250 build tunning and stuff
- Thread starter 69stang_250
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RichCreations
Well-known member
69stang_250":31twrszq said:
I still think you need to be a bit richer at wot...
turbo2256b
Well-known member
Specks on that cam will most likely want to idle around 1000 RPM. Idle AF might do best around 13.5 give or take. Get a power valve in there that for sure isnt opening at idle front and rear if it has both. If the idle feed screw dosent change much in or out its opening.
Idle feed screws only adjust the amount of fuel not jetting of the idle mixture.
Another mark can be made on the damper using the timing marks at say 5 and 10* and use them to add to reading on the timing markers to read total advance and initial if its over the timing marks.
So if the 14* mark on the timing tab aligns with the 5* mark add 5* to the 14 = 19*. If the 5* mark goes past the timing tab use the 10* mark the same way. You will need enough marks to read total timing.
Using different color paint marking pens helps distinguish the marks.
Another help to set initial at idle and timing running down the road is to know advance at ever 500 RPM driving steady speeds and have a really good temp gauge timing is usually best when the temp is lowest.
Its also best to have initial and mechanical advance dialed in correctly before even hooking up to dial in the vacuum advance, which without EGR only about 5* or so of vacuum advance may work out. With that cam and no EGR possibly wont work that well at all.
Idle feed screws only adjust the amount of fuel not jetting of the idle mixture.
Another mark can be made on the damper using the timing marks at say 5 and 10* and use them to add to reading on the timing markers to read total advance and initial if its over the timing marks.
So if the 14* mark on the timing tab aligns with the 5* mark add 5* to the 14 = 19*. If the 5* mark goes past the timing tab use the 10* mark the same way. You will need enough marks to read total timing.
Using different color paint marking pens helps distinguish the marks.
Another help to set initial at idle and timing running down the road is to know advance at ever 500 RPM driving steady speeds and have a really good temp gauge timing is usually best when the temp is lowest.
Its also best to have initial and mechanical advance dialed in correctly before even hooking up to dial in the vacuum advance, which without EGR only about 5* or so of vacuum advance may work out. With that cam and no EGR possibly wont work that well at all.
Ok so I put 68 main jets in this morning and I the second lightest spring I have.
Car drives around town, cruises, and accelerates wonderfully with no issues at the 2700-3000 area any more.
I have the idle mixture hanging around 13.5 and in all driving conditions the AF ratio stays between 12s-13s with a random 14 in there every now and again. When punching the gas though, it leans to 16 and rises to about 11.5 up to 5000rpm. Even then, it's a smooth acceleration up to 5000 rpm.
Car drives around town, cruises, and accelerates wonderfully with no issues at the 2700-3000 area any more.
I have the idle mixture hanging around 13.5 and in all driving conditions the AF ratio stays between 12s-13s with a random 14 in there every now and again. When punching the gas though, it leans to 16 and rises to about 11.5 up to 5000rpm. Even then, it's a smooth acceleration up to 5000 rpm.
RichCreations
Well-known member
69stang_250":ax74uwrd said:
Can you adjust the accel pump linkage now, to give a bigger shot? the leaning to 16 scares me...
I've got the linkage adjusted how it should be, but I have a ton of cams. Do you think that's the issue? Or would it be the squirter?
turbo2256b
Well-known member
68 JETS IN ALL 4 BARRELS oR ARE THE REAR JETS still smaller?
68 mains and 63 secondaries.
I was just looking at the accelerator pump cam profiles and I'm gonna put the blue one on and see how it works out.
I was just looking at the accelerator pump cam profiles and I'm gonna put the blue one on and see how it works out.
RichCreations
Well-known member
Dont know those carbs that well, only that you need a bigger initial squirt ;-)69stang_250":3c7492dp said:
turbo2256b
Well-known member
69stang_250":j4sh8a7z said:
You need some bigger jets in the rear at least the size of the front if all 4 throttles and boosters are the same size. The rears should be larger if the rear barrels are larger or the boosters allow more air to flow.
Fix that issue before messing with the squirters.
Withthe 100s OF CARBS i HAVE BUILT never have I HAD SMALLER JETS IN THE REAR than the front.
Tried to send a PM and email to show you pic of how I set up a secondary idle setting trick to make it easy to adjust while on the vehicle while its running.
I have been working with bill on this and here is what I have this morning.
Took it for a drive and have no issues with easing into the throttle or cruising, even after changing to the blue cam.
AF ratio stays in the 12-13.8 range just normal driving and cruising stays in the 13s.
