What size jets for 351W and Holley 4V?? - Vintage Mustang Forums
 
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post #1 of 12 (permalink) Old 11-20-2004, 08:27 PM Thread Starter
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I got my Edelbrock performer and Holley 600 conversion done, and I'm trying to fine tune. My motor was originally a 2V, and after the install I was getting a stumble while cruising at low RPM, then light punch of throttle. The 4160 vacuum sec. carb. came with #64 primaries even though my book said they were #65's. I dropped one size (I thought 2 until I removed the old ones), and the problem is worse. After the new jets I installed new plugs so I can read them, and they are on the white side, which I understand is lean, so I guess I need to go the other way.

Question can anyone tell me where a good starting point is with a stock 351W and performer intake? At this point it looks like 2 up from where I started is my next attempt, which would put #66 jets in....does this sound right?
(Also I'll add, I have stock exhaust manifolds with high flow dual)...

Thanx!
Kevin

-Kevin- [color:"blue"]69 Mach 1 - 351W - FMX - mostly original.[/color] My 69 Pics
Edelbrock performer, Holley 600, MSD pro billet elect. ignition, Magnaflow 2 1/2 stainless thru X exhaust.
http://www.ppdbillet.com/69%20Mach%201/Sig-Pic-5.jpg
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post #2 of 12 (permalink) Old 11-20-2004, 08:49 PM
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A holley 600VS should work great almost out of the box on a street 351....ESPECIALLY the jets.....the idle mixture screws should be around 1.25 turns out from seated....the float levels have to be correct.


Maybe it wouldnt hurt to have a .028 accelerator pump nozzle.


Dont use the jetting to crutch mistuning other things.


Ignition timing can cause various probs also.



BTW, if the carb wasnt new, it needs to be properly rebuilt before any meaningful tuning can take place.

Ported vacuum IS manifold vacuum ANYTIME the throttle is open on a holley.
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post #3 of 12 (permalink) Old 11-20-2004, 09:39 PM Thread Starter
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Quote:
A holley 600VS should work great almost out of the box on a street 351....ESPECIALLY the jets.....the idle mixture screws should be around 1.25 turns out from seated....the float levels have to be correct.

Maybe it wouldnt hurt to have a .028 accelerator pump nozzle.

Dont use the jetting to crutch mistuning other things.

Ignition timing can cause various probs also.

BTW, if the carb wasnt new, it needs to be properly rebuilt before any meaningful tuning can take place.
1) Carb. was brand new out of the box.
2) Car ran good before changing, and then only other thing that I changed was intake manifold which looks good.
3) Changing to an .028 pump nozzel will only contribute to possible more lean correct? I have stock an .031 that it came with.
4) I set timing to factory specs. 6 degs. BTC. and it's correct.
5) I checked and adjusted floats, rear was high..now they are dead nuts.

I will check idle mixture screws...book says out 1.5 turns. ::

Kevin

-Kevin- [color:"blue"]69 Mach 1 - 351W - FMX - mostly original.[/color] My 69 Pics
Edelbrock performer, Holley 600, MSD pro billet elect. ignition, Magnaflow 2 1/2 stainless thru X exhaust.
http://www.ppdbillet.com/69%20Mach%201/Sig-Pic-5.jpg
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post #4 of 12 (permalink) Old 11-20-2004, 10:54 PM
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Put the 65's back in, its not a jet problem. Its an enrichment problem. Your 31 squirter is probably fine, odds are you have a power valve that is opening too late, but if its new out of the box I doubt that too. You rarely if ever have to rejet significantly. You probably have a 6.5 PV, if you have less than that, buy an 8.5 for a mild motor. In the very least put it back to stock. The biggest relationship to jet size is carb venturi size, so rarely do you go more than 1-2 either way anyway (unless you get rid of a power valve which is a different story)

Here is the next thing, make sure the float level is no-kidding just dribbling out of the holes. 1/8-1/4 inch too low will cause a lean condition on some motors

Then turn your idle mixture screws in one at a time, it should start to stall, then back them out until it idles the fastest. Lower the idle speed on the linkage back to where you want it, then repeat the idle mixture adjustment. If it DOESNT kill the motor when you turn the mixture screws in, you have a vacuum leak somewhere, probably your intake.

