holley 350 setup on 250-2v.

Hi,

I ve just finished my 250-2v swap.
I went for the first test ride today.
the engine in performing good at high RPM, but seems lazy to accelerate from idle.
what setting (meterin block, pump cam, squiter etc ...) would you recommend from my holley 350. I m curently runing on the orange cam in position 1. (Was on 2, i ve try in 1, no change)
I ve pulled plugs after a 40 min intown run. they seems a bit rich.
carb is new from holley and it is said to be a O-7448 primary jet 61 pump nozzle 0.031 power valve 85.

the engine is a 200 block with a 250-2v head, (little oversized exhaust valve) with DS2 ignition, a CI exhaust manifold and single 2" exhaust line. the car is an Auto with mustang stock 7 3/4 rear.

choke is not connected yet (by the way how did you guys dealt with it on 66 mustang (there no room there for it))
when moving form park to frive, rpm are droping, and engine eventually die sometime.

thanks for your suggestion.

regards

F.

What vac reading are you seeing at idle?

What port are you using for the distributor. When its run of manifold vac, the base timing seams to favour 12 to 16 deg initial on the crank with these engines, but total advance at 3500 rpm has to be less than 35 degrees, so you might have to limit peak advance by following Duraspark rebuild requirements.


There is a special 10R plate that limits peak advance.

If the timing is right, and idle is stable, then you can go to pump squirter and cam and idle tuning. Waste of time untill you can verify curb in drive and park and base timing are okay. It needs to be about

650 rpm +/- 50 rpm in drive
850 rpm +/- 50 rpm in park
and base timing needs to exceed 9 deg BTDC to have a chance of missing the off idle hole.

Re that choke and space issues. The Holley has two types of carb choke operation, the later electric one should fit okay, needs 7 volts to energise. The stock Ford 2100 and Stromberg WW carbs as found on early Aussie 250 and 302 2-bbl's have just enough space for there auto choke. Holley replacements were normally manual choke 7508 or 9112 series 350 carbs. The generic 350 7448 needs an electric choke to suit.

HI xtasy,
thanks for answer.
I haven't plug the vaccum gauge yet.
Idle is kinda ok, but i can't acheive anything lower than 1000 rpm otherwise it died when shifting to drive.
Vaccum advance is hooked to the dual port on the manifold itself.
I m thinking about modifying the vaccum routing as vaccum advance and tranny vaccum re ending on the same hose (have to deal with it that way on the hold log head.)

I ve run the car today and it seem to perform better with a bit more of idle speed and little richer idle.
slow acceleration still give the feeling the car in running on 5 cylinders with vibration. Hard throttle usually gives better engine response, but sometime for some reason it does backfire.

Ignition first (read every FSD post)
then carb
then transfer slot exposure, drilling the throttles with 1/8" holes,
then cold crank compression less than 180 psi by retarding or advancing the cam
only then should you contemplate a high stall converter or tricky 350/500 cfm 2-bbl or 390-465 cfm 4-bbl carb adaptions

Thanks to michael_cini and Falconsix delivery , mach1 mark and cfmustang, plus some recomendations from Aussie7mains

Three very important things. Read these three posts.

viewtopic.php?f=1&t=47555&p=357509#p357509

viewtopic.php?f=1&t=64405&p=506921#p506921

viewtopic.php?f=1&t=61762&p=473335#p473335


These are the typical "IT WON'T IDLE, DO I NEED A HIGH STALL CONVERTER" post

After you've done a quick check of the ignition, bearing in mind that a Duraspark doesn't follow the Loadamatic vac routing.

Then the key is that the carb must be slightly open of the transfer slot when idle is set. If you have problems with off idle bog or low rpm, this is your first call to check the throttle blades have been cracked open enough so the idle mixture and speeds can result in the recomended park and drive rpms. With the lines unconnected, and the bdtc figure is without the line hitched to the distributor, and at the right engine speed recomended.

If you don't get idle stable enough, if you have a few spare hours, and maybee a spare throttle shaft and throttle butterflies and screws, drill up to four 1/8" to 5/32 (125 to 156 thou ) holes into the throttle butterflys starting at the smallest practical drill size 1/64 of 16 thou, then go up until you get a stable idle. Reset the idle, still with the transfer slot exposed slightly.

