hello everyone, i havent posted much but a have been in the process of swapping a solid lifter flattop 355 w/ 416 heads into my camaro. its all done and running, but im having some driveabliltiy issues. (no its not just a lopey idle). there seems to be a miss/hesitation at light cruising speeds. also i have the timing set only to 4°BTDC. it runs better when i advance it, but whenever i test drive it and put the engine under any load, it pings. i am suspecting my carb(edelbrock performer from the old 305, unknown CFM) is not enough for my thirsty new 355. this is causing a lean condition, which under no load, likes more timing, but when put under load, preignites due to the demand for more fuel but none is availible. am i just crazy and tired from screwing w/ this thing after 12hrs of work/school or am i onto something?

 

what is total timing? What are the cam specs?
16-20 initial timing with 34-38 total timing is probabyt more like it.

 

What are the numbers on the base of the carb? If you look at the carb from the front of the car, they should be on the bottom left, 4 #'s. With that you could go and get yourself a carb calibration kit for $50 or so and start playing with the jetting. Where is fuel pressure at?

Im having a hesitation at cruising speeds also, but I dont hear any pinging, and if I tip in a little more it goes away. At idle mine also spuders frequently.

 

yea, what cam is it exactly?

4* is far too little. Disco vacuum advance, set it to 12* static. Bring your idle speed back to "right" for you. Rev it up and watch timing at up to 3500* while idling. Roughly 36*, but not more? ok, good, leave vacuum timing disconnected , drive it around. See how it runs.

what lash setting are you at?

 

I found out the problem. Sonix, you were onto it. my valve lash is set to .022
which i found out from the guy who sold me the short block, it supposed to be 0.024 I 0.026 E. then when thats taken care of im going to set up the ignition curve. the guy also said when i set base timing w/ the vacc. advance disconnected, the idle should go up a little bit when i plug it back in. how would that work w/ ported vaccum? that doesnt allow vaccum untll the throttle plates open right? he also said to try running it off of manifold vaccum if it doesnt work w/ ported. any thoughts??

 

not sure if that's enough lash difference to be noticeable, but yea, get 'er right.

if you set advance with vac disco'd (correct), then if you plug in your vac can to manifold, it'll jump ~14*, which will bump up idle speed ~300RPM or so.... Ported it won't do anything.

I'd recommend ported, it'll advance smoothly and linearly on light throttle, then on heavy pedal, disappears (both manifold and ported will disappear on WOT)...

in other words, i'd try ported, then if that doesn't work, try manifold. Still, you didn't mention the cam...? If it's VERY agressive, maybe use manifold vacuum advance.

 

i just found the specs. they are a bit radical from just a "mild" cam like the guy said. they are

valve lash .026 I/E hot
lift @ 0 lash w/ 1.5:1 rockers
.510 int .535 ex
280° duration int.
288° duration ex.
i have other specs but they are at home at the moment

i also was an idiot and reused my intake gasket since i found out i had to swap out hydraulic lifters (since i was told after i was all done, the engine wouldnt idle because it was a SOLID lifter cam ). so now, im doing intake gaskets again! oh well, thats what i get for being lazy i guess