cold start/choke issues? What to look at?

[LARIAT 85]

As far as correct carb goes I believe the tag is on the carb still and it breaks down as being correct for my application. Still the problem lies in the accelerator pump circuit not in the venturi boosters which is what changed between carbs for different vehicles.

Ford designed the 351 cfm (1.21 venturi) Motorcraft 2150 2V carburetors to work with either the 351 Windsor engine or the 351 and 400 Cleveland engines. For your application, the correct carburetor would be a 287 cfm (1.08 venturi) Motorcraft 2150.

If the carburetor you are using was designed for a 351M motor, it will never run right on a 351W engine, let alone a 302W engine. The Cleveland and Windsor engines flow completely different, and the carburetors are set up totally different to reflect that.

Sure you can quickly change the jets out but how do you know that the jets you are switching out to is the ones you need to switch to? or do you just carry a set of jets and do trial and error a few times to find the right jets? After all im sure you know that no two engines are alike and what one engine likes jet wise at a specific altitude doesnt mean another engine will like it.

If the altitude change is temporary, just let it be. If the altitude is great enough, and the time spent at that altitude is long enough, you may want to swap out your jets for optimum performance. Smaller elevation changes can be compensated for by simply turning your fuel mixture screws. If it is necessary to turn them much over 1-1/2 turns, then you may want to replace the jets. A rough estimate is a one jet size reduction for every 1,000-foot elevation increase.

Yeah my york drops more than 125 rpm. Mine drops more around 175 rpm when the AC kicks in. Its why I have mine idled up as much as I do since I dont have the solenoid as it wasnt avaliable for dealer AC. With this new setup I will have the step up in the form of the computer changing the idle speed when the AC is on. I could let it maintain the base idle speed but I am going to program it to idle the engine up by around 100 - 150 rpm. Will play with it to see what the combination likes best.

If it drops that much, I would make sure my curb idle speed was set to 675 RPM in gear. That is about what any modern fuel-injected vehicle idles at anyway. Then when the compressor turns on, it would only drop to 500 RPM. If everything else is set correctly, your engine should idle just fine at 500 RPM.

The solepot is a device that is attached to the carburetor, not the A/C system. (Well, it does wire into the A/C circuit.) There is no reason why you can't bolt one on your Motorcraft 2150 carburetor. When set correctly, it will do the same thing the computer will on the Sniper. The one I had on my original Motorcraft 2150 fit perfectly on my Autolite 4100 and works great.

This is what it looks like:

Now as far as performance/efficency goes I dont care how set up a carb you have the sniper will wake any engine up.

I installed one in a engine that was dyno tuned with a carb and the guy wanted to put a sniper on it instead. The engine you thought rev good in neutral and ran great on the street. Throw the sniper on and just hitting the throttle the engine was so much more responsive and so much quicker in reving it was like a kid in a candy store feeling. Driving the car woke it up so much more as well.

Assuming the carburetor is sized and tuned correctly, a fuel injection system by itself will add very little - if any - extra power on the same engine.

Everything you wrote here that claims the Sniper "woke the engine up" is subjective. If the guy you installed this for had his engine dyno-tuned with his carburetor, how did the actual numbers change with the Sniper? Without actual numbers we are guessing and just going off of feeling. One possible explanation is the Sniper *may* have added some horsepower, but it *may* have lost some torque in the process.

[Rusty_S85]

Ford designed the 351 cfm (1.21 venturi) Motorcraft 2150 2V carburetors to work with either the 351 Windsor engine or the 351 and 400 Cleveland engines. For your application, the correct carburetor would be a 287 cfm (1.08 venturi) Motorcraft 2150.

If the carburetor you are using was designed for a 351M motor, it will never run right on a 351W engine, let alone a 302W engine. The Cleveland and Windsor engines flow completely different, and the carburetors are set up totally different to reflect that.

If the altitude change is temporary, just let it be. If the altitude is great enough, and the time spent at that altitude is long enough, you may want to swap out your jets for optimum performance. Smaller elevation changes can be compensated for by simply turning your fuel mixture screws. If it is necessary to turn them much over 1-1/2 turns, then you may want to replace the jets. A rough estimate is a one jet size reduction for every 1,000-foot elevation increase.