If you go wide open throttle it now drops to 17 and reaches 13.5 around 3500 rpms. this happens no matter what gear you are in and go WOT.
I have not thought about the secondary jets, but that may be what I need to do.
I will be going back to the orange cam, as it did keep the AF ratio curve in the higher12s and 13s when just normal driving.
Regardless I have not had any bogs or things of that sort at all since the spring change and power valve change.
That is also something I wonder if the power valve has anything to do with the enrichment on wot?
Took it for a drive and have no issues with easing into the throttle or cruising, even after changing to the blue cam.
AF ratio stays in the 12-13.8 range just normal driving and cruising stays in the 13s.
If you go wide open throttle it now drops to 17 and reaches 13.5 around 3500 rpms. this happens no matter what gear you are in and go WOT.
I have not thought about the secondary jets, but that may be what I need to do.
I will be going back to the orange cam, as it did keep the AF ratio curve in the higher12s and 13s when just normal driving.
Regardless I have not had any bogs or things of that sort at all since the spring change and power valve change.
That is also something I wonder if the power valve has anything to do with the enrichment on wot?
I mean can that cause that lean spot?
Here is a vid of me explaining what the AF ratio is doing while driving.
https://youtu.be/h-myBdP8v-o
https://youtu.be/h-myBdP8v-o
turbo2256b
Well-known member
https://www.summitracing.com/parts/sad-sa216/overview/
Suggest reading up on Holley carbs would be a big help.
Good chance with the rear jets being too small when the rear bbls cut in your going lean and your using the pump shot to try and compensate.
The power valve should be open when vacuum goes below the valves opening point. 4.5 VALVE SHOULD BE OPEN ANYWERE BELOW 4.5" of vacuum. Some Holleys have power valves front and rear.
If the carb only has one in the front the rear jets are usually 7 to 10 sizes larger than the front jets. Same for the front jets no power valve the fronts would need to be 7 to 10 sizes larger.
Mistake most make is they think making the main jet do some of the power valves work. A main jet is just the cruse jet. The main jet + the power valve is the WOT jetting. Pri main jets should be set up for max cruse speed/economy. I usually set my max cruse speed for 80/85 MPH on a street strip car.
So to select proper Power valve you need to know vacuum at idle and at your max cruse speed.
Send me your Email and I CAN send a pic of how to make the secondary idle adjust ment without removing the carb and while the engine is running. Cant seem figure how to pm you.
Suggest reading up on Holley carbs would be a big help.
Good chance with the rear jets being too small when the rear bbls cut in your going lean and your using the pump shot to try and compensate.
The power valve should be open when vacuum goes below the valves opening point. 4.5 VALVE SHOULD BE OPEN ANYWERE BELOW 4.5" of vacuum. Some Holleys have power valves front and rear.
If the carb only has one in the front the rear jets are usually 7 to 10 sizes larger than the front jets. Same for the front jets no power valve the fronts would need to be 7 to 10 sizes larger.
Mistake most make is they think making the main jet do some of the power valves work. A main jet is just the cruse jet. The main jet + the power valve is the WOT jetting. Pri main jets should be set up for max cruse speed/economy. I usually set my max cruse speed for 80/85 MPH on a street strip car.
So to select proper Power valve you need to know vacuum at idle and at your max cruse speed.
Send me your Email and I CAN send a pic of how to make the secondary idle adjust ment without removing the carb and while the engine is running. Cant seem figure how to pm you.
I was reading an article about that just a little bit ago.
So I am wondering if I should put the # 68 jet in the secondaries and maybe put the #63 or#65 that I have in the primaries. I have no idea how far off that will throw the primaries off, but those are what I have to play around with at the moment. I may play around with that tonight and see what happens.
So I am wondering if I should put the # 68 jet in the secondaries and maybe put the #63 or#65 that I have in the primaries. I have no idea how far off that will throw the primaries off, but those are what I have to play around with at the moment. I may play around with that tonight and see what happens.
turbo2256b
Well-known member
69stang_250":2m6ccxxq said:
68S IN THE REAR AND 63S in the front would be a good place to start. What power valve did you end up with?
Issue with the size of your carb. Figuring a 250 cu in engine max RPM 6500 going through the calculations at 100% efficiency carb size is around 470. 7500 RPM carb size at 100% is around 540. Most builds are under 100%. 80 to 90 is a fairly well match of parts. Because the carb is a bit large jetting has to compensate for lazy air flow through the carb most likely requiring larger jetting that a smaller carb good chance of poor economy and a bit lazy performance.
