Your comments on my upgrades / dyno results added

80Stang

80Stang

Well-known member
That Falcon Bible yet to be purchased (but I will), I have already carried out some preps along with total engine rebuild for my '80 Fox daily driver:

- I rebuilt a '68 200 block, bored .030 over, with engine overhaul kit from NAP
- pistons are stock dished (SpeedPro)
- the head is a E0 unit, shop manual says the chamber is 57.25-60.25. I milled the head 0.8mm, that is 0.031. Stock valvejob done. The gasget is Victor Rentz
- I added Comp Cams 260. Valve train otherwise stock
- the headers will be FSPP duals, as I have access to dual exhaust from a '92 GT
- std '80 carb. Do you think it needs hard tuning after these mods?
- ingition is stock Duraspark, new cap, rotor, wires, plugs...of course

My tranny is SROD and read end is 3.08 non-locking 7.5", but the rear axle will be swithed with the 8.8" unit from the GT; don't know the ratios yet but it is locking =;?) . I assume that it will not be much over 3.00.


I suggest the CR will fall short from what it should be, but what other comments about the package you may have? Let's keep in mind also that this car is my daily driver throughout the year (wintertime we have -30C sometimes) and I don't want to sacrifice too much economy. I had 25mpg average before the rebuild (with '80 block, shouldn't make a difference).

The package is going in very shortly.

Thanks and best regards from the other side of the world. Tuning sixes is global fun, and this great site sure helps a lot.
 
That's quite a mild cam; you shouldn't face any real issues setting it up or using it. Depending on the timing set's advance/retard of the cam, performance could vary (marginally).

Possibly at the top end of your RPM the car will be asking for a little more carburetion. I am not sure the FSPP headers fit your '80 body. One of the guys here (myles) had that problem recently.

MPG should stay about the same even if CR is down a little, as you were probably running a worn engine before.

Adam.
 
the Comp 260H cam is a nice cam. Not much for duration increase, but big difference in lift. I love mine. It works great while keeping the car very close to stock sounding. Just a very slight lope, hardly noticeable except when the car is cold.

I find with that cam, I do run out of air running an Autolite 1100. The tri carb set up like that cam, and I suspect my new Aussie 250-2V head and intake will like it with a 350 Holley sitting on top.

I think you'll like that set up for a daily driver. It is similiar to what I have on my 65 which I drive about 300-400 miles a week from 10*-100*F temperatures. The only thing I would think of adding for a daily driver is an MSD box for your ignition and a hotter coil. It will allow you to open you plug gaps and get more power and economy out. The MSD gained me about 2 MPG for highway use, maybe marginal increase in power (I'm sure it's there, but my butt-o-meter isn't that highly tuned).

Slade
 
I didn't degree the cam.

Milling the head another time costs some 50USD here. Now it would be easy to do as I only need to loose it off the block. Another .030 away, is it worth it?

The '80 block had some 200K on it. Worked fine, but you know these things that happen when some old iron falls into your hands literally for free (I mean the worn '68 engine, from oil pan to air filter...)

The headers are to be the short ones, not those aussie long tubes. I'll have to build it up with cast iron manifold for a while, as the FSPP's are not here yet. I hope FSPP's will fit...
 
CobraSix":xi2mlf4t said:
the Comp 260H cam is a nice cam. Not much for duration increase, but big difference in lift. I love mine. It works great while keeping the car very close to stock sounding. Just a very slight lope, hardly noticeable except when the car is cold.

I find with that cam, I do run out of air running an Autolite 1100. The tri carb set up like that cam, and I suspect my new Aussie 250-2V head and intake will like it with a 350 Holley sitting on top.

I think you'll like that set up for a daily driver. It is similiar to what I have on my 65 which I drive about 300-400 miles a week from 10*-100*F temperatures. The only thing I would think of adding for a daily driver is an MSD box for your ignition and a hotter coil. It will allow you to open you plug gaps and get more power and economy out. The MSD gained me about 2 MPG for highway use, maybe marginal increase in power (I'm sure it's there, but my butt-o-meter isn't that highly tuned).

Slade
Click to expand...

Yep, the lift goes from .371 -> .440. Big change.

I have future plans on the intake, maybe another head that goes through some serious mods and then finds its way on this engine.

I have a new Motorsport SVO coil on the shelf, it was originally purchased for the 64½ V8 but we never run it in there more than a short test. The coil is specified for Duraspark applications. I thought of using the stock unit, but this one is readily available if needed.

What MSD box is the right one, any rocket science to install it? What is the right spark plug cap if I decide to go this way, and is this worth the bucks?

