Drilling carb butterflies

Jack,
I pulled the intake once already and put new gaskets. Compression, eh..I was expecting more but it should still work. With all vacuum sources plugged it drops like a brick below 2k. Its drawing fuel like crazy with the floats are a tad bit low. We beat this down pretty good. I don't want too crank timing any further than the 14 deg its set at. The vacuum gage reads steady but way low as you read. Don't know. A vacuum leak, wouldn't the reading be erratic?

Hi Ronbo, sorry to hear that it's getting put on the back burner for now though sometimes it's good to take a break from a problem for awhile to get a rest.

Speaking of and getting my arse kicked. I been trying to upgrade my old business computer from the defunk XP Pro to atleast Win7 and maybe all the way up to Win10. I am on a real low budget for this project so no new hardware except for a fresh (hard drive) for the next year or so. Yet it seems all my tricks, tries, and long hours, to get a clean install are refusing to work over the last 4 days. Oh well will keep plugging away it's a good thing there isn't a sledge hammer that happens to be near by. :rolflmao: edited Win 7 update! its been working ok now took almost a week of trying different things. Still need a new part or two, like mainly a better Video card and probally a software reload to fix one flaw and to optimize its performance.

As for a Vacuum leak or severial they won't really give you a Erratic Vacuum Gauge reading, just a low reading it's somewhat semular to the readings for retarded ignition timing or late camshaft timing. Erratic vacuum readings are usually from mechanical problems things like a blown head gasket (between two cylinders),a burnt or poor sealing valve or valves, and or worn / loose valve guides. Good luck and take care

Bubba, good luck with that Win install I have WIN 10 and just trouble The car....it'll wait. The best I can tell from pictures I had it running in 2009 and then put the head on, then the rocker arms and then nothing. Tossed the original head when I moved out there BUT I have a modified large log head I can go through and try. The Honda in the garage has dibs on my talents (not) right now, that and regular homeowner stuff. You know how the weather is, soon blistering heat and then monsoons Love it though!

"...and then monsoons ."
in Serria Vista? hard to believe. We had gully washers from the stuff goin on the mountain at Tucson.
But not much in the flats…
Tell me more.

Drilling carb butterflies is a last resort. Its for situations where you have a stock converter and a cam which is above 225 derees 50 thou lift. Real issue is how pig rich a Holley 2-bbl is on a 200 without the right Power Valve Channel Restrictions. PVCR's can be gotten around by other methods, there is no one solution to jetting, but the collective advice is that as capacity falls below 289 cubes, the 2-bbl 350 cfm carb needs some simple changes to avert too much part throttle richness.


Asside from your altitide, your main carb problem is the classic problem with large venturi area 2-bbl carbs jetted for 289 to 400 cube V8's on smaller 200 to 250 six cylinder engines. A 7448 carb is a nominal 351W/351M replacment carb. In your case, it has lost 75% of its airflow and vaccum due to the loss of 150 cubic inches.


1. The power valve channel restrictions are too large if you haven't organised the vaccum advance and static timing to suit the application.

2. The signal to the carb is less than Holley envisaged for its orginal appication.

3. There are also some port to port size issues between the 1.19" venturi 350 Holley 2-bbl on an in line six.

4. The power valve, Power Valve Channel Restrictions, jetting, platic cam and pump squiters and accelerator pump volume and setting can then tailer the right air fuel ratio. The 5 to seven hole variation to the stock 6 hole well tube can be done if there are any problems getting a proper air fuel ratio. So can the air bleeds.



V8's require the two 59 thou power valve channel restrictions with 10.5 to 8.5 power valves, and have jetting from 58 to about 65 call size jets.

That's all well and good for a 289 to 390 or 400 Ford V8. The factory net rating for those was 129 to about 200 hp net (gross ratings, 195 to 265 hp), 165 hp net (230 hp gross) nominal.

But see what happens when you drop capacity. On a little Four cylinder, the carb needs to have two brass restrictors inserted to be about 19 thou, with 2.5 power valves, and 65 jetting for a 125 hp net 2 liter 121 cubic inch Pinto engine.


For the in betweener's, say a 221 to 260 Ford V8 or 200 to 250 in line six, the power valve channel restrictions need to come down to 38 thou, the same size as the front half of a 390 cfm 4-bbl carb. Power valve needs to drop to 6.5 to 4.5.

Jetting stays up, since there is a need for more fuel from the main jets to compensate for a large venturi area.


