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Technical discussions specific to 1964-1967, 1968-1970, and 1971-1973 Classic Mustang. Discuss all tech related to in-line six cylinder and V8 powered Vintage Mustangs here.

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Unread 08-07-2009   #1 (permalink)
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Default should i rebuild if so how?

Ok heres my problem. my motor is a 302 small block 4barrel with a 570 cfm carb. i have been seeing some problems lately like oil on fairly new plugs with little driving of the car. the car just isn't smooth as i think it could be. i have played with the timing but still when im taking off the first few rpms feel like its stumbling or well it feels rough but the upper rpms are smooth. my motor is at least 20 years old. Yesterday for example, i was playin around with it and it started popping out the exhaust like crazy i revved it and pop took one of the spark plugs out and saw it was covered in oil and put it back in the thing went back to normal and didn't do any more popping. i stopped working on it after that but i just feel my motor can have alot more Umph. also i don't see any oil or smoke EVER come out of the exhaust. so here is my question

Should i rebuild? if so how would i go at doing that? buying a rebuild kit from summit with new pistons?

Or another option i have been thinging of is if i rebuild it Should i stroke it? should i save up and get the 330 stroker kit? or the 347?

i need opinions cause i got an uncle who can help me rebuild it as he has rebuilt a 390 b4 and i trust him fully. its just a matter of SHould I? if i do should i upgrade everything? (cam, maybe hei distributer or some other kind) It really got me worried after it did all that popping yesterday so i have to ask.
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Unread 08-08-2009   #2 (permalink)
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Default should i rebuild if so how?

Hello shagadoodle,
First this advice comes from an old back yard mechanic.
You may not understand it all but we can fill you in.

Slow it down a bit and step back

The first thing you should do is find out what's going on inside the motor.
To do this I would do the following:
1. - Take a compression test on all cylinders. - A quick explanation of this is. -A compression test is done by pulling a plug and pull the coil wire.
A compression gauge has a hose, dial gauge and an end that screws into the cylinder.
You crank the motor 2or 3 revolutions then look at the gauge reading.
Repeat this process for each cylinder noting readings.

You can then do what is known as a wet test. In this method, you squirt a little oil into each cylinder and test. Don't do this until we see shat the dry reading are.
The wet test tells how the rings are.

SPECIAL NOTE - they make a compression tester that you hold into the plug hole, DON"T use this type - they can blow out...trust me. Get one that screws into the spark plug hole.

Step 2 - Take a vac reading of the motor when she is running. This will also tell a lot.

My advice is check the motor internals first before doing anything.
What you think is oil on the plugs could be a wet plug (gas).

If you don't see blue smoke or smoke out the exhaust that is a good thing.
It is quite possible what you have is a carb problem.

Since I'm on a roll I'll continue my advice:
1. - Set timming at about 10BTDC - leave it alone.
2. - Check dwell on points.
3. - Check/change distributor cap, wires etc.
4. - Clean/replace plugs.

Is you carb a street avenger? - even if it is not, the carb may not be set up right.

A problem that many people have is that they start to fool with too many things without actually helping anything. I know this seems like a long process, but it can be done and then the car will be right.

PLease understand I am not against building a motor, but it is expensive and my guess right now would be that you don't need to go that route yet.
I would try to learn on this motor and get her running right. By doing this you'll be learning a whole lot and who knows at some time you'll be building a Stroker or something very cool.

I can remember being young a long time ago and I know you want this right.

Just my 3 cents........ Print dad
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Unread 08-08-2009   #3 (permalink)
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alrighty I have to get new spark plug wires but ill get me a new set of plugs along with it My carb is a edelbrock. I'll play around with it 2moro but i had cleaned the carb not to long ago and rebuilt it at the same time. thanks ill try the compression test see if my uncle or if i can get a compression guage
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Unread 08-08-2009   #4 (permalink)
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I remember when I first saw oil on the threads of some of my plugs then soon after well guess what!? I blew a head gasket! So soon after I go into the process of replacing those thin gaskets, its been about a month since I have replaced them and the pony runs great, during this process I took my heads to a machine shop to be checked out. Next thing on my list is to rebuild my carburetor.
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Unread 08-08-2009   #5 (permalink)
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Hello shagadoodle,
I hope you understand, I'm not trying to rain on your ideas.
To me, it sounds like the motor may not need rebuilding.

A compression tester is an important tool but is not used too often. Perhaps you could borrow one?

I pulled my carb apart 4 times and finally gave up. There are so many small passages and ports.

