My Flat Tappet Cam Wiped Out So I Decided To Go Roller

[PlayingWithTBI]

keep turning the screw until idle flag goes off. turn off ignition wait 10 seconds and then restart. tps resetting to 0 after a cycle is normal. once you get min air set theres a gain option you can play with to make sure WOT actually shows 100%

Yeah, you explained that in an earlier post My concern is, it goes out of calibration,while driving after resetting to zero. Any idea why?

do you have another TPS sensor you could try?

No I don't. The WUD is showing .5V when it's at 12% - strange! Voltage feedback is smooth from idle to WOT. I'm gonna delve deeper into the TPS feedback before buying another one.

 

[L31MaxExpress]

I like to turn the idle screw in until I overshoot a bit, then back it off. It prevents me from having to shut off the engine to reset the TPS while adjusting the screw.

 

[PlayingWithTBI]

I went back in this thread and saw where I did set the Min Idle screw so my IAC was ~14 steps. Maybe because I reduced my timing to try and stop KCs at idle and ~2200 RPM? I may have to put it back to the 20s.


Here's where it sits now and, I'm still getting KCs. I think they're false counts from the kinda lopey idle, maybe.

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[CrustyJunker]

More advance with a bigger cams are usually needed at idle. With more overlap and lower RPM, you'll net more knock counts. It sounds cooler with a rougher idle, but 20°+ will get you a smoother idle, more vacuum, and should achieve less knock.

Also, Comp typically grinds an additional 4° of advance in their camshafts. So 24°-27° BTDC may be even better depending on RPM.

 

[CrustyJunker]

I know this is a long thread, I'll have to look up your cam specs a little further.

Edit: I looked, and I spy 110° lobe separation. We'll also have to mind your plug heat range, static compression, and/or cylinder pressure. We might not be able to completely eliminate all false knocks.

Questions - Are you running stoich according to your O2 sensor at idle and are you running a stock converter? Sounds like you're on the right track with your tuning so far.

 

[PlayingWithTBI]

More advance with a bigger cams are usually needed at idle. With more overlap and lower RPM, you'll net more knock counts. It sounds cooler with a rougher idle, but 20°+ will get you a smoother idle, more vacuum, and should achieve less knock.

OK, I went back to an earlier SA table I had and moved it into my current calibration. I'll try that, thanks.

Edit: Here's the map

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I'll have to look up your cam specs a little further. Questions - Are you running stoich according to your O2 sensor at idle and are you running a stock converter?

It's a Blue Print "383" with the 08-432-8 cam

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I'm running a target AFR of 14.5 on my WBO2 right now. My TC is a 2500 stall, maybe a little more with this engine.

 

[CrustyJunker]

My apologies, looks like this was discussed maybe 40 pages ago and I entirely missed the memo. These are just ideas...

Short version: if you're still showing knock at idle with your newly adjusted timing, try adding a little fuel and see if it reduces it or goes away. I'm not sure if it will completely go away with that size cam. Your 850 idle should be friendly enough.

Someone mentioned on page 11 that your O2 readings at idle may start to deceive you. This is true on EFI, the bigger the cam, the worse this can get. Much after 230° duration with a tight lobe separation (under computer control) can result in surging amongst other weird things requiring an OL idle. High MAP, overlap reversion, and fuel falling out of suspension (amplified on TBI than port injection).

Thanks for the sharing the information. I don't know about Edelbrock intake on these. I know the stock TBI intakes had issues with even fuel distribution, and was proved to me when I tried tuning my own stuff. At WOT, a 12.8 AFR would fall on its face no matter where I put the timing, and idle fueling would be all over the place, especially after warming up.

I read somewhere that even though your O2 might show great average readings, a couple cylinders may be more rich or more lean than the others...And the lean ones will knock first.

In my case - When I added fuel to mine, power came back and the knock went away. After that I could continue messing with timing again.

 

[PlayingWithTBI]

When I added fuel to mine, power came back and the knock went away. After that I could continue messing with timing again.

Thanks for the input What EFI and cam were you running?

 

[CrustyJunker]

That situation was on an EBL Flash with a smaller Comp "Computer Controlled," cam. I'm not sure if it was a band-aid for excessive cylinder pressure, fuel distribution, or another error on my part. ...Tuning slightly richer than textbook worked for me.

The big cam learning experience was on a solid roller N/A 540 with an XFI Sportsman system. I thought speed density would be better than alpha-N on the street.

 

[bk performance 19]

I am wondering how long this engine has lasted with the cam and head change? The OP did not state how many miles are on the engine. While I know everyone can't afford the do a total rebuild but investing money into something that is tired is basically a waste of money. First of all the engine has recycled the metal from the cam through out the entire engine. It doesn't magically end up all in the oil filter. Second putting new heads on a tired bottem end usually ends up with the increased compression kicking out the rod bearings. I have lived both of these scenarios and it did not end well.