I've heard so much about the 300 versus the 302 and 302 versus the 300. I personally love my 300, it is slower than a 302 of the same year and has less economy but to me runs smoother and is better off road.

I know all of the good buildups out there available for my 300. 175 hp at the rear wheels can be easily achieved from what I can tell. I've also heard that at this horsepower level the torque will be in the mid 300s to high 300s between 350 and 380 at roughly 1800 rpm. I've also heard that a 175 hp 302 will have only 290 to 340 ft lbs of torque at a higher rpm. I told this a friend of mine who is an ASC mechanic who keeps whacking me and smacking over the head with facts and equations to prove that a 302 and a 300 should have exactly the same torque due to displacement. Which is the truth? I know that at 110 hp factory I still have enough torque to yank stumps and throw rooster tails of mud. he he he

 

the torque on the 2 engines is relatively the same ofter modifications, but the r p m range of the torque peak is different. straight motors make there torque down low, while v engines make their torque in the higher r p m range.


jim

 

Whack the "ASC" mechanic over the head. Torque is a function of stroke as well as bore. The 300 has a much longer stroke, so it makes more torque, and it makes a greater percentage of its torque down low. The tradeoff is that the ultimate horsepower the engine can produce is diminished proportionally.

Bottom line - a straight six will be slower than a V6 or V8 of the same displacement in terms of top end, but it will live longer and be able to pull/tow/haul more weight and more effectively.

 

I agree with Spktyr. Torque is twisting force. The longer your lever (stroke)for a given bore diameter, the more torque you will have. The tradeoff is piston speed. At a given rpm, the longer your stroke, the higher the piston speed and the greater the potential for bore wear. Older engines (pre-1950's) were generally "under square". That means that the stroke was greater than the bore. These engines had much better low speed performance than modern engines of the same displacement because the torque was developed at a lower rpm. But, you could expect to do a valve and ring job on them about every 50,000 miles.

 

So basically what you are telling me is that it is completely possibly and most likely true even that a 175 hp 300 I6 would make 360 to 380 foot lbs torque while a 302 built to a 175 hp would only have torque in the neighborhood of 290 to 320. My mechanic not my friend the ASC tech said that basically with a 300 I6 up to 200 hp basically the torque equals twice the horsepower. Factory the truck is only 110 and it's torque is 243. So it's reasonable to think that. I laugh hysterically and sinisterly at the thought of 360 to 380 ft/lbs of torque not too far off idle. Muahahaha With the low gears of my 4speed she should be quick too.

 

No, that is not what I was saying. My point is that torque is increased by increasing the stroke if displacement is held constant. In fact, I don't think that torque is any where near as responsive to performance modifications as is horsepower. Most modifications are aimed at increasing the high rpm performance; this will increase horsepower which, up to a point, is simply the number of piston strokes per unit time. In fact, most "hop-up" procedures actually reduce low rpm performance by decreasing torque. On a properly carbureted (or injected) engine, normally aspirated, and with a reasonable (stock or nearly) camshaft, torque is largely a function of stroke, displacement and compression ratio. If you want low speed performance, keep the engine stock. If you want lots of horsepower, change the carburetor and cam but be prepared for a rough idle, weak low rpm performance and a driveline that was never geared for the engine you will have.

 

Bummed out now.

 

I still can't believe that that engine's peak torque at 1600 of 243 ft/lbs is as good as it gets. It is still a 300 cubic inch motor. Now I've seen people build motors that are stock except for cam and carb that were very sorry engines. From what I've seen with other motors, if you increase flow, increase compression and you'll bring it back to the bottom end if you have the right cam grind. Through all of these forums I have received such incredible advice but I still have no idea the best grind for torque with this motor. I'm figuring short duration, high lift with a 1.75 chevy bb rocker arm but anyone with a better suggestion would be appreciated. Also carburetor choice plays an important role as well. I'm looking to install an Offy intake with a Holley 4360 spreadbore 450 cfm. I found out that a 500 cfm squarebore will have a tendency at idle and low speed operation to flood the center two cylinders. So at idle up to probably 1500 rpm the truck will be on the small primaries which aren't any bigger than the factory 1 barrel, possibly smaller. The other choice would be a 390 cfm Holley squarebore. On a motor that feeds off a long manifold with unequal length runners, a spreadbore is the best choice. Anyone know where I can find a used or rebuilt Holley 4360 for cheap?

 

Were I trying to hop up the engine, I'd have a long talk with Isky and go with a MegaSquirt EFI system, or multiple Weber DCOEs. 4bbl carbs SUCK for inline sixes, you never get the mixture right for all the cylinders.

 

I've been told the biggest issue with a straight six and a 4barrel is idle flooding and low rpm flooding. I realize with unequal length runners a single carb will never have completely perfect fuel mixture. I can avoid the flooding with a spreadbore carb and the right jetting. The problem is the other two choices are very expensive. I'm a simple man on disability who loves his old truck but still enjoys "hopping up" the engine. A friend of mine goes to all kinds of shows and has seen an Offy intake for as low as $40.00. He told me a rebuilt or used 4360 should run somewhere between 60 and 120 bucks.

 

Was this the same guy that told you that "a 302 and a 300 should have exactly the same torque due to displacement"? It's not only "not perfect", but it's not even close. The big problem is that you will never get more than two cylinders tuned right with your typical intake manifold plus four barrel, spreadbore or not; you'll always have two that are too rich and two that are too lean. Been there, done that, went back to triple SUs. If carbed, a six needs at least two and preferably three two-barrels to get maximum performance. This has been proven over and over and over again by marques like Jaguar and Datsun/Nissan and their racing successes.


Just remember, you get what you pay for. Sure, the Offy manifold is cheap and so is the carb, but three DCOE's and a Ford 300 manifold aren't really that much more expensive, if you factor in the annoyance and frustration of trying to get an improperly carbed six to run right, especially with non-stock cams.

 

adjust the burn pattern through spark plug selection? It's an unusual idea but it would possibly work. Never been good with the hot plug/cold plug selection deal but think about it, a hotter spark to burn the extra gas in the center two, a slightly cooler spark in the next two and then a cold plug in the 2 end ones.

 

That's one way to try to cope with it, yes. However, it's only making it so that the engine is usable, not producing the additional power that you intended, so you might as well not bother.

 

My truck turns 25 this October. I'm not sure about the state of Virginia but I know in some other states 25 years and the truck is emission exempt. Are these 2 barrel progressives? I'm not worried about power I'm looking for fuel economy as well. The 2 small barrels of a spreadbore would have helped with fuel economy. I know the one barrel is about as efficient as dumping gas down the manifold by hand. With a progressive 2 barrel, it would run on a smaller primary. So if my truck is emission exempt, I'd consider it but damn it still sounds so expensive. 3 carbs to purchase instead of 1. A specialty manifold. A special breather cap system. Special linkage. So many things to set up. Synchronizing the 3 carbs. I still can't believe a 300 can't run properly off a small 4 barrel, it runs smooth with the tidy bowl special 1 barrel.

 

I wrote the above without concern for emissions. If your truck is still subject to emissions laws, technically you can only swap like for like so it's a moot point anyway - no spreadbore, no 4bbl in that case.

The DCOEs are like any other two barrel - they have a smaller primary and a larger secondary. They're not all that expensive, and I've seen the manifolds running around for years. No idea what you're talking about with the breather cap, unless you mean the air filters (less restrictive on the DCOEs, which use individual filter pods). The linkage is readily available, and synching them is very easy.

Do what you want - believe your "ASC expert mechanic" friend. I'm done with this subject.