CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
My old man hotrod/dd
- Thread starter 80' 427
- Start date
cant wait to see more of it... such a nice ride
If you only knew
Very cool, I love those Colonnade style A bodies of that era.
Gears in?
Martin
Martin
So 2 tanks in and it so far has gotten 13.446 and 13.39 mpg. Not steller. I bought the 74 Doug roe book that has lots of great info about 2G carbs. It has some good mods for mpg that I think I will try them. Marty, my parts sponsor, has suggested for his reading pleasure I try for mpg tuning on the 2bbl then move to the qjet and compare the mpg. Since that sorta thing floats my boat I will try and do him proud.
Mostly drives great but the lack of radio gets a little old. Bought an ir extender so I can mount the radio in the glove box and use the remote with the door shut. Also bought a factory adapter to mount 2 4x6 speakers in place of the single 6x9 in the dash. Thinking for the rear 6x9s I will pull the rear dash cover and mark out a pattern of 3/8 holes and punch them to let the sound through rather than hack out the holes and put after market covers over the holes.
The 152a is working ok. Lowest vent temp I have seen is 52 except in the cool morning. Still I saw at least 53 on a 100 deg day after 15 miles. Not too bad for keyboard duster and a POA adjustment that is wrong for the refrigerant.
Looking forward to gears. It honestly runs good on the highway up to 3/4 throttle where it makes it a shit load of noise but really no more power. The local farmers coop ordered a set of bfg 295 50 15s and the guy never took them so I agreed to buy them for $100 for the pair. Ordered 15x10 rear wheels for them. Way bigger than what it needs at the moment but they will look good.
The car actually has front and rear sway bars which I find odd. Thinking about buying bigger but other things first. Rear sits a little lower so I want rear air bags but again other things first. Looked at line locks, big brakes, front and rear control arms etc, but again other things first. Pretty much have the 496-510 planned out but just waiting on the money.
Later
Mostly drives great but the lack of radio gets a little old. Bought an ir extender so I can mount the radio in the glove box and use the remote with the door shut. Also bought a factory adapter to mount 2 4x6 speakers in place of the single 6x9 in the dash. Thinking for the rear 6x9s I will pull the rear dash cover and mark out a pattern of 3/8 holes and punch them to let the sound through rather than hack out the holes and put after market covers over the holes.
The 152a is working ok. Lowest vent temp I have seen is 52 except in the cool morning. Still I saw at least 53 on a 100 deg day after 15 miles. Not too bad for keyboard duster and a POA adjustment that is wrong for the refrigerant.
Looking forward to gears. It honestly runs good on the highway up to 3/4 throttle where it makes it a shit load of noise but really no more power. The local farmers coop ordered a set of bfg 295 50 15s and the guy never took them so I agreed to buy them for $100 for the pair. Ordered 15x10 rear wheels for them. Way bigger than what it needs at the moment but they will look good.
The car actually has front and rear sway bars which I find odd. Thinking about buying bigger but other things first. Rear sits a little lower so I want rear air bags but again other things first. Looked at line locks, big brakes, front and rear control arms etc, but again other things first. Pretty much have the 496-510 planned out but just waiting on the money.
Later
Post pics along the way.
Martin
Martin
So I needed to break something today so I tore the carb on the chevelle apart. Per the 74 Roe book I should up the jets one size, reduce the pvcr by 5%, plug the apt, and plug the pull over tube.
Super clean inside, but it is a smaller venturi version, oh well. The worst part was getting the pvcr out. Ended up wrecking one but they are sized .037 now. Found some 6/32 screws from my Holley project in .035s so I will just have to mess with them a bit to get to the .036 I need. This is about the only pic, the screw driver is pointing at the apt port that needs plugged with some lead shot (guess I will be cutting apart some shot shells tomorrow). Going to lean out most of it and keep the stock jetting to see how it runs. Should put in a bung for the wide band but I haven't gotten that far.
