Ford V8 Discussion Discussion relating to getting the most out of your Ford-based V8 Miata's engine

Carbed 302 Running Issues

Old 04-22-2019, 11:16 PM
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Default Carbed 302 Running Issues

I just bought a 1995 with a carbed 302W last week and it ran but would die and sputter at low rpms when I bought it. Now, after just changing the plugs and cleaning the cap and rotor it won't stay running at all and when it does turnover, it backfires out of the carb. The plugs were plugged into the cap in a really weird order, so I tried starting it with the other two SBF firing orders and each ran terribly. Now when I put it back to the way I got the car, it is still not wanting to run. I gapped the plugs to .040 where the old ones were set at about .035, but I can't imagine that is the only issue.

The engine has an unknown aftermarket cam, aluminum heads, high rise intake, holley 600 carb, procomp distrubutor etc.

I will be running a compression check tomorrow, but for now is there anything that comes to mind to you guys for what else I can do?

I know this is an extremely broad post, but I am all sorts of confused.

Thanks for your time,

Aidan
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Old 04-23-2019, 04:54 AM
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Has the distributor been removed? Make sure not 180 deg off?
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Old 04-23-2019, 07:48 AM
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Put #1 up on TDC and check to see where the rotor is pointing. Also make sure the balancer has not slipped.
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Old 04-23-2019, 08:22 PM
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tbone is the man on this subject. But, a couple questions; have you put fresh gas in and have you checked the timing? Back firing through the carb is usually a slow timiing issue or mis-wired plugs. I have no doubt you already know this, but just in case on your engine the cylinders are numbered front to rear 1-2-3-4 Passenger's side front to rear 5-6-7-8 driver side.

Edited to correct major error.

Good Luck,
RonR

Last edited by 5.0MX5; 04-24-2019 at 06:53 AM.
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Old 04-23-2019, 08:25 PM
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Originally Posted by jrmotorsports55 View Post
Has the distributor been removed? Make sure not 180 deg off?
That is a good idea, I will check when I have time. Although I was able to drive it down the road a couple times before changing messing with it.

"Put #1 up on TDC and check to see where the rotor is pointing. Also make sure the balancer has not slipped." I am planning on doing that after I do a compression test. Do you use a screwdriver in cylinder 1 and turn the crank until it's at its highest? What do you mean the balancer has not slipped?Thanks for the response guys
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Old 04-23-2019, 09:06 PM
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Originally Posted by 5.0MX5 View Post
tbone is the man on this subject. But, a couple questions; have you put fresh gas in and have you checked the timing? Back firing through the carb is usually a slow timiing issue or mis-wired plugs. I have no doubt you already know this, but just in case on your engine the cylinders are numbered front to rear 1-2-3-4 Driver's side front to rear 5-6-7-8 passenger side.

Good Luck,
RonR
Uhhh I was under the impression that the cylinders went 1-2-3-4 front to back PASSENGER and 5-6-7-8 front to back DRIVER... All the pictures I see online illustrate that order, but if you are correct this could absolutely solve my issues.

I have put in fresh non ethanol premium gas, but have not checked the timing (honestly not sure how). It could very well be a retarded timing issue as even when we first started it at the guy's shop it backfired out the carb once or twice.

Thanks for the response!
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Old 04-24-2019, 06:56 AM
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It'd been a long day is my only defense. Yep, it's weak I know. You are CORRECT, number one is on the passenger side. Ford isn't my first language and the only way I coulda been right is if we lived in England!

On checking the timing, first is to get #1 on TDC compression. Pull the coil wire, then pull #1 plug, plug the spargplug hole by placing a finger over the hole and have someone SLOWLY bump the starter till you feel compression against your finger. Then manually turn the engine and use the long thin screwdriver against the piston (as you mentioned above) to determine TDC. The distributor must be wired so the rotor is pointed at the distributor tower for #1. At that point it should crank once the proper firing order is followed with the plug wires. I'd go with the HO firing order as a first effort.

To advance timing you ever so sightly turn the distributor in the opposite direction of the rotor rotation, that's be clockwise for more timing. Timing is a simple thing that requires a book's worth of discussion to cover. A timing light and possibly a vacuum gauge are tools to set timing.

The old school shade tree method is to advance timing till the starter slows down while cranking, then back it off a bit. Then go for a drive on a empty road and accelerate in high gear, sorta lugging the engine. If you hear pinging or pre ignition, back the timing off in very small increments till the pre ignition goes away. At that point your timing is adjusted for the octane fuel in the tank. If it doesn't ping initially advance till it does then back off till it doesn't.


Good Luck
RonR

Last edited by 5.0MX5; 04-24-2019 at 07:23 AM.
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