A couple years ago I assembled a “Frankenstein” 351w that I've never been able to dial in. It's in my 1983 Full Size Bronco. I feel like I went too extreme with it. It's not very drivable. I doubt I've drove it 2000 miles in 2 years. I usually add 1 or 2 quarts of Octane Supreme 130 and fill up with premium gas and it still spark knocks. It's definitely an expensive fill up. Whenever I drive it I smell like I've showered in gas. My wife won't ride with me because of that. It runs wayyy to rich.
Has anyone tried a thicker head gasket to reduce compression? Should I try another cam? And ideas?
Here is a list of some things I have in the engine:
1972 or 73 Ford Galaxie 351w block
Edelbrock Victor Jr. Aluminum Heads. (They came with a 5.0 stang i bought. Don't know much about them)
MSD 8478 Pro-Billet Distributor
MSD 6AL Ignition Control Box MSD-6420
MSD Blaster SS coil MSD-8207
PowerMaster starter PWM-9504
CompCams Timing Chain 2138
CompCams cam/lifters CCA-CL35-242-3 (268 int./280 exh, 0.510 int./0.512 exh with stock rocker arm ratio)
CAT Power Main Girdle MG-351w
Melling M83HV oil pump
Keith Black Pistons UEM-KB151030-8 (+6.50cc / Compression Distance 1.774 in)
Well lets see, it's got a 10.7 to 1 comp ratio. As such the cam's a bit small and the LSA is a bit wide, but it should run on 93 pump premium if it's timed correctly. My 331 runs on 93 with a 10.4 to 1 ratio and a 112" LSA Z303 cam with 12* initial timing. Sounds to me like you need to go back to the basics with it. Also probably need to work with the MSD system to dial in the timing curve. As to how that's done I can't tell you, I'm no fan of MSD anything. The 650 is also too small for it, that's probably why it's running way rich. A 3310 Holley 750 would be a better match.(no fan of Edelbrock carbs either) Thicker head gaskets will only exascerbate the detonation issue. I'd back off on the timing advance first and tune the carb to the motor, and see if that helps before doing anything else.
I had a 750 Edelbrock on it at one time and it seemed to run worse than it does now? Maybe the Holley will be better. I just figured if it was running rich i needed a smaller carb. I must be thinking backwards.
Also my distributor came with 3 different sets of springs and stops..I've just never figured out which setup i need.
Where is the timing? Initial and total. The Edelbrock sucks but should be fine. What is un-driveable about it other than the spark knock? Thicker head gaskets will reduce "quench" area, thus causing more detonation as stated above.
I run stock Ford distributors, either a stock Duraspark or a points distributor fitted with an electronic module like a Pertronix. The smaller carb "sees" a high vacuum, thus exerts a stronger pull of the fuel from the bowls. It could have other problems as well causing it to run rich. You need someone there who knows how to sort things out.
I'm not sure where the timing is now. I've messed with it so much I lost track.
It un-drivable because it runs terribly rich, gets 6 mpg, and lacks in low end power. I have a 4spd Granny 1st, so taking off in 2nd it's a dog till about 3,000rpm. If I had to tow anything I would be in trouble.
You need to spend some quality time tuning it(ignition and carb). The comp ratio isn't what I'd pick for a 4x4 either, but it should run on pump premium if tuned right. It would even run on less octane if you went bigger on the cam, you might loose some bottomend (you never did say what intake was on it) but you could get some of that back by running a small carb, like a 570 Holley.
I talked to a guy at work today who has a Demon 750 carb he may sell. Anyone have any experience with these?
Also here are the specs on my cam:
Basic Operating RPM Range - 1,600-5,800
Intake Duration at 050 inch Lift - 224
Exhaust Duration at 050 inch Lift - 230
Duration at 050 inch Lift - 224 int./230 exh.
Advertised Intake Duration - 268
Advertised Exhaust Duration - 280
Advertised Duration - 268 int./280 exh.
Intake Valve Lift with Factory Rocker Arm Ratio - 0.510 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio - 0.512 in.
Valve Lift with Factory Rocker Arm Ratio - 0.510 int./0.512 exh.
Lobe Separation (degrees) - 110
Grind Number - FW XE268H-10