Bottom line, if you are 100% positively sure you dont have a vacuum leak. Its either a PV with a value too low, a squirter problem, or a float level problem. I am sure it isnt a squirter, it probably isnt the PV (unless you have a completely stock cam or close to it) and the float level is easy to misdiagnose, you want it to just dribble, not "just dribble when I lean on the fender" because we all lean differently LOL

Let me know what you come up with.

http://i528.photobucket.com/albums/d...ndarShots2.jpg
70 Sportsroof, 427 FE, 489 cid, 10.7:1, Erson valvetrain, KC ported Edelbrock heads, modified Massflo EFI, TKO-600, 31 spline 4.10, A/C.
71 F100 4x4 shortbed 445 FE, ported iron heads, ported RPM intake, Bullet custom solids, 1000 Holley
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post #5 of 12 (permalink) Old 11-21-2004, 03:56 AM Thread Starter
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Thank you for the tips My427stang .
I looked up the power valve and its a 65 (6.5" hg). I will try the closing of the idle screw to see if there is a vacuum leak. The PVC valve and hose are also new. There was an aditional vacuum line near choke that book calls "full manifold vacuum port", and I have that plugged....am I suppose to hook this into an additional line to the manifold?

Is the power valve located behind the front cover that is behind the 1" hex screw?

Kevin

-Kevin- [color:"blue"]69 Mach 1 - 351W - FMX - mostly original.[/color] My 69 Pics
Edelbrock performer, Holley 600, MSD pro billet elect. ignition, Magnaflow 2 1/2 stainless thru X exhaust.
http://www.ppdbillet.com/69%20Mach%201/Sig-Pic-5.jpg
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post #6 of 12 (permalink) Old 11-21-2004, 11:16 AM
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Quote:
1) Carb. was brand new out of the box.
2) Car ran good before changing, and then only other thing that I changed was intake manifold which looks good.
3) Changing to an .028 pump nozzel will only contribute to possible more lean correct? I have stock an .031 that it came with.
4) I set timing to factory specs. 6 degs. BTC. and it's correct.
5) I checked and adjusted floats, rear was high..now they are dead nuts.

I will check idle mixture screws...book says out 1.5 turns. ::

Kevin

Youre right about keeping the nozzle........


There are two holes for the screw that mounts the accelerator pump cam on the throttle arm....try the #2 position.


Dont assume the factory initial timing spec (or what ran good with the old setup) is the way to go now.....youve got a custom setup that may respond better with different timing. Dont forget to disconnect the vacuum advance hose when setting initial timing.

Ported vacuum IS manifold vacuum ANYTIME the throttle is open on a holley.
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post #7 of 12 (permalink) Old 11-21-2004, 11:50 AM
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Sharkmouth is right, the factory timing setting is probably a little low, I'd go 10 degrees BTDC, that'd rule out any timing issues and is almost always a safe number

The power valve IS the piece that takes a 1 inch wrench. If that makes sense. After you pull off the float bowl and metering plate.

As far as plugging that hose, you did right, its a manifold vacuum sourse, as is the manifold, so connecting them would do nothing.

FInally, 1 1/8 - 1 1/2 is where all Holleys tend to idle right. Turn it in and back it out slowly and listen, you'll hear it change. If it doesnt, like I said before check that float level with the motor running, if that doesnt help the adjustment, you must have a vac leak when you changed manifolds

http://i528.photobucket.com/albums/d...ndarShots2.jpg
70 Sportsroof, 427 FE, 489 cid, 10.7:1, Erson valvetrain, KC ported Edelbrock heads, modified Massflo EFI, TKO-600, 31 spline 4.10, A/C.
71 F100 4x4 shortbed 445 FE, ported iron heads, ported RPM intake, Bullet custom solids, 1000 Holley
13 Ram 2500 Laramie Quad Cab 6.7 diesel
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post #8 of 12 (permalink) Old 11-21-2004, 01:29 PM Thread Starter
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I reset the float level to barely trickle out. I adjusted idle screws all the way in and the car does stall with just one side in, and it seems to run best around 1 full turn out. I have reset timimg to 10 degs and checked pvc by disconnecting and pluging the port.

