Hey Guys, need some help. 79 F250 SC 2wd. Rebuilt and it won't tow worth a d___. Here are the specs on the rebuild.
Edelbrock 2166 Performer intake (non egr)
Edelbrock 2167 Performer-Plus cam/lifters

Duration @ .006 Lift IN 272 EX 282
Duration @ .050 Lift IN 194’ EX 204’
Intake: 8 ATDC 22 ABDC
Exhaust 37’ BBDC 13 BTDC
Centerlines Lobe 110 Intake 105

Edelbrock 1411 Performer 750 CFM carb
Edelbrock fuel pump
Edelbrock 78130 roller chain/gears (72-83 460)
Bored 40 over
Cleveite pistons/rods small dish in piston
Recurved distributor by reincarnation-automotive
8 inital 35 total w/ vacuume
Balanced
Stock exhaust manifold
2” duals
3:54 gears
No head work as of now
92 octane fuel
10.4 MPG solo
7.8 MPG towing 3000 lb boat
Not sure where to start looking for the problem. Any help would be appreciated. Prior to rebuild all was stock except pre 72 429 timing gears/chain. Ran real strong, pulled boat and camper with ease. Rebuilt and I can't break the tires loose. Where do I start, carb, timing gears ??

79 F250 Super Cab Cmpr Spl Lariet
04 F350 Super Cab 6.0 Dually

 

What is your compression test show? Need a little more info on rpm's when running down highway.

 

Had compression testes done and mech said all were 140+ and all within 10% of each other. At 65 MPH I'm turning 2400 RPM. On a hill it will drop to 50 MPH when I'm towing. Thanks for the reply.

 

specs look good with towing with your cam. maybe check your fuel pressure and make sure 5 to 7 psi. I'm guessing you timing is good but make sure you have 12 volts+ at coil. Might be firing but weak spark. Check your distributror and contacts closely. Also need to check you valvetrain and makesure you don't have any flat lobes on cam. usually you will hear valvetrain rattle if this happening. Also on carb while idling make sure your carb is getting enough fuel and squirters are squirting. it will be two stream of gas in center of carb in primarys just beneath choke plate. If you have a vacume gage check and see if any erratic readings on gage. Compression sound perfect for 9 to 1 compression motor. It should spin a tire easily and tow with the specs they have on that 2167 cam and intake package. Good luck and hope this helps. Also does motor rap up while in idle in park then when you throw a load to it then it just goes flat. My gut is telling me a possible fuel psi problem or restriction/filter. On the carb have you done any tuning to carb or set air fuel?? Catch you later and good luck. does the cam have a smooth sound or slight lope or heavy lope? once had a cam installed and wrong cam in box. OOps on our part for not checkin the numbers on end of cam.

 

I'll do a fuel pressure test and see where I'm at. It idles OK. Slight lope to the cam. Wraps up good in park. On the road it is flat. New air filter, going to a cold air induction system. All the local mechs say to loose the Edelbrock and get either a 670 Holley Street Dominator/vacuume secondaries or go to the 750 Holley.
I'm an electronic fix it guy. wish I had listened to my Dad when he tried to teach me about engines. I'll get back to you when I check out the fuel system.

79F250SCCS

 

If I was running a edelbrock on your vehicle I would be running a 800cfm edelbrock. What happens is your 750 isn't apparently opening up and your only getting 375 cfm to engine. Get a vacume secondary type carb and you can change your spring in vacume diaphram and make it open later or sooner. its a little bit of a learning curve but should be happy with the end results. I would stay with a 780 vacume secondary which means you'll be getting 390 cfm when just grocery gettin it. then in a loaded situation the carb compensates as needed per engine demand. I've ran the edelbrocks and they ran well but when needing to get a little more serious go holley type carb. I'm a big fan of the quick tune carbs had some excellent results. PM sent.

 

checked timing, mechanical comes in too late, only 2-3 @ 1500 rpm, and 10' @ 2000 rpm. vac seems to be to high. @ 600 rpm 0", 800 rpm 0", 1000 rpm 12", 1500 rpm 17" 2000 rpm 18" and 20+' at 2500 rpm. is this too much vacuume??? vac was checked in park no on road.

 

an edlebrock 750 should be big enough!! but if you bought the one with the electric chokeit is too lean..get a 1407 jet and pin kit and look in the book and set it very rich.. 460's like rich.. take the distributer loose and advance it untill you either get starter lag or ping..back it off untill the ping disappears or untill the starter lag disapears,then lock it down..now your mpg is going to suffer but you will really like the power..good luck!!