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Dellorto 48 DHLA swap from 13b to 12a not 56k Friendly
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I am documenting this with pics for everyone and because Lloyd said i had to make a thread.
I have taken a Dellorto RB carb for a 13b and rejetted it to fit the 12a. http://www.gruntled.com/ This site was one of the most helpful. Things to note: 13b version does not have omp barbs in the top of the carb... to be able to work on a 12a you must rejet the carb these are the jets you need to get: Idle jet hold/emulsion tube (must get from dellorto.com was about $40 no one else has any) Accelerator pump jet from 80 to 90 Needle and seat...rebuild kits from cb performance come with 225..rb stock uses 300 and dellorto sells 350..you will not find the 300 anymore...so i would go with 225 if your 300 is in bad shape..bc on a stockport 12a..you will foul plugs using the 350. Jetting for 13b Main Emulsion Tube #7772.8 Main Fuel Jet #230 Main Air Jet #230 Idle Holder/Emulsion Tube #7850.8 Idle Jet #75 Accelerator Pump Jet #80 Needle and Seat #300 Jetting for stock 12a Main Emulsion Tube #7772.8 Main Fuel Jet #230 Main Air Jet #230 Idle Holder/Emulsion Tube #7850.4 Idle Jet #75 Accelerator Pump Jet #90 Needle and Seat #300 Now for the pics and install 1. First we started out by draining the radiator...25 yrs old 2. Then we took off the radiator, fan and shroud 3. we removed all the lines to the carb, the manifold and the rats nest 4. then modified the rb header for an a/f sensor 5. installed the dell and massaged the oil filler tube 6. put new radiator on with modified hose and started her up...worked on the first try.. now for the pics: This is the rb header that has been drilled and o2 bung welded for an a/f sensor Attachment 705227 Engine with everything torn off Attachment 705228 old nikki carb w/ hoses Attachment 705229 Engine from a different angle Attachment 705230 Freeze plugs from Pineapple Racing (would recommend if you dont wanna use 0-rings anymore) Attachment 705231 Beautiful carb after being completely polished, cleaned and rebuilt by LLoyd...his first time ever rebuilding a two-barrel carb...(note: the air cleaner gasket that comes in the dellorto rebuild kit from cb peformance must be modified because the holes for the two barrels are two small...just need to made larger to work...the kit that cb performance will give you is for the 45 dhla...you also need to make your own gasket for the accelerator pump..just get some thick gasket material at your local car store.. Attachment 705232 Attachment 705233 Attachment 705234 This carb has been modified to work..the carb did not come with a throttle linkage and choke linkage...the stock choke cable barely fits anyways..The orange lines are all the vac lines..for the vacuum advance and to vent the oil filler tube an also omp lines..the stock ones didnt fit..they weren't long enough..and one snapped because it was brittle Attachment 705235 |
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Heatshield made by lloyd...just like the rb one..but has custom finish...
Attachment 705236 This is a pic of an oil sandwich adapter for oil press or temp...well i didnt keep it on the car..because it leaked a tad bit.. Attachment 705237 The new radiator installed everything put back on (note: dual alt pulley does not work with non stock alternator...i think my dad got one from shucks 10 yrs ago..and the dual pulley will not fit on the shaft) Attachment 705238 Attachment 705239 Another two pics of the intake setup Attachment 705240 Attachment 705241 This is the upper manifold that was modified by Lloyd..he pressed two nikki barbs into the upper center chamber of the manifold... Attachment 705242 The carb did not come with a linkage..in the bottom pic..you can notice the linkage that Lloyd fabbed up..and in the top pic you can see the bracket to hold the throttle cable has been modified Attachment 705243 Attachment 705240 Previous owner had the uim drilled for nos...Lloyd sealed them up http://img.photobucket.com/albums/v4...x/IMGP1042.jpg |
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Wired the omp
Attachment 705245 We cut the top radiator hose and inserted a adapter for the water temp gauge Attachment 705246 Finally a pic of the massaging that was needed to fit the carb with the air cleaner on Attachment 705247 Well i know this is long..but i wanted to well document everything..This did start up on the first try..the only leak was with one of the radiator hoses...I am still using the stock fuel system and ignition system..and it is running great with no bogging issues or any problems with acceleration... If you have any questions or anything that you dont see is right..comment or contact me...and enjoy the thread pinoyremix |
i also..have a holley red fuel pump..but since the stock is working right now..i thought i would just leave it as a spare...heard there can be some problems when wiring
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Ron, I see you got it running finally. Looks real nice.
Remember the stock fuel pump won't keep up but you'll see that on the afr once you run it. I don't have a heat shield and have never had any problems except when the ambient temps get near 100 then if I drive it and let it sit hot, the next time I take off theres a lot of vapor in the bowl and I have to chug it along until cooler fuel displaces it. Just really noticed it this summer down in NC. Previously I was up in Pittsburgh and it never had a problem. So I guess I'll be fabbing up a shield as well. I have the 350 needle and seat and I'm not having any fouling problems but whatever. Heres a lousy pics of the plugs last time I had them out: http://farm4.static.flickr.com/3249/...e81848.jpg?v=0 |
nice! glad to see u finaly got the carb on. so hows it feel? Sorry about the linkage problem i couldnt find it and the nos ports u had to plug up.