If it drops that much, I would make sure my curb idle speed was set to 675 RPM in gear. That is about what any modern fuel-injected vehicle idles at anyway. Then when the compressor turns on, it would only drop to 500 RPM. If everything else is set correctly, your engine should idle just fine at 500 RPM.

The solepot is a device that is attached to the carburetor, not the A/C system. (Well, it does wire into the A/C circuit.) There is no reason why you can't bolt one on your Motorcraft 2150 carburetor. When set correctly, it will do the same thing the computer will on the Sniper. The one I had on my original Motorcraft 2150 fit perfectly on my Autolite 4100 and works great.

This is what it looks like:

http://forum.garysgaragemahal.com/file/n98134/throttle-kicker-l.jpg

Assuming the carburetor is sized and tuned correctly, a fuel injection system by itself will add very little - if any - extra power on the same engine.

Everything you wrote here that claims the Sniper "woke the engine up" is subjective. If the guy you installed this for had his engine dyno-tuned with his carburetor, how did the actual numbers change with the Sniper? Without actual numbers we are guessing and just going off of feeling. One possible explanation is the Sniper *may* have added some horsepower, but it *may* have lost some torque in the process.

1) If that is the case and the tag was just throw onto the carb from the old one and it truly isnt correct, the flow difference would not cause a stumble on initial tip in of the throttle is the main point. Maybe it contributes to the bad gas miliage I get which is around 12 city with 2.75:1 axle ratio and 31" tires. But basic function of the carb on tip in the accelerator pump is to help with transition from the idle circuit to the main circuit to avoid hestiation, stumble, bog. The fact that upping the amount of fuel squirting resulting in an improvement is a indication that there is not enough shot of fuel on the accelerator pump circuit to cover that transition period. Sure the carb may not be right and may be wrong and too big, but the accelerator pump is still sized properly for the carb and should not have that hesitation. Even my 292 with a 1974 replacement 2100 autolite with a 1.08 venturi didnt have any performance issues even though its 287 cfm compared to the correct holley 4000 being 330 cfm. Only issue I had in this case was no power as the timing was pulled back to 0* initial as they were trying to run the load o matic distributor which was powered by a combination manifold vacuum and venturi vacuum off of straight manifold vacuum which ran the distributor at full advance all the time.

I may have to double check my truck maybe it is a 1.08 and I am thinking its a 1.21 like my 351W but I do recall checking years ago and thinking that it was odd that both engines having the same cfm rating. But the truck ran great, it ran great while moving just had that initial tip in hesitation which was almost non existant with the change in accelerator pump setting.

2) Sure one could leave it if temporary but there are cases where you may be on a long trip and be constantly going up in elevation. For me any where I go will be a increase in elevation as I am currently at 25 feet above sea level. So no matter where I go my altitude will increase unless I go to the coast where it drops down to 10 feet above sea level then you have the beach.

The property I have about 110 miles west of where I am currently at is right at 398 feet elevation varying between 350 feet to 450 feet. Then if I go to RWP up north of Dallas like I would like to go to just once with my truck just to watch the carnage I would be right around 1,200 feet elevation. Might not be enough to warrant jet changing for a temporary trip but seeing as I work on cars for a living I have lost quite a bit of interest in working on my own vehicles and if I can make a change that reduces the amount of work I have to do on said vehicle and can enjoy driving more I will do it. When I got my '56 I wanted to keep it all original with points but I eventually upgraded to petronix just so I can enjoy driving vs worrying about having to properly adjust the points.

Like with my truck, its a daily driver, I dont want to have to be on the side of the road tinkering with changing jets for example because I went from 25 feet elevation to 1,200 feet elevation only to have to make the switch back when I come back to 25 feet elevation.

Then who knows if the truck seems to be good for long hauls I might even put my truck in the hotrod power tour that comes through TX.

As far as giving the idle mixture screws a little more juice to compensate for the altitude change for a temporary fix, I dont think that would work. The idle mixture screws only adjust the idle mixture once you are off idle those screws have zero effect on the fuel mixture and it is all reliant on the jets themselves.