It does seem to run a touch better. But still I have a "DAAA DA" slight stumble, this isn't a stall out it's a less then 1 sec. hesitation. Also..I'll add it doesn't do it taking off from a stop, only while at cruise speed with a light punch of throttle.

I will check the acc. pump. setting.

I will reiterate one item, the plugs ARE still reading white (lean), and the book says I should have #65 jets and it actually came with #64 one size smaller. Also the 2 other similar carbs listed come with #66 which is 2 up from mine, and it did run worse when I went to a 63, exibiting the same behavior only more pronounced.

I emailed Holley tech support with the issues, so possibly they could shed some light on this next week....ohhh and I got a great price on carb...Ebay...[prob. a mistake) :pissed: so likely I'm screwed...the carb. was all factory packed and sealed and showed no signs of being prev. installed.

I really appriate the help! :winkgrin:

Kevin

-Kevin- [color:"blue"]69 Mach 1 - 351W - FMX - mostly original.[/color] My 69 Pics
Edelbrock performer, Holley 600, MSD pro billet elect. ignition, Magnaflow 2 1/2 stainless thru X exhaust.
http://www.ppdbillet.com/69%20Mach%201/Sig-Pic-5.jpg
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post #9 of 12 (permalink) Old 11-21-2004, 01:41 PM
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Did you use the cork intake gasket end seals? Have you gone back and tightened the intake manifold?
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post #10 of 12 (permalink) Old 11-21-2004, 01:49 PM Thread Starter
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Quote:
Did you use the cork intake gasket end seals? Have you gone back and tightened the intake manifold?
Funny you should ask. I followed Edelbrocks instructions which says to leave them out and use the silicone seal that they sent. I thought this was odd, so I called a local performance shop and they agreed to use the silicone also. And I do have a slight oil drip in back now, but I believe this is at base and the intake ports are sealed. I am going to get my torque wrench back from the shop and re check to 22ft lbs I believe the manual says.

I dont see how a slight oil drip would effect it running if the intake gaskets are well sealed? This is where manifold meets block, not heads. ::

Kevin

-Kevin- [color:"blue"]69 Mach 1 - 351W - FMX - mostly original.[/color] My 69 Pics
Edelbrock performer, Holley 600, MSD pro billet elect. ignition, Magnaflow 2 1/2 stainless thru X exhaust.
http://www.ppdbillet.com/69%20Mach%201/Sig-Pic-5.jpg
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post #11 of 12 (permalink) Old 11-21-2004, 02:26 PM
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What do you run for a cam in this motor? If its very mild, You may need to go back in and put a PV with a higher value, it may not be getting down below 6.5 inches of vacuum as you roll on the throttle. Also, if you feel better with it, go in and put a set of 66's or even 67's in the primaries, being a tad on the rich side wont hurt a thing.

http://i528.photobucket.com/albums/d...ndarShots2.jpg
70 Sportsroof, 427 FE, 489 cid, 10.7:1, Erson valvetrain, KC ported Edelbrock heads, modified Massflo EFI, TKO-600, 31 spline 4.10, A/C.
71 F100 4x4 shortbed 445 FE, ported iron heads, ported RPM intake, Bullet custom solids, 1000 Holley
13 Ram 2500 Laramie Quad Cab 6.7 diesel
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post #12 of 12 (permalink) Old 11-21-2004, 02:39 PM
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Quote:
I dont see how a slight oil drip would effect it running if the intake gaskets are well sealed? This is where manifold meets block, not heads.
An oil leak wouldn't affect the running at all but intake gaskets that are leaking vacuum from inside the motor will give you the exact problem you are having.
I've had problems with leaky intake gaskets in recent history and I believe the quality of them isn't as good as it once was...

I think the reason Edelbrock warns aganst cork end seals is that they actually prevent the intake from sealing to the intake gaskets... Probably due to a less rigid aluminum casting.
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