Another thing good to know is your cranking compression
Nice work.
Carb size for sixes with 250 cubic inches can be compared to carb sizes for 302 V8 engines.
In the USA, 630 CFM 4--BBL vacum secondary for 175 to 210 hp net (1983-1985 5.0 4V HO),
and in Australia, 800 cfm mechancial secondary 4-bbls for 188 to 207 hp net (1977 TO 1982 4.9 4-BBL ).
On a 20% capacity reduction, 670 cfm is perefect for a performance 250. In fact, a mechanical secondary is evern better, but a vac sec is just fine.
From the 5.0 orientated forum I frequent, we've got some really good guys who run wide bands on their 1984-1985 4bbl HO 5 speed 5.0's.
For full size, click the link below, and select the magnification glass icon
http://i1215.photobucket.com/albums/cc5 ... v2_afr.jpg
http://i1215.photobucket.com/albums/cc5 ... Nv_afr.jpg
The factory rating Ford quoted for this 4-bbl 4180c carb SATURN V uses was under reported in press material at a ludicris 570 cfm at 2"Hg, but it is actually 630 cfm at 1.5 "Hg carb. And its actually a little too small for even a 175 to 210 hp V8, the Aussie 302 had the Mopar 318/360/400 Carter TQ 9800 800 to 850 cfm carbs, and it was ideal for economy and power.
4.1 liter Inline sixes like about as much carburation as 5.0's, since they make better low end torque in the off idle to 2800 rpm range, and in the first 150 feet, they always eclispe a naturally aspirated 5.0. Over sizeing on the cfm basis doesn't created a soggy response on an intake with 2300 cc's of intake runner like the Classic Inines intake has.
The follwing three posts describe how people retune the stock 4-bbl vac sec Holley for a 210 to 355 net hp (SATURN V's 5.0 is upgraded with the 1986 exhaust, BaconB8's smog legal 85 Saleen is 280 rwhp with alloy AFR 165 heads and a host of other hot parts)
http://vb.foureyedpride.com/showthread. ... AFR-tuning
http://vb.foureyedpride.com/showthread. ... ne-jetting
http://vb.foureyedpride.com/showthread. ... -catalysts
The propane method for leaks
wsa111 and SATURN V and BaconB8 do full data plots. Do what I do when tunning my or customers cars.
Mount the camera in the sunvisor, and video the LM-1 Innovate screen as you down load.
In my case, I have a cell phone app that does my AFR linkup, runs off the OBD I port Ford used from 1981 to 1995 Fords, that allows me to make user specified TPS (% throttle), MAP (Abs baro, manifold from Bosch 4.1 Falcon 1986-1992 XF sensor) and AFR ( in my case, narrow band) on one graph.
http://i1215.photobucket.com/albums/cc5 ... 14_957.jpg
http://i1215.photobucket.com/albums/cc5 ... 15_016.jpg
Once you plot everything, you'll find base idle, and curb idle makes a difference, but lets not get ahead of oursleves.
My best advice ever has come from Ethyl Cat, and that is the three points.
First
Carb size for sixes with 250 cubic inches can be compared to carb sizes for 302 V8 engines.
In the USA, 630 CFM 4--BBL vacum secondary for 175 to 210 hp net (1983-1985 5.0 4V HO),
and in Australia, 800 cfm mechancial secondary 4-bbls for 188 to 207 hp net (1977 TO 1982 4.9 4-BBL ).
On a 20% capacity reduction, 670 cfm is perefect for a performance 250. In fact, a mechanical secondary is evern better, but a vac sec is just fine.
From the 5.0 orientated forum I frequent, we've got some really good guys who run wide bands on their 1984-1985 4bbl HO 5 speed 5.0's.
For full size, click the link below, and select the magnification glass icon
http://i1215.photobucket.com/albums/cc5 ... v2_afr.jpg
http://i1215.photobucket.com/albums/cc5 ... Nv_afr.jpg
The factory rating Ford quoted for this 4-bbl 4180c carb SATURN V uses was under reported in press material at a ludicris 570 cfm at 2"Hg, but it is actually 630 cfm at 1.5 "Hg carb. And its actually a little too small for even a 175 to 210 hp V8, the Aussie 302 had the Mopar 318/360/400 Carter TQ 9800 800 to 850 cfm carbs, and it was ideal for economy and power.