Well, maybe it is quite a small investment if I look at the total so far.

Lot of q's here, bear with me.
 
I think it comes out that the extra .030" of milling gives about 6 more HP. Is it worth it? That's up to you.

Slade
 
6 HP is quite a lot for such a small job; 4-5% increase. That 6 would not make much of a difference in a 300HP V8, but in a small six it makes.

The CR will go near 9:1 if I mill it more. That shouldn't cause too much of a problem, do you see any significant changes in economy, reliability etc. More fun, for sure...
 
Just bolted the head off, and tomorrow it goes to be milled again. The calculator came out with 9.2 CR if the head is milled another .030, assuming the chamber size goes down to 51cc.

Any more suggestions of the project?

I forgot to mention that valve springs were replaced with springs from Comp Cams, recommended by their website for that cam. And the port divider is there also.
 
80 Stang;

While you have that head off - there will be sharp edges around the face of the chambers after milling. Smooth all of these off with a file or grinder wheel. At CR numbers over 8.8:1, these can become hot spots, causing ping. Also, take a look at the chambers themselves: if they're like my '79, they're very irregular and not matched in shape very well. Take notice of the area around the spark plug boss: make all of them look the same as the smallest one. This will improve cylinder-to-cylinder balance and the attendant MPG.

I also did some "cleanup" porting on cylinders 1,2,5 and 6, leaving 3 and 4 alone, to balance the flow a little better. Since 3 & 4 get the lion's share of flow to begin with, this helped my MPG go up after my rebuild. The inner faces of the new valve seats were quite 'in the way' of the flow on all 6 cylinders: this much I did clean up on all 6 intakes and exhausts. The valve guide bosses in these heads are nearly gigantic compared to other cast iron engines I've been in: don't be afraid to narrow those down in both intake & exhaust sides. Also on the topic of valves: if you had a valve job, look for "sunken" valves with a sharp ridge around the edges of the valves (in the seats). These must be removed, as they seriously impede flow both at low valve lifts and at higher RPM.

Also, make an exhaust header gasket (I made mine of notebook paper) solely for the purpose of checking the port-to-manifold match. All of my exhaust ports were smaller than the header, so mine didn't need changes, but some do.

If you stay with the stock Holley 1946/C carb that came on the 1978-1980 Fairmonts, it will run rich in the lower midrange (1100-1500 RPM) after the EGR system is removed. This can be compensated by running port vacuum to the distributor advance: the stock '80 engine used no vacuum except when the coolant was below 50 degrees or above 200 degrees (F). Then it switched in manifold (if hot) to cool it down or port (if cold) to improve driveability. In normal driving, the EGR would dilute the air-fuel charge with spent fuel to lower the peak temperatures and NOx: this also diluted power and efficiency, so Ford added 2 degrees static advance on EGR-equipped engines to try to help (10 degrees static timing).
 
Thanks MarkP for your comments!

I did touch the sharp ridges, just a little. I also straightened the exhaust ports (1,2,5,6) near the flange just a little bit, with the aid of the gasket. The ports are still smaller than the holes in the gasket, which are smaller than what cast exh manifold's ports are; still don't know the final setup, as the FSPP headers are not at hand and it'll arrive later this winter. I'll have to put in a cast manifold from the '60s for a while.

I don't want to touch into the ports (for example the guide bosses) as I'm not experienced to do pro porting. I know what you mean and I have the hardware to do it but won't risk the head at this point. Sharp edges I can file down; already cleaned some in the chambers as there were some sharp edges left after casting process.

Now you brought in an interesting issue with EGR. There were two PVSs in the engine, one 2-port PVS at the heater return hose and a 4-port at the heater send hose located on/near the thermostat housing. The 2-port PVS was attached to control distributor vacuum, and the 4-port was doing nothing, as the EGR was disabled by some previous owner of the vehicle.

As it always happens, something breaks while disassembling; the two port PVS was lost and a spare part is not available here, and not very available in the US also (asked a Ford dealer through a friend of mine in CO). So I thought of using the 4-port PVS for distributor. Couldn't find any temps that they operate at, maybe you know if it is going to work or not. Shop manual just says "open when hot" or such.

The head is at the shop; total milling will be 1,6mm, equals to 0.063".
 
80,

Sorry, was reviewing the thread and didn't see your question about the MSD.

Any of the 6 series will work.

MSD 6A
MSD 6AL
MSD 6 DIGITAL +

It really depends on what features you need/want and how much you are willing to pay.

I went with Digital 6+ for a few reasons, but it can be price prohibitive. The MSD6A is a great base unit.

