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Discussion Starter · #1 ·
Hi guys,

So i recently installed a 408 stroker in my 1966 ford custom 500. The motor was ran on a dyno and performed great. I put it In my car and installed a 750ss quick fuel carb, summit ready to run billet distributor, ran it around for a little bit doing the standard brake in procedures and everything was going great. The engine only has around 200 mi. Then it started missing under 2000 rpm??? No noises, all cylinders have great compression. I checked everything in the ignition system, replaced the coil with another blaster 2 coil, replaced the MSD 6A with a new 6Al system and am still is having the same issues. I pulled the plugs and noticed that both CYL 1 and 5 were very lean( whiter then white) so i replaced plugs and jetted up the carb from 74 to 76 on the primary side. It still was lean on cyl 1 and #5 cyl so i fattened it up to 80's on the primary and it still was showing lean on the front cylinders??? I sprayed stater fluid around the intake to check for vacuum leaks and it didn't show any of the typical signs. I am at a loss, and have been spending alot of time and money in the wrong places trying to fix this issue, just ready to cruise and enjoy the summer. Any advice or help would be awesome!! thanks so much
 

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Hi guys,

So i recently installed a 408 stroker in my 1966 ford custom 500. The motor was ran on a dyno and performed great. I put it In my car and installed a 750ss quick fuel carb, summit ready to run billet distributor, ran it around for a little bit doing the standard brake in procedures and everything was going great. The engine only has around 200 mi. Then it started missing under 2000 rpm??? No noises, all cylinders have great compression. I checked everything in the ignition system, replaced the coil with another blaster 2 coil, replaced the MSD 6A with a new 6Al system and am still is having the same issues. I pulled the plugs and noticed that both CYL 1 and 5 were very lean( whiter then white) so i replaced plugs and jetted up the carb from 74 to 76 on the primary side. It still was lean on cyl 1 and #5 cyl so i fattened it up to 80's on the primary and it still was showing lean on the front cylinders??? I sprayed stater fluid around the intake to check for vacuum leaks and it didn't show any of the typical signs. I am at a loss, and have been spending alot of time and money in the wrong places trying to fix this issue, just ready to cruise and enjoy the summer. Any advice or help would be awesome!! thanks so much
what parts are different from the dyno pulls ?

what intake manifolds on the engine ? brand and type

after the increase in jet size , what did 3 thru 8 plugs look like ?

Summit brand , most if not all equal china made
 

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Discussion Starter · #3 ·
Hey DanH! Thanks for responding! The parts that were different from the dyno are, carb, distributor,msd 6al box and coil! So its a pretty broad place to start looking. After the engine was ran on the dyno I pulled the plugs just to take a look and they were coal black on 4 and 8, and really lean on 1 and 5, gradually getting richer towards the back of the cyl bank. I ended up replacing a lot of parts for known good parts and ended up finding 3 bad spark plug wires that got alittle warm from the headers, when the engine warmed up the silicone must of started separating allowing the spark to arc agains the header primaries! I took care of that issue and the plugs are still burning very uneven from front to back?

The intake is an elebrock performer rpm,
Quick fuel 750ss carb with #80 jets primary 74 secondaries.

It almost seems like an intake leak?

After I increased jet size the front plugs #1 and 5 started to get black at the base of the porcelain but bright white at the tip, the 234, 678, cyls just started to burn more rich, slightly black on 2 and then blacker to cyl 4 the same with the drivers side?

Thanks for your help
 

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check the intake bolts /retighten .

call Quick Fuel and get the specs for carb . ... jets , power valve , air bleeds and start from otb specs , plus a good carb seal to the manifold .
(new gasket)
 

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Discussion Starter · #5 ·
so the specs on the carb are 74 primary jets ( now 80)
Secondary Jets #80
Idle Air bleed #70
Hi speed Air Bleed #33
Primary nozzle 31
Sec Nozzle 31
needle and seat 110
power valve 6.5

I contacted quick fuel and they offered for me to send it back so they could take a look, if they pay for shipping and any repairs needed i am going to send it their way. If not i am going to try and find a carb that is know to be good! Thanks so much for the help! Trying to get this engine dialed in is a pain the the ass!
 

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so the specs on the carb are 74 primary jets ( now 80)
Secondary Jets #80
Idle Air bleed #70
Hi speed Air Bleed #33
Primary nozzle 31
Sec Nozzle 31
needle and seat 110
power valve 6.5

I contacted quick fuel and they offered for me to send it back so they could take a look, if they pay for shipping and any repairs needed i am going to send it their way. If not i am going to try and find a carb that is know to be good! Thanks so much for the help! Trying to get this engine dialed in is a pain the the ass!
a pain in the butt . where all the fun is , getting it dailed in .
best built race engine or stock...its the tune that makes it
 
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