Getting More go out of a 304

Jonsalter74

Jonsalter74

Member
I have a 74 Scout II it has a 304 and I would like to get a little more go out of this power plant. I have a pair of hooker headers on it and but other than that I have not done much to it. I am open for sugestions and any information I can get.
 
First we need to know how you intend to use your IH.
We need to know if you intend to do an overhaul orjust want bolt on stuff.

What kind of budget do you plan on.

Basicly anything you find for your Ford or Chevy can be aquired for your 304. Anything from a stock redo to a all out 383 inch stroker. You name your poison.

A nice mild cam and compression bump will give you more go. If iho does an other run of aluminum manifolds you can put a 4bbl carb on it.

Robert
 
The oem ignition system begs for major upgrade! Many ways to achieve that and any thing you do is an improvement over stock.

There is much information throughout this forum that can lead to vastly improved performance for ya, spend some time reading each and every thread to determine the most cost effective route to take and then put together a plan than can be achieved in steps as the budget allows.

An example, try this thread, it's a continuous work in progress regarding all possible ignitions system upgrades:

http://www.forums.IHPartsAmerica.com/ignition-tech/644-ignition-system-performance-upgrades.html
 
I agree on the ignition system upgrades. Improving the centrifugal (mechanical) advance curve on the distributor can make a noticeable improvement. Just tuning the engine and making sure all is well (good parts, timing, compression, air/fuel mixture) with it is the place to start. A tired camshaft can also cause power problems.

Proper gearing (transmission/transfer case/axles) is needed for the best performance in the particular application. Large tires and 3.07 axle gears can cause a perceived lack of engine power, as can a bad torque converter or other transmission problems.

Imo, I don't believe in exhaust headers for an average IH 304/345. The negative aspects (heat, leaks, space, cost) outweigh any minor benefit of a few hp at the higher rpm range.
I think there are better places to spend the money and time on an IH vehicle.
 
Robert kenney said:
If iho does an other run of aluminum manifolds you can put a 4bbl carb on it.

Robert
Click to expand...

Just to clarify we do have plenty of the 304 aluminum intakes as a second run of those was made early last year. We are out of aluminum intakes for the 345/392.
 
I have done some checking. I think my 304 is in need of a rebuild, it is getting about 10 mpg, and seems very sluggish. I have rebuilt the carb and replaced the plugs but I dont think anyone has ever touched the engine. I would like to keep an IH power plant in the vehicle. This is my daily driver so I want something that is drives well and is as efficient as a tractor can be. My budget is limited as of now but this is a project that will be done on a spare 304 motor over time. What type of improvments will make the biggest difference? Is a cam a good idea? Should I have it machined to .60 over to increase cubic inches? I heard that puting 345 heads on a 304 is a possibility. I am looking for options.
 
John,
erik had a good pointabout big tires as they will kill overall zippyness (for lack of a better term) if you have installed larger tires you could be in need of a ring and pinion change.

Could you possibly post as much information as you know regarding specific specs of your IH.
1) rear end gear ratio
2) tire size
3) transmission type
4) how dose the engine run (missing , low compression )?

I would definatly go through the trouble of investigation all of the above before tearing into it blind. There is a lot of items that would improve torque and yes boring .060 is one of them but will yeild limited results like 313 inches (+3% displacement and torque). You would not likely notice the differance.

Robert
 
Jon...ya need to do some basic diagnostics on your existing engine! I bet you would be pleasantly surprised what an all-day massage of your motor would do for it!

That would be a compression test and a leakdown test. Other than a complete teardown and measurement scenario, that is the only way to figure out which direction to go!

And...again...if the ignition system has not been serviced correctly, that is the most prevalent factor in engine performance deterioration! It is not carburetor deterioration if it starts and runs, that comes after the ignition system is squared away.

Your existing engine starts and runs! That is a major plus. Why put $3k+ inna motor that runs to end up with the same thing? No telling how many "engine overhauls" are sold every day just because one spark plug cable is faulty!!! Even if you have no tools for diagnostics, for way under $75 you can get everything ya need at harbor freight, I use the same stuff in my shop.

Once ya know what ya got, then make a plan for improvement. If the diagnostics say "engine rebuild", then ya know what to do and your budget controls that.

The 4v manifold with an appropriate carb can wake up the 304 in a very positive manner...but only if it's in decent condition and ya incorporate an ignition system to support it!

The IH only/rpt version of the oem IH highrise/dual plane manifold (with "air gap") is as advanced as any "streetable" intake manifold that edelbrock/weiand/offy/etc. Make for chryfordrolets.. And it was designed more than forty years ago!

