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84 Corvette Journey
Hi All
Last year about this time I purchased an 84 Corvette as a bit of a project for my son and I. I signed up to this forum asked questions and got help. Initially the car had the usual problems, sensors not working, people doing things to the car they shouldn't have, etc etc. A lot of water has passed under the bridge since then and I have been on a fast learning curve. I've received a lot of help alone the way and the aim of this thread is to chronical the journey in the hope that others will fine it useful. |
Inital Problems (check the sensors)
Initially the car seamed to be running very rich so I replaced the plugs and bent a paper clip to fit in the ALDL port. The ECM reported a code 44 which is a lean condition, As the car was acutely running rich I replace the O2 sensor and that and that code never returned. However the care was still running rich, I down loaded the WinALDL software and made a cable.
The website is here http://winaldl.joby.se For these old corvettes this software works a treat. I was able to see exactly what sensors were doing what. The TPI sensor was reporting that it was 39% open when the throttle was closed and when I tried to adjust it I found I couldn't. So new TPS sensor and the car no longer ran rich. I also had quite a high knock count so I replaced the knock sensor. The knock sensor was all broken but it was also done up very tight, I installed a new one and torqued it up to the correct setting, another problem solved. I have subsequently replaced most sensors on this car, the reason being the originals are 35 years old and the new ones are cheap. Some my disagree but I figure it's just maintenance to replace old sensors on an old car. |
Hunting at Idle
Lots of people on this form seam to have trouble with cars hunting at idle. I had this problem quite severely and searched the forums for a solution and I eventually found it. The answer to my problem was that the throttle blades were cracked too far open at idle. Actually my throttle bodies were a long way out of adjustment as well. I knew the car was idling too fast but I didn't want to turn it down because it would sometimes stall whilst hunting. So in my case the engine was hunting because it was too lean i.e. if the throttle blades are open at idle there is more air in the air fuel mixture. Thinking about it someone had probably adjusted it that way to counter act the rich condition I described in my previous post. Anyway I adjusted the throttle bodies as per the service manual and all was well. Incidentally I had to make my own manometer to do this I simply used a ruler, some zippy ties, some plastic tube and water coloured with food dye. here is a picture.
https://cimg0.ibsrv.net/gimg/www.cor...ec7aed3fc9.jpg Home made manometer |
New Distributor
By now the car was running much better but in my quest for improvements my attention turned to the ignition components. I was planning on replacing the distributor cap, rotor plug, leads, an maybe the module; but once I added it up I decided to just buy a new distributor with everything matched and ready to go. It's probably worth noting that there was nothing wrong with the existing original Delco unit but that didn't stop me. I settled on a Davis Unified Ignition (DUI) distributor which I promptly ordered installed. I set the timing at about 8 Deg BTDC and reconnected the EST connector. As soon as the revs were brought up the engine began to backfire though the throttle bodies and out the exhaust almost at the same time. Something was very wrong. I checked firing order and initial timing the car would run with the EST plug disconnected but it couldn't tolerate any real advance. I swapped the cap coil and module onto the old Delco distributor and the car ran perfectly. I checked the pickup coil and it was ok so I contacted Davis and they sent me out a new distributor shaft. When I compared the new shaft with the original one I noticed that the reluctor had a different orientation i.e. magnetic pickups were at a different angle to the rotor button. One I installed the new shaft the DUI distributor was fine.
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Timing chain troubles
I had ordered a Renegade intake manifold and planed to install it over the Christmas break, but fate intervened. I drove the car home one afternoon, backed it into the garage and then the car stalled an could not be restarted. I had no spark and the injectors were not spraying so I suspected the DC supply to the distributor. Anyway during the fault finding process I noticed that the distributor was not turning when I turned the engine over. I was hoping that the helical gear on the bottom of the distributor had sheared the pin but a quick inspection proved that wasn't the case. So I began disassembling. Here is what I found. https://cimg5.ibsrv.net/gimg/www.cor...24401cbaf0.jpg https://cimg4.ibsrv.net/gimg/www.cor...fb77a859c9.jpg So it looks like the nylon material on the cam gear had become old and brittle and this is the result. But on the up side no bent values no bent push rods and no marks on the pistons so that's a win. |
New parts for an old engine
So I was at the cross roads do I ditch this engine and do an LS swap, do I do minimal repairs to this engine or do I do a top end rebuild. I chose the latter.
