Assuming your engine is identical to mine, a loose quench gasket thickness is .020.
That might be why your getting away with it, unless i read that wrong.
Eta: assuming your deck height is the same as mine

 

Thanks for the info.
it doesn’t appear to have any knock issues at the moment I might take it for a drive with the WinALDL software plugged in before I do the ECM swap so I have a base line. (That will give me a knock count). I thought those pistons were 3.5cc so that’s what I did my compression calculations with.
Thanks again for the tuning info, I’ll post my results once I get the EBL and start tuning.

 

Yeah I think the thin steel gaskets are .0.02” also I didn’t put a dial indicator on the deck when I had it apart so I don’t know how much height there is at TDC.
Incidentally in go kart racing they measure squish by feeding a piece of solder into the spark plug hole and turning the engine over. The they measure the squashed bit of solder to determine the squish. I could probably to the same.

 

I can't remember my measurement, but i stacked feeler gauges @ tdc until i had it perfectly level with the deck/top of the block, then used that to calculate quench.
On my deck that was original (vin number still on the top of the block), a good quench was something like .018 gasket thickness.
I think a tight gasket thickness was something like .014... it has been a while, but i have my build on grumpys performance garage.
Including my transmission rebuild hell while running a fever... lol!
Good times!

I currently have a .020 felpro stainless shim gasket on there, a little loose/safe.
But that thing responds great.

You might have a very loose quench, meaning there is some more power to pull from the engine via a thinner gasket!

Eta: my original build plans had a copper gasket, it was all wrong and caused a ton of problems due to leakage into my cooling system.

 

Wow I had steel gaskets ready to go and then a very respected Chevy guy over here said to me that I should use copper and that the Fel-Pro 1010 was the go for alloy heads. So that’s what I did.
I can’t see any numbers on the photos I took of my deck but I would be surprised if it had been machined, it look 35 years old to me.
Anyway I guess I’ll just suck it and see.

 

If it's a felpro, you're probably fine.
What burned me was that i used an sce copper head gasket.
That gasket said it should be used with a grooved head or block for a ss ring.
I was told that was not needed... it was!

If it has been decked, good chance you're ok.
If the quench was off, the engine would feel sluggish, and not respond very quickly.

All the quench is is the space from the top of the piston, to the flat part of the head.
Keeping that tight helps squish and swirl the air into that combustion chamber cast into the head.

 

Depending on the dish, some 84s could have had 7cc dish too iirc. As far as the quench, it isn't as critical for swirl as with a more traditional chamber vs vortec styled ones... so running one a little loose wouldn't hurt as much. As far as unmarked untouched deck height... around .02 is pretty normal for a sbc... below .06 for quench is okay. .04 is doing really good for a street application and so on. I actually set the 383 in the truck around .05 and its been fine. Excessive quench sucks yea. You both seem fine as far as setup and thanks for the read. This is awesome.

 

Yeah my little engine pulls pretty hard. I think that all the 84 L83 engines had the same pistons they are a TWR forged piston stamped 464664 with a trench type of valve relief. They look to be about 4 cubic centimeters in volume and the internet tells me anywhere between 3.5cc and 4.3cc so I guess it’s somewhere around there. I’m not worried about compression I think I have plenty. I’m glad you liked the read. I’ve learned a lot since I bought this corvette and I notice that the same questions keep coming up. I reckon I’ve dealt with most of them and others could probably benefit from my learnings. I thing the 4+3 crossfires are very special cars.

 

Yeah I trust Fel-Pro gaskets and I didn’t want the steel ones to put indentations in the heads.
i don’t think the engine has been decked (based on looking at it) so quench is probably 0.039” gasket thickness plus whatever the piston height is maybe 0.020” not sure. Either way the engine feels sharp so I think there is plenty of compression there. I also think the combustion chambers on those heads are a good design, I’m actually very happy with my engine build. It’s good now and I can’t wait to tune it. I think 300hp is very conservative, but time will tell. Your build looks pretty good I’m guessing you’re happy with that 2040 cam, it a very popular choice for early C4s.

 

I have been very happy with my estreet heads, they are very tough as well.
No warpage even though i had some serious cooling system problems at one time.

The camshaft runs well, and not too hard to tune with, has a nice sounding idle with the exhaust system as well.


If i ever do it again, i want to go a little more wild, but likely that will be with a stroked engine.

 

Yeah I’m happy with the E Street heads as well. Everything was a perfect fit. I expected that I would need different length pushrods but standard length were spot on with the comp cam roller rockers. I also fingered I would have to muck around with adjusting the push rod guide plates but they were setup correctly so that saved a bit of time.

