87ROCZ

iTrader: (3)

So recently I swapped my ported L98 heads with a set of 062 Vortec heads. Swap went farily smooth, a few minor issues (like the coolant routing) but overall the swap went OK.

When I first fired her up she wouldn't keep herself idling, if I wasn't constantly feathering the gas she'd die out. But after warming up to op temp I was able to let my foot off the gas and she kept herself idling, although her idle was far from smooth, she lopes pretty hard hunting for idle to the point where she'd almost cut out but then brign herself back up and on and on this will go.

I also noticed that my Autometer A/F gauge is showing her, once in closed loop, running on the edge of "LEAN", before with the L98 heads she'd be consistantly bouncing in the STOICH region where she should be.

I didn't get a chance to road test the car as it started snowing and that pretty much shut down any further testing for the winter months. So I would say that the engine has run maybe 15 - 20 mins max at operating temperature/closed loop, sitting in the garage in PARK.

Questions.

1. Will be ECM "learn" that I have better flowing heads the longer it runs with them? My ECM was tuned to run well with my ported L98's and my bigger cam (486/496 Crane 2032) and I guess it will

2. Will increasing my fuel pressure help with the LEAN condition? Right now it sits at about 38 psi idling in PARK and I think 45 psi at WOT. I run 24 lb SVO injectors.

3. I will check/clean the IAC but that was cleaned a few years ago and I dont do much driving with the car.

Any other tips and things to look for from others that have done this swap?

Thanks!

1983LU5TA

These old ECMs dont have any adaptive strategy programming. Are you sure you dont have any vacuum leaks?

87ROCZ

iTrader: (3)

I am fairly confident I don't have any vacuum leaks, my vacuum gauge shows about -20 Hg at idle so she's pulling good vacuum... when I initially started the car I had a major vacuum leak (you could literally hear it sucking loudly) and that turned out that I had the wrong gasket on one of my runners, once I had that fixed I don't think I got anymore vacuum leaks.

I don't have my EGR valve connected, I pulled that off and put a plate/gasket over the hole where it sat on the intake, not sure if that would have anything to do with it, I suppose I could hook it back up....

Z28NZ

Are you running a Vortec baseplate?

87ROCZ

iTrader: (3)

Yes I am...it's the Edelbrock one...and I have the Edelbrock large tube runners as well

87ROCZ

iTrader: (3)

Anyone else got any other info I could check into...there has to be others that have done this swap?

LilSki

iTrader: (1)

I kind of did this swap but I don't use a factory computer. I don't know if this will help but this is what I did.

Started with peanut cam 305 with TPI on top and I run a megasquirt computer. When I installed the vortec 350 with the same TPI unit up top I was able to run the car on the 305 tune with minimal issues. It did run lean but wasn't that bad at all. I added just a touch a fuel across the board and rest of the tune was unchanged and the motor ran great.

Now again this was 305 to 350 so I expected that but in your case all you changed was heads so I would venture to say something is wrong. I can't help but think there is a vacuum leak somewhere. I did hear there were some defective edelbrock bases that had one of the holes drilled to deep and got into a vacuum passage causing a bad lean condition. I would have to look up the thread were I saw this.

Tuned Performance

iTrader: (92)

The thread you saw on this hole drilled through to the egr was about there standard base casting.

LilSki

iTrader: (1)

Part of me was thinking that but I couldn't remember. Regardless I still think something is wrong here as a new tune should not be needed for what was done.

vetteoz

iTrader: (13)

MAF is pretty adaptive to air flow changes unless you do something radical.
I went from dead stock to long tubes , fully ported intake w/ big tubes and a ZZ4 cam all on the stock tune.
Was only when I got around to data logging I found a few things that needed minor tweaks but nothing you
would be aware off SOTP

87ROCZ

iTrader: (3)

So I guess so far you guys are thinking a vacuum leak somewhere is what I should look for? One thing that keeps nagging at the back of my mind is the injector bosses in the lower intake. The bosses protruded into the air stream a good bit so like Jims85iroc done, I ground them down. The first one I thought I ground into the injector seat, but after fitting all of the injectors into base and tightening down the fuel rail it seemed clear to me that the rubber o-rings that seal the injectors were not close to where I thought I ground down so I don't think that is an issue, not sure if a non-sealing injector would cause that big of a vacuum leak anyway??

Tuned Performance

iTrader: (92)

are you using bosh 3 injectors ? If you can't find any vacuum leaks you might increase the fuel pressure a little or start working on your lv8 air flow tables.

87ROCZ

iTrader: (3)

I'm running the Ford 24# SVO injectors... ones like these...not sure if the part number in this pic is the same as mine but they look identical to these....

