1973-302-increasing horsepower

[greggonzo1]

It is my understanding that this year motor had 140 hp. About 7 years ago I rebuilt the motor with the following
- Edelbrock perfomer intake
- performer cam, lifters
- 1406 carb
- 1-5/8 headers

Nothing was done to the heads other than cleaning them up and seals and such.
What kind of HP numbers should I expect from my mods? What holds my motor back from making more HP? Is it the heads? Compression ratio?

Would changing the heads wake up this motor?

Thanks

 

[wildbill]

%) %) %) Just look around and find a 351W and build it in your spair time you will have the HP and also a lot of torque. As for HP the stock 351W in 1969 was rated at 290 with a 4V. I have been running one since 72 they work very good, Good luck.;D ;D ;D Bill %) ;D

 

[BUCKETOBOLTS]

The Performer grind is a very popular 302 cam. It is more of a torque/towing profile. I ran the Melling version in my original '72 302. It was all original 89,000 mi when I swapped the cam, new timing chain, springs, and cast iron 4V manifold. Made a world of difference over the stock 2V. But still was no power house as compared to a fresh engine.

You can build a pretty stout 302 on a budget, but how much do you expect for 302ci? Is this a mostly street driven rig or offroad? Bigger heads and bigger cams can make the mill "peaky".

 

[Broncobowsher]

Looks like you did about all the simple bolt ons you can do.
When you rebuilt the engine, did you keep the original dished pistons? That would be a big killer of power, lack of compression ratio.
Heads would help, but what you really need is more compression ratio. What you would need in aftermarket heads is a small CC chamber in a moderate flowing head. Most of you performance down low will be due to the compression and the abality to keep that power through the powerband will be due to the flow of the heads.

 

[73stallion]

HP is built in the heads. if you bolt a bunch of goodies on and the heads can't flow it's defeating the purpose.

 

[greggonzo1]

Are there heads that are relatively cheap that would get me some more HP?
Or

Is my best bet to just start piecing together a 351? I would like to efi either with the 302 or 351 eventually.

Thanks for the help.

 

[broncnaz]

I'd say you might be pushing about 200 hp with that setup. Biggest holdup on making more HP is timing curve and wether or not your carb is tuned correctly.
A increase in compression wont gain much more than 10hp total. Increase compression will allow using a larger cam but to big of a cam and it will have a doggy lowend.
Heads are a good power builder as SFB's have terrrible exhuast valve/port sizes. There are many aftermarket heads that are relatively cheap world products has cast iron or aluminum windsor JR heads with 190/160 valves and 58cc combustion chambers which should give a slight boost in compression. Overall I wouldnt expect much more than a 40hp increase.
There are many other companies that offer heads might want to check out summit racing or jegs websites or just pick up a mustang magazine there will be plenty of ads and maybe even a article.

 

[greggonzo1]

Well 200hp at my elevation 5280...no wonder its a dog.

 

[DirtDonk]

That's part of what I was going to ask. Just what's wrong and how is it running?
I didn't realize that Albuquerque was that high. You bet it'll put a damper on things. I"m assuming you did the normal high-altitude things though? Carb jetting mainly?
What tire size and gear ratio are you running? That's another killer right there. Your engine can develop all the power in the world, but if the gear ratio is far enough off, you're just fighting an uphill battle all the way.

For heads, there are lots of good aftermarket choices, but for budget builds, I would think that any late model HP engine like out of a Hi-Po Mustang or something, would be reasonably priced at the boneyard and help you a little.
Will it truly wake it up? Kinda' doubtful. It'll help, but how much might still be up to the other things mentioned like timing curves and piston design and whether or not you got the cam in straight or one tooth off! Hey, it happens all the time.

Good luck.

Paul

 

[greggonzo1]

Its tough to say anything is wrong as it has always ran weaker than expected. I had initially thought it was the tranny, it eventually went out and was rebuilt. But that did nothing to change power to the ground.

Yes carb has been jetted appropriately. The gears are 4.11's tranny is c-4. Tires at 30x9.5
Funny you should mention timing curve.. I had another thread going where I asked if anyone was familiar withe timing curves. I have since familiarized myself with.

