Topic: Questions on 351C Performance

[Reggie]

I have a 351 Cleveland 4bbl 1973 Ford Mustang.  The car starts OK but it doesn't have very good performance. The engine hesitates slightly when I agressively step on the gas.  I see a bit of black smoke when I start during warm up, and I think it is running a bit rich.  I changed the plugs, plug wires, rotor, cap and replaced the points with a magnet system.  This really improved the car's performance as it was hesitating real bad before I did this.  I set the timing at 6 degrees before TDC.   I've been told that I now need to rebuild the carb if I am still having problems.  I was thinking about buying an Edelbrock 650 but was wondering if anyone could give me some tips on whether this is a good idea.  I was also looking at a Carter AVS 650 CFM (rebuilt) as it is much cheaper.  Claims are that it is the same as an Edelbrock 650 CFM.  The car has not been modified other than going from a 2bbl to a 4bbl and dual exhaust, but no headers.  

Do you think a carb change will help improve my performance?  Any other recommendations?  I was thinking about also replacing the intake manifold, and would welcome any recommendations.  The car starts good and is reliable.  It runs very smooth but idles a little rough.  If you never stepped hard on the accelerator, you probably wouldn't think there is a problem.  Carb and manifold look like stock Ford equipment.

[racedraper]

defently get the edelbrock card. all adjustments are exturnal. but carter will be fine also. I would also get the Ignitor. Its a direct replacement for points and condincer,this makes its electronic with out all the wires al fit under the distributor cap and only cost 75 bucks. Headers will also help. making it breath is what it needs. Also what is your gear ratio. if it is anything like my 73 its a 2:72 very high gear, out a 3:73 and watch you head snap back.. replace the air filter with a nice K&N it helps with air delivery plus it reusable. Does your car still burn LEADED gas or has the Valve seats been changes out?

what is your spark plug gap? even though they sell pre gapped plugs they are never the same. this will also cause small preformance problems.. with everything I sudjested it should cause about 1000.00 bucks total unless you shop Ebay and get great deals. But I would first get the Ignitor Box for sure

[Reggie]

I tried the Ignitor and it seems to work well.  No adjustments, seems pretty solid.

I think the ratio is 2:72 as this was the original ratio and I don't think that there was any change to the differential.  I will see what it takes to change to 3:73.

I found a rebuilt Carter 650 CFM on Ebay for $175.  I was cautioned about buying a rebuilt, but a new 650 CFM Edelbrock is $330.

I replaced all plugs and gapped everything to 36.  The plugs I removed looked like they were gapped to 45.  The timing spec for a 2V is 6 before TDC, but for a 4V it is 16 before TDC.  I am using 6, but I may try 16 and see how it runs.

I've been running 93 unleaded in the car but I don't know if the valve seats have been modified.

Sounds like I would be better off buying a set of headers before changing out the intake manifold?

[racedraper]

call PAW If  I remember I bought a new edelbrock 600 cfm carb and preformer manifold for 400 bucks as a combo package. you can also upgrade the distributor ,and that a cleveland a 429/460 is the same.

Im with you I never have change the rear end . And yes 2:72 is stock gearing .It was the attempt to help with fuel economy lets see you stang post a pic

[Reggie]

Not sure if I posted the picture right.

The car is in pretty good shape.

[Reggie]

Trying to save a picture again.

[ Attachment Invalid Or Does Not Exist ]

[racedraper]

nice love those wheels ,what size are they? but you need to loose the cobra emblem, just dont look right

[mustanger]

Hi,i got a 72 mach i and had the same problem with carb i put on a new holley for around 275.00 with a electric choke and i haven't had a problem sense.My car was suppose to be a 2v also.

[Reggie]

Advancing the timing from 6B to 16B helped a lot, but I think a new carb will improve the performance a great deal.  I've used to have a Holley carb on a big block Chevy when I was a kid (30 years ago).  Edelbrock was not making carbs back then, but they seem to be well regarded.  I've also heard of a Demon carb, but know little about these carbs.

[Reggie]

I took the Motorcraft carb off and took the top off.  The top gasket was seeping and the body is pitted and has a couple of heavy scratches/dents on the gasket surface that are leaking.  Looks like the bowl was overfull.  I started the car before taking the carb off and the manifold was wet.  That might not be a bad thing, but I know the carb body is not a good sign.  I don't think I'm going to put any time in this carb.

[Reggie]

Racedraper, the wheels are 9.5 inch wide.  The tires are 245/45ZR17  95W.  I agree about the Cobra emblems, I'm going to lose them.

[racedraper]

Il prob use that size or atleast 50's in the back.

Deman carbs are real good on a modified engine. I know who you fill, there are alot of choices out there.

good luck on it

[Reggie]

I was thinking of the 600 CFM Edelbrock or the 575 CFM Demon Jr.  They are compatibly priced.  I called around town for prices, but it looks like I'm better off just ordering from a company like JEGS.  

I finally figured out how to tell if I had 4V or 2V heads, the 4V's have the number 4 cast in the upper corners of the head just next to the valve cover gaskets.  I was kind of suprised because the car was originally a 2V 351C, which was a pretty common engine.

[racedraper]

commen yes and no. they are harder to find these day and people want them. they are getting expensive .I sold mine for 1000

you get good hp out of the cleveland

[Russ]

Okay I guess I let this one slip threw the topics. I have a 2V and cannot seem to get crap out of it, but haven't really tried, so that might be my problem.

  Edelbrock and carter are the same carbs. It is just like Snap on and Blue point, or Chevy and Satrun, . They may not even use the same parts, but the bigger companies make them to branch off from the major name and sometimes get big names in return without trying.

I didn't know about the 4V's have the stamp on the corner, which I guess I won't have to worry about it on my little 2 valve heads,lol. I would like to get someone to break it down to me barney style on the difference in the heads and if 2 BBL and 4 BBL and what is the match of matchs. if you have pic you need to post it on here brother so I can see what race was talking about. I also have the 2:75 and I am not happy with it but I think I am going to go with a 3:55 try to stay right in the middle.


Sorry it took so long to find this but would like to stay in touch.

[fjt226]

Reggie,

You received many great suggestions from the other posters here but let me jump out on a limb here.  There was no mention of the condition of the long block.  Your information says you are a newbie, like me, however I do have a sound foundation in mechanics.  So here goes.

The first thing that you should be sure of is that all the cylinders are working properly.  To do this you need to perform, or have performed, a compression check.  If the compression across all eight cylinders is not within specs you can rebuild carburators, change plugs and wires, add headers, or anything else you want to do, and the engine will never run quite right or give you the advantages of all the things you have added to it.  So if you haven't, do a compression check.  If that shows the motor is okay then definitely consider the comments of those before mine.  If not, then rebuild the block, or get a new one, then consider those comments.

Good luck.