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1966 mustang Low vacuum?

4K views 19 replies 7 participants last post by  GT289 
#1 ·
hey guys,

I got the original 289 engine rebuilt on my 66 with some mods. Bored .30 over, double roller chain, flat top pistons, edelbrock performer intake, edelbrock 500cfm carb, list goes on.

Ever since I got the car back, its never really idled good and it has been getting worse. Lately it feels like the car jerks forward when Im at a red light. Even when I got the carb adjusted via O2 sensor, it ran a little better but it still didn't idle as well.

I recently went to a performance type shop, and they said that because it has a bigger cam, I have to switch the torque converter for a higher stall one. Will a higher stall converter raise the vacuum? I haven't checked what the vacuum is to be honest but I'm pretty sure thats the culprit. I will check when I get back home, currently out of country.

One last thing, when I barely got the car I stupidly drove it on 2nd gear(green dot) for a while. This is my first car and tried to make sure I was driving it so that it will go through all the gears but it was all confusing as everyone said a different thing. could the tranny be on its way out?
 
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#2 ·
First thing I would do is connect up a vacuum gauge to the intake at the point where the vacuum line to the transmission modulator is connected & let the engine idle. You are looking for a steady gauge needle in the range of 15- 21 inches Hg. (depending on your camshaft profile). Next put the modulator hose back on the intake, go underneath the car, pull the vacuum hose off the modulator & connect the vacuum gauge to the hose. Start the engine & let it idle. You are looking for the same reading you had at the intake. If this is so, plug the hose back onto the modulator, grab a strobe & check your ignition timing at idle (with the distributor vacuum hose off & plugged) & total mechanical advance. Post back with the results.
 
#3 ·
OK, first, the 65-66 "green dot" IS the drive position.

P
R
N

O
L

The "O" gives you normal 1-2-3 driving. The "•" eliminates 1st gear for driving in rain or snow. This was very confusing for people who threw away the owner's manual, so Ford switched to a more conventional PRND21 pattern in 1967.

A higher stall converter will have little or no effect on your idle.

We need to know more about your cam. A lot more.
 
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#10 ·
OK, first, the 65-66 "green dot" IS the drive position.
......".
^^^^^^^^ this.

Whoever is telling the OP otherwise should not be listened to regarding the car.

OP: I know this classic car thing is new to you, and sometimes confusing. Even here you will get conflicting advice. Your best bet is to do these three things.

1). Buy an official Ford shop manual, you can get them thru Amazon on CD or in print format. The information there will outweigh 99.9% of everything else you will hear

2). join a local vintage Mustang club. There no substitute for face-to-face help

3). Thru the club you will find a LOCAL qualified and endorsed vintage Mustang repair shop. Bring them some coffee and donuts, and hang out there for a morning. Get to know them.


These three pointers will do more than anything else to ensure your vintage car experience will be a positive and enjoyable one.


Z
 
#17 ·
Yeah, its a c4 green dot auto trans. I will have to check if the numbers match though, since the small dot and green dot have been swapped. I learn new things about my car every year to be honest haha. But its really clean, body shape wise. Its daily driver thats for sure.
 
#18 · (Edited)
Outrage, am I reading your extra small picture correctly that you have 204 degrees at .050 ? That is by no means big, and if that 204 number is right, you certainly don't need a new convertor. Have you checked with a mechanical guage to see what the vacuum actually is ? LSG
Stage

2

Type

Hyd.

.050'' Dur. Int.

214

.050'' Dur. Exh.

224

Cam Lift Int.''

0.296

Cam Lift Exh.''

0.311

Valve Lift Int.''

0.474

Valve Lift Exh.''

0.498

C/L Int

108

C/L Exh

116

Lash Int.''

Hyd.

Lash Exh.''

Hyd.

hahaha extra small picture. I managed to copy the info from the website. here are the specs. I have not checked the vacuum, that should be my first step i know. There should be some youtube videos on how to do it. Ill do some research.
 
#14 · (Edited)
I think it's this one......

Engine Parts Catalog

If so, it's pretty puny. Should be able to get great vacuum numbers with that one.
That's the level of cam the typical generic machine shop would recommend for a slight bump from what they consider "stock."
Especially if they're used to building brand X engines.
 
#19 ·
hahaha puny. the website didnt pop up. its camshaft number ES1020R. But yes, thats exactly what I asked for, just a slight bump from stock. I drive this car every single day and it has been pretty reliable. except now that I have to figure out the idling issue. I just want it to run at its best.
 
#15 ·
yeah i see what you're saying. Im in a classic mustangs group already and they do know mechanics that work on only mustangs. Ill ask them at a future meet and see what they say.

I'm new at classic cars and this is my first car. Ive already learned a lot doing some work myself with my dad. but yeah buying some manuals would benefit me a lot. that way I at least have some clue of how things work. thanks for the tip.
 
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