Recommedations for a mean 351W/393 build.

[65ShelbyClone]

I have a late '70s 351W shortblock laying around in pieces that is just collecting dust. My Edelbrock-headed 302 is pretty fast, but I built that with smog in mind when I had my '89 GT. Now that I have the '68 , I'm wishing I'd gone more agressive on the build. Since getting the '68 the "man" can't tell me what to do anymore, so I'd like to build the 351W to be one mean pump gas mill.

I'm looking for recommendations on building this thing. I had Edelbrock Victors or Victor Jrs in mind; it won't be a daily driver, but I need to be able to drive it on the street. I wouldn't mind 450rwhp or more with a manual trans. With that in mind I'd like to hear what all the engine builders suggest.

 

[351w_swap]

How much money do you want to put into it? Is a supercharger out of the question? What is the compression on that short block? Are you willing to get new pistons?

I would probably just take that short block, get some 11 to 1 pistons, snake the heads from that 302 and stick a victor jr on top with an 800 cfm carb for a budget build. That may not make the power you want though. You could always go with low compression, stroke it and put a nice weiand blower on top. Then you would get the numbers your looking for.

 

[65ShelbyClone]

I'd like to avoid forced induction. I'm not against it by any means; I like big turbos, but I want to keep this engine reasonably simple and fitting under a stock hood.

I was thinking around 10.5 to 10.8:s compression with so less than 2.02 valves, most likely 2.08.

I haven't figured out a budget, but it won't be a dirt cheap build nor "maximum effort"(ie, endless budget). I'm not in a hurry so this engine can be build with good parts as needed. I should have mentioned that even a 408 is also possible, but I'd like a 393W.

 

[351w_swap]

why 393? I know that the 427w or whatever it is stroker has problems because the skirt is to short on the pistons but i have not heard objections to the 408. If you want to avoid forced induction go with the 10.8 to 1 compression as that will help you reach and exceed your power goal. Are you willing to just remove the heads off that 302 and put them on? It will save a lot of money. You could do any number of things to increase power, like lose the power steering, add a electric fan, put on an electric fuel pump and use a radical cam. For the cam you should probably go with something matching the heads that you want or the heads you have. I went with an air gap RPM intake with a 750 cfm edelbrock carb to top it off. I wish that I had gone stroker but simply didnt have the money at the time so I don't really regret it, it will be a project for the future. I went with 10.5 to 1 compression and polished stock heads (may be ported, i dont remember). Additions before i go to EFI will probably be some edelbrock heads (not sure which version yet) and a more radical cam. There is nothing like hearing a nice wide gap between cylinders firing; you can hear the power. If you are trying to push the limit you might consider all forged internals but with your power goal you should be fine with cast (except pistons). You may also want to consider roller rockers and lifters.

 

[65ShelbyClone]

1. A 393 would be easier since I really only need a different crankshaft for it, but a 408 is as far as I would want to stroke a 351W.

The only thing I would like to keep is the A/C. I ditched the P/S already and went to an electric fuel pump(which I hate). A cast steel crank and I-beam rods will be fine for my goals. `Stud mount roller rockers are mandatory, but I'm not sure about a flat or roller cam.

 

[351w_swap]

Roller cam saves friction which adds power and should add life. Im not really sure what advatages the flat has besides price.

I never had ac so I didnt even think of that. You could just build the engine with more power to compensate as well. If this is a street car you wont want to but if you are going to race it too you might consider some cheater juice (N2O). I'm scared of the stuff but You could talk to someone with experience with it. in the end, high compression, less accessories, more air and fuel flow and less friction all add to one thing, power (torque too i guess).

 

[86bluecobra]

Ok if i had my choice i would run vic jr heads and matching intake. A solid roller cam but i would be contacting a custom cam shop for that. 10.5 to 1 compression. I would go h-beam rods and forged slugs. Have it balanced so 7500 rpm is not out of reach. Then a 150 shot of juice just in case. don't forget stud girdle and a windage tray. Maybe even stud the block for the heads.

 

[rbohm]

make sure the bottom end is a strong as you can make it. forged pistons, H beam rods, forged crank, main cap stud girdle. for a cam i would run something like an xe282 comp cam. heads- afr205's. intake-victor jr. carb-something in the 850 range, i prefer the edelbrock or the speed demon. headers-you want a 1 3/4" primary tube with a minimum 3" collector, and a primary tube length around 30" for long tube headers. that should get you in the 500hp range at the flywheel, and with a small nitrous shot, say 100hp, you should make your goal of 450 rwhp.

 

[dennis112]

I want to keep this engine reasonably simple and fitting under a stock hood.

Vic Jr heads will be fine for a 393/408. For a primarily strip vehicle with minimal road duty, you will want a decent cam. That will require an upgraded intake manifold above the normal dual planes and a Vic Jr. intake is recommended for performance usage. Although people claim it can't be done, a Vic Jr. can be fitted under a stock hood with a little planning and a few mods. I have about 1/2" hood clearance which is about the same as my old Stealth intake. Here is what I did on my 393w equipped 65' in order to install the Vic Jr. intake:

1. Dropped motor mounts.
2. Angle milled Vic Jr carb pad--took .300 off front, near 0 on rear. Gives the added benefit of a more level carb. No clearance issues with carb studs.
3. Modded 14" drop air cleaner-maintains the desired minimum 1 1/4" base-to-top clearance.
4. Chokeless HP type Holley carb has lower air cleaner flange.

