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Question on Cleceland specialists
#1
Hello:
I get an offer for a 73 Mach 1 with an rebuilt and tuned engine, but the engine does not run good at idle and at the lower rpms (- 3000 ) and smells like unburned fuel at the exhaust, black smoks at accelerate. The engine has a low vacuum at idle 5 hg and 25 hg at 6000 rpm. The block is a 4 bolt main 0.30 bored with TRW L 2348 F pop up pistons, Eagle H-beam rods, 4 MA crank 0.10 on main and rod journals and is balanced to close tolerances. The heads are open chambers Q code with new valves(Manley) springs, hardened valve seats and Ford Motorsport rockers 1.72. The cam is a 280 H magnum Comp Cams with matched springs lifters and pushrods. The intake is an Edelbrock Performer RPM toped with an Holley Street Avenger 80780 out of the box nothing changed. The distributor is an Mallory Unilite vacuum advance with Pro Master coil and the timing is set at 14° BTDC. There is an 7 qt. aluminium oil pan on the engine and a overhauled C6 transmission with B+M parts.
Should I buy this car with this engine?
Are the parts used on the engine good quality and due they match together or should somthing changed for good power, street and strip ?
The interior on the car is good, but the body needs some work, this is no problem, the engine is the problem. The engine has about 500 miles after rebuilt.
For all help, tips and ideas will be grateful appreciated
Ron
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#2
Sounds like it's running rich if you're smelling unburned fuel and it's smoking. Have you tuned the carburetor?

Steve



[Image: 25yvyp3.jpg]
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#3
The carb, 80780, listed on the Holley site is an 800 CFM double accelerator pump carburetor. This carb, if unchanged from Holley's calibration, has 6.5 in/hg power valves. If it only has 5 in/hg vacuum, and it black smokes, at idle it is very likely that the power valves are open when they should not be causing it to run very rich at idle (or it is not adjusted properly). They could be open because something is not correct with the installation of the cam or other valve train/timing problems. Or, the diaphragm(s) in the power valve(s) may be ruptured, causing them to be open. Most of the parts are good quality but, the pistons are a little heavy by today's standards. The cam is a good quality cam but not well matched to the Q code 4V heads. None of the above says anything about the quality of the machine work or assembly. Should you buy it, It depends on the relative price, how much rust repair is needed, what you want to do with the car, your mechanical ability, and how much money you want to spend. There are a large number of variables in play on this and it is impossible to sat buy it or not. I wish I could be of more help. Chuck
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#4
Great set up but. At .030 with the aftermarket parts. It's probably been run pretty hard. On the plus side, sounds like nothing that can't be fixed and you would have a great list of parts to build a fresh motor. JMO

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#5
c9zx;37284 Wrote:The carb, 80780, listed on the Holley site is an 800 CFM double accelerator pump carburetor. This carb, if unchanged from Holley's calibration, has 6.5 in/hg power valves. If it only has 5 in/hg vacuum, and it black smokes, at idle it is very likely that the power valves are open when they should not be causing it to run very rich at idle (or it is not adjusted properly). They could be open because something is not correct with the installation of the cam or other valve train/timing problems. Or, the diaphragm(s) in the power valve(s) may be ruptured, causing them to be open. Most of the parts are good quality but, the pistons are a little heavy by today's standards. The cam is a good quality cam but not well matched to the Q code 4V heads. None of the above says anything about the quality of the machine work or assembly. Should you buy it, It depends on the relative price, how much rust repair is needed, what you want to do with the car, your mechanical ability, and how much money you want to spend. There are a large number of variables in play on this and it is impossible to sat buy it or not. I wish I could be of more help. Chuck

I'm being totally serious when I say this, Chuck: every time I read one of your posts I learn something. Thanks for the technical insight, it's one of the things that makes this forum superior to some of the other forums (for me, at least).

Steve



[Image: 25yvyp3.jpg]
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#6
on my 302 i had a holly 600 and when it backfired once through the carb it blew out the power valve, and it drove and smelled exactley the same just my 2 cents and c9zx has some very valued points


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#7
c9zx is probably right. Does the current owner understand it isn't running right and is the price of the car adjusted for the poor running motor.

That cam is not going to have a really good vacuum at idle but it should be better than 5.

I would be a little concerned that the pistons were able to seat correctly with it running that rich.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#8
Same as others said plus I would check for intake manifold or carb leaks. Sounds like you may just have a simple leak somewhere.
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