The alternaive is to contact Will (wsa111), and have him recurve your ignition and rejet your 350 to suit. There are annualar discharge boosters and other adjustable componets thatt allow a 350 to give its best with the stock V8 jetting.


As an adjunct to this, Ford knew all this already when they introduced the 1957-1972 2100 Autolite and revised 1973-1983 2150 Motorcraft 2-bbl. They initally used Holley jets, so I know what the differences are in part to wide open throttle fuel delivery.

Ford fine tuned by four things too.


1.They used a one size fits all 8.5 power valve, and
2. used the K memeber rod sizes to control and restrict power valve fuel flow
3. And a 5 or 6 hole Well tube to trim peak and part throttle ar fuel
4. And tailored venturi sizes 0.98 to 1.33 to control peak air speed.

They knew that for best torque and fuel economy, Ford found that happened at 400 feet per second (approx 120 ms-1), so they restricted venturi size to that level for peak power. For best power, the figure is 265 feet per second (approx 80 ms-1). The loss of 50% of the design air speed requires a retrim of the base jetting by four methods in the Autolite/Motorcraft, but there are five or six ways to do the same thing on a Holley 2-bbl.

Whew, I'll get to xctasy's reply eventually but for now I'm thinking the head is set up for a 250 and not a 200. Based on a few comments I chose to ignore because of the difficulty of the work involved (lazy) I rechecked valve timing. Spot on as expected so that eliminates that problem and I hope I didn't introduce an oil leak in the process. Compression still needs to be resolved and that is why I'm thinking the head. I pulled it once thinking head gasket and that was not the problem. I do not have the specs on the head, doom on me, so I'm guessing again. Agreed I need to get with Bill eventually but I'm thinking not until I get the compression issue fixed? Bubba had me tuning, retuning and tuning again so that's not it. Stumped!

Also, so I don't hijack ssm's thread, degreeing a cam, if its stock it "should" be dot to dot on the gears correct? Pardon the grammar/punctuation. Both crank and cam are keyed and the dots line up with each other as well as the dowels, no brainer? I've never had to degree a stock cam. Maybe I AM missing out on something.

Hi Ronbo, in ssm's case he said he had installed an aftermarket performance cam but that he didn't remember the details. Yes you can certainly install a stock cam using the method of just lining up the stock timing marks and very often it works fairly well most especially when it was done in the past and quality control was still very good. Degreeing a cam either a stock or a performance grind though is about knowing if your getting the very best out of it to work with your combo of parts. Some people even find out the difference it can make just by replacing an old worn out timing chain set with a new one and gain back lots of their missing power. IE the power curve has just moved to a different RPM point. So the position that the cam is set at will have a range of effects on the engine from the low end torque, idle Manafold Vaccum, DCR, or its the top end power. The trouble is that on the Ford 200 (250's also) there are a couple types of timing chain sets (an early straight up and 4 degrees retarded for the later emissions specs) and also a number of different manufactures, then add in the differences that the camshaft company's and Ford OEM cams (had good quality control), then cam regrinds etc., and last are inexperanced parts supply people giving you the wrong year of parts, so these manufacturing tolerances can really start to stack up and work against you too. Degreeing a cam is easy and then you also know what it's affect can be on your combination and change it if nessisary.

On the importance of cam degreeing, back in 1969 I was building an 41 Willys A/G car and had bought a pair of experimental Ford 427 SOHC cams from Ed Pink (he was a Ford consultant and an expert builder of these engines used by many fuel funny car teams). I was instructed to set one side so many degrees advanced (think it was 6 degrees trying to remember back that long ago but its in my notes somewhere) and other side was set retarded 4 degrees. That engine had a 6 foot long double roller timing chain set, Ford found in their Dyno testing that at 6000 RPM both cams were now running straight up due the timing chains wave patern of movement. Good luck

Wow! 6ft? That thing must have weighed a ton! But then again it was a 429 DOHC Yeah, I know about the 4 degree retard on newer models due to emissions but being as I was the part guy who ordered it.... But hey, who knows what was in the box right? I started it up tonight and it sounded like the timing was way advanced. Hope I didn't jack something up when I went in. Time is the problem right now, need to find some so I can run it up to temp and check things out. This car WAS easy to work on but with all the accessories on it now, it's tight. I'll keep posting as lightning strikes

Yeah it was a bit heavy was a 427 SOHC (Camer) it was based on the old FE 427 block not the 429. Here's a link that talks about them mine was tuned kind of like the seconded to last picture except had lots taller stacks on the Hillborn injection. Keep up the work on your Mustang Ronbo sooner or later it's going to get better. Good luck

http://www.hotrod.com/features/1505-90- ... 27-cammer/

Car runs great now. All I need to do now is stop all the oil leakage!