https://cimg4.ibsrv.net/gimg/www.cor...40f5561c65.jpg The parts list and modifications list looks like this. CRANE CAMS SMALL BLOCK CHEV HYDRAULIC Z-256-2 CR113501 EDELBROCK CYLINDER HEADS ALLOY E-STREET SMALL BLOCK CHEV COMPLETE PAIR ED5089 COMP CAMS ROLLER ROCKERS HIGH ENERGY ALLOY CHEV 1.6 RATIO 3/8" STUD RENEGADE INTAKE MANIFOLD PACEMAKER HEADERS PRIMARY PIPES 1 3/4 “ COLLECTOR 3” DUI DISTRIBUTOR NEW EXHAUST 2 1/4 “ CAT DELETE AIR PUMP DELETE EGR VALVE DELETE These L83 engines had forged pistons and in my case everything looked ok when I pulled the heads off. The bores were a bit shiny but there are no lips and it wasn't blowing smoke so I stopped short of pulling the engine out and doing the bottom end. https://cimg9.ibsrv.net/gimg/www.cor...4dbd6a3cf6.jpg https://cimg0.ibsrv.net/gimg/www.cor...e789a1882a.jpg BTW does anyone know what the CC volume of those piston dishes are? I've looked online and come up with 3.5CC but I also found someone saying they were 4.9CC. Also does anyone know the above piston deck clearance, I forgot to put the dial indicator on it while I had it apart? |
Cam
So why did I choose a Crane Cam Z-256-2 ? I was looking for a cam that would work with the existing EMC and tune, so I could get the engine running without hassles. I wanted a cam that worked from low in the rev range up to over 5000rpm. I also didn't want to have any vacuum issues. I would have liked to get a roller cam but I couldn't justify the extra expense. This is a pretty mild cam with duration @0.050 of 206/218 and LSA of 112 but it has a pretty wide power band between 1200 and 5200 rpm. I'm quite happy with the result. I used 1.6:1 roller rockers to give it a bit more lift. The cam card is below.
https://cimg9.ibsrv.net/gimg/www.cor...0dd7d10fdf.png |
Heads
I chose Edelbrock E-Street ED5089 Cylinder Heads. The light weight iron heads that were on an 84 Corvette are very restrictive and prone to cracking (although mine were not cracked ). So to my way of thinking a new set of aluminium heads that flow well and have smaller modern combustion chambers and big valves is a fairly logical choice. These heads seam like a good match to the cam I chose as their operating range is between idle and 5500rpm. For the record I used Fel-Pro FE1010 head gaskets. See the stats below
https://cimg9.ibsrv.net/gimg/www.cor...0460e4f27d.png https://cimg0.ibsrv.net/gimg/www.cor...84a89c0708.jpg |
Putting it all together
Here are some photos showing the installation of the Renegade intake manifold, throttle bodies etc. https://cimg0.ibsrv.net/gimg/www.cor...2abf20a211.jpg Roller rockers are installed and the valve lash set. The intake is sitting in place to check fit. https://cimg6.ibsrv.net/gimg/www.cor...f816f584f8.jpg https://cimg7.ibsrv.net/gimg/www.cor...0eae434260.jpg Throttle bodies are hooked up and the headers have been installed. https://cimg4.ibsrv.net/gimg/www.cor...2c1404418a.jpg https://cimg9.ibsrv.net/gimg/www.cor...15508ec0ab.jpg All finished. |
What's next
I've been driving the car for a few months now and it is certainly a lot more lively than it was before. The next step is to get it tuned correctly. To that end I have ordered a EBL Flash II from Dynamic EFI
http://www.dynamicefi.com/EBL_Flash.php So the next adventure is tuning, If there is anyone out there with a bin file for a setup like mine and willing to share I'd love to hear from you. However in reality I'm pretty sure I'll have to step through the process myself. Anyway that's all for now, when I have some tuning info I'll post it to this thread. https://cimg8.ibsrv.net/gimg/www.cor...19eeb93638.jpg |
:cool:
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You are a very resourceful person and have gone far with your Beautiful Corvette!
