17056228 First Test

[blazer74]

Will do, Thanks

[blazer74]

Hello, Checked the primary throttle plates and they close fine. Tried another throttle body I have that is set up the same and still have nozzle drip if I use ported vacuum.  Go back to straight vacuum and can stop nozzle drip.  Drip starts on passenger side and drivers side drips just after that.
Using straight vac, 6 turns idle screws, 2 turns apt  72 jets, cliffs 44 rods, acc pump outer hole.  idle 800 park, 650 drive, vac 14.5, 10 deg initial.
Now runs good,  no stumble, pulls hard thru secondarys.  Does still have some sooting of tailpipes and some black smoke . Going to try 71 jets and see what happens.? Also added edelbrock 3/4 wood spacer and helps with heat soak but didn't notice any other change.

Thanks Craig.

[Cliff Ruggles]

Good news.  Going back over the basic engine combination, the cam is a tad much for the "low" compression 355, and ground on a 111LSA.

882 heads are poor performing heads, with very restrictive exhaust ports, and huge combustion chambers.  Even with the flat top pistons the static compression ratio is probably around 8.5 to 1. 

A set of Vortec or SR Torquer heads would be a BIG wake up call for the engine.  It would idle better, less timing needed everyplace, and more power at every rpm.

I've ran into what you are going thru a few times.  Takes some effort to get everything dialed in, and often we are chasing the fuel and timing curves around quite a bit to make the engine happy.....Cliff

[blazer74]

Hey Cliff, thanks for going back over my info again.  definitely agree on the heads, and step down to about a  comp 268H cam.  I need to pull a head a take some piston measurements to truly see what size cc head I need to get to about 9.1 due to not having specs on my current pistons (older trw's)  Too hot right now for that with this 100 deg weather. But then again maybe its time to build a 383 or 400.

Thanks again Cliff for your input. invaluable!

[Cliff Ruggles]

I'd stay away from any cam on a 110 or tighter LSA.  There are some EXCELLENT cam choices out there for SBC's.  I still have to this day to find a better cam for a 355cid engine with about 10 to 1 compression than the old 327/350hp cam.  It has 222/222/114 specs, over 300 degrees of seat to seat timing.  Idles pretty good, strong power from the moment you load the engine till you decide to shift it!

There are a couple of Melling cams that work just as good, with similiar specifications.  The 280 duration .480" lift on 112LSA is a good one as well.  These cams need at least 10 to 1 compression to be happy, but will lower the dynamic compression enough to use pump gas without any issues.

Another very good choice, is the GM LT4 Hot roller camshaft.  It's a nice upgrade, and will produce over 1hp per cid with a good set of heads on a 350 engine.....Cliff

http://www.jegs.com/i/GM-Performance/809/24502586/10002/-1?parentProductId=761656

[blazer74]

Hello,   Made some upgrades, Vortec 64cc head\intake setup from scoggins. Changed cam to Comps 268HE  218/454/110.  Made a large difference in performance. Puts me just under 9:1 comp with pistons .040 in the hole.

Quadrajet 17056228 minor changes.
Basic Recipe 1

72/44cliffs
Idle tubes .035
Icr            .047
Upper Mains .070 bushed
upper idle bleeds .069
Lower idle bleeds .076
Bypass air     .086
Acc pump      .026
Poe Disch       .052
Air valve   3/4 turn/ with small notches in upper 2ndary blades
Adp   4.5
Mix    4.5
1.5" Edl wood spacer

Runs great except for hot start issue.  Fuel seeping  out of primary venturi nozzles and air bleeds after shut down requiring WOT to start after about 10 min. Seems like fuel is rising in bowl after shutdown.

Need to check a few things Cliff recomended.   Fuel pressure, Inlet side leak. Well plugs.

Will get back with results.   Thanks Craig.   