As it is right now I have been debating to advance the timing even more initially than it currently is..
I have spoken to several edelbroc techs who have told me that at my altitude it is not uncommon to be running 26 degrees initial..I am at 23 now and have not heard any pinging.

I do have a decent bog off of throttle that has seem to improved as I have increased the timing.

 

[blubuckaroo]

Have you changed the pull off springs on the earbureter metering rods to the stiffer springs? According to the Edelbrock tech the Performer cam creates too much vacuum for the standard spring to pull the metering rods open. They also told me to time it to 12 - 14 degrees advanced. 23 - 26 sounds like way too much. Call the tech line again and tell you what you have in this thing and what it's doing. Mine did the same thing. Made a couple of minor tuning changes and its pretty snappy now.

 

[broncnaz]

If it has lack luster performance with 30in tires and 4.10's then somethin is amiss as you should be able to light the tires up.

 

[greggonzo1]

The pistons were replaced with forged pistons. I am not sure what spec's they are but I do remember them having two notches.. Crescent moons?(best way I can think of to describe).

I did change the springs in the carb but maybe I need to try one stronger. or work back from the strongest spring.

Yes I have been told with the gears I have that I should be able to light them up but... I can not.
I have even been told it maybe the torque converter I have as well. It is stock, so whatever came in the bronco.


Is it possible that my harmonic balancer is one bolt off? ( I have checked it and could not see that it as off, but I did not personally install it so I can not verify that it was installed correctly.

Is it possible that the timing marker is in the wrong spot?

Could the rocker arms (stock) be installed incorrectly?

Thanks for all the help I do appreciate it.

 

[Bronco717274]

Head's

Bolt on a set of 351 cleveland heads you'll light up the tires then. A few of the round track guy's around here run this set-up in there car's.

 

[Broncobowsher]

The pistons were replaced with forged pistons. I am not sure what spec's they are but I do remember them having two notches.. Crescent moons?(best way I can think of to describe).

I did change the springs in the carb but maybe I need to try one stronger. or work back from the strongest spring.

Yes I have been told with the gears I have that I should be able to light them up but... I can not.
I have even been told it maybe the torque converter I have as well. It is stock, so whatever came in the bronco.


Is it possible that my harmonic balancer is one bolt off? ( I have checked it and could not see that it as off, but I did not personally install it so I can not verify that it was installed correctly.

Is it possible that the timing marker is in the wrong spot?

Could the rocker arms (stock) be installed incorrectly?

Thanks for all the help I do appreciate it.

Those are flat tops. You should be around 9:1 compression with that.
Have you ever had it tuned up on a dyno? Could just be a really out of tune engine.

 

[greggonzo1]

No I have never been to a dyno. I just recently found out that we have a couple here in Albuquerque. I have been thinking that might be a route to pursue.

Thanks again.

 

[22213evl]

I've got a semi tired 302 with stock exhaust, a edel perfomer intake, ta 670 carb, c4, 410 F+R, 35" tires and I'm not squealin tires on pavement but it will spin em preety good in the rough stuff. with 30" tires i'm sure I could bake them tires off the rim
what exactly happens when your at a stop and romp the gas does it bog or does it sound like power is not getting to the tires. reason I ask is you said you thought it might be the Tconverter

heres somthing to consider, just a thought.
http://albuquerque.craigslist.org/pts/914225346.html
http://albuquerque.craigslist.org/pts/913285641.html

 

[greggonzo1]

Yes I can spin them on light sand, water, rough stuff etc. It is not immediate though..seems like there is a delay before the power is put down. I have said in another post that "launches" really well..but no peeling out and then power seems to die off after 3800 rpm or so.

 

[BUCKETOBOLTS]

From what you just described, sounds like your mixture could be fat on the bottom side.

 

[broncnaz]

Slight delay sounds kind of like a tq converter issue. Camshafts and tq converters have a close relationship but your cam is not all that big so stall speed of a stock converter should be fine. it could just be worn so to speak.
You balancer cant be a bolt off as they dont bolt on they slide on a key way with one bolt in the center holding it on the crank but the outer ring can slip and cause timing to read wrong. Best thing is to set the timing where it runs best without worring about the timing marks.