Tuned Performance

iTrader: (92)

I believe the aftermarket base has a deeper well for the injector did you install 2 o-rings for sealing on the manifold side ?

87ROCZ

iTrader: (3)

Yes the Edelbrock Vortec base does have longer "wells" to accomodate stock Multec injectors due to their length. But the SVO injectors are a fair bit shorter due to not having the "nozzle" piece on the end of the injector, that is the only reason the well was made longer from what I could see, to shroud the "nozzle" of the stock injectors. This is why you can grind the wells down a fit bit when using the SVO injectors. I installed my injectors into the base while it was off the engine, I put them into the fuel rail and bolted everything down so it would sit as it would on the engine. From what I could tell the bottom rubber o-ring was sealing the injector boss, I don't think the second o-ring does much but it's on there as well.

There was only one injector boss that was "questionable" to my grinding but after looking at it all installed I realized that when installed into the fuel rail, the injectors don't get pushed down as far into the boss like the do if you take the injector and seat it in the boss as far down as it will go... so I'm fairly confident that the injectors are sealing as they should.....I could always try a bigger/thicker o-ring if they are even made for this application but I don't think that would be needed.

When I had the car running I used a mechanics stethoscope to listen around the top of the injector boss to see if I could hear a vacuum leak but it sounded fine. How could I test further to know for sure...I once thought I read about using a small amount of propane, if their was a vacuum leak and you put the propane near it, it was suck in the propane and the engine would rev up I believe, is that the way to check for it or is there is a better way?

Tuned Performance

iTrader: (92)

a propaine torch unlit or carb and choke cleaner work well. just keep carb choke cleaner away from the exhaust and just to be on the safe side have a fire extinguisher handy.

Orr89RocZ

iTrader: (20)

Vortecs have different chamber design and port flow characteristics than stock L98 heads. The burn characteristics of the chamber may be so different it requires a different fuel map and tune. Almost definately a different timing curve, generally less timing required.

Once you confirm no vacuum leaks look carefully into the plugs after running to see what the motor is doing. Wideband o2 also helps. I would have figured the maf system would allow for decent idle and drivability with only head change like that. I used 2 different 6e based L98 bins on 2 motors i tuned in person and a few email tunes and it required very little change to stock tables for most idle and part throttle areas. From heads cam stock bottom end cars to my big cammed 383 and another 383 tpi car.
On flip side i tried my known 383 tune on 2-3 other very similar builds and one 406 and they didnt run well with my tune.... So go figure

87ROCZ

iTrader: (3)

Ok... so am I correct in thinking that if I have a vacuum leak, applying propane to the leak will caused the engine to rev up? Is that correct, it certainly makes sense to me if it does, especially right at the injector just inches aways from the combustion chamber.

Also... if I find no vacuum leaks, will increasing the fuel pressure help with the Lean condition? I am sort of thinking that it won't help a lot, if I need more fuel then the ECM needs to keep the injectors spraying a little longer, increasing the pulse width?

Thanks for the comments guys...it sure helps!

the blur

What's the BLM's and INT ?

cuisinartvette

Yes check for vac leaks first sounds like thats the problem

Fast355

iTrader: (2)

I had no issues running my TPI 350 with a mild 214/218 roller cam, heavily ported 350 vortecs with 2.05/1.60" valves, and doug thorley headers on a stock 1991 L98 Corvette calibration. Ultimately I tweaked the tune slightly to make more power but it ran well as it sat.

87ROCZ

iTrader: (3)

Then I definitely got something going on wrong, she shouldn't be loping and running lean, I guess I am on the hunt for a vacuum leak.... my cam timing @.050 lift is only a 214I/220E. And I am running the stock 1.94/1.50 valves.

Z28NZ

Have done this conversion as well, stock vortec heads on a 355 block, same 3817 base, stock plenum and throttle body and runners, 24lb bosch 3's and upon start up ran as you describe yours. I found two things that sorted it, 1- a vacuum leak and 2- timing too retarded, sorted those out and it runs like a dream.
Hope this helps

87ROCZ

iTrader: (3)

Hey Z28NZ...thanks for the tips. I will be definitely looking for any vacuum leaks, there is only so many places a vacuum leak can hide I would imagine!

As for your timing... what did you set it at? With my timing gun (and the brown timing wire unplugged) my timing is sitting at 8 degrees advanced. I ran 10 degrees advanced on my old L98 head combo and it ran just fine but I thought I read somewhere that the Vortec heads don't need as much timing so I put it in the middle of what stock should be (6 degrees) and my old setup (10 degrees)

Z28NZ

Yeah I think you are in the ballpark at 8 degrees of timing, I've milled 25 thou off my heads and run 10 degrees with 95 fuel and 0 deck height so my comp is about 11to 1 and absolutely no detonation. May try a little more yet but it runs so well maybe should leave it be.Just done a 1000km trip, averaged 26 mpg, real happy with that!