With DS2, it was pretty easy to wire up. They have schematics for just about every ignition type possible in the back of the installation guide. It took me about 30 minutes to install.

Slade
 
I'm back with this one as the car has been in use for a while now and some issues need attention.

With mods described previously I finally got it running. The FSP headers are not there yet, I'm running a '66 cast header. Also, the ignition is stock Duraspark.

The basic timing is now at 14 degrees, the counter weights at the distributor are at the original 10R position (+20 degrees). I checked the timing marks at the pulley/damper and found out that it had traveled a few degrees, so this test is sure worth to check, no matter if it is a l6 or a v8...the TDC was marked right, and timing adjusted according to that.

I had to adjust the idle speed screw quite a lot to keep it running and also the idle mixture had to be turned to richer to get even some vacuum at idle, which is now some weak 14 @850rpm idle speed. The vacuum meters needle is quite steady. The carb is Holley 1946 1V, not the C-version, and totally untouched. The mixture screw is quite "numb", you can adjust it but almost nothing happens to vacuum. The exhaust gases were checked at the inspection last week, they were ok but I verified with the results last year (with the original engine) and they were way better. I can post the results if needed.

Ok, the problem. The engine feels lazy, and the mpg went bad.

I don't think it is less powerful but I don't feel noticeable increase either. Obviously it feels lazier than before at low speeds because of the cam. The fuel comsumption went up some 25-30%. A few times it has been difficult to start the engine while hot, and once it died on the fly while I was driving very slowly in heavy traffic. I think there is enough timing advance as it slightly kicks back while driving steadily at low speeds.

I have tested many configurations for the vacuum advance; at the spark port, venturi vacuum port, ported with temp vacuum switch (I have a 4-port tvs, which actually is like two 2-port switches). The PCV is new, and has two ports. The lower port is connected to carb plate (manifold vacuum), but with the upper port I've tried plugging and also connecting to vacuum source. I don't really know where it should go now, previously it was attached to purge valve but all that pollution prevention stuff has been removed.

Also there is a symptom that I quess is because of icing; at highway speeds it usually accelerates only while pressing the pedal very lightly and the same applies even more when I have just exited the highway and drive slower roads...if I try to accelerate faster, it kicks back on me or how could I say, "hesitates to go".

I'll be happy if you can help me with this. Thanks!
 
Okay, Had to review what you had done.

Point #1: The vacuum at idle. With the comp Cam 260, you should NOT be able to get more then about 14-15inHG vacuum. You're not going to get the 19-20 inHG readings that you did with the stock cam. So that number doesn't surprise me much.

Point #2) You say your valve train is stock. Are the springs stock? I would advise going to higher rate springs, like the ones Comp Cams sell with their cams. I'm not sure this is the main culprit or if it has any play at all, but it could. With a high lift cam such as the 260, you should really have higher rate springs in order for the valves to close faster.

Point #3) readjust the idle screw. Two parts here. turn it all the way in, and then turn it 2.5 complete turns out. That will give the starting point. Now look for the butterfly adjusting screw. not sure where it is on the 1946, but there should be a screw that adjusts the butterfly opening at idle. The symptom you describe as the idle mix screw doing nothing for you, usually means that butterfly screw is open too much and is by passing in part, the idle mix circuit. I know, because this screwed me up for a couple of weeks last summer. That should also help you mileage.

Point #4) Do you have the DS2 hooked up to a ported vacuum source on the carb? That will help give you better timing under hard acceleration.

HOpe that helps some. Just some things to look for.

Slade
 
Neither of the dual out headers will fit the fox body, but the single out is OK. I am working on a the idea of shortening the Pacemakers by cutting them off just after the collectors and adding collector flanges. I 'm pretty sure it will work. So if you want to give it a go, let me know and I will have one modified and send it to you. If it doesn't fit, you can send it back for a full refund. :wink:
 
What is your timing with the vacuum hose connected at idle? Vacuum cans are tuned to provide full vacuum at 1" to 2" below what the car's normal engine vac at idle. So if you changed cams and lowered the idle vacuum, you may not be getting full vac advance, hence doggy acceleration. See if your vac can will accept a hex key in the nipple and try to adjust the vacuum, many of them do from the factory and aftermarket. It's helpful to use a Mightyvac pump and see when it starts pulling the vacuum rod and when it reaches full travel of the vac advance. Then look at the vacuum readings off of your vacuum tee, and hook up to the one that is going to provide the most vac at idle. Tune your vacuum advance can so that all of the advance is in below the reading on your vacuum source.
 
