at 69k I'm pulling my -brand new looking SD 305 TPI and swapping in a donor
L98 from an 88 vette MAF. Contemporary Corvette in Bristol, PA has hundreds of C4's C5's along with Gen 4's and Caprices (contemporarycorvette.com). The motor was still warm when they cut the front end off donor 88 Vette. It was a beautiful immaculate car, except for the wreck, 105k. I got the whole enchilada- 700r4 trans, tpi, accessories, knock sensors, injectors and ecm all in one piece. I didn't need the Trans, so they gave me a deal on local delivery.

I will be staying with the speed density setup, and a somewhat stock look. The alum valve covers and the EGR will be the giveaway. The plan is to use the vette's intake and fab an EGR. I'll go with the SD f-body fuel rails as long as I don't have a problem replacing a Multec with a Rochester.

Any suggestions will be deeply appreciated.

Thanks!

In the next couple of weeks I'll have some extra 88 Corvette MAF TPI parts:

harness.
Plenum.
runners.
corvette style fuel rails
88 l98 throttle body.
MAF Sensor.
EGR valve.
I may have an extra ECM, the 90+ SD corvette has the same ECM number as 88 MAF Corvette 12277 I also have read the 90 1227730 works in both 5.0 and 5.7's.
Corvette Exhaust Manifolds
Corvette oil pan.
Corvette Aluminum water pump
Corvette PS
Corvette AC
Almost brand new set of 19" fuel injectors about 5 miles on them.



As for the LB9, it needs to be gone though. I may have over revved it after the new injectors and killed the oil pressure, about a mile from home. It would still start when I pulled the motor out.

 

Engine is here. I looks okay, It has yellow Accell 8.8 wires. Someone sprayed the valve covers silver. Oil is clean. The MAF Harness is 100% except it has a replacement ECM Micro-Tech 59-7165. No apparent oil leaks


couple of Q's-
Can I use my old distributor off the 305 for the 350?
Should I change the harmonic balancer?
Should I use the longer dipstick that came with my Fbody, while the Vette's is shorter?
Should I go after the timing chain and the oil pump while I have this apart, or should I just slap it in there?

 

This has been fun. Due to the center intake bolts, my IROC SD manifold is not a bolt on, and I have ingeniously devised an EGR port from the Corvette intake to the last AIR port on the F-Body manifold.
The distributor has me a little baffled. The Vette has an Hei and I have the F-body wiring harness for the split dist and coil. I have the whole vette harness, and the whole speed density harness. I'm thinking of splicing in the HEI on the F-BODY harness. Can this be done?

 

I may have answered my own question. You can use any cap you like, but the gears have to match. I am going to try to keep the split HEI (original). The EGR tube comes very close to the coil- I wonder if the heat is going to kill it.

Here is a link I found for distributor cap selection: http://www.chevythunder.com/fuel%20i....%20pg%20A.htm

 

since the motor was from automatic, it didn't have a pilot bushing. I bought a new one, and it test fits nicely on the shaft of the T5, so I tapped it in on the rear of the crank. It' is proving difficult to line up with the motor, as I have the flywheel, clutch disk and pressure plate assembled, lined up and attached to the motor. I bent a finger in on the first go round. I hacked the pilot just a bit, so it has a wider mouth. I will hit again tonight.

 

gezuz finally got the motor in. my hoist didnt have enough reach, so I wound up lifting the car about 14" so the hoist could slide under the front tire. now on to better things. Ordered the EGR cutoff for $12. and a new chip for the L98 $175. from TPIS.
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incidently, TPIS also carries the flange to tap into the manifold or headers. I'm staying with the Fbody manifolds for now.

 

The bosses on the '88 Corvette Aluminum L98 heads don't match the Fbody accessories. Good thing I kept all the Vette acc's the Vette AC unit is different, but it fits. The power steering has an independent bottle for the reservoir, and the water pump is aluminum. The vette acc serp setup is centered closer to the motor- which may leave more space. Not done yet.

 

things have gone together nicely, just a few things outstanding, AIR system needs some extra piping to reach. should have my chip and EGR sometime tomorrow, one last go over then fire it up. Looks a little different with vette accessories.

 

here are some pics from my humble abode.

http://picasaweb.google.com/02603sec/L98CorvetteMotor

 

haha.. I set TDC and marked it while on the engine stand. I wonder if I set it backwards. I used a compression tester hose tapped into cylinder 1 with a rubber band around a latex glove, and with the valve cover off, I turned the crank until the second rocker on cylinder 1 was compressed and with an air bubble in the glove. Motor turns over real nice, fast and smooth, but no start tonight. Before I take the cap out and rotate 180, I will install my new chip, which is meant for the #22 injectors and an additional 45 cubic inches. I thought it would start anyways with the stock ECM for the 305 TPI #19 injectors.