87ROCZ

iTrader: (3)

I didn't get to do any datalogging but I will in a few weeks and let you know

abray1

Choke cleaner will find the leak.

Fast355

iTrader: (2)

I prefer an unlit propane torch.


As for timing with the Vortec heads and TPI, IIRC I ran about 10* on mine. Take it for what its worth though, I had a 2-ton C60 series 350 TBI engine with 18cc dished pisonts and ~9:1 compression ratio. It was also pretty rich with the LT1 24 lb/hr injectors and 50 psi of fuel pressure.

Dyno Don

iTrader: (7)

I'm running the Vortec heads, the same manifold but all stock components with a SD
(7730) setup and AUJP prom minus the VATS.

No issues. Runs great. 22# multecs.

ChevyTycoon

iTrader: (1)

I am running 906 Vortec's, using the scoggin-dickey baseplate, 305, MAF TPI with a small cam as well. I spent a lot of time tuning this combination before I found that sweet spot. Even though common thinking is vortec's dont like much timing - I found the opposite.

I kept using timing tables from vortec-based vehicles and was never happy with startup and overall power. I eventually went to a LT1/LT4 spark advance table and that really woke-up the engine. I set the base timing at 8 Deg, with idle timing no less than 20-22 advanced. total timing is the 38 range by 3000 RPMs. My injectors are 24 LBs Venom's but my engine was WAY LEAN up until I actually set the injector constant to 20.35. Even at 43 PSI, the injectors wouldn't fuel properly (BLMs constantly in the 135-160 range) until the constant was changed. Doing this also substantially improved idleing.

Again, in my experience, the whole "vortec's like no more than 30 deg SA" didnt work AT ALL in my combination. I can try to send you my SA table if your tuning your own chips - just to see if that helps or not. This way, you can easily rule out tuning verse a mechancial (vacuum leak) path.

bronc3buster84

iTrader: (2)

What gaskets are you using for the runners to the base plate... When running the Edelbrock base and runners, you have to buy their gaskets, or buy to sets of stock ones... The ports on the driver side wont seal, unless you ust the passenger side gasket on it... Took me forever to figure this out when I was running the Edelbrock stuff...

87ROCZ

iTrader: (3)

I am using a stock set... But I used the same kind of stock gaskets with these Edelbrock large runners and my other Edelbrock baseplate without any issues??

87ROCZ

iTrader: (3)

I found the Edelbrock part number...3866. Although they seem to be identical to a stock set??

bronc3buster84

iTrader: (2)

Look through this thread... It has the pics of the differences...

https://www.thirdgen.org/forums/tpi/...-manifold.html

87ROCZ

iTrader: (3)

Well after owning this car for over 12 years now I learn something new everyday ... thanks Bronco for that link, it certainly makes sense that my car would have a vacuum leak considering I used a set of stock gaskets (even correctly installed stock gaskets). I honestly never put any thought to the fact that the large tube runners were that much larger than the stock runners. I did notice that the stock gaskets didn't allow for as much airflow due to the holes being smaller and I was going to "round them out" but never. But I wouldn't have though that they were smaller to the point where basically the runner would suck air around them.

I guess thinking back on it, before I went the Vortec route I had ordered the L98 version of the Edelbrock Hi-flo runners and baseplate at the same time. And when I installed the hi-flo runners/baseplate I used the gaskets that were included which were the ones for the hi-flo runners. And I am willing to bet this is why I never had any vacuum issues!

Well now... ... guess I got to order me up a set of proper gaskets!

So the question I have now is should I go with Edlebrock's 3866's, Tpis version, or Mr.Gasket's 146's? There is about a $10 difference between Edelbrock and Mr. Gasket's, now $10 to me is neither here nor there... but I think I can get the Mr. Gasket's locally but the Edelbrocks' would need to be shipped in, so that is a factor I need to think about. If Mr. Gasket's are just as good as Edelbrocks' I will go that route!

bronc3buster84

iTrader: (2)

You dont have to use the edelbrock gaskets... You have to use 2 sets of stock ones... The first works on everything else, then the second set you just the the passenger side gaskets to use on the driver side to make it seal...

I learned this all the hard way when I was running the Edelbrock setup...

87ROCZ

iTrader: (3)

I'm not sure I follow.... are you saying you double up on the gaskets or basically use 2 passenger side gaskets, one for the pass. side and one on the drivers side? What exactly will running a pass.side gasket on the drivers side seal better?

bronc3buster84

iTrader: (2)

This... Its to do with the size of the egr ports... The link i posted shows it best