Super clean inside, but it is a smaller venturi version, oh well. The worst part was getting the pvcr out. Ended up wrecking one but they are sized .037 now. Found some 6/32 screws from my Holley project in .035s so I will just have to mess with them a bit to get to the .036 I need. This is about the only pic, the screw driver is pointing at the apt port that needs plugged with some lead shot (guess I will be cutting apart some shot shells tomorrow). Going to lean out most of it and keep the stock jetting to see how it runs. Should put in a bung for the wide band but I haven't gotten that far.
Yay, pictures!
Going to have it back on the road by Wednesday?
Martin
Going to have it back on the road by Wednesday?
Martin
So, I got the cab reassembled tonight. First the mods. Again I used the 11-73 copyright Doug Roe Rochester Carbs book. It has some really great info about almost all early Rochesters that is missing from the '85 version I also have. Definitely worth the extra $8 I paid on eBay. So I followed his suggestions too the letter with the exception of the jets simply because I didn't have any. First I actually disassembled a 71 2gc just so I knew more or less what was going on since I was a bit scared of the power valve restrictor removal. Basically you have too remove 2 plugs and using a small punch drive them through the channel they are in till the fall out of the jet our cluster holes when flip the carb over. No problem on the older carb. On the newer carb I had to also deal with the adjustable part throttle. Unlike the desired apt in a qjet the 2g apt can case tip in problems and saggy driving feel. I removed the apt needle then the apt brass restrictor. I ended up pounding restrictor through to the power valve hole but should have screwed a deck screw into it and pulled it out from the outside. On to the restrictor removal. The book suggests using a drill bit and using the nonfluted end as a punch to drive them out hammering on the flutes. Well after 5 or 6 broken bits I was figuring I am sunk now wondering what I will replace this carb with now that I was past the point of reasonably. I figured hell with it and used my smallest punch and with the carb in the vise between 2 thick stacks of paper and hammered them out. One was damaged most like more from my drill bit escapades but whatever. So first I checked the size, .037. then I checked my stash of 6-32s and found 2 slightly under .036 and drilled them with a number 64 bit till my .036 precision pin just fit. Then I tapped drilled one outter channel to the size needed to tap 8-32 threads and tapped both restrictor channels to 6-32 and installed the .036 6-32 set screws in the channels with med thread locker.
You are so fancy.
Martin
Martin
Awesome.
Pics of said swivel buckets? Never seen them before.
Pics of said swivel buckets? Never seen them before.
The outside of the channels were tapped with 5/16 set screw on the APT channel and a 8-32 on the other.
Fyi the restrictor being a .036 is 5% smaller than the .037 it came with.
Next I pulled and cleaned up the power valve plunger. In the 2g vac holds a plunger up against a spring. As vac drops the spring eventually is stronger and opens the power valve. On the later carbs the spring is too strong and the power valve opens at 10" of hg or above. For you following at home it means they open too early and 6" of hg would be better keeping the valve closed longer. To slow the opening the book says to cut 3 full coils from the plunger rod spring. This was a bitch mostly because after staring at a computer all day it is hard to see a tiny spring and cut it if you can't focus on it. I would like to build a vac regulator so I could hook it too a good running car and adjust it to see when exactly the plunger moves. For now I trusted Mr. Roe.
I plugged the APT port with a 6-32 screw as the tap started perfect in the hole and cut good threads.
The final few things were a bit futile but what ever. This carb is approx 390 cfm. I figured and help in increased air volume would be good. First I lightly filed out the large casting ridge at the seam between the top and bottom of the venturi (see pic), then polished it smooth with some emery cloth. Next I used a dirt tract trick and when installing the booster cluster I used both the new and old gasket. This spaces the boosters very slightly out of the venturi giving the air slightly more a room. This is mostly a waste of time but remember 2bbls are rated at 3" of hg vs 1.5" of hg for 4bbls so even the 390 is really 275cfm in 4bbl speak.
Fyi the restrictor being a .036 is 5% smaller than the .037 it came with.
