Engine Misfire on Cylinders 1,4,5,8

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Engine Misfire on Cylinders 1,4,5,8

Post  bbfguy1 on April 16th 2018, 7:43 pm

Engine is new and this was the initial run in for cam break in. Used known good Edelbrock 800cfm carb. for break in. Engine will not hit on 1,4,5 and 8. All of the middle cylinders 2,3,6,7 are firing well. I have swapped carbs (850 Holley)but still no dice. I swapped ignitions systems (GM style HEI skip white to Ford OEM distributor connected to MSD 6AL) and no dice. Checked lash numerous times. Engine is on run stand, so it is easily accessible. Thoughts/opinions while I dig further? Thanks in advance!

Compression test
#1 160
#2 190
#3 190
#4 160
#5 170
#6 200
#7 200
#8 170


D1 block
Dish Probe Pistons part#13599 1.450CH 10.48:1w/74cc
Eagle 6.700
A429 Heads (fresh from Engine Systems)
Offshore 4340 4.300 crank
Ultradyne flat tappet mechanical 255/265@.050 .623/.606 111.5 lobe sep.
Edelbrock Victor 4150 carb flange (used Ebay item and suspect, since it didn't initially fit and line up with bolt holes in the heads)

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  pmrphil on April 16th 2018, 7:47 pm

Are the outboard holes cold? Have you checked for vacuum leaks? Checked the torque on the intake bolts? Is the intake flange true, seeing as though you said it didn't fit right to start with.

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  69F100 on April 16th 2018, 9:55 pm

have you checked and made sure the wires are firing and plugs I just had today replace the plugs in a 350 in a 57 chevy I just restored it hadn't ran 3 gallons of gas in this new engine. It never sounded just right and found 3 bad plugs they was on the outside corns they was NGK plugs v power 7 replaced them with NGK v power 5 now it sounds like it should
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Re: Engine Misfire on Cylinders 1,4,5,8

Post  rmcomprandy on April 16th 2018, 10:56 pm

Be sure the upper valve cover bolts/studs are tight.

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  Mark Miller on April 16th 2018, 10:58 pm

It just seems strange to me the cylinders with the lower compression are the ones not firing,but the amount of compression they have should be plenty enough to fire!!!

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  Mark Miller on April 16th 2018, 11:00 pm

rmcomprandy wrote:Be sure the upper valve cover bolts/studs are tight.

I bet Randy is right on the money I forgot those would be the cylinders on the Aluminum A-429 Heads that the valve cover bolts go into the intake ports!!!

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  427John on April 17th 2018, 1:53 am

So I take it the A429 heads are like the old iron CJ's that way,I thought about posting that but don't know anything about the A429's.As far as the compression numbers they could be due to the dead holes not seating the rings with no heat from combustion.

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  bbfguy1 on April 18th 2018, 7:41 am

Yes, what a dumb ass here. Randy was correct. In my desire to keep on eye on valve lash, I only installed two valve cover bolts on the bottom row and only the middle bolt on top; holes which are all blind on those heads. As much as I've seen light coming through the valve cover bolt holes and shining on the floor of 1,4,5,8 intake ports, when heads are off, I just totally overlooked the complete obvious. Installed the the outer bolts and what you do you know, an 8 cylinder engine, instead of 4 cylinders. Thanks guys!

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  427John on April 18th 2018, 10:09 am

Its good to see a happy ending with an easy fix sometimes.

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  rmcomprandy on April 18th 2018, 10:41 am

bbfguy1 wrote:Yes, what a dumb ass here. Randy was correct. In my desire to keep on eye on valve lash, I only installed two valve cover bolts on the bottom row and only the middle bolt on top; holes which are all blind on those heads. As much as I've seen light coming through the valve cover bolt holes and shining on the floor of 1,4,5,8 intake ports, when heads are off, I just totally overlooked the complete obvious. Installed the the outer bolts and what you do you know, an 8 cylinder engine, instead of 4 cylinders. Thanks guys!

Personally, I always use valve cover studs in those 4 places for just that reason.

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  Mark Miller on April 18th 2018, 10:01 pm

rmcomprandy wrote:
bbfguy1 wrote:Yes, what a dumb ass here. Randy was correct. In my desire to keep on eye on valve lash, I only installed two valve cover bolts on the bottom row and only the middle bolt on top; holes which are all blind on those heads. As much as I've seen light coming through the valve cover bolt holes and shining on the floor of 1,4,5,8 intake ports, when heads are off, I just totally overlooked the complete obvious. Installed the the outer bolts and what you do you know, an 8 cylinder engine, instead of 4 cylinders. Thanks guys!

Personally, I always use valve cover studs in those 4 places for just that reason.

I use studs in all 6 holes I have the Ford Racing Valve covers no hole in the top middle and it makes it easier to keep the valve cover gaskets in place!!! Smile

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Re: Engine Misfire on Cylinders 1,4,5,8

Post  D. Sea on April 19th 2018, 8:12 am

rmcomprandy wrote:
bbfguy1 wrote:Yes, what a dumb ass here. Randy was correct. In my desire to keep on eye on valve lash, I only installed two valve cover bolts on the bottom row and only the middle bolt on top; holes which are all blind on those heads. As much as I've seen light coming through the valve cover bolt holes and shining on the floor of 1,4,5,8 intake ports, when heads are off, I just totally overlooked the complete obvious. Installed the the outer bolts and what you do you know, an 8 cylinder engine, instead of 4 cylinders. Thanks guys!

Personally, I always use valve cover studs in those 4 places for just that reason.

Same; Loctite studs in those holes flush with the port roof.
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