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Great shots and great writeup Ron!
I picked up the stuff to finish wiring the guages so we can schedule another day to have you come over and finish your Wideband install as well as the water temp and oil temp. Lloyd |
see i just hooked the omp linkage up to the tap on the other side of the throttle rod. then again, mine didn't clear the beehive like yours, prob the fact i had the one piece on like from rotary shack. cb gave me a 48mm kit that came with a 275 needle.
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Originally Posted by Slammed_GSL
(Post 8402017)
Great shots and great writeup Ron!
I picked up the stuff to finish wiring the guages so we can schedule another day to have you come over and finish your Wideband install as well as the water temp and oil temp. Lloyd might have my friend install them tomorrow...that way you can spend the time with the family..i took 2 whole days of your time already..so its ok..plus i gotta come back anyways...for fmoc...maybe fuel pump and setup..and also to install the studs for my rims.. |
zip ties FTW!!!
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Idle jet hold/emulsion tube (must get from dellorto.com was about $40 no one else has any)
You bought the idle jet holder from dellorto.com? And the engine runs okay, not too rich? One of the modifications Racing Beat did to the idle jet holders, both 12a and 13b, is drill a small hole in the top of it. To bleed off the signal from to the idle jets. Otherwise it'll run rich all the way up into the main circuit. Just a heads up. Do you have a wideband air fuel gauge? |
Originally Posted by DriveFast7
(Post 8403112)
Idle jet hold/emulsion tube (must get from dellorto.com was about $40 no one else has any)
You bought the idle jet holder from dellorto.com? And the engine runs okay, not too rich? One of the modifications Racing Beat did to the idle jet holders, both 12a and 13b, is drill a small hole in the top of it. To bleed off the signal from to the idle jets. Otherwise it'll run rich all the way up into the main circuit. Just a heads up. Do you have a wideband air fuel gauge? i thought they modified the emulsion tubes..by adding more holes...not the idle holders..i got this info from gruntled.. |
Not to worry, your idle jet holder is identical to mine and I have a RB prepped Dell I bought new. The emulsion tubes were modified with a lot of extra holes but not the idle jet holders.
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well installed the AEM wideband..and it said it was running rich...well i found out that..the sensor is bad..was saying 8.41 before i even started the car...and i bought it from a kid that must have tampered with it..so i have to buy a new gauge..because the gauge and sensor are wired together..so..we will see..when i get a new gauge..
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When I bought a new idle jet holder from local carb shop it didn't have the small hole in the top like my RB one did. And it ran a lot richer. They did drill the emulsion tube and the top of the idle jet holders.
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Hey Ron, let's get some pics of your new guages installed, I want to see your A pillar guage mount.
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fuel pump
i did the same set up with my stock 12a but its a side mounted manifold and the stock fuel pump wouldn't keep up at high rpm. looking for a holley blue
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Originally Posted by DriveFast7
(Post 8406559)
When I bought a new idle jet holder from local carb shop it didn't have the small hole in the top like my RB one did. And it ran a lot richer. They did drill the emulsion tube and the top of the idle jet holders.
Attachment 705248 Attachment 705249 |
Originally Posted by HI RPM
(Post 8407891)
i did the same set up with my stock 12a but its a side mounted manifold and the stock fuel pump wouldn't keep up at high rpm. looking for a holley blue
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Originally Posted by HI RPM
(Post 8407891)
i did the same set up with my stock 12a but its a side mounted manifold and the stock fuel pump wouldn't keep up at high rpm. looking for a holley blue
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is there a model number on the carter or mallory fp i can ask for.
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That's a hawk of crap! Holley should be his second choice. The Carter sucks. It'll barely feed anough for a street ported 13B. If you ever decide to build an engine then you'd have to buy another fuel pump why waste the money when you can do it right the first time. I'd say Mallory then Holley, then Carter. The only good thing about the carter is that it's quiet.
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Carter would be more then enough for his 12a....Do you need more then 6-8PSI for any 12a or 13b NA application? Just wondering.
RacingBeat instructions say unless you are doing full throttle for 10sec or more the stock fuel delivery will be fine for the Dellorto 48mm 12a setup. 10 sec is a long time at full throttle....about $240 if you get caught...LOL! YawPower modded Nikki carbs are only running 2.5-3psi. Also Yaw really talks down the Holley for it's reliability, check his site http://www.yawpower.com/fueldel.html http://www.yawpower.com/racecarb.html Fuel Pump Thread with specs on both Carter models. https://www.rx7club.com/1st-generation-specific-1979-1985-18/discuss-carter-p4070-vs-carter-p4594-fuel-pump-767880/ Ron! Where are those interior shots of your cool guages dude! |
there coming..i forgot my camera...plus...i had my oil gauge needle bouncing..cuz i forgot that the end was loose and bouncing on the brake proportioning valve...now its all good...
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