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Old 07-27-2005, 03:56 PM
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351 windsor running rich ????

Hello all.
Ok here goes I have a 351 Windsor that I cant seem to get running right.
This is not my first time sending a message on this motor but it is on this problem.
Here goes when the car gets hot its seems to run rich and fouls up the plugs.
I have been all over the map with jetting 750 dbl Demon.
I just put another carb on 750 holly vac secondary.
That still did not solve my problem with the plugs.
So what I did was a compression test.
Here is some info on motor first.
Trw 8.5 comp forged pistons, Dart Windsor Heads 64 cc.
Cam is Comp cam FW XE284H-10
Lift Intake 541 Exhaust 544
Duration &.050 240 Intake Exhaust 246
Ok here is what I found after compression test.
Please keep in mind that this test was done on a room temperature motor.

(Plug Compression ) ........... ( Condition )

#1 102 ........................ Very Black
#2 97 ........................... -----"-----
#3 105 ......................... -----"-----
#4 98 ......................... ----"------
#5 103 ........................ Running Good
#6 98 ......................... -----"-----
#7 100 ......................... -----"------
#8 102 ........................ Very Black

Yes I know it should be hot but I did a test on #1 102 hot and also # 5 103 hot no difference from cold.

OK thats it by the way the motor is Farly fresh maybe 20 miles on it.
Heads where just done also new guides and flow work.
So as you can see it driving me crazy any Ideas ???
I need help lol.
Thanks in advance Ray.

Last edited by ve3ham; 07-27-2005 at 04:04 PM.
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Old 07-27-2005, 04:42 PM
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Ray,

I'll be interested in what others have to say but those compression numbers seem low to me. They are okay relative to each other (which is important), but I can't figure why a brand new motor would have less than 130-150 lbs. (But I'm far from an expert on these things). Also, I can't fit that in with your rich condition at speed. What sort of vacuum are you getting at the manifold?
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Old 07-27-2005, 05:57 PM
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351 windsor running rich ????

Thanks CBoy
Yes that is what I thought also very low compression.
When I was tunning the Demon Carb I got a Maxim of 12 lbs @ 1000 rpm idle. Torker2 intake.
Here is the other thing that I did not mention was when I changed the oil it was about 1 liter down only after a few weeks of driving it a couple times a week,and the oil had a strong smell of gas,that is why I have been up and down with the jets and two carbs.
What I thought was happening was that the gas was contaminating the oil that bad and then loosing its viscosity and that is why the oil is burning off and getting low oil pressure.
Its a weird one thats for shire.
After a few weeks I would have low oil presshure and then change the filter and oil and the oil pressure is back 60 lbs cold 40lbs warm @ 2500prm and 20 at Idle (1000rpm)
As I said after a few weeks those numbers would go out the door and become low say 15 idle and max 40lbs at what ever rpm to dangerous that why.
Ok maybe thats part of my problem keep the ideas coming please.
Thanks Ray.
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Old 07-27-2005, 07:36 PM
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running rich 351W

From what I can see, I would say you are running too much cam for your compression ratio. Another thing I am wondering about, is your ignition timing. With that setup, you should be running about 15 degrees initial advance and about 42-44 total, coming in around 3000 RPM. The timing may help your problem, to some amount. Also curious what octane gas you are running. If you are running higher than 87-89 octane, you are wasting your time on fuel.
Youve also got the totally wrong intake for your setup. That torker 2 doesnt start working til about 3500 RPM.
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Old 07-27-2005, 08:32 PM
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running rich 351W

Max Keith.
Thanks for the reply.
You hit the nail on the head that is exactly what timing im am running.Msd 6al with regular dizzy vac advance hooked to carb.
About the gas your rite I have tried 91 gas and have gone to 87 no difference .
About the cam size you might have some thing there as that is all I did change the cam,heads,lifters from a bone stock fresh rebuild at 30 over.
I ran the stock engine with stock heads and cam for a bit with no problem.
The problem only started shortly after I changed the cam,heads,lifters.
OK hope that brings some light to the problem.
Thanks keep info coming ......Ray.
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Old 07-27-2005, 08:39 PM
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Intake and cam

I am inclined to think that your problem lies in your combination of cam and intake, along with the lower compression. Due to there having been 2 major combustion chamber sizes with the 351, a 60Cc and 69 CC chambers, I am wondering which pistons your 8.5's are related to? If its the 60 cc then your running a 54 CC head will bump you up to about 9:1, however, it that 8.5 was based on use with the 69CC head, you could be very close to 11:1 compression.
Something that occured to me is have you checked your float levels in your carb. If your floats are set too high its going to cause raw gas to run into your engine as the needle valve wont seat, shutting off the gas flow.
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Old 07-28-2005, 02:49 PM
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351 windsor running to ritch