3) I dont think I have ever idled my 302 down to 500 rpm in gear. I try to keep it around 550 - 600 in gear with the AC on which is about 650 to 750 with AC off. Just general guestimates as I am going by the OE tach. I know when I got the AC working the idle speed I had which was right in line with spec was way too low you put the truck in gear and it would barely idle then finally stall without the solenoid. I also know you can add one in, I never added one in had thought about it but seeing as I wont be using that carb anymore there is no point in worrying about it now. I have a 600cfm summit 4V carb which Holley builds for summit and its their updated version of the 4100 carb with annular boosters. I was going to use that but then after installing so many snipers and seeing the benefits of them decided to do the upgrade and keep the summit 4V for my 351W as I had always wanted to upgrade that from a 2150 and see if I could squeeze some more fuel economy out of it with the smaller primaries than the 351cfm 2V currently on the engine. Then if the sniper doesnt work out for me like it has for all the ones I installed then I will simply pull it off and put the Summit 600 cfm carb on. Its why I planned on putting the fuel pump eccentric on the cam gear and using a block off plate on the fuel pump mount that way I can easily convert back to carb without having to disassemble my engine to install the components. But I dont think I will have an issue with the sniper. Too many people have them and too many good reviews, most of the problems people have with them is improper installation by people not following the directions and hooking battery hot and battery ground for the sniper to something other than directly at the battery.

4) I dont believe he took and had it dyno tuned again to see what kind of improvements were made. But I wouldnt call woke the engine up as subjective. His dyno tuning he had done on the carb which was built by Davinci and dialed in by a local dyno shop that still works with carbs got it dialed in as best as they could. I didnt see the dyno sheet to know the exact numbers but the owner states that it dynoed at 400 hp. Putting the sniper on it had improved throttle response, it reved quicker and it pulled harder when nailing the throttle than it did with the carb. Maybe the carb wasnt dialed in right, I know dyno tuning can be hit and miss depending on who you go to but every carb I took off for a sniper resulted in a sharp snappy throttle response and improved power over the carb. There was also a hotrod article about increasing top end power on a engine they had dynoed switching to a sniper which they said was evident that their carb was a bit on the small side. Which lets face it if you are running a carb on the street youd want it to be more on the small side than on the big side for street performance. Thats where the Sniper as I stated excelles it moves massive amount of air but isnt hindered like a carb as it is capable of spraying the proper amount of fuel for said air volume. This helps pick up power in the top end as well as improve throttle response. In some cases I bet it improves low end power as well.

I installed one in a 66 corvette with a 327 small block, took the OE 4V carb off drilled and tapped the snowflake aluminum intake for the temp sensor for the sniper and threw the sniper on. Car idled so much smoother, started up so much better, and reved so much quicker than the OE carb did. On this one I cant vouch for the tune on the carb, I didnt build the car the car was built by someone else that then sold it to this guy who had it brought to us to do a list of work on it from adding off set upper control arm shafts to get it to align properly to adding vintage air and the sniper fuel injection.

That is also the only car to ever come back and he kept blaming the sniper for the overheating problem claiming its running lean cause thats what his brother in law who builds race engines told him the fuel injection is going lean causing it to over heat. Even though the 02 sensor was reading a 13:1 air fuel mixture which was a little rich at idle and could in fact be set a bit leaner at idle around 14.5:1 to 15.5:1. He wanted us to put a carb back on it and see if it would still over heat which he believed it wouldnt but he didnt want to pay us for that so we didnt do it. Realistically with how quick that engine was over heating I suspect it was something wrong in the block itself that we told him and he didnt want us to pull the motor and find the problem so we shipped it out back to the new owner. For a engine to over heat due to running lean youd have to be around 17:1 or leaner where the engine is barely running and your exhaust would be glowing so bright it would appear translucent.