4.1 liter Inline sixes like about as much carburation as 5.0's, since they make better low end torque in the off idle to 2800 rpm range, and in the first 150 feet, they always eclispe a naturally aspirated 5.0. Over sizeing on the cfm basis doesn't created a soggy response on an intake with 2300 cc's of intake runner like the Classic Inines intake has.
The follwing three posts describe how people retune the stock 4-bbl vac sec Holley for a 210 to 355 net hp (SATURN V's 5.0 is upgraded with the 1986 exhaust, BaconB8's smog legal 85 Saleen is 280 rwhp with alloy AFR 165 heads and a host of other hot parts)
http://vb.foureyedpride.com/showthread. ... AFR-tuning
Saturn V":197jqivd said:........
My carb only has mixture screws for the primaries, not the secondaries as some have. Maybe it’s because my carb is a service replacement? I used a 3/32” Allen wrench about 3 inches long. Next time I’ll get a second wrench so that I can leave one in each idle mixture screw. Swapping the wrench from side to side and trying to get the wrench into the screw socket each time with a hot, running engine wasn’t easy. Anyway, the best I could get manifold vacuum at 800 RPM was 19.5 inHG with AFR around 13.0. This seems rich to me for idle. Below is a table of the results. All are with a bare carb at about 800 RPM, except for the last line when I installed the air cleaner, which leaned out the mixture a little . I measured the number of turns on the idle mixture screw as precisely as I could, but these may not be exact.
http://youtu.be/U3adrHH7ENc
http://youtu.be/9gz8UX3eFXo
http://vb.foureyedpride.com/showthread. ... ne-jetting
[/quote]Ethyl Cat":197jqivd said:
http://vb.foureyedpride.com/showthread. ... -catalysts
The propane method for leaks
wsa111 and SATURN V and BaconB8 do full data plots. Do what I do when tunning my or customers cars.
Mount the camera in the sunvisor, and video the LM-1 Innovate screen as you down load.
In my case, I have a cell phone app that does my AFR linkup, runs off the OBD I port Ford used from 1981 to 1995 Fords, that allows me to make user specified TPS (% throttle), MAP (Abs baro, manifold from Bosch 4.1 Falcon 1986-1992 XF sensor) and AFR ( in my case, narrow band) on one graph.
http://i1215.photobucket.com/albums/cc5 ... 14_957.jpg
http://i1215.photobucket.com/albums/cc5 ... 15_016.jpg
Once you plot everything, you'll find base idle, and curb idle makes a difference, but lets not get ahead of oursleves.
My best advice ever has come from Ethyl Cat, and that is the three points.
First
turbo2256b
Well-known member
"In the USA, 630 CFM 4--BBL vacum secondary for 175 to 210 hp net (1983-1985 5.0 4V HO),"
In america these setups from the factory never opened completely and not soon enough.
Have seen 375 RWHP in 302s easy with that size carb .Wouldnt recommend the factory carb as its circuitry was set up really lean and would require quite a bit of mods.
In america these setups from the factory never opened completely and not soon enough.
Have seen 375 RWHP in 302s easy with that size carb .Wouldnt recommend the factory carb as its circuitry was set up really lean and would require quite a bit of mods.
Well I swapped my jets around and re tuned the carb. Honestly feels like it pulls harder now and I have it running in the 13s pretty constant, however, I still have a lean spot at WOT. It jumping to 11s ( was jumping into the 10s) and then it leans out to the 16s, but richens up a lot quicker than before.
Bigger jets in the secondaries? Have 68s in there now and 63s in the primaries.
Or do I need to go back to the lighter spring?
Also the hesitation is back, but it's only at WOT off the line.
I have a spot where out in BFE that I marked a 1/4 and I did a run out there today. It was only me so my time sucked, but ran it in the 15s as it is right now. Want my time a good bit lower, but not bad for that engine with a t5 and 3.00 one legger in the back. I do see changing my gears to 3.55 in the future or maybe a little lower.
One goal I have for this car is to get into the 13s. I do think that is possible.
Bigger jets in the secondaries? Have 68s in there now and 63s in the primaries.
Or do I need to go back to the lighter spring?
Also the hesitation is back, but it's only at WOT off the line.
I have a spot where out in BFE that I marked a 1/4 and I did a run out there today. It was only me so my time sucked, but ran it in the 15s as it is right now. Want my time a good bit lower, but not bad for that engine with a t5 and 3.00 one legger in the back. I do see changing my gears to 3.55 in the future or maybe a little lower.
One goal I have for this car is to get into the 13s. I do think that is possible.