I think if you have made a good cam choice you always think you could have gone bigger.

 

On cam choice I've always gone to what I want then go one size down in the same family. It's worked well so far.

 

 

Hi all
I installed the EBL Flash II ECM today. This was easier said than done. Because this car has been RHD converted some things have been relocated. Anyway let’s just say it was a challenge.
So on the upside the car started right up after the install. There is a long road of tuning ahead of me now but at least I’ve started.
For anyone interested I started with the TB4 bin file supplied with the EBL. That bin file is for a TBI 305 Camaro with a small diameter distributor. I made some minimal changes to the bin file and the car started and ran. I then swapped out the SA tables with the ones from the 3006 bin file which is for an 88 TPI corvette. I’ve made some other small changes to configure the TCC parameters to handle the 4+3 OD (provided by Rbob over on the thirdgen site) and disabled the IAT (I don’t have one).
Tomorrow I will start doing some VE learns and see how I go. If anyone has any tuning parameters they think might be helpful please let me know. I don’t have a WB O2 sensor so it will all be with the NB O2 sensor for the time being. The WB will have to wait for the dyno.

 

For the VE learn and or BLM parameters there is an adjustment to select what RPM ir begins at. If you have your idle set higher than stock I'd reccomend upping those rpms slightly and going in and smoothing out the idle and off idle manually later. I didn't on mine and with the A/C on have a surging idle I can't get rid of....

 

Yeah good advice. I think my idle is a bit low at the moment 550-600. I think 650-700 would be a bit smoother.

 

Hey Greg, you have made a SUCCESSFUL startup! Now, like you said the tuning begins. Set/lock your BLM to 128 and you always start with your VE first which is fuel. Once you get that squared away, then you do the SA (spark). I would highly suggest that you install a WB now since using a NB O2 even street tuning will NOT work properly for you, there is NOT enough resolution in a NB to tune correctly and your will be chasing your tail. Once you install the WB, you can start doing "learns" until you get it pretty close and running fairly well to drive reliably. Once you reach that goal, STOP using "learn mode". The reason is that it will learn the accel side of things as well as the decel side and if you look at the graphs it will be full of spikes and deep valleys. Your motor will/is following those as you drive. At that point, you need a dyno to smooth all that out and tune for drive-ability and power. Once the tuning is done, your motor will be running off of your NB as normal.

Also, I would get with Ben on a few things since he is right there to help you start things out. He is very good at this sort of stuff as you know.

 

Thanks for the advice Tom.
I should have purchased a wide band O2 sensor and installed it at the same time but I just didn’t think about it. And now I am presented with a bit of a problem. Installing that ECM was a serious PITA. Because the car has been converted to RHD the ECM has been relocated to the center of the dashboard, it is in a void behind the radio (not accessible or visible from there) and in front of the heater ducts. So to get at it; Drivers seat out, carpet under dash panel out, under dash kick panel out, plastic panel on the side of the transmission tunnel out, etc, etc. But even once you find it, it like they rebuilt the car around it. The trouble with RHD conversations is that they don’t tend to consider maintenance access and on a Corvette that is generally tight anyway. So to get at the I/O ports I’d have to do the job over again which I am not that excited about. I did think about connecting up some wires for future use but without knowing the exact circuitry I was worried about introducing open collector type issues. I’ll have a look at the car wiring diagram to see if there is anything I can repurpose for the job. Alternatively is it possible to simply replace the NB for a WB and run in open loop while doing VE learns. I’ll try and contact Ben this week but I think he is pretty busy at the moment.

 

UGH! That sucks for sure. I hope you can sort it all out, it will make your life a lot easier in the long run. I've been there and it does suck to have to redo things just when you thought it was a done deal. Good luck though.

 

Yeah if I used the language needed to describe the difficulty of the job and the person who thought it was a good idea to relocate the ECM there I would have the moderator deleting my posts.

So in the absence of a WB O2 sensor and because this car is essentially a daily drive I did some VE learns with the NB today. I did about six learns and then I took to the tuner pro 3D plot and smoother out the bumps and flared the out of range areas in the low speed table, restored the original high speed table wor the time being. Amazingly the car is running quite well, certainly better than it was with the standard 1226480 ECM.

The two main problems I have is a really high knock count, but I don’t believe it’s pinging. It has long pinp headers and roller rockers so maybe they are false knows, anyway something to work on. Secondly the fuel mileage doesn’t work on my digital dash, I thought I have all the parameters configured correctly but obviously not.