Hi again Max.
Well Im not totally shure what type of piston is in this 351 as I bought it as a short block and the stock heads and cam where in it.And I ran it for a bit then I put the 64cc Dart heads (iron) and the comp cam,new lifters in to it.
Im not shure what cc the chambers are also.
I do no that when I took the stock heads off I took a measurement and it was 30 over the pistons did not have a name on them only that they where 30 over.
They looked like a hockey rink oval recessed indent in them.
I looked all around to see if I could see some like it and found some for sale I think on ebay that where from sealed power or trw.
It said that they where 8.1.1 compression @ 69cc heads.
If it is like you say the compression could be as high as 11.1 would I not see that in the compreshion test ?
I will try to upload a pic of them.
Thanks and still searching for a answer to the problem with the running Rich.
Thanks again Ray.
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Last edited by ve3ham; 07-28-2005 at 03:47 PM.
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Old 07-28-2005, 07:48 PM
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351W pistons

Im familiar with those pistons, and since those are 8.1:1 with the 69 CC head then you are at about 8.5:1 with the Dart heads, as they have a 4 CC smaller combustion chamber.
Were I in your shoes, I would opt for a cam that is about 215-225 degrees duration @.050", with 110 degrees or more of lobe separation, and go to an intake more along the line of an Edelbrock Performer RPM or a Weiand Stealth.
You would find a lot better useable performance out of your engine that way.
Have you checked your float levels on your carb? Another thing to do would be to check and make sure your secondaries are closed as they should be. The only time they should be opening up is at WOT, and with the stock spring, should be coming open at about 3500 RPM. I am presuming you are running vacuum secondaries on the carb. If your secondaries are open at idle, this can cause excessive gas to go into the engine as well.
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Old 07-28-2005, 08:58 PM
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Re--351 W

After reading your post it was easy to see why your cranking comp test is so low on a fresh motor. You have too low a static comp with way too much cam shaft--the XE284H is listed as a street/strip cam designed to run in an operating range of 2300--6500 rpm. The overlap is killing the low end cyl pressure with the low stock comp. You already know the comp is too low because you tried 87 and 91 gas and there was no difference, 9:1 or higher comp might have detonated on 87--especially with cast iron heads. That cam needs at least 9:1 or higher comp, 2800+ stall and a low enough rear gear to run. I'm not that familiar with Fords but those pistons should have got you over 9:1 with those heads if they are 64cc. Also the single plane manifold and the cam are killing the low speed signal to the carb making low speed drivability difficult, no amount of tuning can correct it. Max was right on about cam and manifold change, if it was mine I'd go with a Performer RPM, Comp XE256H or XE262H and change the pistons so I know I have 9:1 or more comp, keep the Demon 750DP and tune from there.
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Old 07-28-2005, 09:43 PM
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Too rich 351W

As for cam recommendations, I would a Crane # 443941, RPM range is 2000-5000, and you could use it with your stock converter, or contact Camresearch in Englewood, colorado and get a custom ground job. They dont charge any more for a custom cam than you will pay for a brand name off the shelf cam. Camresearch is a Ford Specialist house.
http://camresearchcorp.com/
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Old 07-30-2005, 07:45 AM
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Walt/Max

Thanks guys for your input.
Well I guess I should have shed some more light on the subject.
Well what I did was contacted Comp Cams and told them that I had a 3000 stall 3000lbs mustang c4 tranny automatic torker2 intake and 750 dpl Demon mechanical secondaries 411 9 inch rear end.
Oh yes I also told them what type of heads that I had.
That cam is the one that they recommended to me as I mostly do the strip with it and some car shows.
I agree the torker2 intake is for 2500-6000 range that is why the cam is from 2500-6500 also I thought.
I still think some thing funny is going on in the oil department but that does not explain the low compresshion.
If I have low compression on the low end due to intake or cam would the compression be there on the top end rpms ?
Ok stll trying to figer this one out boys .
Thanks Ray.
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Old 07-30-2005, 09:54 AM
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could it be that your rings did not seat correctly?
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Old 07-30-2005, 11:18 AM
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Compression at low RPM vs High RPM

