World Jrs on 351

I have a stock 1977 351w with new stock rebuild I purchased from a friend.The only thing it has done is performer intake and holley 600carb.What kind of horspower and torque can I get by putting world jr heads and comp 280h cam in?This motor is going in 1967 mustang.The heads and cam fit in my budget .Will this be a decent combo for a street car?

I think it would be a good combo. The Windsor Jr's 58cc combustion chamber will give a nice boost in compression and the flow will be better than stockers.

Assuming around 9:1 compression and headers I think you'd get 310-320 hp and 350-360 ft/lbs. of torque.

You could go a little smaller on the cam, but I think the 280 Magnum would work fine and the motor will have a nice rumble to it. Depending on the gearing and stall speed in the car I would pick a 270 Magnum or a 268 Extreme Energy cam over the 280 Magnum. Just depends on what you got and what you want.

as always, JMO.

paulie

the Jr's have smaller head bolt holes IIRC, the Sr's are more geared for the 351 and have better flow . The valves are bigger too and the head bolt holes are the right size. If you want to bump some compression just use a thin gasket on them. Wont get the same as the jr head but will have more than stock

Originally Posted by mustang42782

the Jr's have smaller head bolt holes IIRC, the Sr's are more geared for the 351 and have better flow . The valves are bigger too and the head bolt holes are the right size. If you want to bump some compression just use a thin gasket on them. Wont get the same as the jr head but will have more than stock

I could be wrong, but I think the Windsor Jr's have 1/2" head bolt holes and have to use a spacer (sleeve) between the head and the 7/16" bolt on 289/302's. So If I am correct, on 351W's it's good to go with no spacer.

Also, since this motor has (I think) stock type rebuilder pistons, larger valves may have an interference problem with the piston valve reliefs. Even with the 1.94 intake valves on the Jr. it'd be worth checking.

paulie

I might add that the Magnum cams like the 270H/280H cams are 25 year old technology. Look at the Extreme Energy grinds...they are better than old grinds by far.

What could I expect from the extreme energy 268h or maybe the performer rpm cams as far as horsepower and torgue?I like the way the 280h sounds but know not to make a decision on that if I can get better cam with more power. Thanks for any help.

Originally Posted by jody1970b

What could I expect from the extreme energy 268h or maybe the performer rpm cams as far as horsepower and torgue?I like the way the 280h sounds but know not to make a decision on that if I can get better cam with more power. Thanks for any help.

You'd gain around 0 peak hp and maybe 15 ft/lb of torque at peak with the 268XE vs. the 280 Magnum. The 268 XE actually uses a 280 Magnum exhaust lobe so it just changes the intake lobe. The shorter intake duration and faster opening intake of the 268 XE will increase the torque (read low rpm power) and you'll keep about the same top end power. Not a bad cam in my opinion.

The Edelbrock Performer RPM cams are really old designs. Not so great.

If you really want more power, the places to look are at the heads and intake. You said the motor was basically a stock rebuild on the short block so I don't know how far you want to go.

The Windsor Jr. heads are better than factory heads, but not amazing. You could pick up a lot of power with something better. Remembering you're on a budget, how about some Competition Cams RHS 180cc iron heads? I think you can get them with a 58 cc chamber. Just off the top of my head I'd guess you'd gain at least 30 hp over Windsor Jr's. There are a zillion SBF heads out there now.

I'd also consider either a Weiand Stealth intake or an Edelbrock RPM intake. Maybe another 15 hp here with little or no loss at lower rpms? Since you already have the Performer intake, maybe you want to use it and just put an open carb spacer on top of it.

JMO,

paulie

Yeah stay away from Edelbrock cams. They don't produce as much HP as they claim. I would think the XE274H cam would be a healthy cam for ya. It's a 230/236 @ .050 vs the XE268H cam is 224/230 @ .050. There are better cams out there if you got the money to spend....like roller, custom cams, ie. But for the street machine you can't go wrong with an XE cam.

I was contemplating the same set-up with my 74 block. I have windsor Jr'sand no matter how much I wanted to use them in my build, I opted to put them on my 302 instead. From listening to folks, then making my own assessments from that info. my 351 block is built, and tucked away in the garage until I can get a better set of heads for it.

These heads rock in my 302. People think it's a big motor.. when I tell them it's a 302.. they can't believe it. They work for me with the 302.

BTW, they will work on 351.. depends on what you want to do with it.

Thanks for all your help.Now I just need to figure which xe cam works best for me.