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'95 Chevy 350 TBI rebuild woes
4x4 Chevy/GMC Trucks 4x4 Chevy/GMC Trucks Discussions (alt.autos.4x4.chevy-trucks)
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#11
 
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Re: '95 Chevy 350 TBI rebuild woes -
07-10-2004
, 09:50 PM
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Odelrio stated: What's interesting is that when I give it full throttle, timing drops below 0, maybe 2-4 degrees ATDC, it pops and then jumps back to high BTDC and revs nicely. Normal? Mad Dog, |
Didn't mean to offend. Too many beers on my part, I'm sure.
The way I understand a 4 cycle motor is Intake -> Compression -> Power
-> Exhaust and 180 degress separate each stroke. I believe TDC and
spark timing is between Compression and Power. I apologize if my
understanding is all screwed up. Probably why my motor's not
working... :-D
-Omar
Quote:
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Mad Dog stated: The motor is popping because the plug is firing 2 degrees ATDC, the intake valve is already opening and drawing air/fuel into the chamber when the plug fires. Odelrio replied with: PS Oh yes, and Mad Dog, I'd like to see any engine run if the intake starts openning at 2 degrees during the power stroke... It would have to be 360 degrees out of phase... Sorry, couldn't resist. Where did i say the intake valve is opening 2 degrees ATDC PS Maybe you should read your own post and read my replies more carefully...sorry, could'nt resist ;-( -- Mad-Dog '79 Chevy K-10 Slightly modified |
#12
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"Mad Dog" <me (AT) privacy (DOT) net> wrote Odelrio stated: What's interesting is that when I give it full throttle, timing drops below 0, maybe 2-4 degrees ATDC, it pops and then jumps back to high BTDC and revs nicely. Normal? Mad Dog, Didn't mean to offend. Too many beers on my part, I'm sure. The way I understand a 4 cycle motor is Intake -> Compression -> Power -> Exhaust and 180 degress separate each stroke. I believe TDC and spark timing is between Compression and Power. I apologize if my understanding is all screwed up. Probably why my motor's not working... :-D -Omar Mad Dog stated: The motor is popping because the plug is firing 2 degrees ATDC, the intake valve is already opening and drawing air/fuel into the chamber when the plug fires. Odelrio replied with: PS Oh yes, and Mad Dog, I'd like to see any engine run if the intake starts openning at 2 degrees during the power stroke... It would have to be 360 degrees out of phase... Sorry, couldn't resist. Where did i say the intake valve is opening 2 degrees ATDC PS Maybe you should read your own post and read my replies more carefully...sorry, could'nt resist ;-( -- Mad-Dog '79 Chevy K-10 Slightly modified |
#13
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#14
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odelrio (AT) yahoo (DOT) com (odelrio) wrote in message news:<854e7def.0407091753.79272217 (AT) posting (DOT) google.com>... So she's running... albeit a little rough. It sounded like it was missing and the new headers confirmed that cyl 8 was colder than the rest (no discoloring). Sure enough, spark plug was wet with anti-freeze. I didn't use RTV around the water jackets. Damn, my bad. New gaskets, gaskacynch, and black RTV and the leaks are gone. But she's still running rough. Checked #8 again and this time it's hot like the others. It could still be missing but I don't know. Maybe it's the cam, but I wouldn't expect that from the Edelbrock Performer. A new day, a new attitude... In troubleshooting the potential miss, I started unplugging wires to see if the condition got worse or stayed the same. Interesting results, #2 has no effect. #3 got *better* (or rather smoother). All others were perceptibly worse (barely). A quick look at the firing order for a SBC, 1-8-4-3-6-5-7-2, and these two are opposed and exactly 360 degrees from each other. Hmmm... I check the plug at #2, looked fine. Checked for spark, looked fine. Replaced the wire with a known good one, no difference. Checked compression, 190 lbs, again, looks good. WTF? I plan to check the intake valve, maybe it's not openning? |
valve cover (and cursing GM for it), I finally got to the PCV hose (or
boot) which attaches to the throttle body. The bottom side was
cracked. Hmmm, says I. A possible vacuum leak??? Since I had
already drained the coolant and removed the heater hose and the AC
unit, I figured I'd re-adjust the valves anyways just in case. Two
hours later and a new hose, she's purring nicely. No more miss,
pinging or popping!
What a relief, I was going to go after the cam next!
Thanks for everyone's help!
