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Thanks for the ignition map! That is helpful. I will mess around this summer, but I am not going to do the cam swap, bowl blend until late September. I keep having to tow the dyno places when the weather is good. I did look at the dyno runs on the van and there were some leaner areas at low rpm with the stock fuel map, not crazy though, if anything its too rich in the higher rpm ranges but I only run it to 4000.Quote:
Originally Posted by Fast355
A picture I took yesterday. The van has been towing fine all summer. One thing I never thought about when I rebuilt the 4l60e is the 3rd to 2nd gear spacing. Its not that great for towing. If I had to do it over agian I would have found a core 95 4l80e to make 2nd a little more usable. The 4l60e trans durability wise is fine so far.
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I have some questions about the program that some say they use to generate shift points, Blue Cat trans table generator. The information it exports seems to be made for another tuning program (HP Tuners) leaving a lot of tables to the imagination. The lockup tables seem abbreviated, it generates something called shift slope, and the Vss ratio is in a very different format than TunerPro $0D. I ended up not using it at all but I am still curious just to learn what all the fuss was about when using it for TunerPro.
I tore the intake/timing cover off last night. The block is fully roller compatible. So the my 14097395 cam will work. I have also been able to pick up a GMPP vortec intake and an Edelbrock 3704 for less than the cost of a cheap tbi plate. I am waiting to have my heads checked for cracks to see what manifold I use. Torque from 2000 to 4500 is what I am looking to improve. I really do not care about anything above that for this application.
Under 4,500 rpm, I would stick with the swirl ports. If you wanted to make power to about 5,000-5,200 run the Vortecs.Quote:
Originally Posted by donf
Get some GM 0.028" compressed head gaskets rather than the Felpro .038 or 0.43 that are typical of the rebuilder gasket sets.
I am guessing your engine has the dished pistons with long bath tub shaped valve pockets that are 18cc total dish.
If you mill about .010 or .020" off the heads and run the .028" composite gasket with the 18cc dished pistons you should be able to get close to 9:1.
With the Ramjet cam that should work very well on 87 octane in the lower rpm ranges.
Also no matter what else you do, the old GM pellet box cat needs to hit the scrap bin.
Replace it with a modern cat that actually flows decently, the one on my 305 was not clogged and swapping the smog exhaust for anOEM 80s 1-ton van dual exhaust without cats with the OEM tubular manifolds was like unhooking a trailer from behind the van.
Thanks for the heads up. The converter has been changed to a recent 3" but it has a few goobers stuck to the bed. It may get left off for now, to be replaced in the future. No bathtub pistons, the standard ones that all light duty vans have. No ridge and very little carbon build up. My van is 800 lbs short of the heavy duty GVW. I found it has a replacement passenger side exhaust manifold made in China. The front port has the entire top half blocked off with some excess iron.
I just read back all 5 pages. I forgot you mentioned that the cat had been replaced. That exhaust manifold sounds like a junky dorman replacement. I am not a fan of having those cast iron heat sinks dumping heat into my cylinder heads but they are simple and usually reliable. You might be able to port out the casted shut part without hurting the integrity of the manifold. With the standard pistons you should be in the 9.3 to 9.5 range when you use the thin gasket.Quote:
Originally Posted by donf
Out with the flat tappet, in with the roller.
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So new vortec heads will be here in a week via slow UPS from Jegs. They have some house brand castings that are made in the USA. I don't know a lot about them but they should be good enough for this mild engine.
I have looked a lot on here the last few days and this place has a lot of information, but no where that I looked was a simple list of what to change for a starting bin when vortec heads and a mild roller cam are added. Here is what I think needed changed, this is not a tune, just a basic changes to fire the engine and prep for wide band logging.
- Scalar: Change Engine Constants - Injector Flow Rate from 61 to 74 to compensate for 18 psi spring
- Scalar: Temperature for EGR On changed from 74.8 C (0x99) to 149.8 C (0xFD)
- Scalar: Initial Spark Advance changed from 0.0 deg (0x00) to 9.8 deg (0x1C).
- Table: Change both open and closed throttle Main Spark Table vs. MAP vs. RPM to base 1998 truck vortec timing table. zero out all negative numbers, smooth slightly.
- Table: Desired EGR vs. RPM vs. Vacuum changed to 0.
- Table: EGR Fuel Reduction vs. RPM vs. Vacuum changed to 0.
- Flag: Code 32 EGR Failure changed from Set to Not Set.
- Flag: Linear EGR/EVRV EGR changed from Not Set to Set.
- Flag: Backpressure EGR changed from Set to Not Set
The idea is to let the computer know that the injectors now flow more fuel. Get the initial timing to 10 from 0 and load the most conservative vortec timing table. The Egr changes were made according to the instructions for the WBO2 zip and I increased the temp for EGR On to make sure it was off as I have it blocked. Any other suggestions? This is not a tune or even a complete list of what has been changed on my Bin, just some basics to build on and get the engine fired when switching to higher flow heads and a small cam on a TBI. There are a few thread where people lose 10 degrees of timing when messing with the scalars for timing so I just changed the one and will check to make sure its working as intended by setting the timing tables to all one number and reflashing as a quick test with a timing light.
In no way shape or form would I use the stock Vortec timing map especially with a bigger cam than the Vortecs cam with.Quote:
Originally Posted by donf
I would start with the one I attached. Pull about 6° across the whole map if you are running 87 octane then creep up 1° at a time on the dyno until you find the best power or experience knock retard.
I run the same timing tables in Idle and Off-Idle tables. It helps keep the throttle response and transition back to idle from being jumpy.
I would on enable the linear EGR valve if I were using its input for a wideband.
In case anyone wonders the ignition timing map is more or less a computer version of the GMPP HEI distributor that comes in the HO and ZZ series of GM crate engines.
Cool, thank you for looking at this. Yes they linear egr input was changed from not set to set, I am thinking that turns it on for the wideband. I think that turns that input on. I will edit the timing map match the one you recommended and pull some out for starters.
Hey Donf,Quote:
Originally Posted by donf
Just checking in and curious if you had made any headway on this swap.
I got held up a bit. I purchased USA made vortec heads from Jegs. The first one was not bad, but not great either. Just a bit of cleanup below the valve seat got rid of most of the ugly stuff. The second one looked a little cleaner casting wise but was assembled with a defective valve. There was a gouge in the stem and had to go back. They were nice about it and got another shipped within a few days. Some recommended the EQ heads but they have a larger port, I wanted 170cc or below for such a low rpm application. If people get the jegs vortec heads, the castings do look to be thicker than the Gm castings but not as much care is put into the manufacturing process.
My project has hit a stop for a week or two. I ordered "made in the USA" vortec heads from Jegs. I wanted to keep the ports small and the EQ heads were rumored to have larger ports in Brezinski's Videos and other posts. The first Jegs 514080 head was a little ugly under the valve seats but OK. It looked like it had some type of liner on the valve guides. They were advertised has having bronze guides. I cleaned it up a little and went the the next one. The second head actually looked a little cleaner port wise but had a giant gack on one of the valve stems. Like there was something in the guide and they beat it through anyway. I returned that head and the replacement showed up today with a promaxx number on the box and no "made in the USA" Its the same ugly casting but no liners in the guides and the retainer to seal clearance is only .420" When the other head was .475" clearance. It was a big mistake to order these but live and learn. I think I will call Jegs in the morning and see what can be done.
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