That's excellent! I am glad to hear that but also curious as to what it took to get it to run great? Good luck plugging the oil leaks

It appears to have been valve timing. I pulled the cover and it looked fine from the angle I was at but I pulled the gears and chain anyways. After messing around with it different ways (I was in there so I might as well play) I figured there is no way I had it in wrong. Put it all back together, telling you I messed with the gears and chain a good three hours, and right away I knew something was different. It sounded like the timing was advanced severely. Sure enough, 50 degrees! After the now too familiar tuning routine, voila! Drives and shifts really well. When I put it all back together I ended up with a small leak at the timing cover. Small leak with a lot of oil. Its at the dreaded oil pan/timing cover corner so it'll have to come apart again. Oh well, at least it drove well so there is some motivation I'm going to hit Bill up for a distributor and go from there. It has an 80s distributor so there is room for improvement there. Man, if it didn't have the 2.83 rear the thing would scoot pretty good. I'll keep posting as I go.

Ron

:wow: 50 degrees advance that sounds like it could have been off a tooth on the timing marks well that's great it's running so good now and bet the vacuum is much higher now also. Except for you having to go back and fix the oil leaks, but that won't be so bad compared to what you have already been through, congrats your perseverance paid off. Good luck

Ron, sorry about the oil leaks. I had a gut feeling it was camshaft or harmonic balancer problem.
Just give me a shout, Bill

Oil leaks? Shoot...now I'm hung up with a belt. The AC bracket is NOT cooperating! Patience! LOL :chill: Keeping on....

I now have one of Bill's distributors in and it works fantastic!! I want to drive the heck out of it but....still have an oil leak Pulling the timing cover again was a lot of work for nothing. Its that right front corner on the timing cover. The gasket wont stay put. I guess I'll try dropping the pan and changing the gasket from there, can't be any harder than going in the front way. Belt is on, went .5" smaller and it squeals like a son of a gun. It's tight. Man what a pain this is becoming

Glad to see you've taken out time 4 us 'n dinner each day…

Ronbo":12b2b3ui said:

I now have one of Bill's distributors in and it works fantastic!! I want to drive the heck out of it but....still have an oil leak Pulling the timing cover again was a lot of work for nothing. Its that right front corner on the timing cover. The gasket wont stay put. I guess I'll try dropping the pan and changing the gasket from there, can't be any harder than going in the front way. Belt is on, went .5" smaller and it squeals like a son of a gun. It's tight. Man what a pain this is becoming

Click to expand...

Try cleaning the block or cover real good then glue the one side of the gasket to the block or the timing cover, slide a few bolts in so that it stays lined up. You can use some of the Permatex Aviation gasket cement to glue it down, but then before you reassemble the timing cover let those gaskets set over night so it's good and dry and then the gasket won't move. Put a little silicone on the cover and put it back on. Sounds like you need another 1/2 to 1 inch longer on that belt length. Good luck

Ron, get a Felpro timing cover gasket set. The set comes with two gaskets that are like the oil pan gasket but just seals the front of pan to cover as well as the rubber cover to pan & the damper pulley seal. As Bubba stated fasten the cover gasket to the block with contact cement at several locations or permatex.
Now would be a the only time to replace the crankshaft front seal, cause it installs from the inside of the front cover. Place some grease on the mating part of the seal with the crankshaft damper.
Make sure you cut the old pan gasket flush with the timing cover surface of the block & scrape off the old front of the pan gasket.
Use gray or black silicone at the two places where the old pan gasket ends at the timing cover & mates with the two new front pan gaskets. Put a daub of silicone sealer to where the rubber cover seal contacts the new partial pan gaskets.
Then place the front cover in place but push the cover down so it is at the same plane where the pan gasket attaches to the block.
Install the front cover seal & place before this.
Tighten the front cover bolts finger tight.
Install the remaining front pan bolts & snug the pan to the front cover & at the same time lightly tighten the timing cover fasteners.
Make sure the pan mates with the cover & a small amount of silicone sealant protrudes at four places where it was previously places.
Tighten all fasteners & leave sit at least overnight.
Fire it up & let it roll.