Power wise it is why I want to dyno tune my truck or at least put it on a dyno after I get the C6 replaced with the Broader Performance C6 unit I want and swap the center chunk out for a 3.00:1 or 3.25:1 currie true trac chunk. I really want to see what kind of power my 306 with sniper is making. Blueprint claims their 306 crate engine dynos out at 370 hp with 9.5:1 compression. I am looking at 9.2:1 compression most likely wont know for sure till my short block comes in, but I am sure my AFR 165 cc heads flow better than their in house produced heads and my crane roller cam is just a smidge smaller than their cam. So in theory my 306 should be making around 370 hp just like blueprints but I honestly dont see it making more than 350 hp.

Based off their specs, 370hp/350ft lbs, their heads are in house HP9009 with 60cc chambers and 2.02"/1.60" valves 190cc intake runner with a roller cam 112* lsa @ 0.50, 218*/226* duration, and 0.543"/0.554" lift. Looking up their heads its listed at 28" to flow 249 cfm @ 0.500" and 251 cfm @ 0.600" lift.

My specs is AFR Renegade 165 heads with 58cc chambers and 1.95"/1.60" valves, 165cc intake runner with a roller cam by Crane 112* LSA, 216*/224* duration @ 0.050", 0.520"/0.542" lift, 107* ICL. Flow data on my heads out of the box is 251cfm intake @ 0.500" lift, 208 cfm exhaust @ 0.500" lift and 255 cfm @ 0.550" lift intake and 212 cfm @ 0.550" lift exhaust.

With this in mind I could actually see my engine making similar power to the blueprint 306 even at a reduced compression ratio but I honestly do not expect my 306 build to make much over 300 hp. If it does then I would be very impressed with the package I assembled together myself for my intended purpose which is a daily driver street truck.

[rcarlisle]

The hot air does *not* hook into actual exhaust. There is a hollow tube-like compartment built on the side of the passenger stock exhaust manifold. It serves as a *chamber* to collect hot air generated off of the exhaust manifold. The choke tubes pressed into the top and bottom of the chamber (hot air rises) to circulate the air from the filtered side of the carburetor (when the air cleaner is in place) to the choke cap. Inside of this chamber would have been a mesh filter that would also serve to hold the heat in the chamber. It would look like this:

https://www.npdlink.com/product/fitting-and-screen-choke-stove-pipe/143995

The reason for the fresh air tube is so the choke cap will only see clean, filtered air. The air you pull into the choke assembly will ultimately make it's way into the engine. So ideally you would want to use filtered air. Some of the older carburetors like my Autolite 4100 used a piston in the choke cap to operate the choke. If it pulls dirty air, it can possibly jam up the piston and render the choke useless.

(If you do not run the fresh air tube, make sure to cap off the connection under the carburetor air horn so that it does not pull unfiltered air into the carburetor.)

That is why I tapped the second hole in the other end of the [chamber] dome and ran another tube up to the carburetor air horn connection. I purchased the filter above and pushed it into a slighter larger copper tube, and placed that assembly under the [chamber] dome. Then I pushed the choke tubes into either side of the [chamber] dome so it mimicked the factory setup as close as possible. It has been like that for about ten years now, and I haven't had any problems.

OK,, I have the Dorman kit and extra hose kit in hand. If I do the loop as you described, couldn't I connect the ends inside the dorman housing with a piece of tube bridging the two pieces? Making a constant loop from fresh air up to the choke? Keeps varmints out as well.

If it were using the stock manifold bosses, that would be just a passage in manifold without the filter material correct? I think I see how that works on my stock manifold, but would have to remove the manifold to attempt to drill the passages out.

[LARIAT 85]

OK,, I have the Dorman kit and extra hose kit in hand. If I do the loop as you described, couldn't I connect the ends inside the dorman housing with a piece of tube bridging the two pieces? Making a constant loop from fresh air up to the choke? Keeps varmints out as well.

Yes. And that is exactly what I did. I used a small piece of copper (copper will heat up faster) tubing that fit tight inside the dome, just slightly larger than the two air tubes. Then I put the mesh filter media inside of that copper tube. I ran the fresh air tube into the lower hole of the dome and then the [insulated] hot air tube into the top hole. This is more like what the factory did - a sealed hot air chamber that circulates clean, filtered air.

If it were using the stock manifold bosses, that would be just a passage in manifold without the filter material correct? I think I see how that works on my stock manifold, but would have to remove the manifold to attempt to drill the passages out.