Anyway....I still think I would find out how the motor is and then go from there........Print Dad
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Unread 08-08-2009   #6 (permalink)
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i totally agree with print dad. u might not have to go threw all the trouble of spending like 1000 dollars on rebuilding an engine ur not entirely sure even needs a rebuild. my pops payed some dude to rebuild my 302 that i had in my 65, he charged us like 1300, and the engine ended up having a messed up pushrod still. what im trying to say is, that might not be the solution to ur problem, its certainly aint cost effective. figure out why ur engine runs that way, spend ur money else where, sub frame connectors, rear sway bar, ur suspension. those are places that will make the car more fun to drive, with out breaking the bank. u should really consider what print dads saying, he knows what hes talkin bout.

besides stroking out the engine, may give u extra hp, at the expense of big bucks, but how u gonna slow that beast down? how u gonna pull threw the turns? set up the car to handle superb, then mod the **** out the 302. trust me, i took the moded engine route, instead of the suspension and rigidity, its not that fun, going in a straight line fast, but anything come up in front of ur ride, and ur gonna have a big problem.

fix the engine , get front disk brakes (get the brackets from northracecars.com the s197 rotor and calipers ones), subframe connectors, and a rear sway bar. gonna be less expensive, and more better to drive.
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Unread 08-08-2009   #7 (permalink)
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You need to remove ALL of the plugs when doing a compression test and set your throttle to wide open so you don't get any false compression from other cylinders or the carb. keeping pressure in the intake. I always suspect timing first when I hear of backfiring, a bad gasket under the intake or head at worst could also allow backfiring.
Have you tested your vacuum adv. on the dist. to make sure it's working? Remove your dist. cap and find the arm that extends from the vac. adv. and attaches to the dist. base plate. Disconnect the vac. hose from the carb. and suck on it while watching the arm in the dist., it should pull into the vac. adv., if it doesn't the diaphragm in your vac. adv. is torn. You can get a replacement one at a parts store.
When you set your initial timing be sure you disconnect that vac. line and plug or you'll get a false timing reading. Also the vac. hose from vac. adv. to carb. should be hooked into timed or ported vac. vs. full manifold vac. most carbs have both, look up your carb instructions online to see which nipple is ported.
Just a few things to start with.
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Unread 08-09-2009   #8 (permalink)
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alrighty sunday gonna try to see what all i can get done I have the vacuum lines disconnected and am running on mechanical advance as a long time ago i had an issue with carburetor backfire and was told to try no vacuum and do WOT and it worked but thanks guys lol i really don't want to spend money on rebuilding my engine cuz im tryin to save for a granada
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Unread 08-09-2009   #9 (permalink)
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My guess is it may be your timing chain. Does it run pretty good when cold, but when you play around with it gets worse? You said when you shut it down and removed the plug it ran better when you started it back up. When a stretched timing chain warms up it will expand and throw your timing of, but when it is cool you might not notice a problem at all. This was sometimes a problem with older engines when the alloys used in chain technology was not what it is today.
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Unread 08-09-2009   #10 (permalink)
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ok so far today unable to get a hold of the compression test equipment but removed all the plugs ALL of them were dry fouled (black as if it hadsome kind of carbon deposit) so i may be running too lean will try this week to get the compression tested.
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Unread 08-11-2009   #11 (permalink)
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A thousand dollars for a rebuild? Wow I dont even know what to say about that. I just rebuilt my 302 that had only 35,000 original miles on it. (It sat for 19 years and still turned over, I just didnt trust it). Let me give you a quick at a glance rundown of the cost and the process. Before you decide to go that route.

Machine shop to clean, boil, magnaflux the block, check for piston size, press the pistons onto the rods, turn and polish the crank, do a valve job and give everything back to you in bags. $1140.00 That is of course after you tear down the engine and take them the block, heads, crank, and main bearings, and pistons. That includes the rebuild master kit but is without the timing set, cam, and lifters. (As I decided to install a Comp cam, lifter, and timing set at an addition cost of $220.00).

Then you will want to replace the pushrods as you really shouldnt use your old ones after they have been used for 20 years and you now have a new valve job with new lifters, besides its $25.00 worth its wieght in piece of mind.

Then you will need some engine assembly lube, cam installation lube, two torque wrenches, one for the high torqe bolts like head bolds at 60-70 ft lbs and one for the lower torqes like the rod bearings 19-24 ft lbs

Then you will want to make sure all of your old gasket surfaces are cleaned, like the intake manifold ect. With mine I didnt have that problem as I installed all new parts.

Next you will have to ensure that the main caps and rods/rod bearings are all installed in the same positions they were in when you took them out, or the rods will not fit on the crank, ect.

All the bearings will have to be installed properly by somebody that knows what position to put them in. This is very important, you would not want to spin a bearing on initial startup and have to start all over again from scratch. Not to mention a waste of all the money you spent on machine work. ie. the pistons have to go in with the notch on the top facing forward, and the bearings have to go in with the slots over the oiling holes. I would deffinatly not recomend you putting the engine together without somebody that knows what they are doing. Like I said, one mistake can cost you the whole thing. And it could cost you even more if your engine block is a numbers matching original engine from your classic car and it ends up not being able to be rebuilt.

So you can now see that if you rebuild it and you want to do anything else to it like balance it (an extra $160.00 to $200.00) or add an edelbrock intake (an extra $150.00 to $225.00) or a new carb ( an extra $150.00 to $450.00) or add a bigger cam or anything else. Now you are starting to get the picture of how it all adds up. And you are starting to see why I shake my head when people say they can rebuild an engine for $1000.00. Sure it can be done, but the real question is, do you want it done right? You can see some before, durring and after pictures along with a discription of my rebuild on page 4 of my thread at http://www.allfordmustangs.com/forum...akeover-4.html
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