Thread: Rebuilding My 390

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Hey
Ok im starting the process of rebuilding the 390 in my 67 Mustang, its the original engine in the car thats backed with a C6 and a 9" Traction Lok rearend, so my question is im going to rebuild it with a little more power than stock, the rearend is getting rebuilt and so is the tranny except its getting a shift kit and rebuilt with more clutches. on to the motor, im going to get standard machine work done(Bored, Decked, Align Honed) with the oil galleys opened up, its getting speed pro 9.91:1 forged pistons (anyone know what size chambers 390GT heads have stock) with all new bearings and rings, oil baffle with high volume pump, my questions are for the top end of the motor. I am going to get hardended valve seats put in and i wanted to get the heads mildly ported and the chambers cleaned up (anyone know where this can be done at?) my goal is 10.2-10.5:1 compression, im ditching the factory intake for a edelbrock performer w/ BG Road Demon jr. 725 carb and i was looking at either the stock cam 390GT cam, the edelbrock performer cam (194/204 .460"/.480") or the Crane Power max cam for 2k-5kRPM (216/228 .533"/.563"), so thats the motor im looking at building im hoping for between 320-350HP at the crank, so i believe this will be a fairly stout motor for being a crusier and my questions are if this is a reasonable HP range, which cam might work the best, and where i can get my heads ported, and also if the hooker headers flow good and if i have to cut out the bottum of my inner fender to pu them on, thanks for any info and sorry for the long post
Steven

Steven, before you stick a bunch of money in your cast iron heads, you might want to check with Edelbrock and price the aluminum heads they offer. Quite easy to exceed the price of new aluminum heads with the price of the extensive mods you are considering. I did a 390 with the Edelbrock heads and Edelbrock Performer RPM package, (cam, lifters, intake, and carb) it ran very strong and that was toting around a '67 Galaxie !!! You can always wrap your stock heads up in a plastic bag and save them for someone who might want to buy your car with all the original parts.

I'm in the same situation with the 390 in my mustang. I'm planning on going for some of those edelbrock heads. The stock heads on a 390 don't breathe worth a crap so aftermarket is the way to go with them.

Your engine is listed at 335HP in stock trim as is and the heads are 71.2-74.2 cc's. You might want to upgrade the oilpan if your going with a HV oil pump. Or at least use a windage tray and an extra qt of oil. Under hard launches the HV pump can suck the pan dry leaving the bottom end sucking wind. I learned that the hard way long ago. I agree about the heads also. Figure you will spend at least $1100 with rebuild and port work complete. Being that you want to run headers and such it sounds like the "original and correct" theme is not in play. I'd just keep all the original parts bagged and tagged. It's hard to find correct date code parts and should you ever have to sell the car this will only enhance the deal. If I had a dollar for every car I swore I'd never sell.... On the cam I like something with a little more on the top end 6-6.5 rpms but I always run solids. If you do decide to go with the Crane power max cam you might want to upgrade to at least the stock adjustable rockers and pushrods. The non adjustables are durable and will live under .550 lift but not over this. On the block machine work make sure you use a shop that knows the FE block. Hopefully the block is std-.030 leaving you some room. If the block is under .030 sonic checking is really not needed and some will go to .040 without a sonic no problem. Core shift is the culprit here and always a risk after .030 on badly shifted blocks and you just never know. G.

thanks for the info guys,
Im trying to keep the car mostly period correct and thats why im wanting to port the stock heads, i thought about headers and i wasnt sure if i could get them into the compartment without cutting out the inner fender. I know the edelbrock heads i know are good and make the power (my truck has a 390 thats 60 over with all edelbrock top end ) but im trying to retain the majority of the correctness. i was looking at getting a windage tray, but not for revving the motor out to 6-6.5k RPM's try and keep the rotating assembly from being to stressed, dose anyone know how much power a stock crank and rods can stand up to stock? Thanks for the info
Steven

Maybe look into a set of CJ exaust manifolds for a little more flow then if the original look is wanted. They are getting expensive though. As for the crank your 390 nodular iron crank can take 600-700 hp. Your stock rods will be fine and you can upgrade them with a nice set of ARP bolts and nuts. Following the "correct" theme maybe look inot a Blue Thunder PI repop intake. It will like that 725 a little better. Looks like the original 428 PI aluminum intake and flows better than the Edel RPM. JMO, G.

