Rebuilding ford 302 HO any idleas ?!?! :)

[Jaysad]

I have a ford 302 HO. This winter I plan to rebuild it and I'm looking for any good advice on this.

I have a set of 351 heads - to be rebuild
Holley 650 4bbl & cast iron intake
pentronix ignition
GLM exhaust manifols

So, whats should i do?

I want more power, low end, and top end.
Want to go faster!!!!
41mph@4,450rpm now.

 

[Jaysad]

Re: Rebuilding ford 302 HO any idleas ?!?!

Anybody????

 

[ohiophoto]

Re: Rebuilding ford 302 HO any idleas ?!?!

Well I am a ford guy and love those small blocks, the 351 heads make sure you get em cc'd cause if they are large camber it will actually drop your compression. I like Isky cams for fords they make a whole selection of I/O camshafts. Flat top pistons and maybe alum intake if you are fresh watering only. Wind-age try if you wanna get fancy

My thoughts

 

[Jaysad]

Re: Rebuilding ford 302 HO any idleas ?!?!

Thanks Ohiophoto,
?
What is Windage?
Isky cams, where can I get info.?
Sorry, but what is cc'd?

Again thank for you reply!
Just looking for info.

 

[a70eliminator]

Re: Rebuilding ford 302 HO any idleas ?!?!

Those are some really basic questions for someone attemping to "soup" up an engine.

 

[haulnazz15]

Re: Rebuilding ford 302 HO any idleas ?!?!

Well, first off I wouldn't go with the 351 heads unless they are the early versions which were 69cc or so. Anything after the early 70's will have a larger combustion chamber (74cc?) that will lower the compression a good bit. If you want new heads, it's be better to just buy an aftermarket set. I would say that a slightly hotter cam would be okay, but you need to find a cam that is rated from 1000-4200rpm so that it makes all of its power by that point, but you will have to worry about reversion if you get too wild. Personally, I think if you want to gain muchmore than 30-40HP, a 351w would be the easier way to go.

 

[Jaysad]

Re: Rebuilding ford 302 HO any idleas ?!?!

Ok, that it 351!
How much more HP is the 351 vs. 302?
Do you think the stern drive can handle that much HP?

 

[Aloysius]

Re: Rebuilding ford 302 HO any idleas ?!?!

You could get the GT40 heads, or some lightweight aluminum aftermarket stuff. I also agree that someone planning on rebuillding an engine for more power needs to get a little more knowledge.

There's no substitute for cubic inches. The 351 is a taller block with different intake manifold. A stock marine exhaust is pretty restrictive for higher rpm breathing..so is the stock flame arrestor.

don't expect the simple installation of a cam and heads to work wonders if it can't breathe air in and out..an engine is simply an air pump!

 

[Jaysad]

Re: Rebuilding ford 302 HO any idleas ?!?!

You could get the GT40 heads, or some lightweight aluminum aftermarket stuff. I also agree that someone planning on rebuillding an engine for more power needs to get a little more knowledge.

There's no substitute for cubic inches. The 351 is a taller block with different intake manifold. A stock marine exhaust is pretty restrictive for higher rpm breathing..so is the stock flame arrestor.

don't expect the simple installation of a cam and heads to work wonders if it can't breathe air in and out..an engine is simply an air pump!

Ok, Please, tell me more, I'm all ears!!!!

 

[haulnazz15]

Re: Rebuilding ford 302 HO any idleas ?!?!

Well, a 351w in stock form w/4bbl carb will run 260HP easily. With a dual-plane intake and a slightly more aggressive cam, you will run 280-300HP depending on supporting mods. The outdrive (assuming Alpha I) can handle up to 300HP. Some parts from your 302 will swap over except the intake manifold and possibly the dampener/flywheel. Exhaust manifolds, wiring, etc should be the same.

 

[Jaysad]

Re: Rebuilding ford 302 HO any idleas ?!?!

Well, a 351w in stock form w/4bbl carb will run 260HP easily. With a dual-plane intake and a slightly more aggressive cam, you will run 280-300HP depending on supporting mods. The outdrive (assuming Alpha I) can handle up to 300HP. Some parts from your 302 will swap over except the intake manifold and possibly the dampener/flywheel. Exhaust manifolds, wiring, etc should be the same.

Thank You Sir,
The 351w is what I'm going to do, but I have the OMC outdrive. I've been told the OMC would handle 300hp. So, my luck, I'll get a great engine and then BOOM! I'll blow the outdrive! Maybe not. haha.
I'll keep it stock for now, and see how the outdrive holds up. Save my $ do a little more planing, and play around here and the Mustang forum and then
Thanks Man!

 

[ohiophoto]

Re: Rebuilding ford 302 HO any idleas ?!?!

Windage tray goes under the crank keeps the crank from hitting the oil. If you get the ford performance by pat ganahl its an old book updated in 97 but it will tell you a lot of info! Summit and jegs carry em

ohiophoto

 

[Jaysad]

Re: Rebuilding ford 302 HO any idleas ?!?!

