Grrr... still no luck! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

shuttermutt · 11-13-2003, 01:18 AM

For anyone that's been following the saga of my 68 CST troubles, here's a quick update...

Symptom: Backfire through the carb on initial throttle and under a moderate to heavy load. No backfire at all once the initial blip of the throttle is over with. Sounds fine at idle, 2000k, and 3500k.

Basically, it acts like a big ol' vacuum leak or completely hosed timing, but I'll be damned if I can figure it out. At one point I reported that I heard a strange noise, but I'm almost certain now that it is/was a combination of exhaust leak on the passenger side and/or the heat riser was acting flaky.

I just had the carb (Q-Jet) rebuilt by a reputable guy, put it on this evening, and while you can tell he did a whole lot of good, the root cause of my problem still hasn't been identified.

After I threw the carb on and reset the idle, I played with the timing (I was/am at 8 degrees and tried it at about 4 and 12), but that didn't make a lick of difference. I also tried moving the vacuum advance from the port on the carb to the manifold. That didn't make a dent, either.

Guess it's time to tow the old girl over to The Professional and let him figure it out since I'm running out of patience, time, and good weather. Damn!

Longhorn Man · 11-13-2003, 01:38 AM

You checked for a chipped intake valve?
Fire the truck up and let it warm up. While the engine is sitting at an idle, hold a dollar bill over the opening at the end of your exhaust. The 'wind' blowing out of your pipe(s) should blow the bill out, however,a chipped valve will try to momentarily (and repetitively) suck it into the pipe.
A compression test would do it too, but the cash test is quick, neat to see...in a heart sinking sorta way...and the tool only costs you a buck.

jorgensensc · 11-13-2003, 02:52 AM

Cool Idea Longhorn!!!!

Class of 69 · 11-13-2003, 11:50 AM

A couple ideas...did you ever pull the valve covers to check for a loose rocker arm?? I.E. out of adjustment..worn, or flat lobe. If it has power brakes, you have the potential for a "big ole' vacumm leak". Pull the hose off the carb base, and plug the port (naturally!). Then see what it does. I wouldn't recommend driving it with the rebuilt carb till you get this solved, as you probably know, cause you don't want to ruin the rebuild. Sorry to hear you're still having trouble...we've all been there, and it gets REALLY frustrating....dammit!!!

sneakysnake · 11-13-2003, 12:32 PM

had one burn a head gasket between 3-5, that would put a sputter in the garb, as time went on things got worse you might run a compression check that would rule out valves,gaskets and what not.

ckhd · 11-13-2003, 12:34 PM

cracked cap? bad rotor? bad/leaky wires? screwed up firing order (it happens more than you'd think, I got an awesome deal on my '68 because the kid said there was something wrong with the cam, and it was just that #5 & #7 were mixed up)? worn points? points out of adjustment? dwell off? #5 and #7 wire run together (like tied in the same bundle running from the cap to the plugs)? hmm.... that's all I can think of real quick.

shuttermutt · 11-13-2003, 01:35 PM

Well, before I tow it over to The Pro, I'm going to swap on an HEI unit with a new cap, rotor, and wires. That'll eliminate any possibility of the vacuum advance being flaky, the points being goofy, the dwell being off, a cracked cap, and wires being fudged.

I'd try the old dollar bill trick (man, that's a classic), but the exhaust is so eat up with rust that I don't think it'd be a reliable test. Once I get the ignition stuff replaced, I'll run another vacuum test and see if I made any difference. If not, then I'll let someone else have a look.

Southpa · 11-13-2003, 03:44 PM

I'll bet that dollar that Andy was using that all your problems will be gone once you change over to HEI. I had similar things going on a few years ago. HEI was already installed but I was getting serious intake backfire under load, going up hills etc. Got it home and pulled the dist. cap. The center point was shattered. It must have been a real light show in there when the truck was running.

lukecp · 11-13-2003, 04:00 PM

One of my friends had a '67 with points....the truck didn't have very much power (283/2bbl), and when he would go over 20mph in first gear, it would start back firing and sputterign really bad. One day it would barely run at all....$30 and one junkyard HEI later the truck ran great. It made that little 283 come alive...he had no problem keeing up with a 318 Dodge Ram, and before a VW rabbit proably could have whipped it. Not to mention that the truck got better MPG, started better, and it even quieted down the exhaust!

**smitty62** · 11-13-2003, 04:29 PM

If all the above fails, check the timing chain/sprockets for sloppiness (is that a word)???

Class of 69 · 11-13-2003, 09:13 PM

Shuttermutt....I thought I read you had a HEI in there already!!! Points need to be replaced, and dwell set...that's all it needs. I would change them first to make sure it takes care of the problem before you change out the distr.