I have looked on ebay and didnt see any sets of 428CJ exhuast manifolds, is there any other place to get them beside ebay or at at swap meet? Also i was looking on the DSC Motorsports webpage and is the blue thunder manifold for the 428 4v intake the one you were talking about? if not were can i find one of these at? Thanks for the help guys
Steven

Yep thats the BT PI intake I was talking about. DSC also sells new repop iron CJ exaust manifolds for $480 pr. They are down 6 or so items from the BT intake you looked at "Ford 428 CJ exaust". Sounds like an exaust system but click and you'll see it for the maniifolds. The originals bring this and more on ebay. Sometimes you see a set that has a broken ear or has been cracked and welded a little cheaper. FPA www.fordpowertrain.com sells a Tri-Y header for about the same. Then there is always the Hooker super comps but don't know the current pricing. G.

Hi Steven,

Mustangs Unlimited and others sell good reproductions of the CJ exh manifolds. The originals pop up from time to time, but are expensive.

As far as the heads go, depends on what you have. I don't know much about the '67 390GT. My C8OE-N heads ran about $2500 to rebuild, but they had cracks and pins, and went to a really top-notch shop since I needed the date codes and all to match. You've got a different situation, and that was five years ago. At that time, a set of the Shelby aluminum heads was about the same price as my rebuild, but they didn't make the Mustang exh flanges, and the Shelby needed the original parts to retain value.

The C8AE-H heads came in a bunch of configurations, and were apparently common on the 428 motors (not the CJ). They are pretty good heads, though. I don't have the specs right at hand, but they weren't much off the C8OE-N CobraJet heads, mostly had the wrong numbers. Cost-effective approach to moderate power.

If you use the big port Ford heads, be careful of too much head work. They end up being great for high RPM, but lose a lot at the bottom. My semi-stock (balanced/blueprinted, all stock specs) 428 runs strong to about 5800 by the tach in the car, and starts down in the 2500 range. Went up a steep freeway onramp the other day, spinning tires through first and second, and had to slow down at the top of the ramp to merge. Not bad for HP or torque.

Lunati makes a "Nostalgia" cam that looks pretty good, and the Comp Cams CCA-K33-240-4 kit from Summit Racing is probably what's going into my hotrod pickup.

Good luck.

Good luck.

Alright, havnt been on in awhile(been trying to get some money for rebuild and racing) my rebuild plan has been revised a little bit, as of getting my pay check this week im going to order a 625 Road Demon Carb, and all the stuff to rebuild my rearend and its posi. Iv found someone that will rebuild the tranny for me if i supply the parts +2kRPm Stall, so the motor is the only thing left to figure out. My plan as of current is to use a 625 carb for Daily Driving(Holly 780 Double Pumper for track) use the repo 428 4v intake and the repo 428 CJ exhaust manifolds with 2 1/2 or 3" piping after manifolds with edelbrock/spintech mufflers(anyone know which sounds better), now heres my question what cam should i use and what to do to the heads, my goal is between 350-400 HP with roughly 6kRPM redline. (utilizing HV oil pump and baffle/windage tray in stock pan) so iv heard that the stock 390GT camm is fairly good so its down to crane powermax/stock 390GT/Edelbrock Performer. For the heads i was just planning on a "street" port and polish(cleaned up bowl and chambers?), valve job, hardened seats, SO anyones advice appreciated its starting to come down to ordering parts and i wanna do this right the first time, motors a little hard to work on in that engine bay thanks guys

Steven

PS where can i get some stock replacment forged pistons(10.5:1)?? the only ones in summit are SRP and only account for a listed 9.6:1 Compression. Where can i find out what heads i have and what size the chambers are?? Thanks for the help and sorry bout long post

Steven, there are fellows on here who have built more FE motors than I have and have a better insight as to what works than I do, but I'm gonna jump into the middle of it anyway....

First off, I absolutely know that FFR428 is givin' you the straight skinny on the oil pan. If you don't put some pan under this motor, you're messin' up bigtime.

Secondly, I think you're shootin' for way too much static compression ratio if this is gonna be mainly a street motor runnin' on pump gas, particularly with iron heads. As you move the c.r. up, you also have to go wilder on the cam to match the c.r. to the intake closing point in order to bleed off some of the cylinder pressure so the motor doesn't rattle like a can of rocks on premium pump gas.

