351C Build Help
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Thread: 351C Build Help

  1. #1

    351C Build Help

    New to the forum here, trying to get some advice on an engine build I plan on starting soon... proud owner of a 1970 Cougar with a 351C 4V motor.
    I’ve been reading online and some people say stroking the motor will make the most out of the 4V heads while others say that it’s not necessary... confused as to who is right?

    So far in my head I have this rebuild idea...
    Stock stroke
    ARP bolts in the bottom end
    Balanced
    Oil restrictor kit by Moroso
    Windage tray


    The valvetrain gets hairy... consensus is to replace the valves. Check.
    What type of cam to run?
    Mechanical, hydraulic? Roller? Too many options and loads of cam specs.
    I’d buy the entire kit (valve springs, pushrods, etc)...

    Torker intake

    Open to carb suggestions.

    Looking for power to ~ 6.5k. 10.0-10.5 —1 CR.
    Motor is mated to a wide ratio top loader and open to rear end gear selection. Reading that Clevelands love 3.5-4.10 gears in the rear.
    From what I’ve gathered, the stock crank and rods are sturdy but the valvetrain is the killer... trying to spend my money wisely and invest in what is most important to a solid 351c performer.

  2. #2
    Join Date
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    Re: 351C Build Help

    There are far too many questions left on the table here to get a perfect answer yet, but it is a good start.

    How much power are you looking for? How will you be driving the car? Is drivability going to be an issue?

    You say you want to spin it to 6500. I would go with a hydraulic roller. Much more reliable and lifters will last forever. Solid is only needed if you want to spin it higher and take the top end apart to replace lifters every 1000 miles or so. I personally would never go back to a flat tapper cam again, too many chances for issues with modern oils.

    Be careful with the oil restrictors if you go with a hydraulic cam. They need the oil supply and are basically restricted themselves. They are definitely needed if you go solid. Also make sure you get the correct lifter for a Cleveland engine. Windsors will fit, and most parts people will tell you they are the same, they are not, and the difference lies in the oil restriction. Also, Smith Brothers makes restricted pushrods to limit oil past the lifters, I use them in every engine I own and highly recommend them.

    Pushrods should always be measured in after assembly. Mine required different sizes between the intake and exhaust, then again, I have a solid roller. Your results may vary.

    Definitely replace valves with a quality one piece design, stock ones will ultimately come apart because of heat from modern fuels.

    Cleveland's will always benefit from being stroked, it all depends on how much you want to spend if it is worth it. I opted to use the stock crank and make an 8500 rpm screamer. If you do run the stock crank, don't worry about it coming apart, Prostockers ran the factory crank and would spin them past 10 grand and with nitrous.

    Torker intake isn't bad, but the Parker Funnelweb with tongue plates is an amazing intake for the Cleveland, if you can find one.

    Carburation depends on the build ultimately. But I highly recommend a Quick Fuel carb.
    Last edited by 1970fastcat; September 10th, 2018 at 05:59 PM.
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  3. #3
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    Sep 2005
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    Re: 351C Build Help

    Check out 351c.net. All the info. you ever wanted. I'm doing a 396 stroker. I got a smoking deal on it. Stroking will get the torque way up which will help motivate the car.

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  5. #4
    Join Date
    Feb 2004
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    Re: 351C Build Help

    Quote Originally Posted by Robertem70 View Post
    New to the forum here, trying to get some advice on an engine build I plan on starting soon... proud owner of a 1970 Cougar with a 351C 4V motor.
    Iíve been reading online and some people say stroking the motor will make the most out of the 4V heads while others say that itís not necessary... confused as to who is right?

    So far in my head I have this rebuild idea...
    Stock stroke
    ARP bolts in the bottom end
    Balanced
    Oil restrictor kit by Moroso
    Windage tray


    The valvetrain gets hairy... consensus is to replace the valves. Check.
    What type of cam to run?
    Mechanical, hydraulic? Roller? Too many options and loads of cam specs.
    Iíd buy the entire kit (valve springs, pushrods, etc)...

    Torker intake

    Open to carb suggestions.

    Looking for power to ~ 6.5k. 10.0-10.5 ó1 CR.
    Motor is mated to a wide ratio top loader and open to rear end gear selection. Reading that Clevelands love 3.5-4.10 gears in the rear.
    From what Iíve gathered, the stock crank and rods are sturdy but the valvetrain is the killer... trying to spend my money wisely and invest in what is most important to a solid 351c performer.
    I built my 351 4V 4 years ago for my 70 Cougar and turned out very nice. I went stock stroke, original cc 4V heads and hyd roller cam set up. My next car with a Clevland I may consider stroked and CHI heads we'll see when the time comes but the cost is a bit more compared to machining original stuff.

    Definately go ARP everything incld head bolts or studs and balance.
    Get good quality machining done on all the parts and good bearings, I went with King bearings.
    I went with SS performance single groove valves, hardened seats, bronze guides, head surface machined flat and machined for screw in studs. I think the machining for the heads alone was about $800 plus parts.
    I went with file fit rings on forged flats and had the crank and rods machined .0025 mains / .0020 rods
    I went with Tmeyers restricted cam bearings kit for the oil control, you should look into them.
    I have the standard volumn oil pump with ARP drive.
    I went with a custom ground Hyd roller cam set up with scorpion roller rockers and Morel link bar lifters. I got my cam spec'd and from Brent LYKINS at Lykins motorsports, highly recommend. The cost to go custom ground is like $50 more and you want to get one custom ground for the Cleveland either roller hyd or standard.
    You will want to go with good fully adjustable distributor, I made the mistake going for the stock look Pertronix and they cant be dialed in worth a damn... I run a 20deg lock out and 17deg initial all in by 2800 with my better distributor.
    I have the Eddy Air Gap and its a very nice manifold with a Quick Fuel 680VS, I'm still trying to dial in the carb tho to get it crisp. I just put in a air/fuel ratio guage to aid in that.
    Hooker full length headers into Magnaflow 2.5" stainless X pipe system. (I ordered the system for the 70 Stang, installed it myself and to fit the Cougar you will have to extend the tail pipes after the diff aboult 3 or 4 inches).

    My build is very reliable and pulls hard, I run it through an FMX with 2800 stall and 3:50 gears in the rear. You are fortunate as you run a stick so you can run it for a higher RPM curve than an Auto. Depends on the driving you do city or highway but gears in the 3:91 range would be sweat! Get good quality machining, take your time assembling, get a custom grind cam, degree in the cam and have fun!

    My $.02
    Last edited by 7TXR-7; September 16th, 2018 at 05:46 PM.
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  6. #5
    Hey y’all,

    Haven’t been on in a while. Got busy with school and what not.

    I’ve been doing some research on parts and studied some builds.

    Update, learned I have open chambered heads. (Going off of the old ‘4 cannonball’ tale).

    Having open chambered heads really throws me off. Seems they are more prone to detonation and raising compression is done by shaving the head and zero decking the block.
    Reducing the amount of volume SEEMS straight forward.
    Shave the head, flat top piston, thin head gasket and decking the block.
    The trick is how the heads have no “quench.”
    So how can I go about avoiding the dreaded pinging.
    Flat tops or domed pistons?
    Depending on how much compression I run is how much cam I can run too.
    I was looking at CompCams but after some reading... they might not be the best company to dead with? Might just be hearsay. I’ve read some people are super happy with them.
    I’ve been looking at Lunati, Isky. Any other recs?
    Looking to do a hydraulic roller cam. 6500, maybe 7000 rpm when I get brave.

    Appreciate all of the guidance guys.

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