 

Oh yeah. My oil pressure gauge shows signs of life. It went dead on the last mile driven with the 305 69k miles. I tried to bench test it, but it had no reading, so I was guessing engine bearing(s) The autopsy has yet to be performed.

 

Cranks but no start. I reset TDC with the vc off, starter spins really fast, coil has a spark, got fuel pressure (holds 39) in the rails, blink test gives me 2-3 blinks in the 5 seconds I'm cranking. No gas seems to be getting past the injectors. every injector tests in the 15 range. SES check light comes on when the ign key is turned to start. I did unhook my TPS and gave it a crank, but nada, and my EGR is blocked off. I am running the FBody ignition, speed density, vette acc's, TPIS sent me a chip to run the 22 injectors, 5.7 and 5 spd manual. the original cpu is a 730. open to suggestions. thanks in advance.

 

my chinese test light quit, I'm going with with a digital voltmeter tonight. Baechtel's TPI book says if both injectors lights blink- then it's a faulty ignition module. If only one blinks, then it's the harness to the injector, no lights mean there is an open injector circuit. My ign module only has a few miles on it.

 

Autozone tested my ICM and it was bad on 2 counts- Energy and dwell. The new one went in and alas, my injectors pulsed. I followed the book to set TDC with the valve cover off. However, it only backfired. I did the 180 turn on the dist. and it FIRED. I can hear the diff the extra cubes make in the exhaust. I have codes 42 and 43 and the idle is a little high. I'm hoping it's only the brown ground wire coming from the ESC module, which hopefully will cancel 42 also.

 

Closing list:
solve code 42-43- high idle
mount p steering bottle
rewire connections to AC, and convert to 134a
reattach hood
have a couple of scratches fixed

 

new knock sensor. the new one Ohms out to 9800. The connection is showing 12+ v. I think this means the new sensor is not the right one, considering the book says 3500 to 4000 ohms. Next test ECM.

 

It was running smooth, with high idle, and code 43 somewhere in the 2000's. I did a test drive, and a rocker noise started up. I pulled the valve cover and adjusted #7 exhaust rocker a bit. Also had a pass side exhaust leak at the doughtnut in the manifold (near knock sensor) and fixed it.

Tappit noise gone. code 43 still present. Now it runs rough and rich, and stalls at idle. However, the timing does advance on acceleration, so ICM and knock sensor seem to be communicating. It seems like the plug wires are crossed, but after checking several times, eliminated this possibility.
Timed at 6 degrees, and confirmed spark to all cylinders.

All of my harness grounds are to the bosses at the rear of the aluminum head.
I just did a fuel pressure test from the schrader valve on the rail, and it holds 40. It jumps back and forth between 40 and 45 while running. All 8 injectors are in the 15-16 range with the ohms check.

Something is off here. I need a checklist. Any suggestions?

 

Been out, but I'm back for a few days. Runs like hell with the code 43. starts right up and it will idle. I need to go and get a new knock sensor. daaaaaang it. now where is the receipt for the SOB?

 

NOTE to self- Need to do the ECM test- but don't understand the pin layout tables in Baechtel's TPI book. I wonder if the Helms manual has the pin layout for the '730, or if there is another resource that actually has a diagram with arrows designating the pins???????

 

hey man ur forum was awsome im going to do a 5.7 swap myself on an 87 iroc when i went to pick up my engine turned out there was a misunderstanding and it was a van 350 so then i found an 87 corvette 5.7 that i was going to buy tomorrow but after reading ur forum i really cant spend the time and money at the time eventually ill go with a 383 but for now i want a stock 5.7 to get around i guess ill just go with the iroc l98 since its a bolt on asside from injectiors prom knocksencor and ignition control module. ur the man good luck with ur swap hope every thing goes ur way but u and i both know its all worth it thanks again ur forum was bad ***

 

Irocmaro- good luck on your swap. I'm wishing I could have found an L98 with IRON HEADS. The Aluminum heads on the "J" motor complicated my swap- No EGR passage, and the accessory bolt pattern required use of the Vette acc's including the separate PS reservoir bottle. IMHO the vette acc's have a more refined look, but PITA.

I'm on my third knock sensor. I finally got one from NAPA that ohms out to 3800. The original one on the '88 vette block ohms to 104k The one from Pep Boys was 9800. New plug wires. Still runs like *** and still getting CODE 43. Baechtel's TPI book says voltage should be less then 6V coming from the harness to the knock sensor.. I am getting 12V. I have 2 different Memcal's- the original from my 305 SD TPI and a new one for a 5.7 SD corvette. Switching them makes no difference. The SES light has a fast blink when grounded with motor running.