According to the old time experts, with Holley 2300 series carbs like the 350, 500 and 650 cfm 2-bbls (and 4-bbl/4150/4160 ), timing is touchy when you cam them up. Just a little too much cam timing, and the carb can suffers a 'fuel standoff' situation at just off idle, due to the carb not having enough stable air flow. Thats where the rooster tail of atomised droplets of fuel no longer stabiliy sits in a haze above the throttle blades. This is technically stemming from the valve duration at 30 thou inlet and exhast valve being more than the stock 240, 252 and 256 cams 200 cube engines typically ran. The off idle hole can be avoided by proper ignition and carb set up.

Opening up the carb blades at idle should cure this problem, then you can set mixtures and idle speed. If you don't get an improvement there, make throttle holes as the cams get bigger.You can start small with four If a new 2350 to 2800 converter is not on the horizon, the last option, if it all fails, is to use the Aussie7mains trick of swapping the bigger 500 carb on to the stock 350 throttle body. This is an old spin on putting smaller throttle bodies onto a bigger 4150/4160 4-bbls carb like they do on Tunnel Ram V8's.

(According to the old SA bookes on Holleys, various changes to Holleys by scrambling components can help fuel standoff with big cams. For intance, drag racers or street and strip duty cars could have 660cfm 4-bbl Centre Squirter throttle bodies on 800 cfm carbs, or 390 cfm throttle bodies on 465 cfm 4-bbl carbs. It was all to improve the signal, to avoid unstable fuel flow. Signal is the difference between the venturi bore size and the throttle bodade bore diameters. 35 to 41% difference helps if there is a driveablity problem on a tunnel ram, and it should work on 200 and 250 cube engines with cams and carb changes)

hi there,

I finally had the engine tune properly. I spend an hour looking for the tuning devices i had, hand finally end up setting the engine almost correctly using timing light, digital tachmeter and a vacuum gauge.
I ve also reset the valves clearance and the engine is now running strong thanks to all your advice.
correctly set choke, .28 squitter and green accelerator pump cam on the holley also helps a little the off idle stumbling situation.


my question now is what would be a correct idle speed for this engine (holley350+200 block + 250-2v head, oversided exhaust valves + ds2 + C4 auto transmission) ??
I'm now somewhere around 900 in N and 750 or so in drive. I not sure i can go as low as what is recommanded in the 66 mustang original shop manual (525RPM for auto) I m not even sure it would be desirable too. when switching to drive engine is slowing down a lot before getting steady, but is shaking a lot.
when the engine was stock i have never been able to acheive this recommanded idle speed as well. might not work good anymore with modern gasoline ( local gas is 95 octan) .

with the curent setting i get a free massage every time i m stopping at the traffic light while in Drive as the car is shaking and the engine sounds like an old harley davidson 2 cylinders engine ...

thanks for advises.

regards

What I'm going to ask you to do will cost two jets, one power valve, two squirters, a plastic cam, and a Holley throttle blade kit with replacment screws, plus a set of small drills from 16 to 156 thou, but some metric 1 to 3 mm 39 thou to 120 thou in 20 thou teps drills in 0.5 steps will also do fine. I've got some here I can air mail to you if you'd like. A trolley jack and some axle stands will help raising the rear axle off the deck with safely getting the total advance figures.

xctasy":2x5jobrl said:

What vac reading are you seeing at idle?

Click to expand...

Your answer depends on what to do next. Based on what you've said, jet down.

Right now you need to have # 58 Jets in it, a # 28 squirter and a brown pump cam adjusted at 0.015 clearance warmed up at idle. Do you have less than 16 inches of vacuum at idle with a person in the car holding the brake with the car in park.

Use a #65 power valve, and make sure it is undamaged.

Does your Duraspark II come with a control box that has a red, green, yellow or blue at the connecter. Some versions pull the timing out after starting, and there are three versions of Duraspark, 1 and 11 and a rare 3 found in CFI 5.0's which doesn't concern us here, but if you are using the red, green, yellow or brown control box, it might be a problem.

The yellow control unit is a really good set up, but it makes setting timing a pest unless you use the right procedure.

Is your base timing 9 deg btdc, or up to 16. At 1500, 2000, 2500, 3000 and 3500 in drive with a person holding the brakes on, what is the total advance. And then in park or neutral. (Ford specifically say don't rev a car above 3500 in neutral).