PanelDeland · 11-13-2003, 09:41 PM

I had a buddy who did a timing chain. "TWICE" on a 318 and it still wouldn't run.We took it to a pro I knew and he took one look and sent his helper for points and condenser.

Brand new P&C were bad. Just goes to show always"Pick the low hanging fruit first"

shuttermutt · 11-14-2003, 12:06 AM

Quote:

Originally posted by Class of 69
Shuttermutt....I thought I read you had a HEI in there already!!! Points need to be replaced, and dwell set...that's all it needs. I would change them first to make sure it takes care of the problem before you change out the distr.

Nope, no HEI yet. I did change the points, condenser, cap, wires, plugs, and rotor a couple of weeks before this problem came up. I've already pulled the old distributor and the new HEI is stabbed, but...

D'OH!

Guess who forgot to pick up a blade connector to hook up to the coil? C'mon... you know the answer! It's ME!

So, I'm about 90% there on swapping in the HEI unit. I also picked up some proper vacuum caps to plug everything up right. To top it all off, I've also got a buddy's compression test rig borrowed (mine's broke).

I give the new distributor a 40% chance of taking care of the problem. If that doesn't do it (and even if it does), I'll run the compression test. If that comes up okay, I'll be opening up the timing cover.

Keep your fingers crossed for me, gang!

shuttermutt · 11-14-2003, 12:08 AM

BTW, anybody want to buy a used points distributor with a new cap, rotor, condenser, and wires REAL cheap?

Longhorn Man · 11-14-2003, 12:36 AM

Quote:

Originally posted by shuttermutt
I give the new distributor a 40% chance of taking care of the problem.

I give it a 50/50...either it will or it wont...that is a 50/50.

krue · 11-14-2003, 12:43 AM

In the Navy we had a saying.."50/50/90"...in other words if you have a 50/50 chance of something working 90% of the time it won't! Hopefully it won't work out this way for shuttermutt.

shuttermutt · 11-14-2003, 12:43 AM

Quote:

Originally posted by Longhorn Man

I give it a 50/50...either it will or it wont...that is a 50/50.

Using that same logic, however, parking it in a field and throwing rocks at it has a 50/50 chance of fixing it, too!

shuttermutt · 11-24-2003, 12:59 AM

Update...

I just finished the HEI conversion this afternoon (hey, gimme a break... wife's been in the hospital). The result? No love at all.

Oh, and that noise? It's back. Well, then it goes away again. Then it's back. Now that I've heard it come and go all while the engine's running, I'm thinking I've got a lifter acting up on me. Grrr...

To make matters worse (or better depending on how you view it), I noticed some fuel (not much, but enough to get my attention) down by the driver's side front near the idle screw after kicking the engine up to about 2500 rpm for a minute. I'll be giving my carb rebuild guy a call in the morning about that one.

Somebody want to sacrifice a <bleep> chicken for me? Geez... my freakin' inspection sticker's gonna run out before I get this thing fixed at the rate I'm making progress!

68cajun · 11-24-2003, 03:22 AM

I had the same problem once in a 73 pickup 350. It was a flat lobe on the camshaft.

shuttermutt · 12-01-2003, 05:11 PM

Well, I stumbled into what I think is a pretty good deal and should solve the problem once and for all... a new engine!

Turns out a friend of a friend runs a small garage and towing service. He pulled in a totalled 85 Chevy 4X4 that had a later model 350 built by a local circle track guy in it. I told him that if I could hear it run and it sounded okay, we could probably come to a price.

I heard it run this morning and it sounds awesome. No unusual noises from the bottom or top and, from the sound of it, I'd say they weren't lying about having a little bit of a cam in it. Not even a puff of smoke from the open exhaust (and yes, I'm absolutely positive this was the first time the engine had been fired in 2 months).

Long story short, I bought it for $250. Actually, we made a deal... he'll sell me the engine, do the engine swap, and hang a new set of duals on it for $700 total. If that engine runs 1/2 as good as it sounded then I think it's a pretty sweet deal. He's supposed to pull my truck into the shop today and get started. Woo-hoo!

greasemonkey · 12-01-2003, 05:43 PM

Awesome deal. Some people have all the luck.

shuttermutt · 12-01-2003, 05:48 PM

Well, I don't know about luck, but I'll take what I can get. Now if I can get 'er running pretty good, I'll have to start working on the body! Black primer and flames? Here I come!

Longhorn Man · 12-02-2003, 01:35 AM

That's one way to fix it.

Sounds like a good deal.

