help!!!!79 suburban - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jims72 · 08-04-2013, 01:23 AM

Just bought a 1 ton 4x4 suburban 350 4bbl sm465 4speed. The thing will not accelerate engine rpm in gear or not without bogging down and it has a knocking mixed with a ticking sound coming from some where. It will also at certain times pops out of the carb and starts running really rough and then just fixes itself for a bit. I have replaced the carb with a new eddy 1407 and the timing chain with a cloyes double roller. I thought it could of been a rod or wrist pin but after pulling the pan there is no evidence of either shown. The flywheel is not cracked either. I just bought the thing and its my only car right now and could really use the help on identifying what is up with it. I have been allover the engine and the only other thing I could think of was a bad HEI which it does not have [just now checked]or a bad fuel pump [it does deliver fuel still but is it enough and is it my knock?]. any ideas or pointers are appreciated! I have officially confuse 5 master techs with this truck as well 2 being mechanics at a gm dealer!

izzy_Britton · 08-04-2013, 01:33 AM

timing? double check that. might be that timing chain has jumped a tooth or that the distributor is just off.

85$ new HEI distributor from NAPA.

-Izzy

jims72 · 08-04-2013, 02:53 AM

timing was dead on at 8 deg. and doesn't seem to move when it starts to run bad and miss. I just did the timing chain today It was exhibiting the same symptoms before the chain was replaced. Gonna look into the possibility of a broken valve spring broken cam etc tomorrow.

izzy_Britton · 08-04-2013, 11:53 AM

20 years ago i had an HEI coil that i thought was going bad, chased that gremlin for a few days and then the truck quit running altogether while cruising down the freeway. new coil, same problem, ran good for a few days then died. finally figured out that one of the fuse-able links from the battery was fried just enough to be the problem. put a new fuse-able link on it and the problem went away. never had another problem with it. there is one that goes between the battery and the 2 post junction block thing on the firewall to the drivers side of the carb. and maybe one on the starter solenoid. either could be the culprit. or maybe a bad voltage regulator? i do not recall if your truck would have a separate one on the inner fender, or if yours would be built into the alternator/gennie

-Izzy

jims72 · 08-06-2013, 03:11 AM

well I ripped the pan off to inspect the crank and bearings. found that every single cap was loose and only torqued to 30lbs. So I retorqued them after establishing that the bearings were ok .Also the hei was welded yes I said welded in place to the block via electrolysis and has to be busted into pieces to come out. No amount of heat or wd40 was working to free it up either. Also found that someone had the heads rebuilt but put the wrong size guides in 4 of the exhaust valves so they were running too tight. Also found a ton of carbon deposits on the heads and lifters. So in conclusion I was lied to an obviously th etruck needed more then a carburetor lik ehte previous owner had said. Oh I would like to add I replaced the timing chain too. Also put a different set of known good heads on it to reduce the chances of the heads being the culprit all together. Bores were clean and round no scratches or gouges and no slop in the pistons or wrist pins. If it has the same problems after this I will be lost all together.

jims72 · 08-09-2013, 01:15 AM

ok so I got it started after checking everything out and changing heads yada yada. in the end it was a freaking plugged catalytic converter! It has been plugged for quite some time water will not pass through it. because of how plugged up it was it wreaked havoc on the old valves causing the knocking issue. So in the future if you have an engine that will run at idle but wont accelerate check the cat. its probably plugged. I only caught on to it after bolting the exhaust back up to it and getting the same symptoms where as before I had started it with open exhaust and it ran fine. too bad I didn't catch it earlier there would still be 700 bucks in my pocket and I wouldn't of had to do a rebuild on the engine for nothing!

08-04-2013, 01:23 AM	#1
jims72 Registered User Join Date: Mar 2010 Location: Mesa az Posts: 5	help!!!!79 suburban Just bought a 1 ton 4x4 suburban 350 4bbl sm465 4speed. The thing will not accelerate engine rpm in gear or not without bogging down and it has a knocking mixed with a ticking sound coming from some where. It will also at certain times pops out of the carb and starts running really rough and then just fixes itself for a bit. I have replaced the carb with a new eddy 1407 and the timing chain with a cloyes double roller. I thought it could of been a rod or wrist pin but after pulling the pan there is no evidence of either shown. The flywheel is not cracked either. I just bought the thing and its my only car right now and could really use the help on identifying what is up with it. I have been allover the engine and the only other thing I could think of was a bad HEI which it does not have [just now checked]or a bad fuel pump [it does deliver fuel still but is it enough and is it my knock?]. any ideas or pointers are appreciated! I have officially confuse 5 master techs with this truck as well 2 being mechanics at a gm dealer!

