edelbrock 1904

[cdwelch]

 :)just finished my blueprint engines bp3503ct1 engine install into my 81 malibu. this engine is a advertised 375hp and the dyno sheet supplied with it shows 382hp and 418tq. cam is a hyd. roller with 495i and 502ex lift and 221 i and 226 ex dur at .050. car has a turbo 350 trans now. i have no complaints with this 1904 until i look at the plugs. i would like to have a little more color in the plugs.they are too white for my taste. this carb works flawlessly. throttle response is great,starts real good and with the 3:73 rear it's quick as a cat from street light to light. hit passing gear and your gone. i only have about a hundred miles on it now and i have the apt out about 5 turns just to start to get some color in the pugs and it's still almost bone white. at 50 mph and 2500rpm it's pulling about 20 inches of vacuum. 73 jets and 50m pri rod. i have a 46k rod and 74 jet i might try. just seems like the 50m rod and 73 jet is at is max right now. i'm tuning by seat of the pants and ear right now and i'll use the wide band as a last resort right now. this carb is stock except for Cliffs rebuild kit i installed when i bought it. i think i'm real close. most of my ride time is below 3000rpm on the county roads i travel,but there is a couple of mile long straightaways where i have some fun. sorry for the long post.

[77cruiser]

I wouldn't worry about it. If it doesn't surge or miss at cruise or light accel. & you feel good about the response & driveability just run it.

[cdwelch]

thanks for the reply cruiser. yes i feel good about the performance of this 1904. i have several q-jets on the shelf that have been calibrated per cliff's specs. i'm going to get some more seat time with this one and then try to get just a little more color in the plugs.  Denny

[Cliff Ruggles]

It is impossible to tune by reading spark plugs, so forget that deal.

With a well tuned q-jet completely normal for the plugs to be very light tan to almost white anyhow.

We tune for results.  If the engine wasn't happy with the part throttle A/F it would be "flat" on power at light throttle, even hesitating, surging, or bucking in protest.

If it is clean and smooth and attains adequate vehicle speeds w/o any issues then for sure leave it alone.  I don't care what the plugs read or what an A/F meter tells you.  Not uncommon at all to achieve perfect results with a very well thought out engine even if you have very lean A/F ratios at light throttle cruising.

You do want it to fatten up nicely at heavy and full throttle, to avoid high EGT's and potential detonation.

The vacuum advance is also a key player in being able to run lean A/F at cruise.  Tight squish, decent compression, and efficient airflow through the engine are other contributors as well.  The more efficient the engine is the less fuel it will need to get the work done......Cliff

[cdwelch]

got an update on my edelbrock 1904. what i forgot to mention in my original post was that i felt the idle could be better. didn't seem to idle that good but response was good everywhere else so i let it slide until it was bugging me more. took it apart and it passed the eyeball test so i enlarged the idle mixture screws to .090 and went to a .074 pri. jet from a .073. pulled the pass. side idle tube out and went to .036 then pulled the dri. side out and saw it was clogged up. i think i found my idle problem. ordered two idle tubes from Cliff last night. i think i'll go back to the .073 jets with the new idle tubes and leave the rest of the carb. stock. while i'm waiting for the new tubes i put one of my spare q-jets on so i can cruise around a bit on labor day. i have 4 spares with cliffs kits in them and set up per the second recipe as close as i can get it. the spare i put on is 17056202 with 037 idle tubes,052 down channel,090 mixture screws,46k pri rod,74 jet,ax sec rod,036 sec tubes. this carb has everything the 1904 has with a very good idle.i'll have to make a call when my idle tubes show for my 1904 cause this 170 series it on it. i'm open for suggestions for my spare but it sure is nice now.

[Frank400]

Just out of curiosity, that 17056202 you have came with large .120" upper and lower main air bleeds, did you leave them that size or reseized them ?

[cdwelch]

thanks for the reply. yes i left them the factory size. seems to be working very good for this crate motor. am keeping an eye on the performance and probably will install the 1904 when the idle tubes show up. i also have a buick 800(17059247) and a couple more 170 series carb with Cliffs kits in them and set up for the second recipe and i resized the air bleeds in some of them. i'll have to check the notes on them to see what i did to them. were done a few years ago and my memory is not as good as it used to be. i'm always looking for improvement and open to the suggestions from this forum. i have more time now to work with them now that i'm retired. it's fun. you know the old saying, if its not broke,try to fix it better,or something like that.