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Anonymous
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Yes, there is a membrane inside the modulator. If it ruptures fluid can pass through to the manifold. Now that you have it out look in the vacuum port, there is a set screw you can turn to raise or lower your shift point. I believe the last modulator I bought was about 10$. Be sure to replace the fluid.
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Anonymous
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maybe your timing is off 180 degrees but is advanced enough just to run. that would expane low vacume and the no throtle response or chek out ur tranny modulator and vacume advance unit. and or look for a vacume leak
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Anonymous
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My timing is right on...now. I have 20HG of vac at manifold at idle. Just replaced the modulator and resealed the carb gaskets. Replaced the power valve last night. Going out now to give her a run.
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Anonymous
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All of the newer Holleys have the check valve built in to the throttle body to prevent power valve blow-out in case of a carb backfire (I don't know the exact point when they started, but I know when my friend got a new one about 8 years ago it had it, that was a 4v, but I'm sure the 2v's have them as well). I'm sure it's possible that it may blow out anyways, but I've never had a problem with this. If your PV was blown out, it would be giving you FULL enrichment at idle (or any throttle point for that matter), and I'm sure it would just be bellowing black smoke out of your exhaust. The power valves are also rated at a certian vacuum which is their opening point.. .usually the carbs come with a 6.5 or 7.5 power valve (6.5 or 7.5 being the opening point, when the vacuum drops below this amount the valve opens and gives you full enrichment) if your motor is idleing with less than that amount of vacuum, it will open the valve... it would be similar to having a blown valve being that it is full enriching the carb. So if you're not pulling that much vacuum you may need to change your PV to a 3.5 or 4.5 (I just read your newer post and you said you had 20" of vac, so this shouldn't be a prob... but remember the vac will drop when you put it in gear... but it shouldn't drop all that much... if you're at 20" in park, it may go to 15-17" in drive)
If you're saying when you pulled the mod out of the trans, fluid came out.. that is normal, if you just pulled the hose off of the mod and fluid came out then that's NOT normal.. the mod is blown out.
How to check it was already described.. you mention how it seems to 'stick' then advance.. The applications the DS2 came in were 'smog' era motors, so they didn't have the greatest advance 'curves' (rate and amount of mechanical advance) so they usually they are pretty slow to advance, and have a little too much overall. For performance use it's usually typical to quicken the rate of advance and limit the amount of advance (so you can run more initial advance as well, without having too much total timing)
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Anonymous
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OK, the stock PV was a 50. I replaced it with a 65. I've got 20HG's of vac at idle. Do I need to go even higher with the PV? At what point during acceleration should the PV open? Right at impact of the throttle? I guess I need to take a vac reading at that moment. If it's higher than 6.5 HG's, does that mean my PV still isn't opening?
How do i "fix" the advance setup on the DSII? Is that something left to the professionals? I've heard of having them recurved, but I have no idea what that is or how it's done.
Even after adding a touch of RTV to the carb gaskets and adapter (Holley adapter for the OZ intake), I think I still have a vac leak under the carb or under the adapter. I spray some carb starter fluid aroun the base and the idle does cahnge a bit. Do I take it all off again and goop it heavier with RTV? If I had a vac leak there (manifold vaccum essentially), how would I still have 20HG at idle? Wouldn't it be much lower and fluctuate?
How do i "fix" the advance setup on the DSII? Is that something left to the professionals? I've heard of having them recurved, but I have no idea what that is or how it's done.
Even after adding a touch of RTV to the carb gaskets and adapter (Holley adapter for the OZ intake), I think I still have a vac leak under the carb or under the adapter. I spray some carb starter fluid aroun the base and the idle does cahnge a bit. Do I take it all off again and goop it heavier with RTV? If I had a vac leak there (manifold vaccum essentially), how would I still have 20HG at idle? Wouldn't it be much lower and fluctuate?
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Anonymous
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I suggest you try a vacuum guage in the car. I have found it to be very helpful in my tuning and understanding. Plus it's a lot of fun!
You are moving from 20" at idle to 0" at WOT. The 6.5 will begin to open at 8" and be fully open from 6.5" to 0". You'll be able to see and feel exactly when it opens and tune to suit your needs. I am using a 8.5, at 65 my car is pulling 16" at 75, 15".
