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Discussion Starter · #1 ·
Im looking to improve low end torque witout going to extremes just yet. In the long run, I plan on doing plenty of work on my truck, but right now Im just a beginner. I realize that making my engine a stroker would give me tons of torque, but thats years away. Ive been reading a book by David Vizard (a really great one, too) on improving engine performance, but most of it seems to improve horsepower only, often at the cost of low-end torque. So if anybody knows of anything that works, let me know, Id be happy to give it a shot.
 

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Without any stats on your rig its hard to do. Carb tricks are different from TBI tricks are different from MPI tricks.
All do however benifit from a bit more CFM than stock and free'er flowing exaust just about always helps.
 
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You can still fiddle with the timing a bit. Bumping up the initial timing with a twist of the distributor will increase the initial timing (yes, even on the TBI units), and this will help low rpm power. The trick is to balance this with detonation (rattling) from timing versus the octane fuel you're willing to pay for. Still, you should be able to sneak a few degrees of advance in there.
 

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It's possible to bump up the torque with basic hod rodding techniques. Yes you did notice that in a gas engine many things you can do tend to improve power in the mid to upper rpm range.

There are a few options you can look at. First, gears act as torque multipliers. Lower axle gears will multiply the available torque at the expense of speed. Since you want low speed torque, you can build the engine for mid range power and gear down, but remember the fuel economy will not be as good unless you can get an overdrive tranny. Speaking of trannys and gears, it's possible to replace the planetary gears with lower gears in some automatics.

Anything you can do to improve breathing helps torque thru the entire rpm range. Headers, a free breathing air filter, etc. You may want to consider forced induction (Supercharging or Turbocharging). Machine work can help as well. Doing a valve job or porting & polishing will improve breathing.

You can also increase torque with automatic trannys by replacing the torque converter which is another device designed to momentarily multiply torque. Stay away from high stall torque converters as these favor high rpms.

Ed
 

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there is not an easy way to get a massive increase in low end torque. there are ways but they require chaning major engine parameters.

plus may require knowledge of physics chemistry fabrication and engineering. sounds like a fun do it your self hobby project.

stuff like tuned headers. tuned long "ram tube" intake like on early chrysler.

port shape design. im told a tall narrow intake port does wonders on low end torque. possibly using a good 318 2bbl head like the #302. keeping the port at the stock width of 2bbl gasket. but increasing height to that of 360 gasket. but just hogging out does nothing. shape and contour would need to be designed. valve would need to be planned.

there is a lot of engineering involved. would take experience or much trial and error.

basically there is not any magical $300 part that will dramatically increase idle speed power output.

a properly designed stroker engine with good fuel and induction system can put out tremendous low end but cost money time or fabrication skill.

i suppose a turbo could be choosen that "tops out" at a muc low rpm. would only be for extreme low out put and would run out of steam very fast. it is all part of correct sizing.
 
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Before you go and re-engineer the heads, after the timing bump, slap on a set of 1.6:1 roller rockers. That'll kick the cam up to the lift area of a good RV type torque cam. This is if you are not planning on adding a cam soon. They're easy to swap with minimal invasion on the engine and can be done in a couple hours. It'll really wake up the engine since the stock cam is so small.
 

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hey gen 1, im just stating a "massive" improvement requires re engineering. a cam swap or compression or timing helps a little. will make it feel more peppy.

thats why i say u gotta know what you are expecting. if u wanted diesel like power curve, it is possible but only with much engineering.
 
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He said......... "Im looking to improve low end torque witout going to extremes just yet. In the long run, I plan on doing plenty of work on my truck, but right now Im just a beginner."

You said.....port shape design. im told a tall narrow intake port does wonders on low end torque. possibly using a good 318 2bbl head like the #302. keeping the port at the stock width of 2bbl gasket. but increasing height to that of 360 gasket. but just hogging out does nothing. shape and contour would need to be designed. valve would need to be planned.
there is a lot of engineering involved. would take experience or much trial and error.

He's asking for simple stuff to start with. Besides, this isn't really an area of trial-and-error because the cylinder head upgrade paths are pretty well defined already. Just trying to not shut him down. All that info can be intimidating.
 

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A dual plane intake always helps, something like a edelbrock performer. If you put on a carb spacer that converts it to a 2 bbl carb it will help with bottom end power, without spending a ton of cash. A "do it yourself" cold air induction would help too.
 

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Discussion Starter · #12 ·
I think this is a great suggestion. I forgot that this had been mentioned in the book. This seems like something I could do without lifting out the engine (not an option at all at this point). I think that, as I get more and more into working on the engine, the cylinder heads and valvetrain are going to be my first area that I really go in-depth on. Do you have any experience with the higher-ratio rockers? My one main concern with it is binding my valvesprings. I realize the change from 1.5 to 1.6 is minute, but I dont want to take any chances. But that would be a good project, especially because it would give me a good chance to examine all the small parts, make sure everything is in fine condition.

My first step, however (completely unrelated to this topic) is replacing my thermostat. It sticks open with pretty much every start. So I think thats a good place to start. Thanks again for the great suggestions!
 