If you'd like some help in performing the diagnostics, once ya have the tooling post up a new thread just for your situation and we'll step ya through the process of using the stuff and then analyzing the data you record! A thread like that would be of great interest to many of our members!
 
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Thanks for you help. I have not checked the compression yet but I will this weekend. I have increased the tire size to 33x12.50, I have a torque flite 727 transmission and my gear ratio is 3.73. The engine sounds like it runs good and does not smoke except at start up. I think I May have a bad lifter because I get a ticking sound at start up that usualy goes away. If a ring and pinion change is what is needed then what ratio would you suggest.
 
As a basic starting point and to get your engine into it's peak torque range 2500-2600 rpm @ 60 mph. Now you are only turning 2250 (calculated) with your 3.73's. 4.10's (4.11 if you like) will put you on the Mark. I don't know the going rate to swap gears. You will need to call Jeff @ ihon for a quote.

I have friends who made the change and have been happy.

But first get her running top notch first. We will piont the way for you if you want to dial her in.

Robert
 
Jon,
where do you feel that your Scout is sluggish. Is it around town driving? On the highway? The trails? Needs more lowend power? Topend power?
We need more details as to what you are looking for, or what trouble you are having.
 
My Scout is the most sluggish in the low end. I drive 3 miles to work every day but I have to jump out onto the highway and it just will not get moving untill it hits about 40 mph. In the top end it seems to do well. What I really want to see is a bit more go when I put my foot to the floor. There does not seem to be any major problems I just want more power from the motor that I have and would like some advise on what are good routes to go for with an IH 304.
 
33" tires and 3.73 gears is at least part of your problem. Drop gearing down to 4.09 or 4.27 and getting on the freeway will be much easier. Seeing that you have a short commute I would lean more towards the 4.27.

Keep in mind the engine still needs to be up to par so keep following our techs advice on the engine tune as it could be as simple as a stuck mechanical advance in the distributor.
 
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John,

adding to our prior posts and after reading your performance comments: check the following

do you have a tach in your rig? If so where do your upshift's come in while you have it floored (1st -2nd-3rd). I would like to see 3500+. From a standing start and full throttle 1-2-3 up shift's should occure at max hp which is at roughly 3800 - 4000 for a stock 304. If you dont get close to that rpm you won't ever see rated hp.

Also do you get a full throttle down shift when you are crusing and floor it?

Both of these characteristics are controled by the kick down linkage between the carb and trans. Full throttle should bottom the kick down lever travel at the trans. This is a start point. Fine tuning only if kickdown is excessive.

Rk
 
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Personal opinion.
I think your gearing is decent for what you have.

I would look more on the lines of your tune. Can you check ignition timing? That can help torque, and fuel economy. Another easy one to check, is the carb opening all the way up when the gas pedal pushed to the floor.
After you come back from your commute shut the Scout off and pull a spark plug (allow the engine to cool some). Try not to idle too much after pulling into the drive. Than either take some pictures and post them, or describe what you see. Look at the full length of the center electrode under a good light.
You said you rebuilt the carb (or had it rebuilt). Is it a Holley carb? If so was it rebuilt with Holley parts? I say this, just because I've seen far too many of the "generic" power valves to be incorrect, some not even close to spec. The gaskets are ok, but I've gotten to the point of only using Holley power valves.

As others have mentioned a compression test will give valuable information on the overall condition of the engine.
 
I rebuilt the carb with a Holley kit. Needless to say it is a Holley 2bbl. The plugs have been recently done but looked a little soot blackened when I pulled them two weeks ago. I will check the shifting this weekend and see what I come up with. I know that I when I put my foot to the floor it does not consistantly down shift. Also I had some questions about the ignition upgrade. I have points in my distributor and the rest of the ignition system is stock. I read the thread about upgrading the ignition system and wanted to see if I understood this correctly. Is there a mollory aftermarket destributor that offers a better ignition system than the stock or is my only option to go with a dui unit. If an after market system is available then what is the perfered system? Any advise is welcome. Once again thank you for your help.
 
jonsalter74 said:
I rebuilt the carb with a Holley kit. Needless to say it is a Holley 2bbl. The plugs have been recently done but looked a little soot blackened when I pulled them two weeks ago. I will check the shifting this weekend and see what I come up with. I know that I when I put my foot to the floor it does not consistantly down shift. Also I had some questions about the ignition upgrade. I have points in my distributor and the rest of the ignition system is stock. I read the thread about upgrading the ignition system and wanted to see if I understood this correctly. Is there a mollory aftermarket destributor that offers a better ignition system than the stock or is my only option to go with a dui unit. If an after market system is available then what is the perfered system? Any advise is welcome. Once again thank you for your help.
Click to expand...


