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more torque for my 351C?

  
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more torque for my 351C?

 
Sprockets72 Sprockets72
New User | Posts: 22 | Joined: 06/09
Posted: 07/06/09
10:12 PM

I have been interested in cars for a long time, but I just purchased my first classic, a 72 grande with a 351C 2v and I noticed it doesn't have much torque.  I have heard it said that the Cleveland engines are set up to have more top end power.  I was wondering what I could do to get a little more torque out of my car.  I was planning on upgrading the carb and intake to an edelbrock system because I heard that would provide more horsepower.  Any tips for more horsepower or torque that I could install as a new hobbyist would be fantastic.  

 
shiftthis shiftthis
User | Posts: 188 | Joined: 04/09
Posted: 07/07/09
10:24 AM

How many miles are on the engine since last rebuild ? A worn engine should first be rebuilt, do a compression test. If the compression is low then first rebuild but dont go over about 9.7:1 compression with those heads. A 351c "2V" makes very good low end torque and a 351c "4V" makes less low end and more top end power. If the engine is in good shape install a set of full length 1-5/8" headers into 2.5" exhaust , an Edelbrock performer rpm intake , a Holley 650 cfm double pumper or 650-700 cfm vacuum secondary carb , a Comp Cams XTREME ENERGY XE256H or XE262H hyd. cam and double roller chain , and either an aftermarket ignition or have your stock point dist recurved and use an Accell super coil. This combo with the 2V heads should make plenty of low to mid power and you could also install a 3.25 or 3.50 rear gear with a Trac Tech Tru-Trac posi.  

 
Sprockets72 Sprockets72
New User | Posts: 22 | Joined: 06/09
Posted: 07/07/09
02:50 PM

awesome, thanks for the advice.  I don't believe the engine has ever been rebuilt, it has about 65,000 miles on it.  This may sound stupid, but i don't know how to adjust the compression.  Can you point me to some good resources for learning more about all this?  I was planning on installing the headers like you suggested as well as the intake/carb combo.  Do you think that the holley is a better bet than something like the edelbrock thunder series?  I know we put that on our 57 and it works great.  

 
shiftthis shiftthis
User | Posts: 188 | Joined: 04/09
Posted: 07/07/09
03:17 PM

I would recomend rebuilding before doing a cam change. However adding a carb, headers and intake would be ok as long as the compression isnt low. Compression is determined by the top of the piston as to dished vs flat top ,engine deck heigth ,if the heads have ben milled , exact combustion cc ,head gasket thickness ,how much the block is overboared and you would select a piston with a particular compression ratio and with 92 octain pump gas and large combustion chamber iron heads about 9.7:1 is the upper limit to keep from detonating which can crack piston ring lands and most engine shops should be able to help you select the right pistons however I would not use "HYPERUTECTIC" pistons as I and others have had these break easily so a stock type "cast" is the way to go unless your building a really high power engine. Have the engine shop install hardend valve seats. As for as the carb I dont use anything but a Holley , easiest carb to tune and the best performing !  

 
Sprockets72 Sprockets72
New User | Posts: 22 | Joined: 06/09
Posted: 07/07/09
10:33 PM

Should I stick with a two barrel carb or switch over to a four barrel?  

 
shiftthis shiftthis
User | Posts: 188 | Joined: 04/09
Posted: 07/07/09
10:39 PM

If you want to make more power go with a 4 barrel , if your just gonna be cruising around or using it as a daily driver the 2 barrel is fine ,depents on what your gonna use the car for.  

 
mechanicalguy48 mechanicalguy48
Enthusiast | Posts: 704 | Joined: 12/07
Posted: 07/07/09
11:18 PM