The A/F meter I have learned is only reliable in the broadest sense unless you spend the bucks for the wideband. (I like it anyway)
Your PCV valve is a controlled leak and you are still running 20" at idle,so I guess you could have a small leak and still pull your 20".
The engine needs to operate normally proir to doing any fine tuning. I enourage you to deal with the broad issues first.
You didn't give us any update, is it any better?
You are moving from 20" at idle to 0" at WOT. The 6.5 will begin to open at 8" and be fully open from 6.5" to 0". You'll be able to see and feel exactly when it opens and tune to suit your needs. I am using a 8.5, at 65 my car is pulling 16" at 75, 15".
The A/F meter I have learned is only reliable in the broadest sense unless you spend the bucks for the wideband. (I like it anyway)
Your PCV valve is a controlled leak and you are still running 20" at idle,so I guess you could have a small leak and still pull your 20".
The engine needs to operate normally proir to doing any fine tuning. I enourage you to deal with the broad issues first.
You didn't give us any update, is it any better?
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Anonymous
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Well by the shear Grace of God, my header has stopped leaking. I tell you, I got more copper RTV on me and the rest of the car than I did on the flange or the block, but I guess it was enough. What a difference allready. Just getting that header to stop leaking has made a noticeable difference in idle, acceleration, etc. Still not quite right but much better.
I was thinking about running a vacuum port into the car so that I could quick-connect a vac gauge inside when I want one. I don't want to add any aftermarket gauges.
My next tasks will be to try and track down the intake leak if there is one and to take notes on advance vs acceleration as CobraSix suggested to see if my DSII needs attention.
Thanks again gang!
I was thinking about running a vacuum port into the car so that I could quick-connect a vac gauge inside when I want one. I don't want to add any aftermarket gauges.
My next tasks will be to try and track down the intake leak if there is one and to take notes on advance vs acceleration as CobraSix suggested to see if my DSII needs attention.
Thanks again gang!
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Anonymous
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those gauges are really cool
and it looks like very helpful
and it looks like very helpful
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Anonymous
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they are cool but my wife would hang me if I started mounting a bunch of gauges on her pristine dash. I added a Sprint Tach up there and she almost had a kiniption (spelling).
How does the A/F gauge work? Sensor somewhere?
How does the A/F gauge work? Sensor somewhere?
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Anonymous
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No sure if anyone else already mentioned this (to many posts to go through and not enough time) but RTV silicones are a bad idea around Gas. The gas will eat it up and disolve it over time. I used some on an O-Ring gasket for a float bowl on one of my bikes and sure enough out in the middle of the desert it stopped running. The gas had turned the RTV into jelly and was clogging up my main jets. It's probably safter at the bas of the carb then say around the bowl but still not a good idea. This was blue RTV but they all say the same thing on the back regardless of what type RTV your using.
Just an FYI.
Just an FYI.
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Anonymous
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that's ungood. I didn't realize that. Thanks for the heads up. I guess I'll be pulling the carb back off and cleaning the RTV away, adding new gaskets back on, and seeing how things go.I have the Holley on top of the OZ adapter from FSPP. What gasket do I need under the adapter (essentially, what carb fits that intake stock)? Is it a Rochester config? The holley gasket is easy. Should I be looking for an extra thick gasket or some special trick to getting it not to leak vac?
Thanks
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Anonymous
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63DropTop":1c9hdo4j said:
A/F gauge works off O2 sensor in header.
The gauges were mounted using an extra speaker grill with a mulligan in mind. I have no plans to do that however as I now enjoy diddling my P/V far too much!
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Anonymous
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Okefenokee Comet":2j5vmz8e said:
OK, that's a little disturbing.
I need to start a new thread on tuning this holley RIGHT. I hate carbs. I have always had trouble getting it right. User error I'm sure!
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Anonymous
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Put a "t" in the manifold vacuum line, run the hose inside, and keep an eye on the gauge. You'll soon get a sense of whats going on and then you'll be diddling too!.. Reread William's (WSA11) post's on carb tuning, they really helped me.