Need to run at a constant speed around 1/2 throttle or more for 3- 5 minutes then shift to neutral and instantly kill the motor but be carefull not to lock the steering ( don't ask) :mad5: ( no idling or coasting). Pull a plug tan or off white (on the ceramic surounding the center electrode) for an emmisions truck. Any farting around town at low speeds will ruin plug color so I would not worry about the sooty color until you do a hot plug reading. May just be a high float setting or Rich idle.

They won't always down shift depending on vehicle speed. Better to look at full throttle shift points when you get a chance.

I May get over ridden on ignition choice "but" a points ignition can be fine if your settings are ok. Dwell is the important one as it dictates how much time the points are closed during which time the curent flows through the coil creating a strong feild called saturation. To short a time and you get a weak spark. Sorry I don't have the numbers handy but hopefully mr mayben will chime in.

The mallory unit is a good in the magnetic pickup version. Imho.

Other manufacturers make electronic conversion moduels to eliminate points. I have never used one so I can't say how well they last.


Robert
 
Like was previously mentioned, make sure you can achieve wot with the accelerator pedal while the engine is off. The sii accel pedal arm is a flimsy piece of shit that wasn't made to hold up to 35 years of lead foot stomping. Make sure it isn't bent or broken which often prevents full pedal travel. Jeff sells new ones if yours is tweaked beyond repair. Robert's suggestion about the trans pressure adjustment (kickdown) is spot on too. If your upshifts happen too fast, that equates to dog-like performance.
Ya got the Holley points dizzy in that thing? You should be able to swap in a pertronix II for way less than a dui setup would cost, while avoiding all of the fitment and adjustment issues inherent with that upgrade.
Keep your eyes peeled for a IH spec'd delco dizzy. You can put a crane xr-I module in one of those for even less than a pertronix. I'm running that combo on my 392 and it's a very affordable and user friendly electronic ignition setup.
I think you'd be better off incorporating either of those module swaps as opposed to modifying a relatively rare points dizzy with a hodge-podge of j/y and aftermarket parts from the big 3, but that's just me.
If none of the above works, swap a 392 in that pig and leave everybody in your dust cloud:dita:
 
We have a forum and sub-forum just for ignition issues and upgrades, let's use that for some research!

Here's the "upgrade" thread which is a continuing project, I have much more info to add in there, just don't have time recently to post all the stuff, and everything in that thread also pertains to I-4 applications as well:

http://www.forums.IHPartsAmerica.com/ignition-tech/644-ignition-system-performance-upgrades.html

Everything that is going in that thread is all commercially-available, drop-in stuff that anyone with reasonable mechanical ability can perform.

None of the commercially-available electronic trigger systems/conversions are a complete solution, they are all inductive technology. But ya combine an electronic trigger with a "box" of your choice, that is an upgrade.

A dui distributor or any other type of "hei" conversion is a simple inductive system, though those units can trigger a "box"... No matter if it's crane, msd, mallory, accel, etc.

The workaround distributor conversions installing the guts of one distributor into the body of another distributor is not a performance upgrade, just a boneyard methodology of achieving an electronic trigger. And performing that kind of workaround on a worn out distributor is less than useless!
 
The 33" tires with 3.73 axle gears is fine for general-purpose driving with a 727 trans. My Scout II w/ 304 engine has that tire size/axle gearing, and it cruises quite well on the freeway. But I also modified the drivetrain by installing a low 1st/2nd gearset in the 727, and replaced the Dana 20 transfer case with a Dana 300 for a bit better 4l ratio.

4.09 or 4.27 axle gears would allow for better off-the-line performance, but then the engine rpm would be up there on the highway.

As others have suggested, work on the diagnostics and make sure the engine, transmission, and all the adjustments/specs of those are correct.
 
Michael has it right...peruse the ignition upgrades threads. Lots of good info/advice there. Biggest performance upgrade I did was a pertronix/jacobs combo. This was even after rebuilding the stock 345 w/better compression and an isky cam. Drove it for two months before I ditched the ghost box, and haven't looked back. Totally different truck now. Points/gold box had their moments, but now the aftermarket offers soooo many choices, its foolish to crutch the stock stuff.
 
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