Cam lobe separation will play a somwhat critical part in compression of your engine.
With a narrower lobe separation, due to the overlap of the valve operation, you will have more bleed off of compression at lower RPM, however, as your RPM builds, there is less time for this bleed off to occur. Where as a cam with a wider lobe separation will have less bleed off at lower RPM than will the other.
Other factors:
1.As your RPM increases, the amount of time that the cylinder has time to fill with fuel/ air mixture dramatically shortens, there fore, at higher RPM, your cylinder wont get as good a breath of mixture as it does at lower RPM.
2.Intake manifold design will also effect cylinder filling as well. An intake with a large plenum chamber and large, short runners wont be as effective at filling the cylinder at lower RPM, as a dual plane with longer smaller runners; This is because the dual plenum with smaller, longer runners will have a higher velocity of the fuel air mixture. What makes a dual plenum intake with the long skinny runners at lower RPM, is exactly what kills it for extreme high RPM, The more restrictive plenum and runner size will tend to restrict the air flow. What makes the single plenum with shorter fat runners so good at high rpm is exactly what kills them on the lower end.
3. Fuel pump pressure Could be a major factor in your extreme rich condition. What kind of fuel pump are you running and at what pressure? If you are running a fuel pump that puts out more than approximately 6-7 PSI, you have too much fuel pressure, and its forcing your float valves in the bowls to open, the pressure lifting the needle valve off the seat. With this occuring, youre fuel will keep flowing even though the needle valve should be seated, and in effect is injecting excessive fuel into the carb, from there into the intake, and to your oil by way of washing down your cylinder walls.
4. If your floats are set too high, this will also create the same condition, even with a fuel pump that has the correct pressure.
4A. Having the wrong power valve, could be causing your mixture to run too rich as well, as it could be opening with too little vacuum.
5. The reason for running high compression, particularly in hi RPM engines is to compensate for the drop in actual compression, due to the shortness of time for cylinder filling.
To give an example. Gasoline that you can easily run at 8.5:1 would probably work quite well in an engine that runs 10.5:1 or 11:1 compression at extreme rpm, because of the dynamic lowering of compression at those RPM.
In 1963 or 1964, A NASCAR type Mercury was built for the Pikes Peak Hill Climb. The engine was a side oiler 427, with compression around 16 or 17:1. The problem was that there wasnt any gasoline available with enough octane at that time to run the enine at anywhere near sea level. So in order to work on the engine, they had to take it to an altitude of above 10-12,000 ft, where the thinness of the air, in effect dropped the compression down to a level where it could run on the best available gas at the time.
Going to the higher altitude had the same effect on compression as turning the engine extreme RPM. This is why a lot of piston driven aircraft used during WWII had superchargers, to boost the compression back up once at high altitudes.
Another example of this is down at low altitudes, and engine that requires 91 octane at below 1000 feet will run just fine on 87 octane gas at 6000 ft. If you think Im kidding on this, take your car up into the Rocky Mountains or a state like Montana, and you will see.
Your camming, intake, etc are correct for your gearing, stall speed, etc.
With this added data, Im becoming more convinced that the problem you are having is with your fuel float adjustment, fuel pump pressure, the power valve, or even incorrect settting of the closed throttle setting on your secondaries.
While you are weak on compression for the RPM you are wanting to turn with your engine, Im inclined to believe that your compression isnt the culprit.
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Old 07-31-2005, 12:30 PM
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Max Keith

What a great right up Max,you should be a writer lol.
I see that since I have shed some light on the subject that you have now turned to the Demon Carb.
I have thought the same thing as I have been up and down on the primary's and secondaries but never have I ever play with the butterfly position and the
power valves ,needle and seats.
You just might have some thing there Max.
I think I am going to have a long hard look at the Demon carb and see if it is in the power valve.
If my memory serves me right it was about 11 psi vacuum when I tuned the idle circuit for max input.
That might be to much for the power valve to handle and there for allowing gas to enter at low rpms.
Just to let you now I am not expert at the mechanical area as I just started racing 1/4 mile about 3 years ago and that is when I started to do motor work also .
Im a Welder/Electrician by trade but its never to late to learn.
With people such as your self Max it makes learning much easer.
Well im out of town here now at the outlaws for a visit but I am going to start next week at having a look at the carb and see what I can find out there.
Thanks again Max and others I will keep you in touch with my progress.
Have a good one ......Ray.
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Old 07-31-2005, 12:42 PM
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Rings

Hi Steven C
You say it could be that the rings did not seat properly ?
Have you looked at the post I have put up here in regards to my compression test.
They seem to be very consistent ,with some cylinders rings not seating properly would I not see that in the compression test ?
Thanks for info keep it coming and I an gong to try to mess around with the carb as Max was saying and I have a funny feeling that the power valve in the demon carb is to small.
Well my sister inlaw just call for dinner YUM better get out of here before its all gone lol.
Thanks again........Ray.
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