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I have not changed rocker ratios. Typically, I've done a cam swap, however, as a future swap, I'd like to add some rollers. The stock springs will handle a 1.6 upgrade. Of note is the mileage. Tired springs will float valves at high rpm. Increasing the ratio will stress the springs more, so if they're already old, get some new ones like CompCams classic 901's. Just remember to factor in the increased ratio if you get a new cam later. Good luck on your learning experiences. I'm doing the same thing with the 4-speed automatics now. Just got an A500 torn down.......hmm......wrinkled face, scratching ass......"Now what?" That's half the fun. Enjoy.
 

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changing rocker ratios is not the answer. the cost would far outweigh the gains.

I just ran my engine on my dyno program, which is not accurate, but does show trends correctly, using both rocker ratios.

The difference between 1.5 & 1.6 ratio rockers on my cam, was 2 ft lbs of torque, and 3 hp, and the peaks moved up 500 rpm.

Springs ARE a concern. My cam is .473I .491E with 1.5's, and it comes out to .505I .524E with 1.6 ratios. That is a pretty decent change, and it can affect the springs unfavorably.

Hardly justifies spending the 300 or more for the rockers now....doesn't it ??

1.6 ratio rockers will work well, but only when the engine is designed for it, and then it works best at high rpm.

if you want more bottom end, advance the cam 4 deg....that will give you about 15 ft lbs at a lower rpm.

If all you want to do is open the valve more (which is all changing rocker ratios do), go buy some lash caps and put them on the valves. That will open the valves about .060" more, and only cost around 30 bucks, but may require shorter pushrods.
 
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TheRamChargerMan said:
changing rocker ratios is not the answer. the cost would far outweigh the gains.

I just ran my engine on my dyno program, which is not accurate, but does show trends correctly, using both rocker ratios.

The difference between 1.5 & 1.6 ratio rockers on my cam, was 2 ft lbs of torque, and 3 hp, and the peaks moved up 500 rpm.

Springs ARE a concern. My cam is .473I .491E with 1.5's, and it comes out to .505I .524E with 1.6 ratios. That is a pretty decent change, and it can affect the springs unfavorably.

Hardly justifies spending the 300 or more for the rockers now....doesn't it ??

1.6 ratio rockers will work well, but only when the engine is designed for it, and then it works best at high rpm.

if you want more bottom end, advance the cam 4 deg....that will give you about 15 ft lbs at a lower rpm.

If all you want to do is open the valve more (which is all changing rocker ratios do), go buy some lash caps and put them on the valves. That will open the valves about .060" more, and only cost around 30 bucks, but may require shorter pushrods.
First of all, we're not talking about your cam and springs. My comments were directed towards a stock 318 cam/springs.
Second, your program comparing the difference in 1.5 vs 1.6 ratios does not take the less than ideal stock stamped rockers into account, which run short of their stated ratios (more like 1.40-1.46). Aftermarket rollers are dead-on their stated ratios. There's also the reduced friction and net power increase when going to a roller device vs the stock system. Typical results of said swap is 20-30 hp (with corresponding torque increases), depending on how limited the other components are.
While not the most cost-effective power increase, it's not bad either, and, once again, he's asking for simple things first, more advanced things later. I'd say swapping rockers would be less involved/complicated than pulling the front off the engine and advancing the cam (which will improve low rpm power, but only by trading a similar amount at high rpm....rollers do not cost power anywhere in the rpm range, and add power everywhere.
Also, Magnum engines come stock with 1.6 ratios, and a stock Magnum engine isn't exactly a high rpm engine as delivered. Guess maybe they work well on stockers too, huh?
Ummm, lash caps are intended to spread the rocker tip load in high lift cam applications. They do not increase valve lift. The whole point is to have near zero lash to allow higher rpm limits. The shorter pushrods (or rocker shaft shims may be used) are needed to eliminate lifter pre-load. None of this increases valve lift. The ratios must be changed, or the cam must be changed.....or both.
 

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Well, to begin with gen1dak, I am not trying to argue with you. He said simple and with the tone of his posts, I figure cost effective is also in the requirements.

The program I use does not take into account if the rockers are roller or not.

My springs do not have any effect on the info I gave. They were just used for a baseline. I simply compared what the effect would be on MY engine, not his. I would bet the change would be very similar, if not LESS of an increase.

Yes, magnum engines may come stock with 1.6 rockers, but they are MADE for 1.6 rockers. They also use a different method of mounting. Just because a part was stock on one engine DOES NOT mean it will work on a different engine where it was not a stock item. If this was true, we'd all have roller cams from the newer engines in ours, because they would work with no problems or machining required, since they were used as stock..right ?

Yes, lashcaps are designed to center the rocker tip on the valve tip, which does spread the load across a wider area of the valve tip, but they also increase lift if you do not get shorter pushrods because they effectively lengthen the valve tip. Sorry, but it's a proven fact. They can also keep your valve from seating properly if you don't get new pushrods.