Next I pulled and cleaned up the power valve plunger. In the 2g vac holds a plunger up against a spring. As vac drops the spring eventually is stronger and opens the power valve. On the later carbs the spring is too strong and the power valve opens at 10" of hg or above. For you following at home it means they open too early and 6" of hg would be better keeping the valve closed longer. To slow the opening the book says to cut 3 full coils from the plunger rod spring. This was a bitch mostly because after staring at a computer all day it is hard to see a tiny spring and cut it if you can't focus on it. I would like to build a vac regulator so I could hook it too a good running car and adjust it to see when exactly the plunger moves. For now I trusted Mr. Roe.
I plugged the APT port with a 6-32 screw as the tap started perfect in the hole and cut good threads.
The final few things were a bit futile but what ever. This carb is approx 390 cfm. I figured and help in increased air volume would be good. First I lightly filed out the large casting ridge at the seam between the top and bottom of the venturi (see pic), then polished it smooth with some emery cloth. Next I used a dirt tract trick and when installing the booster cluster I used both the new and old gasket. This spaces the boosters very slightly out of the venturi giving the air slightly more a room. This is mostly a waste of time but remember 2bbls are rated at 3" of hg vs 1.5" of hg for 4bbls so even the 390 is really 275cfm in 4bbl speak.
After this the final assembly was per the napa carb kit specs I had. I did look at the accelerator pump recommend height to see where the station wagon setting was vs the reg 350. Mine was already at the station wagon setting.
I plopped it on with a new base gasket and started it. Started and once all the idle speed settings were reset and the engine was warm it idled nicely. Air screws were 2.5 on one side and 3.75 turns out on the other. Final setting is right at 3.5 for both.
So how does it run? Noticeable better. It feels much more crisp where it used to feel very laggy like throttle cable was attached with a rubber band.
Accelerating crusing speed felt stringer and the one full throttle pull I did from a stop resulted it a nice little chirp then we were gone pulling hard to the 2-3 shift.
At cruising though there is a slight lean surge. The carb has I believe .048 jets (tiny numbers) and I thought it was a 49 at first thinking one step to 50 would be great. I ordered jets Monday night off ebay and no shipping confirmation yet. Crap. So that leaves me drilling the .048 to .049 which would be great if I had a drill that size. Seems a 1.25mm would be perfect. Yep, I don't have one.
I plopped it on with a new base gasket and started it. Started and once all the idle speed settings were reset and the engine was warm it idled nicely. Air screws were 2.5 on one side and 3.75 turns out on the other. Final setting is right at 3.5 for both.
So how does it run? Noticeable better. It feels much more crisp where it used to feel very laggy like throttle cable was attached with a rubber band.
Accelerating crusing speed felt stringer and the one full throttle pull I did from a stop resulted it a nice little chirp then we were gone pulling hard to the 2-3 shift.
At cruising though there is a slight lean surge. The carb has I believe .048 jets (tiny numbers) and I thought it was a 49 at first thinking one step to 50 would be great. I ordered jets Monday night off ebay and no shipping confirmation yet. Crap. So that leaves me drilling the .048 to .049 which would be great if I had a drill that size. Seems a 1.25mm would be perfect. Yep, I don't have one.
Not sure what to do, might try "filing" the 48 to a 49 with a 1.2mm bit I have.
So why would this carb run better leaning out most of the circuits?
72-73-74 are the last years of converter less exhaust. In an attempt to control NOx the main circuit was leaned out but the rest of the carb was designed to go stupid rich very early so there would be no oxygen to make NOx.
I wish I had the larger "500" cfm 2bbl just for fun but I doubt there would be much difference.
Was it worth the few hours of work on a stupid little 2bbl? Most definitely.
It may not make any more power but the driveability is much better even if the power & mpg doesn't change.
So why would this carb run better leaning out most of the circuits?
72-73-74 are the last years of converter less exhaust. In an attempt to control NOx the main circuit was leaned out but the rest of the carb was designed to go stupid rich very early so there would be no oxygen to make NOx.
I wish I had the larger "500" cfm 2bbl just for fun but I doubt there would be much difference.
Was it worth the few hours of work on a stupid little 2bbl? Most definitely.
It may not make any more power but the driveability is much better even if the power & mpg doesn't change.
Not many people would take the time to modify a carb like that, good for you for applying yourself to the task and enjoying the rewards.