1. Knock sensor is 38k
2. Harness is 12v (not good)

So I must have shorted wire somewhere in harness- or bad ground. I'll be gone for a couple of weeks, then I'll take another shot at it.

 

I just had a code 43 today, and am trying to figure it out. Your thread is great, hopefully you are able to solve your problem.

 

Check the ECM ground. I chased a problem on a Bonneville for about a month, turned out the ground from ECM to battery was bad in the bulkhead connector. One symptom was 12V to the sensors, IIRC.

 

I'm back; Every ground wire is re-cleaned and re-connected. Still code 43, still 12v going to Knock sensor. I'm going to unplug the ECM and take it in for a diagnostic. I had it last night with SES light on, and going about 35 MPH, something let loose in the motor. Had to call AAA for a Flatbed. It sounds like a metal playing card that is clipped and fanning against a gear. much like a card in the spokes of a bike. I pulled the drivers side valve cover and started it, noisey as hell, definitely in time with valve/piston/cam/lobe. Probably the same lifter I adjusted previously (hope so). Oil pressure is still good. Stopped by the mechanics shop and he was excited about the prospect of working on a SB Chevy, but he was going to send it out...I can do that! Time for some diagnostics. I was hoping for an end to this thread.

 

there is a broken clip? on the intake valve guide. cylinder #7, unbolted the rocker, and the spring just came off. the end of the intake valve is hammered.

 

Sorry to hear it...No fun.

Since you can see that the intake valve is hammered, do you have the head off already, or is the back end just messed up? I would do a compression check on the motor if you still have the heads on to see if it sustained any internal damage.

 

thanks, Ron the pro, says it's broken, so no compression check. The place where I got the motor from said they would get me another head, so we're going to pull the old head off, take a look at the piston, and I hope it is a forged one, slap the head on, bolt it up, then do a comp. test and see what the deal is.

 

DELETED

 

the iroc has been sitting inside the shop for about 5 weeks. Sent the whole motor back and the guys at contemporary replaced it. I am within a couple of days of being able to hopefully drive it again.

 

Just been reading about you swap and you code 43 problems. Try tapping on the ECM. It sound like you may have a bad one. You should only have 5v to the knock sensor if you have 12v either its a bad ECM or the dark blue knock sensor is shorted to 12v. Also check that wiring to the knock sensor is not mixed up with the coolant sensor on the pass side. They have the same plug on them. Let me know if you want me to send you ECM pin data I can get it from my work and scan it for u.

 

Butcher hehe like the handle. Motor is in, bunch of new parts including an ECM. The shop GROUNDED THE ECM to the Block instead of the aluminum head. Runs nice and smooth, doesn't heat up. I think the mechanic overrode my electric fans, they turn on with the ignition. I've only driven it a few times, but the SES is intermittent. Tap test can trigger SES. My original ECM actually works better, but still fails tap test. I bought a chip from JEGS for the L98 w/22lb injectors, but that shouldn't make a difference? Running like a champ this morning. The power increase is not substantial, maybe a 10% increase over the 305. This swap story isn't over yet. I still need to place the independent power steering bottle and hook up the AC. The Vette AC is a smaller unit, only has 2 wires with one connect to the harness, while the Camaro had 2 connections to the harness. I need to figure out which ones to use. Thankfully I have the vette harness to cannibalize.

 

How many miles are on this engine? If its over 50k I'd defently replace the timing chain while you have it apart. I just pulled a worn 108k mile L98 out of a 91 the other day, the chain had so much slop in it I could almost move it a tooth without unbolting the cam sprocket. Also IIRC 89's pistons arn't forged.

 

right on bro, timing chain, water pump, hoses, new seals, freeze plugs, plugs, wires, knock sensor, temp sensor, o2, just a partial list. so far, no smoke at all. It runs like hot rails to h_ll on the highway. the vette L98 has 10 to 1 so premium is a must. no clue on the actual engine miles- although the innards appeared clean. My engine decode says June of 1987 for 88 model yr.

 

I've driven it about 100 miles. runs nice. I changed back to the original prom and the original computer. Runs good. no codes no SES no heating up. The original prom was from the 305 TPI. The prom for the L98 (JEGS) kept kicking out when I hit bumps. Next couple of weeks I am going to dump all my extra parts including the MAF, a MAF penum, 90 iroc serp, some other stuff.

 

Glad to hear everything is working out for ya!