Did you set the base timing with the vacuum disconnected? Setting it with the vacuum connected gives you too little advance when the throttle is opened. You should be at 10-14 degrees btdc at idle, without vacuum.
 
CobraSix: #2: the springs are Comp Cams, should be just for that cam according to Comp's catalog. Funny though, the springs are rated 48lbs @ 1.600 which does not seem like much higher rate than original 51-57 @ 1.590 (source: shop manual). I was a little surprised when I got the springs. The set is part no 902-12, open pressure 146lbs@1.250, 280lbs/in., coil bind 1.125. The springs seem to do fine up to 5000 rpm, have not revved it higher yet.
#3: I'll try that when I have access to vac gauge again, hope tomorrow
#4: I have tried both the spark vacuum port and the venturi vacuum port. I understand that the spark port is below the throttle plate i.e. is manifold vacuum. Tried the manifold vacuum on top of the log also.

Mike: we have our multi-piece header business uncompleted. Seems like you did not connect me with me :wink: I'm looking forward to get your product into my car, it will finish the engine bay as you've seen the pic of it.

Doug (& MustangSix): the timing is now 14 degrees at idle vacuum hose disconnected and plugged. There are no vacuum cans, this is a 1980 Fox Mustang.


What if there is a vacuum leak somewhere? All other places are checked and doublechecked, but the brake booster was sandblasted during the projeect and it got holes at the back (rust, rust...). I blocked the holes with some sealer, but as I understand there should be no problem even if they were there as they are at the back. But of course it is possible that sand went thru the diaphragm...well, the booster works and I can gauge the vacuum after disconnecting and plugging the booster hose. It was connected when the engine was setup.

Anyway, thanks everybody for the prompt answers!
 
Hey, 80;
Some things come to mind about that carb:
1.) the 1946 is sorely prone to icing. If you can, put a warm-air system on the intake of the air cleaner: a Fairmont setup is very easy to incorporate. They have a nice little air stove that fits over the exhaust manifold, right under the carb.
2.) the 1946 is also sorely prone to power valve leakage at vacuums less than 16 inches. This might be a problem with that cam. The result is sluggish low end and low MPG. For starters, check the tightness of the screws on the top cover of the carb: chances are very good that they are stripped and the top plate is warped - both extremely common. This lets the vacuum passage to the valve leak and the valve pops open too early. Fortunately, Checker sells a Holley-rebuilt version for about $100. I fought mine for years before just buying a rebuilt, was worth every cent!
3.) Without EGR, you are going to get low MPG with that carb unless you rejet. It is curved to be extra rich (12:1) in the range of 1/4 - 3/4 throttle to cope with the "intake leak" effects of EGR. The only real saving grace of the 1946 is its 187 CFM rating.
4.) Check the 'hot idle compensator' on the side of the carb, under that little cover plate. Most of the covers leak after while, or if it was rebuilt with the wrong gasket, it won't seal. I had to modify the gaskets in most of the rebuild kits I used.
5.) You never mentioned the "deck height" value from your block. Some of the early 200 I6 units had .100" or more - I hope yours doesn't, or the huge quench band height will kill your MPG until you deck the block down.

The 1946 has a lot of features no one asked for, like too-strong power valve springs. The Dodge version of the carb (non-"C" models) were curved differently, less rich in the midrange, but more rich on the top end (1/2 - full throttle). But, their idle circuits were ported differently, very rich, because the attendant engines used full-time EGR in the intake tracts.
Last time I tried one of these, I had the idle mix screw at 1/2 turn out to get it lean enough, then icing was a problem on even 50-degree days!

If you're in a position to do so, try the H/W 2-stage carb. It will give better MPG and better top end, both (235 CFM). Rumor has it that some 80s Mustangs had these on the 3.3L engines, all jetted right, etc. - I'm still looking for one, though.
 
The warm air system is there, though it is not tested if it functions (those temp switches in the air cleaner) and there is no pipe from the inlet to anywhere near the exhaust; I 'll put that to work when I get the headers, this cast header is temporary setup

The screws were just tightened yesterday, they were not too open but there seems to be some moisture at the gasket of the top cap; it is a little wet all around the carb.
I'll check the gaskets and use sealer to get them tight; I don't have new gaskets available at this time

The block is a C8 casting and it was cast in summertime 1967. If this turns out to be a problem I'll rebuild the original '80 block and put that back.

Rejetting: is it a realistic option to do and what size of jets should I go to? Just asking if it is wise to stick with the 1946 after all. What is your recommendation for a new carb, which model? I might also go to some 2V applications if you can recommend a good setup.
 
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