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Need Mark V Carb advice

8K views 10 replies 5 participants last post by  v8440 
#1 ·
I have had lots of fun reading this forum, but I now have a pressing carb issue which requires a not-so-easy decision. I read bad things about the default Carb on my 1977 Lincoln Mark V with the 460. I have the reman’d version by Autoline. Actually I have two. I had the C8041a that was the right version for that year, and it got wonky. My mechanic felt that the c8040 in the trunk would work better. Perhaps it did for a while.

However, despite adjustments, it is now flooding the engine. The local carb rebuilding guy suggests I should just get another reman. Price seems to be $260 on rockauto. However, I worry that it will just be another carb that Mechanics complain about. I have heard nothing but complaints about the crappiness of the carbs that are original for these by most mechanics who have worked on it.

I have had lots of issues with the performance and almost all were blamed on the carb. This could be true, or not. It’s not my area of expertise. My cylinders have been getting fouled up throughout the last 2 years (basically, since I bought the car).

The other advice I was given was to get a Holley. Apparently 0-80783c, and that it would be a much better performing and more reliable carb. However, that carb is $498. If it won’t be a significant improvement, and if the reman would be perfectly fine, I can’t justify the extra cost. However, I am torn, because I want it to just work and I am getting a bit bored of excuses. Please wisdom-heads, advise...
 
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#2 ·
Look for a used edelbrock performer 460 intake and get rid of that spread bore intake.

A holley 600 vac secondary carb with ford kick down
Properly curved distributor
Straight up timing set.

The above will significantly improve driveability, performance and economy.

On a more temporary basis your can use this adapter from transdapt to use a square bore holley and get rid of the troublesome 4350 spreadbore carb.

https://www.summitracing.com/parts/...O-dDUuky2lM6uu7xmsc3gX33Z9vjfTRRoChBgQAvD_BwE



SJ
used 2b RHP

:D
 
#3 ·
Thank you for the fast response, and for the info. Some updates...

Since I posted this, an old mechanic who I love got back to me. He doesn't do private work often, anymore, but he is an amazing mechanic. He has suggested that I could just bring him the c8041a and a rebuild kit and he would rebuild it. It would be much cheaper than getting a new carb. But I assume there are other advantages to switching to a new carb, like the aforementioned efficiency and performance? I am waiting to tell him about the info you gave for when I think he is done with his work for the day. If anyone was to install a new carb and tune it, I would prefer it if it were him, as he has tons of experience with carburetors and is reliable.

Is the 600cfm a better choice than the 650 that Holley recommended last year (the 0-80783C)? Or is it just less expensive? Eventually I would like to build up the engine, and I was hoping long term to get a carb that would support that without being terribly inefficient, and that was the model Holley suggested when I said that. They also said to get their part 20-91, which is the ford kickdown, and a 108-12 adapter to use as a spacer. Would that be a proper spacer for this, or is that Transdapt better? Other long term suggestions they gave when I informed them of various issues were:

For spark issues I have had, with one distributor replaced already, and plenty of misfiring"
MSD 8350 Distributor
MSD 6425 6AL Ignition Box
(no solid core wires to be used with these)

Is that distributor a "properly curved" distributor? I don't really know what that means.

I have had starter issues when more aggressive timing was set, and have burned out solenoids, and they offered the following suggestion:

Model 509223 Starter
and a MSD 8984 "Starter Saver"

When I thought I was having fuel pump issues again:

12-460-11 Fuel pump

What do you think of these suggestions for long term goals (1 year out or so)?
 
#6 ·
My mechanic said that Mad Porter’s advice is better than original plan of rebuilding and that the Holley would save a lot of grief from that reman factory carb. I spoke with Holley to ask about a 750 or 850. They said that 600 or 650 would be appropriate, but that based on the displacement of the engine and assuming a top rpm being around 5000 under normal use that a 750 would not perform as well across the lower ends of the operational range.

Seems to make sense, but I know some build ups call for larger and larger carbs without increasing displacement. So maybe not that simple? Would love your feedback.
 
#7 ·
In a completely OEM configuration excepting the straight up timing set and properly curved distributor with factory exhaust manifolding and duals a 600 to 650 is the best choice at this time. At best the engine will be making 275 hp.

If at some point you graduate to a better breathing engine with mid length headers making 350 to 450 hp then a 750 holley is the better choice.

This particular carb is almost $150 less than a 650.


https://www.summitracing.com/parts/hly-0-80457s/overview/



SJ
used 2b RHP

:D
 
#9 ·
I hate when people don’t follow up to post their results and then I do the same damned thing. So here goes:

I got the transdapt adapter, and the Holley 650 (0-80783C), and the 20-91 ford kickdown. Gave all parts to the mechanic. He found out he needed a dual inlet fuel adapter, and some sort of throttle cable extension. Also, with the transdapt installed, there was a slight issue with the height of the air filter housing pressing into the insulation of the hood.

Performance was much better, even though he didn’t finish tuning it before I took it back. This was in the spring, and many car issues meant I needed a car to drive. But I’m hoping to bring it back soon to retune. The pump the pedal to set the choke does not result in the “high idle warm up” setting, so I have to do that by pressing lightly on the pedal for 30 seconds or so to get it smooth and to keep it from stalling.

Still having some poor spark issues, and my plugs get dirty quickly. But so much better.

Thank you for all of your help!
 
#11 ·
This is too late for you, but I'm a big believer in the newer street demon carbs. They're spreadbore, and have small primaries for economy, but great big secondaries for power-without the problems many old rebuilt carburetors develop over the decades. They're also fairly cheap. They make them in 625 and 750 cfm versions. I have a 750 on my '71 chevelle with a 468 big block chevy, and I love it.

Here's a link: Demon Carburetion 1901: 625 cfm Street Demon Carburetor 1-3/8" Primary Throttle Bores | JEGS
 
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