1974 K5 Blazer 355 sbc
Vortec setup
Comp 268HE
Headers, dual 2 1/4 exhaust
35's  4:10 gears

[blazer74]

Checked fuel pressure at inlet to carb.  Found to be between 7-8 psi while running. 
After shut down with fully warmed engine fuel pressure holds steady and then slowly rises after

aprox 10 minutes 9 psi, 15 minutes 9.5, 20 min 10 psi, using inline gauge non liquid filled. Heat soak at gauge could be a factor.

Restart fuel pressure goes back to 7-8 psi.   After sitting  2 hours starts fine.
After approx ten minutes can see fuel in upper main bleeds and venturi nozzles.
Starts rough after about 5-10 min and hard to start after about 10-15  minutes.

Stock fuel pump typical 70987 2 lines.

Seems about right or just a little high for fuel pressure running.

Thanks Craig

[Cliff Ruggles]

7-8 psi is fine for later carburetors.  As long as the gauge holds pressure hot, it shouldn't be flooding, and how much fuel can be in the line after shut down under pressure that would make it's way into the carb and flood the engine.  One would think if the pressure built up, and pushed the needle off the seat, the pressure would go down quickly?....Cliff

[blazer74]

Changed the fuel pump to edelbrock street pump. Puts out 5-6 psi. I don't have the hot start problem with this fuel pump. Pressure also drops off also after a few minutes of shut down. Seems the stock pump was holding pressure after shut down and was increasing with heat soak in the lines upward of 10psi.  I also bypassed the stock metal fuel line on the block.

I think fuel was creeping past needle just enough to cause fuel to raise in carb just enough to allow fuel to drip and not showing on gauge do to heat soak, sounds good anyway.

It still does idle very low when started warm until given just a little throttle, but starts easy.

Going to go back thru the carb  and install bottom plugs, replace and vac test needle/seat etc.

Going to open idle tube from .035 to .036 as per stage 1 of Cliffs book.

(Do you think .086 bypass air is a little too much or ok for a 268adv  218@50  cam?)


Thanks;  Craig

[Cliff Ruggles]

Should be fine....Cliff

[blazer74]

Went back thru the carb, installed bottom plug kit/with marine epoxy. Replaced needle/seat and vacuum tested. opened up idle tubes to .036 from .035 and installed Cliff's .044 2nd rods. Still using Cliffs .044 primary rods and 72 jets with dark power spring.

Seems to be a little less crisp of idle, but only drove it once could just be me, got caught in rain with full convertible blazer  ( was fun tho).  Going to readjust mix etc. Have not driven long enough to judge hot start issues which is considerably better with new fuel pump.

Thanks Craig

[blazer74]

Went for a run today, ended up turning mix in total of 1 turn and made big difference after opening idle tube from 035 to 036. Will see how it is cold next run.

Question about apt and mixture, relationship between the two. Should adjusting apt lower affect mixture? I've had stumble off idle in the past when apt adjusted too low. If I turn apt lower say 1 turn should I have to readjust mixture?  Just a thought.  Also went from CH 2nd rods to Cliffs .044 rods, Could be a tad to much on the 2ndarys. Think the CH rods are .054 tips.

Thanks Craig

[Cliff Ruggles]

Lowering the APT leans up the primary side at light throttle only.  It may develope a hesitation/stumble if you get them too low  (lean).....Cliff

[blazer74]

Wow been 3 months, Had some issues with wide open throttle, popping and breaking up. Replaced needle/seat and float again, cured most of the problem but had to go 1 full turn on 2nd spring ( new spring). Seems to have cured that. Still have a little hot start issue, have to give it a little gas while cranking but not hard to start like it was. Did have the float every where from 1/4 to 15/32. 3/8 seems to work the best for me.
Ended up with   4 turns ADP, could probably go a little less.
                          3 turns mix
                          72 jets, Cliffs primary and 2nd rods
                          Set up with recipe 1

Thanks again: Cliff

[Cliff Ruggles]

WOT problems are usually fuel delivery related, or ignition.  Takes a pretty good fuel pump to keep up with a strong running engine.

Glad things are going well.....Cliff