 

how did you finally make out? I'm thinkin bout swapping my 89 305 tpi with a 350. need to know what's different. Doesn"t look like much. injectors, ecm.Was thinking about going Jasper reman.

 

350's came with larger injectors, 305 19lber's will work on a 350 though, people have had luck just bumping the fuel pressure up a little via an AFPR. 350's require a different knock sensor and a different prom. A custom burn would be your best bet. There are way better engines for the money than jaspers FWIW. Jasper tends to slap on whatever heads they have laying around onto a block with dished pistons etc..

 

After you spend the dough you're going to wish you bought an LS1 setup. My C5 runs like a bat out of h_ll. The L98 aluminum headed vette motor really really runs nice, 10-1 compression. it will spin the tires no prob. They should have made this an option for the 3rd gens. I haven't had time to follow up with Jegs on the prom that makes my ECM blink out. the original prom with 19lb vs the 22lb is working fine. 300 miles and getting 18 round town. Your 89 TPI will have the MAF so I you plan on using the original harness, plan accordingly. The easiest transplant is to find an L98 with the cast heads, with EGR provisions that way you'll be certain to pass emissions.

 

I know I'm a tad late on this one but either tpi base will work, you simply need to reangle the center bolt holes with a drill to make it bolt up. Looking at the pictures of your L98 it appears to have f-body runners on it and an f-body dist cover (plastic) just something I noticed.

 

yeah, I used the Fbody -speed density runners- The Vette runners had the gaslines going in the opposite direction. I used the plastic cap in the mock up. It has the vette one now. up to about 400 miles no probs.

 

How would the runner effect the fuel lines? The only difference I can see between the two is the finish on them.. unless you are refering to one set having the hole for a cold start injector?

 

hey RS Power sorry i havent been keeping up, been on the boat (formula sr271 w 502 fuel inj) and been having a great summer. I had the IROC convt in the paint shop, for the chin and clear coat. The inj setup on my donor L98 was from a vette, so the fuel lines on the L98 went down and to the right, while the fbody fuel lines went down to the left. The motor runs good. I went to syn oil. I really don't drive it too hard. The T5 handles the power well enough for me, but 1st is a little low. It will get down and lay rubber until you let up on the gas. To make this one 100% I need to fix that dang RPM gauge. I also cracked the corner of the dash with my fg knee. My PS bottle is still independent (corvette) without a secure mount. I will get to this stuff this winter. Looking to rent an airplane hangar.

 

Oh yeah I know the fuel rails have the lines going in a different direction, I just didn't know what you ment about the runners being different.. the only difference I've ever noticed on the runners is the vetts had a rough appearance to the casting where as the f-body runners were smooth in appearance. Otherwise they are interchangeable AFAIK (aside from different years with or without the hole for the cold start injector)

 

had it out today, been sitting in the garage for months. fired right up, no smoke, no leaks, and sounds bad aas. The heater blower hasn't worked since the transplant and the AC isn't hooked up. I pulled the blower motor and bench tested. it works fine. There's something wrong with the connections. Too bad the harness is so freaking hard to get to- I have a little mirror and a flashlight- it looks like maybe the ground isn't connected, because I can see a body connection that's hanging there. I think the only way to access is to drop the motor off the mounts (hassle). The AC is a different story. The original AC for the 305 IROC still blew cold before the transplant, and it had 2 sets of plugs from the harness. The vette compressor is smaller and has a cast aluminum look to it, with only two wires. What do I need to do to connect the vette compression up to my iroc wiring harness?

 

Some of em have 2 connectors, others had a single connector. Also depending on year some vette had different style compressors. I think you would be ok if you simply got the correct 2 pin connector and swapped it with the 2 pin connector you currently have. That connector is for the compressor clutch, I'm not really sure what the other single pin connector is for..

 

thanks- I'll give it a shot this week

 

High pressure switch.

 

I figured it was something along those lines but isnt there already a pressure switch in the receiver/drier?

 

That's the low pressure switch.

 

Thanks again five 7 and RSpower. The AC from the IROC had 2 plugs with 2 pairs. One pair went to the clutch, the other to the compressor housing. The 1st plug wire pair is green and light blue. The 2nd plug wire pair is green and black w/white stripe. I got aggressive and cut out the (diode?) from the original IROC harness. (The diode basically was green and black w/white stripe. It was a solid piece about 6 inches long, solid) The Vette just has 2 black wires and they look like they go into the clutch. Is this just a matter of connecting wires to each other? or is there another mystery behind this? Which wire is recommended? I have wiring schematics for both vehicles, but no sense can be made of either.