what i know:
1973 Ford F100 lwb styleside
rebuilt 360 .030 fully stock w/ 2brrl motorcraft w/ .054 jets
timing- 10btdc advances past the btdc around 2,000 rpms (around 30btdc w/o vac advance) Installed dizzy cap adapter to allow use of fords larger cap found on windsor's-petronix electronic ign. system is only mod to entire motor
rebuilt C6 w/ 3.00 9" in the rear

Alright both were rebuilt roughly 5,000 miles ago...Not getting the performance that i've been told i should get. truck gets 10mpg on a really good day but lags on takeoff....will the use of .057 jets make that big a difference???? can't even spin one tire when it rains around a curve!! gvw is only 3400lbs!!! Not sure where i should go from here except a gas station! Any help welcomed!! thanks

 

well there is 2 problems. first if you want to spin the tires a 3.00 rear end won't do it. second for gas mileage you want the timing at 10 btdc and the vacuum advance hooked up that will net you at least 3 mpg.

 

As gashog says the 3 to 1 rearend pretty much kills acceleration, but it is what is getting you 10 mpg. Also the vacuum will improve the mileage. A 360 is not a barn burner to start with and even with a 3.73 rear end they aren't know for power in stock form. And bigger jets won't help, as the jets only restrict fuel flow ay or near WOT. The carbs idle and air bleeds control at low and mid range. Been told by who that it isn't preforming right?

 

Well i work in a auto fleet shop and my boss used to have a 70's model full size ford pickup just like mine with the 360 and he drove it and said it felt like it was missing something...or something wasn't quite right. i know that sounds sketchy and nothing to go on but i think i've decided to just go ahead and put on some hedmans but i'm trying to decide if the $160 hedders will burn out over time and if their lifetime warranty covers such. as for the jets...i'm thinking i'm gonna go ahead and try some 57's just to play and see if i can tell a difference anywhere. thanks so much for info....still learning on rear end ratio's and how everything works together!

 

also should i be able to power brake my truck with a 3.00 in the rear?? thanks! haven't been able to so far....the rear just raises up

 

well no you won't and will just boil your tranny fluid doing so. are you running the stock tire size. skip the 160.00 headers and use the 110.00 ones from dynomax from summit , you will need a complete new exhaust system to so add another 400.00 for that unless you do it yourself like i did for about 100.00 . the stock tire size is p235/75/15 that will give you the most out of the 3.00 gear .

 

yes i'm using 235/75/15 bridgestones duelers with 15" american racing wheels. as for the exhaust, the days of me driving the truck as a daily driver are over i think b/c of gas prices plus now i have a 1990 honda accord so i don't guess header burnout will be much of an issue. ya i'm gonna do the exhaust myself b/c i've already got 2 year old pipe on it with flowmaster original 40's on it so i can manage myself. thanks!

 

also is there a reason i should go with dynomax over hedman b/c the dynomax headers are just 18gauge and the hedmans look alot beefier b/c i'm just thinking about it warping now?? thanks !

 

both are 18 gauge. the real expensive headmans are 16 ga but are like 370.00 . i have dynomax on mine right now and have been fine.

 

ok thats what i needed to know...just some confirmation thanks!!

 

'73, the reason you're not happy with the engine is because it is a 360. The 360 was a mistake, Ford never should have built them, they were a quick & dirty way to supply a smaller than 390 engine and use up thousands of leftover parts at the same time. Ford had, when they began making 360s, thousands of 352 cranks and rods laying around, and plenty of 390 flattop pistons from 10 to 1 390s that they weren't making anymore. So they put the 390 pistons ( 1.759 tall ) on the 352 rods ( 6.540 ) with a 352 crank ( 1.75 throw ). These pieces give an assembled hieght of 10.049, in a block that is 10.17 tall. The pistons being to far down in the hole, .121, is what gives too little compression and no quench at all. The clearance with the factory shim gaskets is .138, and with the felpro replacements it is .162. Unless you use custom pistons, this is a fatal flaw in the 360. You can play with the timing and add headers and all that kind of stuff, but it will never give the power or efficiency that it should. You should have made it into a 390. You need to go over and beat your engine builder within a inch of his life for not suggesting the 390 when you were doing your engine. But all is not lost, there are only 5000 miles on your rebuild. The one and only good thing about a 360 is how easily they can be converted to a 390. If you were to give your cylinders a quick hone and swap out the rods and crank for 390 pieces, the engine would be a whole new animal. You'd have compression. You'd have quench. You'd have power. You'd boil those rear tires. And you would use less fuel doing it. 390 cranks and rods are available cheap, and you don't have to change anything else. I can't imagine why anyone would ever rebuild a 360 as a 360, unless they just didn't know any better. Where do you live ? maybe we can suggest a shop to help you fix it. DF, on the Boss' computer at lunch

 

so what your saying is i'll just be redoing the lower end of the motor. i won't have to change the heads,cam, or anything else to make it a 390??? why hasn't anyone else told me of this??? my dad had a '67 fastback with a 390 that he rebuilt just like he rebuilt my 360 and there was such a difference between the two but i just figured it was b/c it had 10:1 compression which made him run premium and i didn't want to pay for premium so i never considered making mine into a 390. could you give me a rough cost of all that i would need to make it into a 390?? i live in toccoa, ga but my truck is in south atlanta. thanks for any more info!

 

ok ok after talking informing my dad of this information, he agrees b/c he's been told the same thing by his copilot at work. now, where do i get the best deal/quality on a 390 crank and rods??? summit/jegs?? and is there any other inexpensive tweeks i can do to the engine this time when i disassemble it to help fuel mileage and power that much more??? another carb? are 360/390 intake manifolds that restrictive that it warrants getting an edelbrock??also what is the best timing chain/gear set that i can get that won't stretch much b/c we've bought a set from advance auto before and 10,000 later it already had a good amount of slop in it?? thanks so much for your help!!!

 

ok some other questoins i thought of:
what kind of compression will i have by just using the 390 crank and rods and using my original pistons?
will it be so much compression that i have to run premium all the time?? don't want that with gas prices the way they are!
and finally after using the 390 crank and rods, what kind of hp/torque will i be making?? id like some numbers just to get me excited about this....if it's anything like my dads old 390....droooooool thanks guys i know this has been alot of questions but i'be never had access to so many guys that knew so much!! thanks so much guys@!!

 

well i would try a timing gear instead of the chain they never stretch and are durable. you need 390 pistons the 360 pistons are low compression.