help me fix my missing 302HO

DarkoStoj

DarkoStoj

A mysterious figure named Darko
I just bought a 65 mustang and its got a 302HO in it with a miss that i've been trying to figure out. I hate when things like this happen because it seems like you just have to guess as to what the problem might be and you end up replacing a lot of stuff that you dont have to to fix the problem. Its a 87 302 with a F303 cam, air gap intake, holley 750 double pumper, world windsor jr heads, msd large cap distributor, msd wires, 6AL ignition, and NGK UR4 spark plugs. I pulled the plugs and they were the wrong kind for the heads, they were like a .700 reach plug where the heads need a .460 reach plug and I thought that would have fixed it, but it only runs a little better after I did that. I cleaned all the terminals in the dist cap and that also helped some but there is still a miss. I was thinking about getting new taylor plug wires next but the wires on it look like they are brand new and i think it would probably be a waste of money. What do you guys think I should do next?
 
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check the wires resistance

bypass the MSD box

whats the timing set at?

is the F303 degreed properly?

compression/ leakdown test

750 carb seems big to me for a 302

just throwing it all out there before you buy parts. these things should tell you at least something before throwing parts at it.

wanna sell it?
 
Cheapest test would be to measure the resistance of each wire... corrosion on a contact somewhere could also cause a miss.
 
LT1Pat said:
Cheapest test would be to measure the resistance of each wire... corrosion on a contact somewhere could also cause a miss.
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Although this is a very true statement, how can any one with a mustang take advice or trust someone who's screen name is LT1pat? Maybe just a set-up to get us to waste alot of time so we can't be out picking off LT1's ? :icon_mrgr
 
89notchback said:
Although this is a very true statement, how can any one with a mustang take advice or trust someone who's screen name is LT1pat? Maybe just a set-up to get us to waste alot of time so we can't be out picking off LT1's ? :icon_mrgr
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Pat told me a little about his car. **IMPRESSIVE**
I'm not sure there are many mustangs on here up to the challenge.

The thing that impressed me is that Pat does ALL the research before starting a project. I'm sure he will forget more about forced induction/turbo's than I will ever know.
 
The optispark was and always will be the king of all ignitions.




89notchback said:
Although this is a very true statement, how can any one with a mustang take advice or trust someone who's screen name is LT1pat? Maybe just a set-up to get us to waste alot of time so we can't be out picking off LT1's ? :icon_mrgr
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ok there is 5000 types of misses or more...

Be alil more descriptive as to what kinda miss you have and when it happens?


Is it a hard miss thats present at idle and any load and throttle postition.

does it start in high gear only or under signifcant loads only..

Is it only at idle?


Stuff like that needs to be answered.


You can have a miss caused by fuel stuff, ignition stuff, hurt hard parts, fubbared valve train etc.. get my drift?



Everyone that just jumped to an assumption its a ignition problem needs to go work on lawn mowers.
 
well i messed with it. I changed the plug wires to taylors, new NGK UR4 spark plugs, cleaned the terminals on the dist cap.

I got it running much better now and I only have a little missing when I am at cruise speeds. Say i'm cruising along in 5th gear and give it some throttle it will stumble/miss. I have the idle mixture screws 2.5 turns out now and its still a little lean because when I stop at a light the car wants to die for a second if I dont tap the throttle. I'm thinking it may be lean on the transition circuit on the carb so i'm gonna open up the IFR's a little more to see if it helps.

a thing that is really bugging me is the clearance with the plug wires on the headers on the drivers side. I have world windsor jr. cylinder heads and they were "clearanced" by the PO with a big hammer...but the plug wire boots are still touching the headers. I have the heat boots over them but I dont think its going to help much since they are in direct contact.
 
DarkoStoj said:
well i messed with it. I changed the plug wires to taylors, new NGK UR4 spark plugs, cleaned the terminals on the dist cap.

I got it running much better now and I only have a little missing when I am at cruise speeds. Say i'm cruising along in 5th gear and give it some throttle it will stumble/miss. I have the idle mixture screws 2.5 turns out now and its still a little lean because when I stop at a light the car wants to die for a second if I dont tap the throttle. I'm thinking it may be lean on the transition circuit on the carb so i'm gonna open up the IFR's a little more to see if it helps.

a thing that is really bugging me is the clearance with the plug wires on the headers on the drivers side. I have world windsor jr. cylinder heads and they were "clearanced" by the PO with a big hammer...but the plug wire boots are still touching the headers. I have the heat boots over them but I dont think its going to help much since they are in direct contact.
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Why do you think its lean? Have you checked the bowl levels?

Are the air bleeds clean on the carb or all nasty cuz no ones ever checked them?

Instead of just changing stuff and risking just making things worse try and find the cause and correct it.
 
igotaneed4speed said:
Why do you think its lean? Have you checked the bowl levels?

Are the air bleeds clean on the carb or all nasty cuz no ones ever checked them?

Instead of just changing stuff and risking just making things worse try and find the cause and correct it.
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i checked the bowl levels and they are set properly. I took the carb all apart and blew out all the passages with compressed air.

I checked the ohm resistance on the wires so I changed those because one of them wasnt showing anything at all. I changed the plugs because the car had the wrong ones in it.

I don't really know what else to check so i'm gonna mess with the carb this week to see if it has something to do with that
 
Check your jet size on the carb. Chances are it still has the jets in it that it came with. I had to rejet my 302 after my cam swap because it was running rich and missing. I went down a few jet sizes and it cleared right up. Another thing you should do is a compression test. If you have even the slightest problem with the valvetrain your going to get a miss. I never take for granted that the previous owner knew what they were doing (especially if I see indications of a BFH being used).

Throwing parts at it doesn't usually fix the problem it just hides it a little more.
 
DarkoStoj said:
i checked the bowl levels and they are set properly. I took the carb all apart and blew out all the passages with compressed air.

I checked the ohm resistance on the wires so I changed those because one of them wasnt showing anything at all. I changed the plugs because the car had the wrong ones in it.

I don't really know what else to check so i'm gonna mess with the carb this week to see if it has something to do with that
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Like its been mentioned I think you need to do a compression test. That way its ruled out even more so if it had the wrong plugs in it and they were to long, you could have a some piston or valve damage from interference with too long of a plug.



glh_turbo22 said:
Check your jet size on the carb. Chances are it still has the jets in it that it came with. I had to rejet my 302 after my cam swap because it was running rich and missing. I went down a few jet sizes and it cleared right up. Another thing you should do is a compression test. If you have even the slightest problem with the valvetrain your going to get a miss. I never take for granted that the previous owner knew what they were doing (especially if I see indications of a BFH being used).

Throwing parts at it doesn't usually fix the problem it just hides it a little more.
Click to expand...


You have your baby yet?
 
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