(FEandGoingBroke) Hijack of my own thread on Fan clutches...

[slik]

A quote that raised another question I am having with my set-up.

"A direct fan pulls MORE HP the faster you spin it. but it does have a center mass only the size of your pulley roughly 1/3rd smaller than a fan-clutch, which allows more airflow... Faster rpm's + more airflow until the sweet-spot is reached and the air is tumbling and no longer flowing past the engine..... But that's for another story..."

I wanted to address this part of your comment:

"Faster rpm's + more airflow until the sweet-spot is reached and the air is tumbling and no longer flowing past the engine..... But that's for another story..."

It's interesting you say this because this is exactly where I am at with my build. I am at 217-227 with my cam.. and using iron DOE heads with 1.94/1.60 valves in them. No port work at all. This is a custom grind and was designed to work with an AOD transmission, advanced 4 degrees. I don't have a tach hooked up yet so can't tell you where this things starts getting rough, but it does and I have to get out of it. My question is, should I be looking at a better carb/intake for this combo or wouild better tuning get me there.

I currently run a 500 cfm manual Edelbrock and a RPM intake. My mechanic thinks I need to change my cam (one geared more for the RPM range of my intake and carb). He thinks I have a full race cam that's out of the range of carb/intake. I don't know. My dad TOLD me to run at least a 600cfm carb, but as most of you know... dads know diddly squat right. I am thinking now maybe he was right. I thought the bigger CFM=more gas and I was avoiding that because she's already running rich. I adjusted the accelerator pump and it helped a lot. No moe black smoke when you step on it from idle.

He did mention IT WILL BE A TAD BIT RICH on the bottom end (as it still is, but not as bad with accel. adjustment) so that I would not starve it when I get up top. Someone please tell me what I need here to smooth this motor out. One other note, it was discovered that I need to recurve my distributor so that it comes in at around 2800-3000 rpms. I was told it's now coming in too soon. Procomp Dist. I was thinking this was the culprit, but was told by many they run great once you get them all dialed in. Sorry so long, but wanted to give as much detail to help solve this puzzle and put a smile back on my face.

[Mikes66]

Your Carb and intake are a good match for your setup. I would not change a thing on that part of your setup.

How heavy is the car you put it in? Under 300 HP fir sur, but the torque converter and rear gear will have a ,lot to do with how that engine runs.

Really sounds like all you have is tuning issues. We need to know a lot more about your motor and set up to help you. need full details, and we can tune this to work for you.

Or, you can spend $600.00 up grading to a new carb and intake, then find it is impossible to tune your car, cause the heads are an issue. Those stock heads have very small exhaust ports, and without removing a lot of that material, your going to be limited.

[frdnut]

That's a very mild camshaft certainly not a "full race" unit..You may not even be able to hear it at idle..The componants don't look too bad to me.The rpm is a good intake although I probably would have went with a 600 holley carb..What is the roughness you talk about?..Is the engine missing or laying down?..What kind of fuel pump are you running?

[slik]

I was also wondering about fuel as well. When I first picked the car up from mechanic, the first stop I made was to the station to put 91 octane in it. Once that ran out, I put regular 87. Could this be part of the problem as well. On the heads, I think the only porting was to the bowls to accommodate the larger valves. No other port work to my knowledge.

When I say gets rough, what I mean is it's not as smooth as when you are lower in the rmp range. I really need a tach to see where things start to get fuzzy. It has plenty more to go in the pedal (that's what I asked for from my cam grinder). I wanted a cam that if I'm cruizing at 75 or so on the hwy, I could have plenty left in the pedal if I mashed on it.

What happens though is it seems like the rpms are up kinds of high. I have not driven it hard to see what will happen so I pretty much get off of it. It goes, but it's not as smooth. Almost as if it needs more air or fuel. I just don't know which one.

What other details will you need. We have a stock bottom ARP'd, the heads, cam. The full specs on the cam are 480I/505E, duration @.50 217-227. I did not think this was too radical at all, but again, it was built for an AOD car. I can see where an extra gear will help things. I am also wondering if advancing the cam 4 degrees is why it seems like I am at the end so soon. I was told that that should not matter, but I don't know. Please help me get this dialed in. My grinder told me to install the cam 4 degrees advanced due to the AOD. I changed my mind about what car this motor was going in. It's a 70 Maverick and AOD's will not fit trans. tunnel.

