Stumbling after 4-5k rpms |
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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I think you expect us all to be PCM mechanics by day, and real jobs at night. We are all hobbyist here. So lay off.
It was timed at 10 with the knock and 16-18 with it off. But you dont have to respond. Continue sitting behind your laptop on your front porch yelling at school kids as they step on your lawn passing by. |
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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first off you can't change the 3600 timing you can only change base timing. Secondly if you had a regular 351w and added gt40p heads that doesn't instantly make it a ProBoss engine, did you also replace the Cam? did you also flash the computer to the ProBoss specs, hell know you didn't, and it's the F computer that drives weather it's 26 or 30 not your unskiiled mechanics.
so leave the knock sensor attached read timing if it's not at 10 BTDC then you have it WRONG, change it so that it is, then disconnect the knock sensor the timing should advance since all the knock sensor does is retrad timing. You set base timing and the computer does the rest, get the right tools and listen or just go ....for all I care I'm done d*cking with your stupid .... |
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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I was looking at my 92 manual and the 93 manual online and they are the same.
The 351 standard timing is 18 @700 and 30 @3600rpms 351 HO (proboss GT40) is 18 @700 and 26 @3600 So here is probably what i should do.... gap my plugs to .045 re-time the beast at 26 degrees at 3600. |
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21131 |
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What numbers are wrong? I cant think of a single reason why the timing would be any different between the base and HO engines. The only thing that changed between the 2 are the heads.
If you have a factory HO (Proboss) then you have GT40 heads, not GT50p's. Pick yourself up a decent timing light with an advance feature- theyre really handy. |
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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See, those numbers are wrong. 351 HO is what it is because I have the GT40p heads. Im pretty sure my pointer scale goes to 30, but Id have to double check.
Using a standard light. There is only one knock sensor on the back of the block. |
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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so called non existant manual that exists here on this site
static timing 10 700 rpm 18 3600 rpm 30 so which one is checked with the knock sensor disconnected? all of them? none of them? two of them? one? If you don't have the corrrect style timing light how are you even setting timing guessing maybe? must pointer scales are not high enough to use a standard timing light and why a advancing timing light is required so that only the zero mark is used. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21131 |
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There appears to be a difference of opinion here. No, there is no dedicated ProTec manual on this site as far as I can tell. Yes, the system is discussed in the 1993 PCM Engine Manual that both of you are referencing. This does seem to cover the intial timing of the engine.
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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Knock senser was off per the manual i have.
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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so was the knock sensor connected when you set the interupter's timing? |
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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I had a hard time listening to you because what you said with the protech was completely wrong. There is no manual for the protech anywhere. So when you say keep looking at the manual, there is none.
My manual says 18 degrees at 700 RPM, which it is. I did not time at 26 degrees at 3600... so possibly that is why its stumbling. or the spark plug gap.... Instead of smartarse comments, constructive input is usually the preferred input on forum boards instead of your constant last word bickering with everyone. You have great knowledge, and we all appreciate it, but to a point. |
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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You didn't want to listen then, on either site, I don't think you've learned anything at all, beside you asked, I told.
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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Thanks for the wasted post 79nautique.
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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YEA those PN guys got you all hooked up, too bad they're not to good at reading a manual and how to set the timing correctly.
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3335 |
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I don't believe the carb needs major internal adjustments to cure your symptom.
If you gapped larger then .045 i would suspect issues but not if gapped.035 Sounds like a classic fuel supply problem. I don't fully understand the protech timing method but you could be too advanced now. I would verify the system is not exceeding 36 degrees final. |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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I know, im waiting for 79nautique to tell me I f'd it up already. (jokes!). yeah, Im hoping someone will have some insight if not gaping my plugs is what is causing it. Before my heads a couple years back, I had a stumble and backfire issue around 3k. But I put in new fuel lines and new inline filter and plugs and it solved that problem. Ran fine.
Im wondering if the carb needs adjusting to the new heads. wonder, wonder wonder right?! |
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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mtguy
Senior Member Joined: August-04-2008 Location: Priest Lake, ID Status: Offline Points: 165 |
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I know my GT40 manual shows the .045 gap as well. One of the 'real' motor guys will have to answer the rest of your question.
One question for you is whether there is a break-in time for new heads like with a new motor? Maybe it would have something to do with that. Good luck ~Peter |
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tommer12
Senior Member Joined: February-05-2004 Location: United States Status: Offline Points: 366 |
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First time out with the new GT-40p heads. Replaced last weekend, ran some test in the driveway for an hour or so at different speeds. All ran good. Solid idle speeds, etc. Between idle to around 4k, she is solid. No issues. after about 4k to 5k rpms, I noticed all of sudden it would jump a little, then continue to 5k, then 5 seconds or so later, start to stumble.
So either Im looking at timing or some kind of carb adjustment. I did re-time the beast. Started off at 10 degrees, finished at 16-18 degrees. I have not re-timed it since we went out. I dont think I need to since it seemed ok from idle to 3k or so. She ran good though. No leaks, (water, oil, exhaust) from the head or valve covers. Had some paint burn off. I had painted the exhaust when I had it off and the elbows must have burned away. (and the head). So to recap- - Replaced heads with new GT40-ps. - Holley stayed on the intake, never took off. (nor adjusted) - re-timed protech ignition to 16-18 degrees with 87/89 octane - new plugs autolite 764. Although, I just noticed this: at skidim site, it says to gap for protech to .045. Would this be my issue at the high end? Would i have to gap the plugs, then retime everything?? Or do I have another issue with my holley? Thanks fellas! |
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84 SN, 92 SNOB, 2005 SANTE 2006 SN 206
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