Some pics of my 393w with Vic Jr:

Although my 65 has a Shelby scoop, no part of it is needed to clear the 14" air cleaner shown. The Accufab headers that I installed helped me to maintain above average ground clearance, even with the drop mounts.

 

[SoCalCruising]

For a 393, I would use a 6.2" or 6.25" rod, but I am one who really prefers a rod ratio around 1.65, or better. You can only get about 1.62-1.63 on a 393, but that's close enough. I'll say again that if this was a race motor, I wouldn't care much about rod ratio. For a sreet motor, I like a better ratio. AFR 205s would be my choice for heads. The intake would be a port-matched Vic. Jr. with a 1" or (preferrably) 2" spacer. Hood clearance would be an issue, though. The XE 282HR would be a good choice for an off-the-shelf cam. I'd probably run tweeked 750HP-style carb, like a QuickFuel. It would have to be proven to me that this carb was too small before I would move up - I like the throttle response of smaller carbs. Again, if it was a race-only motor, I'd use a larger carb.

 

[65ShelbyClone]

Cool, thanks everyone.

 

[danny clemens]

This engine doesn't have the hp that you want but it may give you a referance for a starting point to know how much upgrading you'll have to do.
http://www.mustangsteve.com/351W_Parts.html

 

[67Dylan]

Ok if i had my choice i would run vic jr heads and matching intake. A solid roller cam but i would be contacting a custom cam shop for that. 10.5 to 1 compression. I would go h-beam rods and forged slugs. Have it balanced so 7500 rpm is not out of reach. Then a 150 shot of juice just in case. don't forget stud girdle and a windage tray. Maybe even stud the block for the heads.

I concur w/this build. A few things I didn't see mentioned: carb, tweaked 750DP, LT 1 3/4" to 3" exhaust, straight thru muffler, and if you go sauce get either a NX Express or Nitrous Works kit. They put down to the wheels what they advertise. NOS brand says 150 shot, but you don't get 150 to the wheels. Both kits I mentioned will get you AT LEAST 150 to the wheels; this has been observed more than once by myself and quite a few ppl, as well as dyno #'s ppl have posted.

 

[86bluecobra]

Good point on the 1 and 3/4 inch headers. I think if you are going to run to 7500 rpm or so you mayneed a carb that flows a bit more then the 750. That being said i know my 750dp on my 351w runs rich so you may get away with a 750.

 

[brin0357]

If you plan on running over 7500 RPM and 393 inches, your probly gonna need upwards of 750. I would probly go with an 850 if you want it to pull hard to 7500. Go with a Braswell, HP style Holley, or Dominator.

 

[65ShelbyClone]

I should have mentioned that my car is going to be set up more road race oriented, not as a drag car. With that in mind, I can't really use nitrous. As fun as it would be taking the engine out to 7500rpm, I also want it to last a little while. I was thinking maybe 6300-6800rpm.

 

[Fostang]

Do something like my set up

383 3.75 crank 6.25 rod dished pistons hoged out vic jrs. All 4340 with arp 2000 rod bolts. 0 balanced etc. The heads flow 320/215.

It is hard blocked half way and has a custom cammotion solid roller blower camshaft.

After decking the block and getting the correct cometic gaskets it's got about an 8.4 comp.

This on toped off with a blow thru CSU carb and a NOVI 2k rengade maxed out.

 

[65ShelbyClone]

Any dyno numbers for that monster?

 

[65ShelbyClone]

I'm still feeling everything out and I still want to use a 351W, but I'm debating whether or not to go with a stroker. I'm starting to get concerned with the rpm ceiling of a stroker. I know my 302 is a different animal, but it starts goin flat at 5500, right when Crane's cam said. I think it would be safer for my power and drivability goals to shift the powerband up about 1000rpm. That would mean at least 6500, but I figure 7000 for good measure. Any thoughts on this?

Also, I'm aware that AFRs are some of the best heads on the public market, but I want to do something different. I really want some Victor Jrs, but I've also been looking at Canfield, Brodix, and even the Jegs/Kaase heads as possibilities. I'm just not sure how much port CFM I should be looking for considering the power levels I'm after.

 

[dennis112]

I'm still feeling everything out and I still want to use a 351W, but I'm debating whether or not to go with a stroker. I'm starting to get concerned with the rpm ceiling of a stroker. I know my 302 is a different animal, but it starts goin flat at 5500, right when Crane's cam said. I think it would be safer for my power and drivability goals to shift the powerband up about 1000rpm. That would mean at least 6500, but I figure 7000 for good measure. Any thoughts on this?

Windsor strokers can turn some Rev's too. I have a self imposed 6400 limit on my 393 and I hit it often shifting gears. 7000 rpm is quite possible with a good build, especially on the top end. I have Vic Jr. knockoff heads and a fairly small cam and it would continue to rev if I didn't have the rev limiter. The aftermarket heads really make a heck of a difference.

If you are concerned about the bottom end, you could run spacers in your windsor and a cleveland crank. Not really needed for a primarily street car.