Yes, I agree swapping rockers would be easier, if that was all there is to it. BUT, to put 1.6 roller rockers in his engine, he will have to do the following at a minumum:

1) buy the rockers & new shafts to go with them ($350-$400 for the rockers, & $100-$150 for the shafts)
2) get new pushrods since almost all the 1.6 aftermarket rockers are roller AND adjustable ($90-$120)
3) go thru the hassle of adjusting the new roller rockers with the new pushrods (very hard to do accurately without removing the intake)
4) go thru the hassle of adjusting the side play on the new rollers rockers so the roller stays centered on the valve tip side to side (requires shims $15, and a lot of aggravation, and maybe some grinding of the hold down clamps)
5) verify the valvetrain geometry (again, hard to do with the intake on)
6) verify the new pushrod/rocker combo does not allow the pushrods to contact the head in the pushrod hole area due to the new configuration
7) verify sufficient oiling to the new pushrods thru the adjustable tip (requires a pre-oiling tool - $10, and also requires removing the intake)
8) install new valve cover gaskets ($15)
9) verify the new rockers actually clear the valve covers (1.6's may not with stock covers, if they don't, new valve covers $75)
10) run the engine, and go back and re-adjust the rockers while warm

(you can save some money, about $200, by using ductile iron rockers, which are not roller, but are adjustable, and require special pushrods to use, and will not gain you the hp/torque gen1dak is talking about by going roller)

I just did this on my engine with the comp cams pro magnum roller rockers, 1.5 ratio, so I think I know what it takes to do it.

In light of this, I think pulling the timing cover off and advancing the cam would be much easier, and cheaper too. Even if he got a new timing chain, he'd spend less than $100 bucks to do it. Seems like to me, $100 for 10-15 ft lbs is far better than almost $600 for 30 ft lbs. at best.

I'm not saying your idea won't work, I am saying that as far as being simpler, and gains for the buck, it is not the answer. Not to mention the sheer hassle of doing it.

It isn't so bad if the engine is out of the truck, but with it in the truck, it is a royal PITA!
 

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I'm not taking sides or anything, but I'm with RamChargerMan for this... If I bought a timing chain - I'd go ahead and get a double. If the funds allowed I'd check into a new cam as well. How does the fund situation look? Give a ballpark figure to work with and I think you could get better info for some mods.

just my .02
 

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Am I missing something or what??
You guys are going on and on about Mag rocker this and LA rocker that, we dont even know what kind or rockers he has!!! lol
Hell, he could have a slant 6 with adjustable rockers!! lol

I would like to know if hes carb'd pre spark control, post spark control, TBI or SMPI. Lots of ceap different tricks with each.
 
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Unless I'm getting the posts mixed up, he has an '89 318, which would mean 1.52:1 shaft-mounted rockers.
RC, can you tell me how an LA is "made" ready for 1.6 rockers when the Magnum heads are swapped on? There is no pushrod hole enlargement, though a different length pushrod is required (not exactly re-making an engine).This is true on pre-roller blocks as well.
It doesn't matter to me what he does. I initially only suggested bumping up the timing. A simple 10-minute deal, and free. Then someone chimes in about heads, yada, yada. So much for cheap and easy. From my angle, changing rockers is much easier than the other mods, and goes towards improving the engine for the long run. The rocker swap isn't nearly as complicated as you make it seem, but since everyone jumped into heavier mods, I offered a second option. Personally, I go for cam swaps first, since rockers can only improve minimally on the cam they follow (decent lift, but lazy ramp angles). In this case, the rocker swap is minimally invasive on the engine, and less daunting to a beginner.
As for the costs, once again, your experiences aren't necessarily what he'd have. New chromed shafts can be had for $60 a pair. A full set of rockers for under $200. Not all kits require every aspect to be set up by the installer, being essentially a bolt-on affair. For that matter, just some true-ratio MP HD rockers would help, and would be very inexpensive.You don't need to pull the intake to set the rockers...if sighted, a person can watch the valves (stems) move, and adjust accordingly. The way you describe it makes it sound horrible. If it's so much trouble, why'd you do it?
Now, once and for all, running lash caps. They effectively lengthen the pushrod and increase lift. Granted, there can be some minor increase (though not consistent), but this is dependent on hydraulics. If running a solid lifter, I can see where it'd be fine, and would really work, but with hydraulic lifters you run the chance of bottoming the lifter, especially in a low oil pressure situation. Why get caps when you could just get longer pushrods? Because the same problem can happen. When the rest of the world is out there shooting for near zero-lash, you're advocating what amounts to an effective increase in lash (lifter pre-load), which limits upper rpm potential, and again, increases the chances of valvetrain failure. In higher lift applications, these lash caps can cause an over-angle of the rocker arm and contact with the bottom of the rocker. Increased rocker ratio doesn't impose any of these problems. Again, I'm not out waving the rocker-swap banner. I prefer cam swaps first, but I can damned sure do a rocker swap a lot faster and easier than a cam. Less time, less return, but that's life.
 
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