Hi, I've got another post here about my intake manifold and got some great help about it. Here is the new problem with this motor. Its a 360 in a 73 F 250 4x4. New Edelbrock 600 cab, new Edelbrock performer intake. Runs a little rough at idle but not bad. I've had to up the timing to about 15 btc just to get power at take off. Set where it should be it just bogs and wants to die, although idling great. So set high it has good power at take off, but at higher speeds it does not. At about 40 if I step on it, does nothing. It will accelerate slowly, but with no power. Then there is this big hill I go up sometimes, with a 50 mph speed limit. Well half way up this hill, she starts back firing! Loses all power and I have to let up on the gas and get up the hill with out putting too much gas in her. All my vacuum hoses are new, the vacuum advance is working. Any idea's? Any help would be so much apreciated!

 

Well I installed a Edelbrock Performer intake on my 360. I used a Holley 600cfm vacuum secondary carb. I ran into timing/power problems too. The problem was the heads. They are 2v heads (2 barrell), and can't quite flow all the fuel and air that your 4 barrell intake and carb is putting into the heads. I did a little research and I couldn't find any 360s with factory 4v heads. They only seemed to be on the 390. I called a local machine shop and told them my problem and asked if they could port the heads and possibly make room for bigger valves. They told me to bring the heads down and they'd take care of it, but it might be a little expensive. I only had one truck at that time so I didn't do it because I'd have no ride to work. I never did get the heads ported, but atleast I knew it could be done. It'll let your engine "breath" and not choke on all the extra fuel. I ended replacing my distributer to acheive more acurate timing because the old wore out one had my timing "jumping around". This made a huge difference, and I gained lots of power. It was still getting to much gas, so I re-tuned my carb so it wouldn't choke my motor to death. It has good power and easily runs 120mph, but still has too much fuel going in. It would blow alot of unburned fuel out of the exhaust, but I just dealt with it. I looked into buying aftermarket heads in Summitt Racing's catalog, I beleive they do make them, but they just don't list them in the catalog because not many people build up 360s. I'd almost bet that you could get aftermarket 4v heads cheaper than having a machine shop work on your 2v heads. Here's Summitt's # 1-800-230-3030. GOOD LUCK!!!!!!!!!

"Don't Laugh At This Truck Mister, Your Daughter Might Be In Here!!"
'78 F250 4x4/351w/NP435/NP205
lifted/"35 mudders
'78 F100 2wd/360/C-6/"9 inch
4bbl int+carb

 

georgiafordman78, if the problem was your heads why did replacing your dizzy help so much??..Have you checked your float level, fuel pressure, and your power valve?..This could be why you have so much unburnt fuel..I have an Ed. and a Holly 600 on my '74 360..Other then the springs the head is stock and I don't have this problem..I am REALLY interested in your research that came up with "2v" and "4v" 390 heads..funny..Would I need the "8v" heads to run a duel 4v carb intake?..lol..How about "3x2v" heads for a 3x2v intake?..Expect for the 427 mr,hr, and tp the port widths are the same..And the heights of the 427 mr, hr, tp, 428cj, and 60-62 352/390spl are the only expections (according to the book)..The rest are the same..You are the ford guy working for a chev. dealer right?..

 

Thank you guy's, for your help and entertainment. I hope the problem is not the heads! I have been very frustrated thinking those people sold me over $600 worth of gas sucking power that I can't use effectively on my motor! I will be checking my fuel pressure which may be low, since it seems to barely keep the filter wet while running. I would hope the float level is right, the edelbrock was supposed to be a out of box ready to go. But I will check it if I don't need a fuel pump. The power valve? I will have to check into that, not sure what that is, although I should like it, being power something...

 

[updated:LAST EDITED ON 25-Feb-02 AT 11:31 AM (EST)]Sorry. wrong thread.

D

 

The Edelbrock carb dose not have a power valve. I bet it is your distributer. If it is the original one it will not be as accurate. If your valves are not seating properly any longer may cause this as well. In that case you will need a valve job. Check out the Distributer first.

 

Sorry Taliesin, my comments and suggestions were for gerogiafordman78..Like sideout2 said, you don't have a power valve in your carb..It is a Holly thing..Sounds like you have a timing problem..Again, check the dizzy..If everything was fine before you replaced the carb and intake, retrace your steps and make sure everything was installed correctly..

 

Tal,
Weren't you the guy with the intake vacuum leak? I guess you fixed it?
Backfiring is almost always caused by ignition or ignition related problems.
1.If you have to advance your timing, your running lean on the idle circiut. Enrich idle circiut.
2. Back fire under load. Excessive resistance in the ignition circuit. First check your plug wires. Don't route plug wires together for long distances. If they cross one another, cross at 90 degrees if posible. Check your plugs for color to determine a rich or lean condition. Cap and rotor may help. Do you have points?
Your heads are fine. I've got a set of 2-barrel 302 heads that rock! I don't think I've ever owned a set of "4-barrel heads".
My Way is the Highway
KingFisher

 

Hi, yes I am the guy who had the intake leak. It turned out I had a bad intake. I bought a new one. I'm glad I wont have to replace the heads, but rebuild, possibly. The truck ran good before this whole deal, just got about 6 or 7 mpg. Some people told me a 4 barrel might help the economy. I just wanted more power So other than the back fire occasionally. It also lacks in power most of the time. If I just step on it, she bogs down. No accelleration, makes a loud groan so to speak, but no power. That happens from a slow speed and about 40 and over. I can get up to about 5 mph then she will have some power if I don't give her to much. I do have points. New cap and rotor. I heard that I may need more spark, like a high power coil. What do you think about that?

 

[updated:LAST EDITED ON 27-Feb-02 AT 09:02 PM (EST)]since you took the manifold off, you had to take the dizzy out too, you might have put it in 1-2 teeth off :-staun and made the timing retarded, thats why it only runs better when the timing is advanced just guess??

 

Tal,
Do you know how to set your points? Do you know what dwell is? Set your points at about 0.016", that's 16 thousandths. Check your voltage to the coil during start up and then while running. You should see 12VDC at start and something like 7VDC while running, I think, I can't remember, exactly. If your points are out of adjustment you can get all sorts of strange symptoms. Check your points and let me know.
KingFisher

 

Hi,
I've got the points set at .017. That is what the book says. I will try .016 which shouldn't make any difference, but I will try any thing. I haven't checked the voltage at coil yet but will this weekend. Do you have an opinion on the to much gas and hotter coil theory? I tell ya, I've been driving it, but trying to pass some one on the highway is a joke. It seems okay a normal driving, but when I step on it, bogger is her new nick name! Just kidding, we will figure it out and get her back on top!