11-13-2003, 01:18 AM	#1
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Grrr... still no luck! For anyone that's been following the saga of my 68 CST troubles, here's a quick update... Symptom: Backfire through the carb on initial throttle and under a moderate to heavy load. No backfire at all once the initial blip of the throttle is over with. Sounds fine at idle, 2000k, and 3500k. Basically, it acts like a big ol' vacuum leak or completely hosed timing, but I'll be damned if I can figure it out. At one point I reported that I heard a strange noise, but I'm almost certain now that it is/was a combination of exhaust leak on the passenger side and/or the heat riser was acting flaky. I just had the carb (Q-Jet) rebuilt by a reputable guy, put it on this evening, and while you can tell he did a whole lot of good, the root cause of my problem still hasn't been identified. After I threw the carb on and reset the idle, I played with the timing (I was/am at 8 degrees and tried it at about 4 and 12), but that didn't make a lick of difference. I also tried moving the vacuum advance from the port on the carb to the manifold. That didn't make a dent, either. Guess it's time to tow the old girl over to The Professional and let him figure it out since I'm running out of patience, time, and good weather. Damn! __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-13-2003, 02:52 AM	#3
jorgensensc Registered User Join Date: Jul 2003 Location: Cypress, Tx Posts: 4,005	Cool Idea Longhorn!!!! __________________ 1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE

11-13-2003, 11:50 AM	#4
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	A couple ideas...did you ever pull the valve covers to check for a loose rocker arm?? I.E. out of adjustment..worn, or flat lobe. If it has power brakes, you have the potential for a "big ole' vacumm leak". Pull the hose off the carb base, and plug the port (naturally!). Then see what it does. I wouldn't recommend driving it with the rebuilt carb till you get this solved, as you probably know, cause you don't want to ruin the rebuild. Sorry to hear you're still having trouble...we've all been there, and it gets REALLY frustrating....dammit!!! __________________ 69 GMC K10 ..some restoration required....still..

11-13-2003, 12:34 PM	#6
ckhd Registered User Join Date: Oct 2000 Location: St. Johns, Arizona Posts: 2,660	cracked cap? bad rotor? bad/leaky wires? screwed up firing order (it happens more than you'd think, I got an awesome deal on my '68 because the kid said there was something wrong with the cam, and it was just that #5 & #7 were mixed up)? worn points? points out of adjustment? dwell off? #5 and #7 wire run together (like tied in the same bundle running from the cap to the plugs)? hmm.... that's all I can think of real quick. __________________ my 2¢ - t.i.o.l.i. Bowen 1968 K20 fleet 1969 K10 swb fleet 1972 K10 Suburban 1972 C10 lwb step 1992 K1500 'burb 1995 K2500 'burb 1997 C1500 'burb 1999 K1500 2000 K1500 'burb Why do I own so many Suburbans?

11-13-2003, 03:44 PM	#8
Southpa Registered User Join Date: May 2000 Location: Victoria, BC, Canada Posts: 2,409	I'll bet that dollar that Andy was using that all your problems will be gone once you change over to HEI. I had similar things going on a few years ago. HEI was already installed but I was getting serious intake backfire under load, going up hills etc. Got it home and pulled the dist. cap. The center point was shattered. It must have been a real light show in there when the truck was running. __________________ 1970 GMC 1500 Custom Original 350/TH350 Victoria, BC, Canada You can wish in one hand and crap in the other. See which one gets filled first.

11-13-2003, 01:38 AM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	You checked for a chipped intake valve? Fire the truck up and let it warm up. While the engine is sitting at an idle, hold a dollar bill over the opening at the end of your exhaust. The 'wind' blowing out of your pipe(s) should blow the bill out, however,a chipped valve will try to momentarily (and repetitively) suck it into the pipe. A compression test would do it too, but the cash test is quick, neat to see...in a heart sinking sorta way...and the tool only costs you a buck.

11-13-2003, 12:32 PM	#5
sneakysnake It's a catastrophic success. Join Date: Jan 2003 Location: Oklahoma Posts: 2,077	had one burn a head gasket between 3-5, that would put a sputter in the garb, as time went on things got worse you might run a compression check that would rule out valves,gaskets and what not.

