiperformance.aspx
They all work. I have used then on TBI builds i have done. A bored TB is a must have. The stock TB is around480- 500 CFM. You need around 600 cfm to make a roller camed 350 run.
New injectors!!! be sure they are Flow matched. 65 lb hr cop car injectors will be best for mods i am recomending. But stock will work with an adjustable fuel pressure regulator and higher fuel pressure.
Dont go over 9.5 to one compression. TBI is too hard to tune at higher compression ratios. unless you put it on a dyno.
Hmm what else??? Oh yeah ignition.... Gotta get a DUI. Best on the market IMOhttp://www.performancedistributors.com/gmcomputerdist.htm Puts MSD to shame. Get their coil too. Plug wires are good stuff.
There is probabally a little more stuff. but this is a good start.
 
I think 4X4 high was asking how you id the cylinders because if the cyl were next to each other you may simply have a blown headgasket and an easy fix. Looking at the pic below, which cyl were low?

Chevy_V8_Firing_Order.jpg
 
Cylinders 4 and 6 are the culprits then. Head gasket? No hard starts, good oil and coolant. 180,000 miles I think I'm committed to a rebuild. Love those Edelbrock headers. And I love all the ideas. Thanks guys. I'm getting excited!:laugh:
 
Yep, British Slave got it right, i was asking because two adjacent cylinders with low compression means a blown head gasket and a cheap easy fix (if you do the work yourself). My original engine went 240K before i built a new one so if money is tight at the moment i would do a head gasket and keep running the current engine as you plan a future engine build.
 
That is a tempting way to go.... Head gasket would explain bad compression and fouled plugs/miss at idle. Do you think it would cause my nasty pinging as well?
 
OK, So after spending way too much time online I have come up with the following plan. 350 2 bolt with a .30 over rebuild kit. Maybe a flat top piston to just barely raise compression. Slightly worked stock TBI heads. My machine shop had a nice looking set of roller rockers for $130. I was thinking this roller cam set up. I'm not sure if the block I have will work with it though. Find out tomorrow when I drop it off at machine shop hopefully. Now comes the part where I'm not sure where to spend my money. Jumping to exhaust, if the stock manifold bolts come out OK and I don't manage to destroy my cross over pipe I'd like to re-use all of it for now. Especially with fresh bolts in there I could go back and upgrade to those sweet looking TES headers and dual exhaust. In the mean time I might just cut out the factory muffler and weld in a Magnaflow or something. Mostly for the sound. I can't hear my motor at all right now.
I'd like to also reuse my stock intake, throttle body and injectors. I'll send my stock injectors out to be cleaned/flow tested. Put a Vortec fuel pump in tank and a adjustable fuel pres. regulator set at what? 14psi??? So what do you guys think? I figure if I buy the guys down the street at the powder shop a case of beer I should be able to do this completely freshened motor for $1200 or so. Then down the road a bit, I'm closing on my first house two months from now.... Send out the throttle body to be bored, Bolt on a nice exhaust, maybe buy a EGR friendly intake. Crank up the fuel pres. and re-tune with Brian at http://tbichips.com/.
Sorry for the long post but like I said I'm excited about this build. I would love to drop more money on this but I need this done so I can use my Burb for what it was meant to do. Move my **** and give me a place to hide in back and drink beer in peace. Thanks agiain guys.:bow:
 
Oh what about push rods? anything special I need to know. Or just a good set of stock ones. Retainer springs? I scored a sweet electric fan/shroud combo from a body shop next door. Figure I'll lose my belt fan and wire this one in on a relay/temp sensor. And lastly I think distributor. Should I replace mine? Would hate to get this motor built and find out it was my distributor making this pig ping all along. I've got fresh stock plugs, wires, brass cap and rotor and one of those fancy MSD coils. I splurged. Timing chain? I figure go with the timing gears for that killer Super-Charged Burban sound. No, just a stock chain from summit or something.
 
AlphaVictorTango said:
Really?:( no one's going to tell me something good? I know 4X4 high has something to say.
Click to expand...

If you're going to go from a hydraulic flat tappet to a hydraulic roller cam the pushrods are different (shorter length). I like to buy Comp Cams stuff and they have an inexpensive version that is plenty good enough for your application.
 
just a little heads up.
If you go with flat top pistons make sure you have 76cc heads. Look in the center of the lifter valley you will see a string of numbers. If they end in 191 you have 76cc heads.
If they end in 193 you have 64cc heads. flat tops and the .030 over bore will raise the compression ratio way too high for the stock chip to handle. You will be close to 10 to one.
If you have a 2 bolt main engine you will most likely have 193 heads.
4 bolt mains got hte 191.
Your bilder should cc the heads to make sure you get the right compression ratio. the stock chip cant handle over 9.5 to one. many people/ engine builders do not know TBI came with 2 different cc heads. many just assume they have 76Cc like most all other truck SBC heads.

Dont really need dual exauhst unless you really want it. TBI really likes 3" single. If you go with the TES system the Y pipe and headers are really made to complement each other and work best on a single 3"

DO NOT GO WITH TIMING GEARS!!!!!!!
They will really screw up the timing because the noise affects the knock sensor. The ECM will think the engine is knocking and never allow you to get full advance on the timing. and cause other problems. Use a chain. I like Cloyes double roller timing chain sets.

IMO the cam you listed is a little too much for a TBI engine. you are better off with a cam that is all done by 5000 rpm. The stock heads quit flowing about 4800.
I would use a Comp # 12-464-8 grind #252XFIH it is an excelent cam for a mild TBI build.
with 1.6 to one rockers.
You can get the whole kit with everything you need from Comp cams.
 
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So does that mean that the 2 bolt's run different pistons than the 4 bolts to compensate for the smaller combustion chamber? Or do 2 bolts normally run a higher compression ratio? And would I be ok with a .030 over bore, dished pistons and 193, 64cc 2 bolt heads on a 4 bolt block? I'd rather not have to run premium if I can help it.
 
2 bolt and 4 bolt ran the same pistons, The heads have diferent size combustion chambers.
2 bolts are higher comp ratio.9.2 to one. VS 4 bolt 8.2 to one
You should be fine with a .030 overbore if you stick with the stock type pistons. It wont raise your CR enough to need preimiun gas.
 
TBI heads suck ass... if anything at all, put some vortec heads on... if your doing a full rebuild then stroke it for sure.... 383 with decent set of heads and a cam will make some big torque #s :D
 
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