Thanks a lot all for any help!

Also, I do not have any stall. I wanted as much cam as I can get before I needed to worry about that. My guy said that yuo get about between 18-2100 with stock converters, so I didn't add one.

[slik]

FE makes a very good point and identical to the problem I am having.

"Faster rpm's + more airflow until the sweet-spot is reached and the air is tumbling and no longer flowing past the engine....."

This is what we're trying to figure out here. I am not sure if my restriction is the heads I have, timing, or carb tuning. Could the head flow be maxed out. Sounds like it.

[Motorhead]

I think FE's comment was in regards to your fan's airflow, not the airflow inside the engine. If you are running rough at higher RPM you need to look at 1: carb tune 2: ignition timing and 3: plugs/wires/cap/rotor 4: fuel system. Too much or not enough total timing or worn out cap/rotor/wires/plugs will cause it to run rough, and so will being way rich or way lean or fuel starvation due to a plugged fuel filter or bad fuel pump. If you have no clue where those variables are, you can throw parts at it all day and it will still run like crap. FIRST thing you need to do is go buy a $30 tach and tape it to your steering wheel or something, but by god, get a tach! Next, buy or borrow a timing light and get your timing set up right, 35 degrees total (3000rpm and up) should be within a couple degrees of ideal, or take it to a shop and spend 20 bucks and have them do it, should only take 5 minutes for them to do. Then put some new spark plugs in it, and if the cap/rotor/wires/fuel filter are old, might as well spend 50 bucks and replace all of them too. Then take it out and floor it and it should pull clean up to at least 5500rpm. Pull over and pull out one of the spark plugs and take a look. If it's white, start jetting the carb richer... if it's black, jet the carb leaner. Keep doing this until it pulls clean and hard 'till redline, and the plug should be a light tan color. Then you will be about as close as you can get in one day. From then on, pay attention to how it drives, try changing one thing at a time and see if it drives any better or gets better mileage... check your plugs after a long highway cruise to see how the cruise jetting is, etc. It takes time and effort and especially THE RIGHT TOOLS.

[slik]

Yeah, maybe your right about his comment, but because this is what I'm experiencing... just sounded right. One thing I will be doing in the near future is getting the distributor re-curved. This might help solve a lot of things in itself.

[PaulS1950]

If you are running rich low in the rpm's and it gets leaner at the higher rpm's I would look into a different tune on the carb. It may be borderline big enough but the jetting and power valve are off. It should run just a bit rich at idle (not enough to smoke for sure) and then when you open the throttle it should richen up as soon as the vacuum drops and your power valve opens up. It should stay open and rich until you clost the throttle. At any cruise your engine should be running on the lean to neutral side of the mixture but never rich above an idle while maintaining your speed. You definitely need to look at the tune on your engine and your carb.
If the engine is running rough above a certain rpm then I would look at all the above and valve springs. If the can you are using is a fast lift cam it can cause the lifters to pump up before they would normally. Did you get the springs with the cam?

[FEandGoingBroke]

OK, I am taking all that was said in asn absorbing it.... Been kid sitting all friggin day...

Motorhead really hit the nail on the head with his post. (also about airflow around your engine)

First; adjusting your accelerator pump cannot effect the way ANY car idles. The car does not draw any fuel from the accelerator pump passages while at idle, and does not at speed either, there are check valves/ball bearings to prevent this, and metering rods and idle circuts to help the car run without the squirt from the pump.

That 500 CFM carb should work exceptionally well with your engine.

We need more info on what rpm the engine stumbles at and we need more info on the actual action that happens when it stumbles or turbulates or bumbles... We need you to describe as accurately as you can exactly the sound and feel of what happens when it hit's it's "sweet spot"


FE

[slik]

Got it, will get it out this weekend and investigate further. I still need a tach to really see where I am in the rpm range. All the driving in the world won't tell me that unless I have the tach. Will get within next week.

Also, I did not mean anything about the idle on the accelerator pump. I was talking about when you step on the gas FROM idle, what comes out of the tailpipes. Ajdusting the pump seemed to help have LESS black smoke.

I think we are on the right track hear and I am happy to learn that I did not waste the opportunity to exchange for the 600cfm from Summit before I started the car. Sounds like the 500 will work.

I will get the dist. curved (as I know this still needs to be done), dial the timing in at exactly 10-12 degrees, and get a tach and report back soon. Will not touch the carb just yet.