Need some help....

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Re: Need some help....

Post  Straubtech on February 25th 2017, 12:13 pm

Once you get the carb situation fixed tighten the lash down on the exhaust only until it quits picking up power. You have a ton of power left in the engine.

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Re: Need some help....

Post  XF-66 on February 25th 2017, 2:59 pm

supervel45 wrote:
I agree with Scot on a tunnel ram with side mounted Holley's and even inlines to a lesser extent. Double Pumper 4150's with 4 corner idle would make life a lot easier.

33 shooters and a yellow or brown pump cam will give you a full pump shot and should extend it nicely. Pump cams control the volume of the shot and the timing of it, shooter size does not affect fuel volume, a smaller shooter extend's the duration of the shot.

PS: I have gotten a few brand new power valves that were leaky, Not QFT's though. A small leak is not good at all. You might want to get it idling as best as you can timing and idle screw setting's, then pull the carb's and see where you are at on the primary transition slot, and go from there on adjusting the secondaries.

Supervel45

That's the manner or game plan I'm planning on following. When I get my Mag back I plan on starting from scratch. I'm thinking that the parts are fine. More than likely I just got ahead of myself anticipating what I thought the engine's needs might be. Obviously the motor is not happy with the fuel it's getting...now. I can make those changes.



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Re: Need some help....

Post  XF-66 on February 25th 2017, 3:09 pm

supervel45 wrote:
Scott Foxwell wrote:I don't have any input or experience with 02's and a mag.

I don't either but, since I believe it is just reading a voltage from a thermocoupling more or less, if a digital volt meter gives an accurate reading off a battery or something next to the running engine with a mag then it should be ok? I would use a very cheap meter for the test LoL.

This makes sense. I've had an voltmeter about a couple feet away from the Mag while checking the charging system and it worked fine without any interference. Like you say, I'll plan on a in dash self contained model and fab a sheet metal box for it to act as a shield.

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Re: Need some help....

Post  XF-66 on February 25th 2017, 3:49 pm

supervel45 wrote:

You would be better off cost wise selling the new 600's and buying the carbs. you want. Around 660cfm with a 750 base plate and a little more with an 850 base plate but probably not 750, plus they will not have down leg boosters like real 750's and 850's. You will have to chamfer the main body and they will still be two corner idle unless you do the 4 corner conversion. I really don't see it being cost effective, since they are new and I see them sell for 300 plus on Ebay regularly. Don't bother changing main bodies and using the 600 metering blocks and bowls, it's just a lose lose deal.

You are right on using the 600's for parts, the only parts usable are the bowls. Once I find the out what this engine needs/likes, I'll have a little more knowledge of what I can fit a top it. I more than likely will convert my 750's to 4 corners for now, I did some reading last night. All I would need are new metering blocks for the rear and to drill through passages that already exist in the main bodies.

Thanks for your input...

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Re: Need some help....

Post  XF-66 on February 25th 2017, 4:12 pm

Straubtech wrote:Once you get the carb situation fixed tighten the lash down on the exhaust only until it quits picking up power.  You have a ton of power left in the engine.

Thank you for the tip, I'll enter it into my engine note book.
I figure I'm leaving some on the table by tuning the motor myself this time.
Later on I had planned to spray the motor lightly(w/new carbs). In doing so I had planned on swapping out the magneto for a Daytona Sensor CDI box to manage the systems. The motor will see a dyno to get some accurate baselines recorded before a gas valve is ever opened.

Again thanks for the tip!

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Re: Need some help....

Post  supervel45 on February 25th 2017, 10:38 pm

XF-66 wrote:
supervel45 wrote:

You would be better off cost wise selling the new 600's and buying the carbs. you want. Around 660cfm with a 750 base plate and a little more with an 850 base plate but probably not 750, plus they will not have down leg boosters like real 750's and 850's. You will have to chamfer the main body and they will still be two corner idle unless you do the 4 corner conversion. I really don't see it being cost effective, since they are new and I see them sell for 300 plus on Ebay regularly. Don't bother changing main bodies and using the 600 metering blocks and bowls, it's just a lose lose deal.