11-13-2003, 01:35 PM	#7
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Well, before I tow it over to The Pro, I'm going to swap on an HEI unit with a new cap, rotor, and wires. That'll eliminate any possibility of the vacuum advance being flaky, the points being goofy, the dwell being off, a cracked cap, and wires being fudged. I'd try the old dollar bill trick (man, that's a classic), but the exhaust is so eat up with rust that I don't think it'd be a reliable test. Once I get the ignition stuff replaced, I'll run another vacuum test and see if I made any difference. If not, then I'll let someone else have a look. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-13-2003, 04:00 PM	#9
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	One of my friends had a '67 with points....the truck didn't have very much power (283/2bbl), and when he would go over 20mph in first gear, it would start back firing and sputterign really bad. One day it would barely run at all....$30 and one junkyard HEI later the truck ran great. It made that little 283 come alive...he had no problem keeing up with a 318 Dodge Ram, and before a VW rabbit proably could have whipped it. Not to mention that the truck got better MPG, started better, and it even quieted down the exhaust! __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

11-13-2003, 04:29 PM	#10
smitty62 Registered User Join Date: May 2002 Location: North Carolina Posts: 1,234	If all the above fails, check the timing chain/sprockets for sloppiness (is that a word)??? __________________ Stepsides look like real trucks! Smitty

11-13-2003, 09:13 PM	#11
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	Shuttermutt....I thought I read you had a HEI in there already!!! Points need to be replaced, and dwell set...that's all it needs. I would change them first to make sure it takes care of the problem before you change out the distr. __________________ 69 GMC K10 ..some restoration required....still..

11-13-2003, 09:41 PM	#12
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	I had a buddy who did a timing chain. "TWICE" on a 318 and it still wouldn't run.We took it to a pro I knew and he took one look and sent his helper for points and condenser. Brand new P&C were bad. Just goes to show always"Pick the low hanging fruit first" __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

11-14-2003, 12:08 AM	#14
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	BTW, anybody want to buy a used points distributor with a new cap, rotor, condenser, and wires REAL cheap? __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-14-2003, 12:43 AM	#16
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	In the Navy we had a saying.."50/50/90"...in other words if you have a 50/50 chance of something working 90% of the time it won't! Hopefully it won't work out this way for shuttermutt. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

11-24-2003, 12:59 AM	#18
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Update... I just finished the HEI conversion this afternoon (hey, gimme a break... wife's been in the hospital). The result? No love at all. Oh, and that noise? It's back. Well, then it goes away again. Then it's back. Now that I've heard it come and go all while the engine's running, I'm thinking I've got a lifter acting up on me. Grrr... To make matters worse (or better depending on how you view it), I noticed some fuel (not much, but enough to get my attention) down by the driver's side front near the idle screw after kicking the engine up to about 2500 rpm for a minute. I'll be giving my carb rebuild guy a call in the morning about that one. Somebody want to sacrifice a <bleep> chicken for me? Geez... my freakin' inspection sticker's gonna run out before I get this thing fixed at the rate I'm making progress! __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list



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11-24-2003, 03:22 AM	#19
68cajun 68 C/10 Join Date: Oct 2003 Location: Houma Louisiana Posts: 367	same problem once I had the same problem once in a 73 pickup 350. It was a flat lobe on the camshaft. __________________ (2009) GMC Sierra Denali 6.2 AWD (67 C/10 fleetside SWB) (2018GMC Yukon Denali) Wifes Car

12-01-2003, 05:11 PM	#20
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Well, I stumbled into what I think is a pretty good deal and should solve the problem once and for all... a new engine! Turns out a friend of a friend runs a small garage and towing service. He pulled in a totalled 85 Chevy 4X4 that had a later model 350 built by a local circle track guy in it. I told him that if I could hear it run and it sounded okay, we could probably come to a price. I heard it run this morning and it sounds awesome. No unusual noises from the bottom or top and, from the sound of it, I'd say they weren't lying about having a little bit of a cam in it. Not even a puff of smoke from the open exhaust (and yes, I'm absolutely positive this was the first time the engine had been fired in 2 months). Long story short, I bought it for $250. Actually, we made a deal... he'll sell me the engine, do the engine swap, and hang a new set of duals on it for $700 total. If that engine runs 1/2 as good as it sounded then I think it's a pretty sweet deal. He's supposed to pull my truck into the shop today and get started. Woo-hoo! __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

12-01-2003, 05:43 PM	#21
greasemonkey Registered User Join Date: Dec 2001 Location: Pace, FL Posts: 2,155	Awesome deal. Some people have all the luck. __________________ 1942 Master Deluxe 1969 C/10 1985 Blazer CUCV 1987 Jimmy 2004 Tahoe 2005 Silverado 1500 2005 Silverado 3500

12-01-2003, 05:48 PM	#22
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Well, I don't know about luck, but I'll take what I can get. Now if I can get 'er running pretty good, I'll have to start working on the body! Black primer and flames? Here I come! __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

12-02-2003, 01:35 AM	#23
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	That's one way to fix it. Sounds like a good deal.

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