If 58, 28, 15 thou, 16 or greater, 6.5, Duraspark II with blue connector, and you still don't get a nice stable idle, then go to the shop and buy a 1 mm (39 thou drill) and take to the two throttle blades with it and drill four progression holes, two each blade. Then follow the tuning process again.

xctasy":2x5jobrl said:

Then the key is that the carb must be slightly open of the transfer slot when idle is set. If you have problems with off idle bog or low rpm, this is your first call to check the throttle blades have been cracked open enough so the idle mixture and speeds can result in the recomended park and drive rpms. With the lines unconnected, and the bdtc figure is without the line hitched to the distributor, and at the right engine speed recomended.

If you don't get idle stable enough, if you have a few spare hours, and maybee a spare throttle shaft and throttle butterflies and screws, drill up to four 1/8" to 5/32 (125 to 156 thou ) holes into the throttle butterflys starting at the smallest practical drill size 1/64 of 16 thou, then go up until you get a stable idle. Reset the idle, still with the transfer slot exposed slightly.

Click to expand...

Stop increaseing the size of the progression holes when the car will idle at 650 in drive.

Hi,
Thanks for detailled answer.
My ds2 had a blue modul.
Power valve seems a bit trucky to replace as the carb had to be disassemble. Still I ll think about it as it is definitly not an expensive item.
I actually thought aboyt it earlier as when cold car still stumble a bit before launchin just off idle. Once throttle is.open enought engine, stumble stop and engine accelerate perfecty. Sound l
Like power valve not correct with vacumm level.

I ve read.also about the drilled butterfly thing and it seems to make sens.


Where does the butterflies have to br drilled? One hole each side of the axle I guess, right in the middle?

Small enough so dieseling (run on after igntion turned off) doesn't occur, and large enough to eliminate too high an idle speed. 16 thou is too small, so try 40 thou, then bank on the holes likely to be 128 to 180 thou.

Take the carb of its base, drill from underneath, and use a vac cleaner and high speed drill.

I learned from the Rochester 2 jet, which had 3.8 mm holes stock, and I've had a lot of experience with them.
Sadly, my 2CG is missing the throttle blades, but here's a photo of one that's not mine

http://image.circletrack.com/f/35144703 ... retors.jpg

Throttle Plates and the Idle Mixture
One of the few things that basically works the same with these carburetors as the four-barrel Rochesters is the throttle blades. Photo 1 shows the throat holes in the throttle plates, which are relatively large. In these photos the holes are 0.180-inch. It doesn't matter where on the plates you put the holes but their size does matter.


The purpose of the holes is to allow enough air through the carburetor and into the engine so that it idles correctly without having to open the butterflies and expose the transition slots. And with a race engine, you are almost always running a larger camshaft which requires more air, so those holes will have to be enlarged. The transition slot is barely visible in this photo, which is what you want. You can see it on the lefthand side in the throttle bore at the 12 o'clock position.


As you are drilling out the holes, be careful to only make it larger in small steps. This is true with a lot of the changes you make on the carburetor-since a race motor will want more air and fuel than a street motor, just about everything you do will be to make the channels and openings larger. But it's always easier to make a hole bigger than it is smaller. In fact, in some cases, like with the throttle blades, it can be practically impossible to make the holes smaller. If you wind up making the holes too large your only option will be to go out and find new throttle blades to replace the ones you've ruined. So, try to sneak up on those throat holes until they are just the right size.


Read more: http://www.circletrack.com/enginetech/c ... z1zAYS4t3i

Click to expand...

When running a 500 Holley 2-bbl, which has 11/16 throttles, I run a Holley 26-96 Throttle Plate Kit from a 4-bbl, which has a 0.150 " (3.81 millimeters)

The 350 cfm has 1 3/8" blades, so the hole can be less than 150 thou, but my suggestion is 39 thou (1mm first), then go up

Std Holley aftermarket part =

After market big 4-bbl 4150 is just a dual 2300 2-bbl, and they often have holes drilled http://img87.imageshack.us/img87/1474/img2199co4.jpg

Big 4-bbl engineers do it often http://www.460ford.com/forum/showthread.php?p=564045