With a 0.030" overbore, 74 cc heads, a Fel-Pro #1020 10 cc head gasket and the L2291F30 pistons from TRW (10 cc valve reliefs) and zero deck, you'll be at 9.6:1, a God's plenty for a street motor. Zero decking the block and using the 0.041" compressed gasket will help the motor tolerate pump gas at 9.6 due to the squish. You might look for a cam along these lines, but heed the warning from FFR428 about the lift limit for non-adj. rockers. This cam has a ton of lift on the exhaust.
http://www.cranecams.com/?show=brows...tType=camshaft

You've got the best head porter on the planet right there in Paso Robles. Ever hear of Mondello heads? Joe has been porting heads since I was poopin' green.
http://www.mondellotwister.com/

haha, yes iv heard of mondellos, i know he specializes in Olds motors, and i had heard that he was only building complete motors for customers at this time but it could have changed.

I wanted to keep roughly the same compression ratio as stock which is 10:5 so thats my main reason, and i know i always have to put 91 gas in with a little octane booster to help, im currently running the setup your talking about with my F1 except i have edelbrock heads and a cam with over .500" lift with stock rockers, so im not exactly sure whats going on with that then, but my plan with compression was that it runs fine right now, so i figured id probally run good after being rebuilt, but the cam could change all that as you stated, i still wish to make my 350-400HP goal which im thinking is either going to require alot of head work or fairly high compression, so maybe ill have to swing by modellos tomarrow after school thanks for the help, i need to start ordering stuff so this is helping out alot
Steven

octane booster that is funny. even the best octane boosters only raise you octane .7 point. these engines were built back when leaded gas was still around. now the lead done several things including detonation resistance. two ways to run high compression huge cam to bleed compression and high octane race gas. 11:1 is doable on pump gas but you have to have everything tuned perfect 10.5:1 is a little more forgiving but still a little touchy just like techinspector said 9.5 is a gods plenty and the 10.5 really won't gane you that much maybe 25 horse but if you still insist on the 10.5:1 all i have to say is good luck i've been there done that and i'm sure these other guys have too.

Hi again. My stock 428CJ runs 10.6 cr. Factory timing 6BTDC, and no problems with pinging. Stock cam (stock everything - it's just a service motor that was balanced/blueprinted before being assembled), which matches 390GT. Mild lope at 600RPM in drive. Hard on back tires, though

One of the things Morgan did when machining the heads was make sure they were smooth, and had no potential hot spots. The C8OE-N heads spec 73-76 cc chambers, while the 390GT shows 71-74 (mentioned earlier). I've run the timing up to 10BTDC without pinging here in the flats. I worried a bit about the compression, but it doesn't seem to be a problem. Wouldn't go any higher, though.

I had really good success with Morgan's Machine and Marine in Walnut Creek, CA. Tim Morgan listened, discussed what I was after, pointed out ways to save money (new heads, but I needed the numbers), and did what matched my plans. Great work and great people, IMO.

My '69 had Hooker headers on it years ago, and they ran back to collectors about halfway back on the front floor pans. Only problem was dragging on speed bumps, high/steep curbs, and a friend's gravel driveway. Oh, and you have to drop the power steering ram, but there's a bracket available to do that. Wish I had the stock one back, now. I'd trade my dropped one for the stock. Tony D. Branda, Mustangs Unlimited, and a bunch of other supply houses sell H-pipes and stock exhaust systems that hook right up to the headers. Those stock 428CJ exhaust systems should fit your 390 with headers or the CJ exh manifolds, and sound terrific. Great presence at idle, seem to flow pretty well. If you're going stock, they work well.

Only issue I've had with the stock engine (which is basically a bit larger version of the 390GT, with terrific heads and a higher rise intake) has been heating. Infrared thermometer shows 230-235 idling after a good warm-up (20 miles or so), with a 180 thermostat. Or a 160. Or a 195. Lotsa iron, new motor. Of course, new rad, too. Don't forget to look to that with your new motor.

If I weren't worried about the correct numbers/date codes, I'd run the aluminum PI manifold that's pretty readily available. It's about like the CJ intake, but probably 70 lbs lighter. Even has Ford numbers, but they aren't right for the Mustangs.

Post details as you go along. Sounds like a fun project.

alright havnt been on in a few days but i figured id do an update, tomarrow im going down to mondello's shop to talk with them about what to do with my heads, along with my machinest, my plan to run high compression is at a stand still because of the unavailibility of high compression pistons iv been able to find, so i might have to run the 9.6:1 SRP's. if im running a full point lower in compression, what will i have to do to make up the power, to still hit my goal of around 375HP, the only visible mods to the motor are going to be the 428 PI intake (repop) and the CJ exhuast manifolds, what do you guys think, i had started reasearching to build it to the early 60's 401HP specs but im not sure how much that would change without running the 3x2 intake, so, besides running a big cam what else might i have to do to make up the power, thanks for the help, its been really difficult trying to figure out which parts will work right together

STeven