Windage tray goes under the crank keeps the crank from hitting the oil. If you get the ford performance by pat ganahl its an old book updated in 97 but it will tell you a lot of info! Summit and jegs carry em

ohiophoto

OK, I under stand.
I'll check into the book also!
I think I'll put a 351w long block in it.
I was told, "There's no replacement like displacement" or something like that. haha.

Thanks Man!

 

[ohiophoto]

Re: Rebuilding ford 302 HO any idleas ?!?!

there is no substitute for cubic inches, key to a 351w is heads the pedy rockers suck and the heads need some work to flow good! At least match port. I wouldnt do more than pocket smoothing in a boat. The bottom end of a 351w is awesome!!

 

[Aloysius]

Re: Rebuilding ford 302 HO any idleas ?!?!

"Horsepower" is a computed number. HP=Torquexrpm/5252.

TORQUE is all that's measured. also remember, "horsepower" is RPM specific. Horsepower at maximum rpms has no relationship to horsepower at a lower rpms, except is a rough indicator of torque. So where am I going with this? What you want is an engine that has a relatively FLAT torque curve from 2500 to 3500 rpms or so. Gasoline inboards may produce maximum power at 4800 rpms, but they won't last long run at that high rpm. You'll be running 3200-3500 with occasional higher rpms.

ALL components have to work together. Single valve springs inhibit high rpms, so what good is a major head porting? The intake and exhaust are very restrictive, so they limit the amount of air you can pump.

 

[45Auto]

Re: Rebuilding ford 302 HO any idleas ?!?!

"Torque" is also a computed number. Torque = Force x Distance.

Torque is just a measure of a type of work. By itself it's totally useless in an engine. You'll be lucky to see 350 ft-lb of torque in your 351. I can easily provide you with over 500 ft-lb of torque by putting my weight on a 3 foot breaker bar. Does that mean you'd be better off having me turning a breaker bar to propel your boat?

What you're actually looking for is power. Power is the rate of doing work. With additional power, you can do the same amount of work (put out the same amount of torque) at a faster rate, or do more work (put out additional torque) at the same rate.

 

[haulnazz15]

Re: Rebuilding ford 302 HO any idleas ?!?!

Lol, the main point is that high-rise intakes, carb spacers, and head porting aren't worth a whole lot in most marine applications because the added flow only gets bottlenecked in the exhaust. It also doesn't help when the flow doesn't change much when you aren't spinning 5K+ rpms.

 

[Aloysius]

Re: Rebuilding ford 302 HO any idleas ?!?!

torque is a measurement of force. work equals the integral of F.Ds. By putting weight on the end of a breaker bar, you've done no work unless you move something. Torque is what is measured on a dynomometer, and it is indeed an actual measurement for engines..it is the ONLY aspect measured along these lines. From the measured torque, horsepower is calculated. You cannot get "horsepower" without torque, and torque is what is actually measured. If you want "horsepower" at 4500 rpms, you gotta have the necessary TORQUE at 4500 rpms to produce the horsepower you want.

Ever wonder why the numerical equivalent horsepower and torque curves cross at 5252 rpms? It's FROM the FORMULA.

There is a way to estimate horsepower by utilizing the energy in the fuel, fuel usage, and efficiency of the engine. This is only an estimate.

 

[ohiophoto]

Re: Rebuilding ford 302 HO any idleas ?!?!

Lol, the main point is that high-rise intakes, carb spacers, and head porting aren't worth a whole lot in most marine applications because the added flow only gets bottlenecked in the exhaust. It also doesn't help when the flow doesn't change much when you aren't spinning 5K+ rpms.

Well fords need to be port matched and cleaned up under the valve pocket to "breathe" as good as a small block chevy. The head castings are the same as the 302's after 74. I understand everyone here is a "marine master" I am an engine builder I bleed ford blue! The reason for matching and pocket is not for flow it is to reduce the turbulence which is detrimental to the atomization of the fuel mixture. I agree not to smooth port or increase runner or change runner except to match. I would open up the exhaust to match it to.
"The castings on these heads have all kinds of "Bumps" and casting notches that create turbulence. Which is a great deterrent to HP/Tor ratio even at 3000"

Don't take my word for it take look it up in Roush, Gapps machine booklet for ford marine applications.

 

[ohiophoto]

Re: Rebuilding ford 302 HO any idleas ?!?!

Since everyone has an opinion heres mine:
I would go with: Cam part number SUM-K3601 from summit ( degreed +4),
heads Canfield or early casting (with the work I proposed), Intake Offenhauser 6009DP, Eldebrock carb, or holly (hollys run better, eldes more drive ability)
Mallory ignition 12 initial 36 total benched in at 2200 rpms.

plenty of torque off idle would have a nice smooth flat torque curve and go fast on the water!