-Omar
#15
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"odelrio" <odelrio (AT) yahoo (DOT) com> wrote in message news:854e7def.0407101007.ad99bf8 (AT) posting (DOT) google.com... "\"Doc\"" <noway (AT) nope (DOT) com> wrote in message news:<YLKdnQf_lroaz3LdRVn-hw (AT) adelphia (DOT) com>... You need top recalibrate your ECM to run the bigger motor. It'll run like shit till you get a custom PROM burned. Doc Thanks guys. So what's the best way to do this? A quick search of OTC Genesys shows the GM Reprogrammer and Tech 2 to run at or above $1,000. Can this be done via component description to some place like Turbo City or do I need to take this in to a local Tuner? (Any you guys in sunny San Diego??? ;-) ) And last, how much should I expect to pay for this? A quick search here shows custom proms to be ~$350. Don't know what a Tuner would charge... Thanks, Omar I'd call jegs or summit racing (www.jegs.com or www.summitracing.com) and see if they have the ability to do it for you. If they can't, they'll sure as hell know who can. You should expect to pay between $150 and $350 for the ROM. They'll need to know displacement (bore and stroke), compression ratio, cam specs (lift, duration i/e + lobe seperation), valve specs (size of combustion chamber, i/e valve size) and also what kind of exhaust you're running. Doc |
it's running smooth, it feels very similar to what we had before with
the 350. In addition to the longer stroke, I added the Edelbrock
Performer manifold, cam and TES headers. This was supposed to give me
primarily more torque but I would have thought noticeable HP too.
-Omar
#16
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"\"Doc\"" <noway (AT) nope (DOT) com> wrote "odelrio" <odelrio (AT) yahoo (DOT) com> wrote in message news:854e7def.0407101007.ad99bf8 (AT) posting (DOT) google.com... "\"Doc\"" <noway (AT) nope (DOT) com> wrote in message news:<YLKdnQf_lroaz3LdRVn-hw (AT) adelphia (DOT) com>... You need top recalibrate your ECM to run the bigger motor. It'll run like shit till you get a custom PROM burned. Doc Thanks guys. So what's the best way to do this? A quick search of OTC Genesys shows the GM Reprogrammer and Tech 2 to run at or above $1,000. Can this be done via component description to some place like Turbo City or do I need to take this in to a local Tuner? (Any you guys in sunny San Diego??? ;-) ) And last, how much should I expect to pay for this? A quick search here shows custom proms to be ~$350. Don't know what a Tuner would charge... Thanks, Omar I'd call jegs or summit racing (www.jegs.com or www.summitracing.com) and see if they have the ability to do it for you. If they can't, they'll sure as hell know who can. You should expect to pay between $150 and $350 for the ROM. They'll need to know displacement (bore and stroke), compression ratio, cam specs (lift, duration i/e + lobe seperation), valve specs (size of combustion chamber, i/e valve size) and also what kind of exhaust you're running. Doc Thanks, I'll do that. I expected more power out of this 383. Now that it's running smooth, it feels very similar to what we had before with the 350. In addition to the longer stroke, I added the Edelbrock Performer manifold, cam and TES headers. This was supposed to give me primarily more torque but I would have thought noticeable HP too. -Omar |
thinks you have a 350 and is delivering fuel and spark as such.
Doc
#17
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"odelrio" <odelrio (AT) yahoo (DOT) com> wrote in message news:854e7def.0407110955.376ceec2 (AT) posting (DOT) google.com... "\"Doc\"" <noway (AT) nope (DOT) com> wrote in message news:<jNidnYCZSOWNp23dRVn-sQ (AT) adelphia (DOT) com>... "odelrio" <odelrio (AT) yahoo (DOT) com> wrote in message news:854e7def.0407101007.ad99bf8 (AT) posting (DOT) google.com... "\"Doc\"" <noway (AT) nope (DOT) com> wrote in message news:<YLKdnQf_lroaz3LdRVn-hw (AT) adelphia (DOT) com>... You need top recalibrate your ECM to run the bigger motor. It'll run like shit till you get a custom PROM burned. Doc Thanks guys. So what's the best way to do this? A quick search of OTC Genesys shows the GM Reprogrammer and Tech 2 to run at or above $1,000. Can this be done via component description to some place like Turbo City or do I need to take this in to a local Tuner? (Any you guys in sunny San Diego??? ;-) ) And last, how much should I expect to pay for this? A quick search here shows custom proms to be ~$350. Don't know what a Tuner would charge... Thanks, Omar I'd call jegs or summit racing (www.jegs.com or www.summitracing.com) and see if they have the ability to do it for you. If they can't, they'll sure as hell know who can. You should expect to pay between $150 and $350 for the ROM. They'll need to know displacement (bore and stroke), compression ratio, cam specs (lift, duration i/e + lobe seperation), valve specs (size of combustion chamber, i/e valve size) and also what kind of exhaust you're running. Doc Thanks, I'll do that. I expected more power out of this 383. Now that it's running smooth, it feels very similar to what we had before with the 350. In addition to the longer stroke, I added the Edelbrock Performer manifold, cam and TES headers. This was supposed to give me primarily more torque but I would have thought noticeable HP too. -Omar It will kick some massive ass with the new PROM; right now the computer thinks you have a 350 and is delivering fuel and spark as such. Doc |
small blocks run very strong.
Brian
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