Having the first year of the C4 is a challenge by itself here in the United States, In Australia it must have been difficult to find the parts. It looks like you did a great job on the Engine as well. I hope the folks around you appreciate all your work and creativity. I really liked the ingenuity of your Manometer! I have been using a four cylinder Manometer for a motorcycle on my cars for balancing carburetors, fortunately my brother is the only nut with multiple carburetors on his Porsche. My daughter loves my Corvettes and has helped work on my C4, she is trying to learn about these old beasts and what makes them tick. I love seeing interest in these Corvettes of the millennial generation, too often you see older folks at the Corvette Events and it appears that only old people can afford these cars. I bought my 1968 C3 28 years ago and added a 1988 C4 to my collection in 1999 to accommodate the birth of our second child. We have the C3 convertible for Dad and Son to drive and the C4 Coupe for my Wife and daughter. Corvettes and Car seats it certainly made it more fun for Mom and Dad. My older Corvette is a 1968 C3 with the 427 engine in it and a four speed. I don't let anybody besides my wife drive that car, it is too much car for most young drivers (it is Traction limited). My daughter has been learning about carburetors first so she can understand How the fuel injection system works. I plan to give her my 1968 C3 when I no longer can use it, she knows how to drive a stick which is rare for the younger generation in this country. How expensive is good gas in Australia? Do you have any troubles getting high enough octane? I had a Cadillac that used to get 12 miles per gallon (on Premium fuel) until I switched it to have a water/Methanol injection system from Snow Performance. After the installation I was able to run the cheapest gasoline and have more octane than the pump gas. The power jump is fairly substantial when it supplies 115 octane to the fuel system and my compression loves it. It reduces the combustion chamber temperature and increases the octane of the fuel and you can inject as little or as much as you want depending on how your engine tolerates it. I just bought a Snap On MT 2500 and am impressed what it can do on the OBD1 cars like the early Corvettes. I am able to use it up to 2009 vehicles and it displays everything that the engine sees. One of the best tools for checking your modifications is a gadget called a GTECH PRO and I have an older one but it still helps when I am testing or tuning the car. It is a able to measure the Horsepower and torque of your engine as long as it has an accurate weight for your particular car. I replaced the catalytic converter and installed a Chambered Exhaust system and I gained just shy of 14 hp for the effort. I tested my carburetors to see which gave me the best power without ever seeing the inside of a Dyno room. Take a look at them and see if it might help you with your project. Another tool I use regularly with our Corvettes is something called a "Power Probe" and it pays for itself the first time you really need it. I have the 4th version and it is incredible, it lets you apply either +12 Vdc or Ground/Earth at the tip based on which way you push the toggle switch. I use it to verify voltages and test devices like fuel pumps at the harness. With our wacky ground system it is very helpful, it also shows voltage drops as you go further into a circuit. It is so useful that I have two of them now and have used them on aircraft, boats, computers, motorcycles and cars. Thanks for sharing with us your Corvette project! It is a gorgeous Corvette you have there and you should be very proud of your accomplishments! Best Regards, Chris |
Originally Posted by ctmccloskey
(Post 1599509426)
You are a very resourceful person and have gone far with your Beautiful Corvette!
