Hey guys need some help on making my engine run better thanks in advance

[Mustang ttop]

Ok I have a 1985 gt with a 1990 mustang 5.0 motor in it it has an edelbrock 600 carb and I thinck it has a mild cam from wat I was told first question is what would be the ideal timing I have it set at 12 degrees advance that's stock Right and also when checking vacume with a vacume gauge where do I hook the gauge to the carb or the manifold and what should it be reading thanks for any info and if their is anything els I should be checking out let me know I'm also new at carbs I've always had fuel injection thanks in advance

[erratic50]

What you want to do is start by figuring out if your timing marks are close. Put tape on the balancer. Put a pin down the spark plug hole on #1. Turn the motor by hand until it touches the pin and mark the balancer. Rotate it the other way and mark it. Measure it out and mark the mid point, that's your TDC.

Now pull the passenger valve cover and see where your cam timing is at. When you bar over the motor you should be able to get a rough idea on cam lift and even duration using the same tricks.

What the ideal timing is depends upon a lot of factors like compression and fuel octane, swirl factor in the head, etc. You should be able to use a timing light and rev the motor up and keep adjusting your base timing until you see around 36-38 degrees total advance all in.

Frequently you can turn the distributor until the motor just starts speeding up then back just a little bit. If the motor cranks hard it's advanced too far.

[dynodon64]

There are a lot of factors that effect how much timing an engine needs. Basically stock engines are fine with 12-14 degrees initial. Max all in timing shouldn't go over 34-36 with mechanical advance. When vacuum kicks in under light load, then you could go as high as 40. If the engine is low compression, less than 9:1, premium gas, these numbers are fine. If you use 87, then you will most likely run into pinging.

[ashley roachclip]

Connect the vac gauge to the manifold .

[Mustang ttop]

Thanks for all the advice and how about the vacume advance to the distributor a guy I work with said to disconnect it and cap it off is that a good idea or not and lol i mean I've seen them disconnected before but I don't know is their any benefit in doing so

[Walking-Tall]

The (mechanically-disconnected) guy you work with must be interested in less-than-mediocre function, and horrible fuel efficiency (unless your foot's on the floor everywhere you go anyways), which is what disabling the vacuum advance will do. Bad idea, the polar opposite of the word benefit.

Good article for understanding Ford distributors and for timing/tuning an engine to perfection :
http://www.fordmuscle.com/archives/2000/03/timing/

[erratic50]

Totally agree - lots of factors determine what timing should be.

Bear in mind that if you bring in more timing without adding fuel you can end up lean. If you go up a jet size and add more advance and it responds positively you're on the right track.

If you go overboard on timing you can cause some big problems. Head gaskets, burnt pistons, etc.

A safe tune has a margin of safety that will often leave up to 10% power on the table.

[Mustang ttop]

Thanks guys for all the info I'm trying to get this thing running rite you guys are awesome I have soooo many more problems it need's wire harnesses a floor a radiator core support with fender aprons I'm trying my best to restore this car I got it for 150 plus getting his car running I figure that car is a little rare being a 85 ttop wat I don't want is to take it to the scrapper so all I can do is do my best to restore it one again thanks

[KevinVarnes]

The only reason you should disconnect and cap off the vacuum for the vacuum advance is when you are adjusting the base timing. Is it possible that is what guy at work was referring to? Otherwise as mentioned there is no good reason to remove it or disconnect it.

[Mustang ttop]

No he said everyone caps them off then he said do you see drag cars with them on I mean he is a pretty good mechanic I go to him for a lot of different stuff but I was kinda second guising that and I figured I mite get a better answer here lol he's a Chevy guy anyway lol I'm a die hard mustang fanatic I mite as well ask the other die hard fanatics you know

[Walking-Tall]

What you will see is numerous "drag cars" that, as mentioned above, do nothing but "function" either on or off, sitting gathering dust, or foot to the floor down the 1320, which has nothing at all to do with any kind of functioning and driven street vehicle. Anything driven on the street, and with most instances of even racing, a properly functioning vacuum advance pays more dividends than if it's disconnected. Anybody who doesn't understand the benefits of vacuum advance, most especially connected to MANIFOLD vacuum, has no business working on cars, much less giving advice to others looking to optimize how theirs runs. Sorry, but he's unfortunately a typical bow-tie blow-hard. Bow-tie blow-hard Chevys make a whole lotta f-ing noise and GO NOWHERE. Dialed-in Fords can be refreshingly noisy, and they haul ass.

[Mustang ttop]

Hahahah your awesome

[Mustang ttop]

Yea I think I'll stop asking him questions and listen to you guys

[xctasy]

Yea I think I'll stop asking him questions and listen to you guys

Ask him all the questions you like, but play dumb...and then check it out. At days end, you deecide what is the best use of your time to fix the bolts falling off the space ship.


Failing on the "Checkin it out" phase is the problem.


Talk is good, even crap talk. It only costs your time, and sometimes, even the most wrong guys, give you little snippets of advise. Again, you don't have to do what everyone says, you check it out, and pick your battles.


Hey, normally idle issues are float level surges with Edlebrock carbs, often a little hard to fix. The replacement Carter fuel pumps are often now similar to the 1982 on Ford 5.0 spec, way above 7 psi. At that pressure, its time to fit a fuel regulator. The old 4-bbbl Factory Holley, it was designed around 8.5 psi peak, and that kind of pressure will cause problems.

Just major on what you need to do, Rome wasn't built in a Day..you don't have to do it all.

Just make sure you don't do a Nero if it p!55e$ you off. 20000 parts sometimes decide to conspire against you at exactly the wrong time....


Great car. Get some advice, and enjoy it.

[KevinVarnes]

No he said everyone caps them off then he said do you see drag cars with them on I mean he is a pretty good mechanic I go to him for a lot of different stuff but I was kinda second guising that and I figured I mite get a better answer here lol he's a Chevy guy anyway lol I'm a die hard mustang fanatic I mite as well ask the other die hard fanatics you know

Top fuel dragsters don't have starters or alternators, but that doesn't mean I want to remove them from my street car. As Walking-Tall stated most are dedicated race cars that don't need to be drivable on the street. This guy might be a fine mechanic, but I would certainly question that after receiving advice like that.

[Mustang ttop]

I don't really have a idle problem the car sounds pretty good I'm just trying to get the best out of the motor fine tuning type but I do have a Holly mity mite rule pump with no regulator and it only has like 3 and a half psi and when I hit the throttle it will drop a little is that bad I read that edalbrock carb should have like 5 and a half psi I do have 2 other fuel pumps I just need to get a a regulator thanks again everyone for the info Im glad I joined this forum

[erratic50]

Read the plugs. Do they show evidence that it is lean? If so fuel pressure can help but in a carb setup delivery is more so decided by float level and jet size, etc.

All pressure is going to do is determine how fast the carb bowl fills and how much pressure from the float is required on the seat to turn off the flow of gas.