No. There is a filter media inside of the choke stove chamber on the stock exhaust manifold. Your chamber and filter media is probably very dirty and rusty inside at this point with both chamber holes being open to the elements.

The only reason I used the choke stove kit was because I am running exhaust headers, and they do not have a choke stove chamber built into them like the stock manifold does.

[rcarlisle]

OK,, I have the Dorman kit and extra hose kit in hand. If I do the loop as you described, couldn't I connect the ends inside the dorman housing with a piece of tube bridging the two pieces? Making a constant loop from fresh air up to the choke? Keeps varmints out as well.

Yes. And that is exactly what I did. I used a small piece of copper (copper will heat up faster) tubing that fit tight inside the dome, just slightly larger than the two air tubes. Then I put the mesh filter media inside of that copper tube. I ran the fresh air tube into the lower hole of the dome and then the [insulated] hot air tube into the top hole. This is more like what the factory did - a sealed hot air chamber that circulates clean, filtered air.

If it were using the stock manifold bosses, that would be just a passage in manifold without the filter material correct? I think I see how that works on my stock manifold, but would have to remove the manifold to attempt to drill the passages out.

No. There is a filter media inside of the choke stove chamber on the stock exhaust manifold. Your chamber and filter media is probably very dirty and rusty inside at this point with both chamber holes being open to the elements.

The only reason I used the choke stove kit was because I am running exhaust headers, and they do not have a choke stove chamber built into them like the stock manifold does.

Ok, thanks. I figured out your headers as I was studying the photo.

[Rusty_S85]

OK,, I have the Dorman kit and extra hose kit in hand. If I do the loop as you described, couldn't I connect the ends inside the dorman housing with a piece of tube bridging the two pieces? Making a constant loop from fresh air up to the choke? Keeps varmints out as well.

If it were using the stock manifold bosses, that would be just a passage in manifold without the filter material correct? I think I see how that works on my stock manifold, but would have to remove the manifold to attempt to drill the passages out.

THis is what you need for in the manifold.

https://www.ebay.com/itm/224118208366?epid=1222069255&hash=item342e7c776e:g:lD0AAOSwo2FfNvSx

OE part number for our trucks is D3TZ-9A714-B

[rcarlisle]

OK,, I have the Dorman kit and extra hose kit in hand. If I do the loop as you described, couldn't I connect the ends inside the dorman housing with a piece of tube bridging the two pieces? Making a constant loop from fresh air up to the choke? Keeps varmints out as well.

If it were using the stock manifold bosses, that would be just a passage in manifold without the filter material correct? I think I see how that works on my stock manifold, but would have to remove the manifold to attempt to drill the passages out.

THis is what you need for in the manifold.

https://www.ebay.com/itm/224118208366?epid=1222069255&hash=item342e7c776e:g:lD0AAOSwo2FfNvSx

OE part number for our trucks is D3TZ-9A714-B

I hope if I get all this, that 1) I can get it installed and 2) that the rest of the choke system will cooperate and work.

Thanks

[rcarlisle]

OK,, I have the Dorman kit and extra hose kit in hand. If I do the loop as you described, couldn't I connect the ends inside the dorman housing with a piece of tube bridging the two pieces? Making a constant loop from fresh air up to the choke? Keeps varmints out as well.

If it were using the stock manifold bosses, that would be just a passage in manifold without the filter material correct? I think I see how that works on my stock manifold, but would have to remove the manifold to attempt to drill the passages out.

THis is what you need for in the manifold.

https://www.ebay.com/itm/224118208366?epid=1222069255&hash=item342e7c776e:g:lD0AAOSwo2FfNvSx

OE part number for our trucks is D3TZ-9A714-B

Offered $5 and seller accepted. Yayyyy. I guess. If I can get it to work.

[Rusty_S85]

Offered $5 and seller accepted. Yayyyy. I guess. If I can get it to work.

Hardest thing you might run into is getting the meal cap on the bottom of the manifold out. I bought a NOS one as well but wasnt able to get the cap out on the truck. If the manifold is in a vise I think the cap can be gotten out easily.