Having the first year of the C4 is a challenge by itself here in the United States, In Australia it must have been difficult to find the parts. It looks like you did a great job on the Engine as well. I hope the folks around you appreciate all your work and creativity. I really liked the ingenuity of your Manometer! I have been using a four cylinder Manometer for a motorcycle on my cars for balancing carburetors, fortunately my brother is the only nut with multiple carburetors on his Porsche. My daughter loves my Corvettes and has helped work on my C4, she is trying to learn about these old beasts and what makes them tick. I love seeing interest in these Corvettes of the millennial generation, too often you see older folks at the Corvette Events and it appears that only old people can afford these cars. I bought my 1968 C3 28 years ago and added a 1988 C4 to my collection in 1999 to accommodate the birth of our second child. We have the C3 convertible for Dad and Son to drive and the C4 Coupe for my Wife and daughter. Corvettes and Car seats it certainly made it more fun for Mom and Dad. My older Corvette is a 1968 C3 with the 427 engine in it and a four speed. I don't let anybody besides my wife drive that car, it is too much car for most young drivers (it is Traction limited). My daughter has been learning about carburetors first so she can understand How the fuel injection system works. I plan to give her my 1968 C3 when I no longer can use it, she knows how to drive a stick which is rare for the younger generation in this country. How expensive is good gas in Australia? Do you have any troubles getting high enough octane? I had a Cadillac that used to get 12 miles per gallon (on Premium fuel) until I switched it to have a water/Methanol injection system from Snow Performance. After the installation I was able to run the cheapest gasoline and have more octane than the pump gas. The power jump is fairly substantial when it supplies 115 octane to the fuel system and my compression loves it. It reduces the combustion chamber temperature and increases the octane of the fuel and you can inject as little or as much as you want depending on how your engine tolerates it. I just bought a Snap On MT 2500 and am impressed what it can do on the OBD1 cars like the early Corvettes. I am able to use it up to 2009 vehicles and it displays everything that the engine sees. One of the best tools for checking your modifications is a gadget called a GTECH PRO and I have an older one but it still helps when I am testing or tuning the car. It is a able to measure the Horsepower and torque of your engine as long as it has an accurate weight for your particular car. I replaced the catalytic converter and installed a Chambered Exhaust system and I gained just shy of 14 hp for the effort. I tested my carburetors to see which gave me the best power without ever seeing the inside of a Dyno room. Take a look at them and see if it might help you with your project. Another tool I use regularly with our Corvettes is something called a "Power Probe" and it pays for itself the first time you really need it. I have the 4th version and it is incredible, it lets you apply either +12 Vdc or Ground/Earth at the tip based on which way you push the toggle switch. I use it to verify voltages and test devices like fuel pumps at the harness. With our wacky ground system it is very helpful, it also shows voltage drops as you go further into a circuit. It is so useful that I have two of them now and have used them on aircraft, boats, computers, motorcycles and cars. Thanks for sharing with us your Corvette project! It is a gorgeous Corvette you have there and you should be very proud of your accomplishments! Best Regards, Chris Thanks for your kind words and encouragement. Yes it is a bit of a challenge getting Corvette parts in Australia. Ebay has of course made it easier, for the nuts and bolts Chevy stuff I tend to use Rock Auto because they are reasonably priced and their delivery is pretty quick. For Corvette specific stuff generally have been using Ecklers or Zip, but both can be expensive and Zip just took 6 months and 28 emails to sort out a stuff up so I'm unlikely to use them again unless I'm desperate. No wrecking yards here have Corvettes siting in them. Often times the Australian Holden had the same parts fitted so you can have a bit of a guess. An example is my current Holden SS Commodore has an LS engine (confusingly it is referred to as an L98! It is a 6.0L engine with an LS2 bottom end and LS3 rectangular port heads and intake. I purchased most of the go fast bits in Australia at Outlaw Speed Shop http://outlawspeed.com.au/shop/ that saved me international shipping, that's also why I chose the Edelbrock heads they were reasonably priced and available. My two boys have been brought up with a love of Corvettes like your daughter. Both my boys can drive stick which is getting rare here too. I agree it's great to see young people appreciating these cars, too many grey haired old bastards (like me) in these cars because they are the only ones that can afford them. About 10 years ago I was on the lookout for a late 60s early 70s big block and I could get one for around $20K a show car was about $40. C3s were still a bit unloved even them particularly 1968 models (Too many