You are right on using the 600's for parts, the only parts usable are the bowls. Once I find the out what this engine needs/likes, I'll have a little more knowledge of what I can fit a top it. I more than likely will convert my 750's to 4 corners for now, I did some reading last night. All I would need are new metering blocks for the rear and to drill through passages that already exist in the main bodies.

Thanks for your input...

Don't forget to change out you secondary idle air bleeds to the larger size matching the primaries which are usually in the 70 range. The base plate will also have to be modified, at least Holley's do. You can put paper clips on the secondary vacuum pod rods and make a full throttle pass and try to gauge how far they are opening also.

I assume you have the QFT adjustable Vacuum Pods that come with purple springs supposedly set at 1 1/2 turns open and did you check them?

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Re: Need some help....

Post  XF-66 on February 26th 2017, 2:32 pm

supervel45 wrote:
Don't forget to change out you secondary idle air bleeds to the larger size matching the primaries which are usually in the 70 range. The base plate will also have to be modified, at least Holley's do. You can put paper clips on the secondary vacuum pod rods and make a full throttle pass and try to gauge how far they are opening also.

I assume you have the QFT adjustable Vacuum Pods that come with purple springs supposedly set at 1 1/2 turns open and did you check them?

Petty much so, before I installed the carbs I took them and gave them a going over, looking for any differences between the two of them.
Actually they were spot on when compared together and the pods are set 1 1/2 turns out. I'll have to check the spring color after I nail the idle fueling issues.

Boats take a lot pounding vs a car. Paper clips might not work so well, but I could be wrong. I had planned on using a GoPro camera to record the vacuum secondary operations. Then tweak from there, real time.

Art

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Re: Need some help....

Post  supervel45 on February 26th 2017, 3:19 pm

The paper clips are tough to do even on a Car but, sometimes work. The GoPro would be great. Open the the secondaries all the way with the engine off and put a mark on the vacuum pod shaft even with the bottom of the vacuum pod housing that you can see on the video replay easily to gauge the opening. The OFT Pod's I have used say they have a purple spring in them. I had one that came adjusted only open about 1/2 turn is why I mentioned it.

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Update

Post  XF-66 on March 25th 2017, 11:20 pm

First off thanks to you all for the tips and advice.

I converted the carbs to a 4 corner idle setup. I was all set to do some crafty drilling when to my surprise I found the main bodies are pre drilled for the circuits and the base plates where all good to go too. All I needed to do was to add secondary metering blocks and to epoxy the idle dribble hole below the transition slots. I then swapped out the air bleeds to match the primary bleed setup. The transition slots on the primary side of the carbs were about 50% or a tad less exposed! So that's were my idling fueling issues came from. I opened the secondary blades up a bit more to allow the motor to breathe better at idle, while closing the primary blades so the transition slots looked like a square hole on the bottom side of the throttle blade. I also swapped the shooters and the accelerator pumps back to stock sizes.

I set the timing to 33* with the magneto now locked out. I can now see just how wet or condensed the fuel charge was at 8* vs 33* when it was fired off. The combustion area is much larger at firing at 33* before full compression, making for a much cleaner burn. Duh!!

I assembled everything this afternoon, except for the throttle linkage. I gave each carb a couple of pumps to prime the motor and hit the starter.
The motor sounds so much more alive and crisper. Monday I'll hook up a hose and finish dialing everything in.

I purchased a Innovate Motorsports O2 reader so I need to get that wired up to square away the idle fueling.

I'm on the right track now!

Again thank you all for your advice and tips in getting me pointed in the right directions!!Very Happy

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Re: Need some help....

Post  BOSS 429 on March 25th 2017, 11:42 pm


Power valve has nothing to do with idle. Two completely different circuits in the carb.[/quote]



unless they leak,or have failed
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Re: Need some help....

Post  BOSS 429 on March 25th 2017, 11:43 pm

lose the quick fuel carbs
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Re: Need some help....

Post  supervel45 on March 26th 2017, 12:01 am

I think a couple of Holley 80513's would be nice if he can't get enough out of the 750's. Cool

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