08-04-2013, 01:33 AM	#2
izzy_Britton Registered User Join Date: Apr 2013 Location: Nor-Cal Posts: 632	Re: help!!!!79 suburban timing? double check that. might be that timing chain has jumped a tooth or that the distributor is just off. 85$ new HEI distributor from NAPA. -Izzy __________________ WHO_DCTC - Wifes 05 Z-71 Build - Now defunct as she decided she wants an Escalade too Cream Puff - LS'd Square - Slow going on the back burner Tripple Threat - 3 Wrecks for the price of one build thread Project Delongdium - Step-Sons Plastic Clad 2003 Avalanche - DONE and Delivered.

08-04-2013, 02:53 AM	#3
jims72 Registered User Join Date: Mar 2010 Location: Mesa az Posts: 5	Re: help!!!!79 suburban timing was dead on at 8 deg. and doesn't seem to move when it starts to run bad and miss. I just did the timing chain today It was exhibiting the same symptoms before the chain was replaced. Gonna look into the possibility of a broken valve spring broken cam etc tomorrow. Last edited by jims72; 08-04-2013 at 03:13 AM. Reason: added stuff

08-04-2013, 11:53 AM	#4
izzy_Britton Registered User Join Date: Apr 2013 Location: Nor-Cal Posts: 632	Re: help!!!!79 suburban 20 years ago i had an HEI coil that i thought was going bad, chased that gremlin for a few days and then the truck quit running altogether while cruising down the freeway. new coil, same problem, ran good for a few days then died. finally figured out that one of the fuse-able links from the battery was fried just enough to be the problem. put a new fuse-able link on it and the problem went away. never had another problem with it. there is one that goes between the battery and the 2 post junction block thing on the firewall to the drivers side of the carb. and maybe one on the starter solenoid. either could be the culprit. or maybe a bad voltage regulator? i do not recall if your truck would have a separate one on the inner fender, or if yours would be built into the alternator/gennie -Izzy __________________ WHO_DCTC - Wifes 05 Z-71 Build - Now defunct as she decided she wants an Escalade too Cream Puff - LS'd Square - Slow going on the back burner Tripple Threat - 3 Wrecks for the price of one build thread Project Delongdium - Step-Sons Plastic Clad 2003 Avalanche - DONE and Delivered.

08-06-2013, 03:11 AM	#5
jims72 Registered User Join Date: Mar 2010 Location: Mesa az Posts: 5	Re: help!!!!79 suburban well I ripped the pan off to inspect the crank and bearings. found that every single cap was loose and only torqued to 30lbs. So I retorqued them after establishing that the bearings were ok .Also the hei was welded yes I said welded in place to the block via electrolysis and has to be busted into pieces to come out. No amount of heat or wd40 was working to free it up either. Also found that someone had the heads rebuilt but put the wrong size guides in 4 of the exhaust valves so they were running too tight. Also found a ton of carbon deposits on the heads and lifters. So in conclusion I was lied to an obviously th etruck needed more then a carburetor lik ehte previous owner had said. Oh I would like to add I replaced the timing chain too. Also put a different set of known good heads on it to reduce the chances of the heads being the culprit all together. Bores were clean and round no scratches or gouges and no slop in the pistons or wrist pins. If it has the same problems after this I will be lost all together.

08-09-2013, 01:15 AM	#6
jims72 Registered User Join Date: Mar 2010 Location: Mesa az Posts: 5	Re: help!!!!79 suburban ok so I got it started after checking everything out and changing heads yada yada. in the end it was a freaking plugged catalytic converter! It has been plugged for quite some time water will not pass through it. because of how plugged up it was it wreaked havoc on the old valves causing the knocking issue. So in the future if you have an engine that will run at idle but wont accelerate check the cat. its probably plugged. I only caught on to it after bolting the exhaust back up to it and getting the same symptoms where as before I had started it with open exhaust and it ran fine. too bad I didn't catch it earlier there would still be 700 bucks in my pocket and I wouldn't of had to do a rebuild on the engine for nothing!



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