small block firing on every other cylinder in firing order - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dlh760 · 11-18-2012, 06:48 PM

Problem has been fixed after I put my carb back together and back on it is running much better,really rich now but better. I am a mechanic by trade as well but had never come across anything like this before. I appreciate everybody's input and help. Dan
Posted via Mobile Device

Claus · 03-21-2017, 05:26 PM

I'm experiencing the same problem on my sbc 350,

I bought a project truck with a 350 and electronic ignition, had the heads checked, new plugs, 4 ported edelbrock carb.

the engine runs rough, with only little torque, pulled plugs and they are not wet or black.

it sounds like all cylinders are firing, but in the right sequence, have double checked firing order.

1 8 4 3 6 5 7 2, it seem odd that every other cylinder is misfiring

1 8 4 3 6 5 7 2

Have spark on all 8 plugs, by grounding individual leads one by one, while running, I narrowed it down to cylinder 2 8 3 5 can be grounded without the engine changing sound, which seem to me like a problem.

Hope someone can help.

Moose Monkey · 03-21-2017, 08:11 PM

#27 is the answer, I hope

Moose Monkey · 03-21-2017, 08:20 PM

Sorry, not much of answer. If those cylinder's are firing spark good, just might be fuel. Had
Elderbrock crack inside, sucking to much air.would not idle, very bad time starting

garyd1961 · 03-21-2017, 08:37 PM

Do you have a duel plane intake? Have you tried turning the motor over with the spark plugs out of the motor and grounded on the outside to see if they actually fire or not? If you have a duel plane intake I suspect one side of your carb is not working.

GASoline71 · 03-21-2017, 09:07 PM

Check your spark plug gap. With an HEI you need to open up the gap to at least .045

Gary

volksworld · 03-21-2017, 10:24 PM

not looking at a small block as we speak but does anything tap into one runner of the manifold like a brake booster hose? a small leak could kill that cylinder or a major one(blown booster diaphram?) might affect the whole manifold plane....if you got a 4 hole 1 inch spacer and put the carb on backwards you could see if the 4 dead cylinders suddenly became the live ones...then you'd know its a carb issue

Moose Monkey · 03-22-2017, 09:35 AM

Volksworld what a great idea

Claus · 03-22-2017, 01:54 PM

Hi Guys

it ended up being one side of the carburetor that was blocked, that became clear after your feedback and I took another look at the intake manifold, cylinder 2-8-3-5 is all in the same side of the carb.

I was able to clear out the block, now the engine runs like a champ.

Thanks for sharing your ideas,

11-18-2012, 06:48 PM	#1
dlh760 Registered User Join Date: Oct 2012 Location: valley center,ca Posts: 124	Re: small block firing on every other cylinder in firing order Problem has been fixed after I put my carb back together and back on it is running much better,really rich now but better. I am a mechanic by trade as well but had never come across anything like this before. I appreciate everybody's input and help. Dan Posted via Mobile Device __________________ 68 Chevy c10 longbed 307 with 305 H.O. heads,edelbrock performer intake,edelbrock performer plus cam,hei,Holley 650 double pumper and th400. Daily driver. It hauls butt,it hauls my butt where I need to go

03-21-2017, 08:11 PM	#3
Moose Monkey Registered User Join Date: Sep 2016 Location: south jersey Posts: 118	Re: small block firing on every other cylinder in firing order #27 is the answer, I hope

03-21-2017, 08:20 PM	#4
Moose Monkey Registered User Join Date: Sep 2016 Location: south jersey Posts: 118	Re: small block firing on every other cylinder in firing order Sorry, not much of answer. If those cylinder's are firing spark good, just might be fuel. Had Elderbrock crack inside, sucking to much air.would not idle, very bad time starting

03-21-2017, 08:37 PM	#5
garyd1961 Registered User Join Date: May 2016 Location: Henderson NC Posts: 975	Re: small block firing on every other cylinder in firing order Do you have a duel plane intake? Have you tried turning the motor over with the spark plugs out of the motor and grounded on the outside to see if they actually fire or not? If you have a duel plane intake I suspect one side of your carb is not working.

03-21-2017, 10:24 PM	#7
volksworld Registered User Join Date: Apr 2011 Location: formerly NY currentlyNC Posts: 390	Re: small block firing on every other cylinder in firing order not looking at a small block as we speak but does anything tap into one runner of the manifold like a brake booster hose? a small leak could kill that cylinder or a major one(blown booster diaphram?) might affect the whole manifold plane....if you got a 4 hole 1 inch spacer and put the carb on backwards you could see if the 4 dead cylinders suddenly became the live ones...then you'd know its a carb issue __________________ 1970 short step c10 leaf spring 454

03-21-2017, 05:26 PM	#2
Claus Registered User Join Date: Mar 2017 Location: Portland, OR Posts: 2	Re: small block firing on every other cylinder in firing order I'm experiencing the same problem on my sbc 350, I bought a project truck with a 350 and electronic ignition, had the heads checked, new plugs, 4 ported edelbrock carb. the engine runs rough, with only little torque, pulled plugs and they are not wet or black. it sounds like all cylinders are firing, but in the right sequence, have double checked firing order. 1 8 4 3 6 5 7 2, it seem odd that every other cylinder is misfiring 1 8 4 3 6 5 7 2 Have spark on all 8 plugs, by grounding individual leads one by one, while running, I narrowed it down to cylinder 2 8 3 5 can be grounded without the engine changing sound, which seem to me like a problem. Hope someone can help.

03-22-2017, 09:35 AM	#8
Moose Monkey Registered User Join Date: Sep 2016 Location: south jersey Posts: 118	Re: small block firing on every other cylinder in firing order Volksworld what a great idea

03-22-2017, 01:54 PM	#9
Claus Registered User Join Date: Mar 2017 Location: Portland, OR Posts: 2	Re: small block firing on every other cylinder in firing order Hi Guys it ended up being one side of the carburetor that was blocked, that became clear after your feedback and I took another look at the intake manifold, cylinder 2-8-3-5 is all in the same side of the carb. I was able to clear out the block, now the engine runs like a champ. Thanks for sharing your ideas,



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