help needed with misfire -429 capri

although this is my 1st post here i have been lurking a couple of years and active on another 460 ford website
any help with the below problem i would be gratfull --please dont be afrade to ask me any questions -i realy want to get my car running once and for all thankyou
Help needed

I have a 429 in a European ford capri and have been fighting a missfire for two years now , I have not been able to spend much time on the car lately as its located an hour away from were I live
This week I got totally fed up with the holley carb leaking fuel into and onto the engine and went out and bought a brand new eldebrock 800 avs carb it is running a little bit better –not hunting now

Engine spec as follows

Dive +30 429
Stock dished replacment pistons
D3v3 heads (I also have some d0ves)
Cc 268 hydraulic cam
1 ¾ headders 3” COLLECTORS and rest of exhaust
preformer non rpm manifold
elderbrock 800 avs carb
brand new duraspark dissy- duraspark 2 box
acell yell coil

its basically a stock engine with a bit of a cam

the problem is it had a missfire mainly on no 1 cylinder I took the head off a while ago and it looked like it had never fired on that cylinder with a quick clean with a rag it looked like a new piston
ill try to find a pic

the compression tests out perfect all 8 cylinders between 150 and 155 psi vacuum is 14 “/hg
all new leads ,caps ,rotar arm , plugs, cam, lifters etc

I checked the temp of the headders with a lazer temp gun
And are as follows
After a run and allowed to idle for a few mins


Cylinder 1 = 60F
Cylinder 2 = 155F
Cylinder 3 = 120F
Cylinder 4 = 130F
Cylinder 5 = 278F
Cylinder 6 = 230F
Cylinder 7 = 100F
Cylinder 8 = 224F

The temps of cylinders 1 and 7 are very low

And help info or questions would be really helpful this is my first big block (there aren’t many big block cars here in the UK )and the car sounds the nuts and I realy want to get this thing going and will use it as my daily driver , two years to fix a missfire is crazy and I need help now

i recently swaped the dizzy and coil for an points set up -this made no differance
i have checked the valve pre load loads of times they are fine same on all cylinders
swapped leads plugs etc ,still same result i have even blown compressed air down the exhaust headders and inlet to check for any rags etc!

the only thing left that i can think of is to swap the heads left to right that way i should know if the fault is in the heads or block / cam unless some one can think of anything to check first thanks john webb

Have you got a good ground cable from block to frame and the ignition box grounded to the frame good ?

56Tbird wrote:Have you got a good ground cable from block to frame and the ignition box grounded to the frame good ?

yes , -same size as the starter cable cant rember what size its called but its very thick both crimped and soldered both ends (ignition also grounded well) -thank you, 56 Tbird for your input,john

a few pics

Have you cheecked the dizzy cap and try changing the or swap #1 to another by move in it to another plug and try that and do a compression check and make sure you not down on compression on #1

cam lobe down?

Do a leakdown test on cylinder at tdc, both valves closed. you want a very low percentage of leak down say 5% or less. if alot more listen at carb, exaust and valve cover breather hole. should be noticable if either valve is not sealing.

69F100 wrote:Have you cheecked the dizzy cap and try changing the or swap #1 to another by move in it to another plug and try that and do a compression check and make sure you not down on compression on #1

perfect compresion all all cylinders --all 155 +or- 3 psi thanks

cool40 wrote:cam lobe down?

i removed the head a while ago and could see/ feal the cam lobes --all good ,thanks

stanggt wrote:Do a leakdown test on cylinder at tdc, both valves closed. you want a very low percentage of leak down say 5% or less. if alot more listen at carb, exaust and valve cover breather hole. should be noticable if either valve is not sealing.

the compresion test is perfect all 155 + or - 3psi i dont have a leak down test gauge ,but i could take it some were that has -it maby be easer than swapping the heads over,thanks ill give that ago in the next week or so ,john

dfree383 wrote:Measure the lift on all the Rockers.

Swap Spark Plug wires and Plugs from a known good cylinder to one of the bad ones. New plugs would be a good idea if you where having carb issues.

great idear ,ill do both of them asap ill keep you posted thanks john webb

Years ago i bought a fresh rebuilt 68 302 for 200 bucks from a boat guy because he could'nt find the misfire problem and he checked all the stuff you did and still it would misfire. So he bought another 302 my brother rebuilt and put his dizzy in it and had the same problem again the motor i bought from him ran like a charm after all the crap he did swapping motors and all the parts it finaly came down to a cracked distributor unit.