Well I generally agree with Shifthis but I have a little different take on it. The 72 Cleveland 2v was a low compression motor, and pretty weak all around. What you need is to return to the specs of the 70 2v motor which supplied 355 ft/lbs at 2600 rpm compared to the 250 @ 2400 of the 72 model. The change ,,,, compression ratio. The 70 was 9.5:1 versus the 8.6:1 of the later model you have. Both used a 2100 Ford 2v. Since this will mean different pistons I suggest you order them to  the specs of a 70 model 2v. Unlike Shifthis I dont like holleys and I do like hypereutectics. Probably due to our different experiences with them. A holley leaks like a sieve whenever you either (a)connect the fuel lines or (b)change anything by removing the float bowl. Neither Ford 2100's or Edelbrocks do that and they also dont blow power valves with one backfire like a Holley(just my opinion here). Hypereutectic pistons run with much tighter piston to bore clearance and that means longer piston life, less contamination, less noise, better oil control, better better,,,,(follow the piston mfg suggestions as to rings and end gap). Now some hypereutectics are heat treated and some are not but in my experience they perform strength wise the same as cast pistons handling loads up to 2hp per cubic inch , but your not going near that so I think its worth considering. Nothing wrong with staying with the stock 2100 carb which is probably the best 2 barrel carb ever built. You dont need to go with a 4 barrel but if you do, you will sacrifice a little low end and gain a little top end. You want low end torque and thats good because you mean stoplight to stoplight and having a responsive motor, so keep the duration and lift(on your cam) at reasonable figures because the higher velocity of smaller cross sectional area is what gives you low end torgue(horsepower). The search for top end Horsepower means big valves high lift and long duration all of which limit the low end HP and consequently the torgue because thats what low end HP is ,,,its torgue. to that end I would change shifthis recomendation to the next lower cam in that series the XE250H which reduces the duration a little and gives you a crisper throttle down low. Its not disagreement,just a little different take on it is all.  

 
Sprockets72 Sprockets72
New User | Posts: 22 | Joined: 06/09
Posted: 07/08/09
02:25 PM

Hey, thanks for your input mechanicalguy, all points of view are welcome.  its good to hear different points of view so that I have more information.  We have all had different experiences and that lets us bring something different to the table, no worries about having a different opinion.  Thanks for the info on cams and what gives more torque, gives me more of an idea of what to look for.  now, silly question, probably pretty obvious but if I make these changes to get more low end power than I will be sacraficing some high end power correct?  Right now most of my power seems to come about the 3500 rpm range.  When I first take off its a little sluggish, not quite what I was expecting when I first heard 351, but it definitly seems to kick in to gear once the rpms are up.  

 
mechanicalguy48 mechanicalguy48
Enthusiast | Posts: 704 | Joined: 12/07
Posted: 07/08/09
02:42 PM

Well nearly everything in life is a compromise sprockets, but in this case if you increase your compression ratio it will add power thruought the band. The shorter duration cam may not have as much HP on the top end as the longer duration cam, but street driven cars that dont see the dragstrip seldom see the top of the power band either, so i think its a win for you. Shiftthis recommended you changing your rear end ratio and I agree. Thats a seat of the pants difference many people overlook. A little more rear gear will give you a crisp feeling and make it easier for the engine to accelerate because it has a gearing advantage. Torgue at the rear wheels is multiplied by the gearing. so do you want to multiply the torgue by your stock 2.89 gear or would you rather multiply it by 3.25 or 3.5,,,AHhhhh you see now. Heck I would rather multiply it by 4.30 but then I probably couldnt stand the noise at 60 mph either,,,so compromise,,lol.  

 
shiftthis shiftthis
User | Posts: 188 | Joined: 04/09
Posted: 07/08/09
09:35 PM

CompCams doesnt make an XE250H for the cleveland and my recomendation for that cam was based on a conversation I had with the CompCams tech line about a similar 351 I am building for a 67 Fairlane daily driven cuzecruiser. I have used a HIGH ENERGY 260H and an XTREME ENERGY XE256H and both fall off below 5000 rpm but the XTREME ENERGY cam has a little wider power band and the XE262H should pull to 5400 before falling off, CompCams says 5600. You could have CompCams custom grind an XTREME 4X4 cam which has an even wider power band but it depends on how much cash you want to spend cause they only make those cams for the "W" not the "C" engines. About 15 years ago I had CompCams custom grind me a cam with chevy lobe patterns for a FORD 460 I had and then a few years later CompCams added those lobe patterns to the 385 series lineup. The Fairlane has 9" with 2.75 gears, a TRUTRAC posi, C6 auto, & air cond.(Its the "wifes" car !!!!)! I have a completely woe owt .040 289 if someone needs a boat anchor.  

 

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