rattles, panels don't fit, blah, blah, blah). I was born in 68 so I always liked them. Anyway I didn't fine the right one so I bought a new car instead. These days in Australia you are not allowed to put a kids car seat in the front so I guess that rules out corvette ownership for the young mums. Back to the topic of your 68 427. I know a bloke with a fully restored tri power 427 68 it is for sale for $85K so I guess people appreciate early C3s now (I always did). Funny thing I was never a big fan of the C4 but since owning one that has all changed. My 84 handles better than any car I have ever driven it's a 4+3 with the Z51 option and I think its great. Also the tech that GM put in those cars is astonishing for the time. all corvette are beautiful but I think those early C4s are more special than what most people realise. Ok so petrol in Australia. Firstly we advertise our octane rating differently to you guys. We advertise the RON (research octane number) you guys advertise the average between the RON and the MON (motor octane number). So our regular unleaded is referred to as 91 octane but it is actually the average of 91RON and 82MON so that's 86 or 87 in you money. I tend the use 98RON which is available everywhere it is 98RON and 88MON so that would be 93 octane at a US pump. So price, today the average regular unleaded price in Brisbane is $1.48 per litre ( prices are high here at the moment, was $1.10 a little while ago.) Also remember that our dollar is rubbish at the moment it's about 66 US cents (the lowest its been in 10 years). So putting that all together, today you would pay $3.70 US per gallon of regular unleaded. That Snap On MT 2500 was a very good tool. I have an OBD2 reader for my newer cars and soon the Corvette will be communicating via Tuner Pro. Interesting about your Power probe I made one of those when I was an apprentice and worked pretty much exactly the same. I'd forgotten all about it, I'll go down to the shed and dig it out, it would be very useful. Oh and I think that photo makes the car look better than it is, the rubbers are shot and it needs a respray. Regards Greg |
Hey Greg, thanks for the link to your thread. :thumbs: I love that color of red, looks real nice IMO. Also like your manifold and hope you enjoy the performance you gain. I think with Ben right there to help you out, you are in good hands my friend. Did you by chance get your EBL from Bob? I will be sneding you a PM tonight about your other items which are now ready to ship. :D Thanks again. Tom
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Originally Posted by Buccaneer
(Post 1599513495)
Hey Greg, thanks for the link to your thread. :thumbs: I love that color of red, looks real nice IMO. Also like your manifold and hope you enjoy the performance you gain. I think with Ben right there to help you out, you are in good hands my friend. Did you by chance get your EBL from Bob? I will be sneding you a PM tonight about your other items which are now ready to ship. :D Thanks again. Tom
The EBL shipped on he 29th from Pennsylvania but it has only made it as far as JFK. Who knows with any luck it should be in Hawaii tomorrow, but my guess is it will be in LA. regards Greg |
Google around, there should be a few bin files posted here and there.
I have mine, but there are some settings you might have some issues with due to my large injectors and vac referenced fuel pressure regulator. I'm also curious how well your car runs with those heads, 64cc chamber is quite the bump in compression! I have the 70cc version of those heads. Also the thirdgen forums has a diy tune/prom section. Rbob the creator of the ebl flash posts there. |
Originally Posted by Gibbles
(Post 1599522778)
Google around, there should be a few bin files posted here and there.
I have mine, but there are some settings you might have some issues with due to my large injectors and vac referenced fuel pressure regulator. I'm also curious how well your car runs with those heads, 64cc chamber is quite the bump in compression! I have the 70cc version of those heads. Also the thirdgen forums has a diy tune/prom section. Rbob the creator of the ebl flash posts there. Yes I have been lurking around the Thirdgen posts and have been in contact with Bob (Robb) about settings for the 4+3. I guess with your different regulator and injectors you have different pulse width etc. It would be good to see mainly as a comparison and for some clues. I plane on doing it myself but I expect some confusion along the way. |
Dish volume was something like 4cc if i remember correctly.
I would love to hear how your data logging goes, i have some later c4 vette timing tables that worked out well. Pretty much i have a table from an 89 vette, and take the sa latency value from the 3006 bin file that comes as an example. Those two really woke my car up! And i would love to hear how well it runs, knock sensor stuff too. Your setup is close to what my engine stroked would be at. And if you do stroke the engine, those heads will make life easier with the piston choices. |
Also, how thick is your head gasket (quench)?
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Originally Posted by Gibbles
(Post 1599523917)
Also, how thick is your head gasket (quench)?
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