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390 vs 428

 
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Old 09-24-2003, 11:03 AM
FE 390
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390 vs 428

New to the FE engines.
I read you bore a 390 out to a 428, is this true?
Or are the 428 blocks actually different castings?
 
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Old 09-24-2003, 11:51 AM
Mike G
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390 vs 428

Welcome to the group!
It is true, you can bore a 390 to 428 specs, depending if the block can go that far. This is determined by having the block sonic checked by a (respectible) machine shop. If it is OK, then you will need all the parts to build a 428. The CJ blocks had additional webbing to strenghten them up. Let us know where your going with this (and your budget of course), we can add additional information if needed.
--Mike G
 
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Old 09-24-2003, 12:40 PM
FE 390
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390 vs 428

Reply;
Okay its not a truck, but I have a factory 390 GT engine in my '68 Mustang. The motor and car had sat for 17 years before I got it, but it had a fresh rebuild. In the process of building the car I put Edelbrock heads and Supercomp headers on the motor (long story). The rest of the motor looked VERY clean so I didn't do anything else (ran out of money).

4500 miles and 3 years later I have a "tick" in the motor, which I have traced (with stethoscope) to the #7 exhaust. Now I am assuming I have a collasped lifter...but really could be a number of things.

My theory is backed up by the following: A year ago I had the car dyno'd. The engine did alright (265/335RW), but vacuum was not steady. They said I probably have a stuck valve. I translated that into a valve staying open because my valve geometry was not correct. (Edelbrock suggests using adjustable rockers, but again I ran out of money...so I used the stock Ford set-up). So anyway, maybe this valve was putting constant pressure on the lifter...and collasped it.

Unfortunately, I can't tell by rotating the pushrod, they all seem about the same right now. But the "tick" is loud.

Okay long history. So now I have two options. Rebuild what I have, or build a Bigger Better Badder FE. If you are familiar with FE's in Mustangs you know it is a bear to remove the engine, if not trust me. So if my problem is in the valve train I'll leave the engine in the car and replace; cam, lifters, pushrods and use a Harland Sharp adjustable set up, and top it off with Edelbrock Performer RPM manifold.

If the problem is not in the valve train, and I have to pull the motor, I want to know what my options are for a BAD FE. I have heard the hot set up is 428, SCAT stroker crank, aluminum heads, etc. (410HP/460T).

So back to my question can I bore my 390 block out to 4.23" (like a 428) or is it better to start out with a 428 block.

If there is a difference in the castings, I do not want to be so close to the water jacket as to have overheating problems.

I also just picked up a 390 out of a truck, complete. Since the Mustang is relatively rare, I also thought of storing the original motor and just building the one I just picked up. What are the differences between truck and car blocks?
 
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Old 09-24-2003, 07:44 PM
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390 vs 428

Standard 428 block is 4.13" bore. You'll have to find one of the limited 390 blocks to bore the necessary .080 over to become 4.13".


4.23" bore is a 427, that'll really cost you.

HP/TQ numbers look a bit conservative for a stroked 428. I'm currently assembling a SCAT stroked 428, at .020 over (4.15" bore) it is 446 CI. I am running a full hydraulic roller cam and valve train. HP and TQ numbers are in the 500+ range according to DD.
 
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Old 09-24-2003, 09:37 PM
FE 390
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390 vs 428

Thanks, Gtex.

So I think what I am hearing is my #'s matching 390 GT block at .040" over is probably done. Time to set it on the engine stand in the corner.

Additionally, it probably makes more sense to start with this truck 390 block I just bought (which has never been rebuilt).

What is this "limited" 390? Is there any difference between a truck 390 and a car 390 block? Probably not the truck block I just bought, huh. So maybe forget the stroked 428 idea, and stroke the 390?

What can I expect for HP/TQ numbers from a stroked 390, hydraulic (non roller) cam with good vacuum, Edelbrock heads?
What compression ratio should I shoot for? Is it best to use a 428 crank? Or does Scat make a 390 stroker crank?

The goal would be to spend less than $5k, I already have the Ed heads, Mallory Unilite dist, Holley 750 and hopefully a good 390 block.

Thanks for all your help. Still learning...
 
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Old 09-24-2003, 10:05 PM
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390 vs 428

I thing .060 over is a typical limit for a 390 block. You should just have it checked. Some will safely go the .080 over for a 428 bore, might as well check.

HP will depend a lot on your cam choice. Use the search featur in this forum to find many threads on 390 buils and HP ratings. If you already have the heads and ignition and wanted to stay with a hydraulic non-roller setup, you can do quite well with $5k.

By limited, I was just referring to the number of 390 blocks availble that will safely go .080 over.

I wen through Flatlander racing for my 428 SCAT stroker, at $3999. I can't reccomend them based on a huge delay to recieve the motor and the generally terrible service. But, they have a good website to price some SCAT stroker FE stuff.

http://www.flatlanderracing.com/stroker390430.html

http://www.flatlanderracing.com/stroker406448.html

Flatlander thought 10.5:1 with Aluminum heads is OK on pump gas, others think I'm pushing it. We'll see. Hopefully, it will fire by Saturday.
 
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Old 09-25-2003, 06:41 AM
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When you say sonic testing is that when you test the thickness of each cylinder wall with ultrasonic tester? Do I run the risk of overheating problems if cylinder wall is so thin?

10:1 Okay with aluminum heads, 10.5:1 Okay with aluminum heads and reverse cooling is what I have always heard.

Thanks for all the help.
 
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Old 09-25-2003, 03:49 PM
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What about going with a .030 over 410 set up?
 
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Old 09-25-2003, 04:03 PM
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Originally posted by hotrodfeguy
What about going with a .030 over 410 set up?


You'd probably needa 428 crank and rods and custom pistons for the desired CR.
 
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Old 09-26-2003, 06:57 AM
FE 390
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After a little more research, it appears it the #7 intake lobe on the cam that is wiped out. I'll take it out and check all around for other damage, but if that is all, Im going to put the following in the existing block (without removing it from engine bay):

Edlebrock 7105 Performer RPM manifold
Edelbrock 7106 Cam and Lifters
Edelbrock 7808 Timing chain and gears
Harland Sharp 4006B Adjustable Rockers
Harland Sharp 4006S rocker shafts
Crane 9.234" pushrods
Keep the .040 over bottom end together and of course keep the EDL-6006 heads.

Comments?

Thanks to all for the help.
 
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Old 09-26-2003, 07:03 AM
FE 390
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By the way, there are some pics of my project and a smoky burnout at the bottom of this page (link) that will give you some idea what I am working with. The "burnout" movie is 10MB, so it will take a while to download, but (in my opinion) worth it: www.doodlescustomartwork.com/HISTORY.HTM
 
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Old 09-26-2003, 10:50 AM
kpavitt
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Sounds like a fun project,I've always wanted to build a fe powered mustang. I have a possibility on that no.7 exhaust valve. I too bought someones abandoned project 390 which had been sitting for about 11 years and then sat in my shop for another 2 (do the math,it's not a lucky number!).After about 15k the head gasket went (no, I didn't retorque anything). I pulled both heads and something caught my eye right away;the exhaust valves were all recessed about 1/8" into the seats.The engine had been rebuilt in the early 80's when leaded gas was still available and hardened seats were not used. If they weren't on yours fix this now before it's too late. Everything else on this mill was done right and after 65k it still makes brutal power and torque. As far as the block for the 428 conversion, from what I have heard, you want to use a mirror image 105 block. Confused? This refers to a number cast into the back of the block. These were used in some mid 70's pickups and as service replacement blocks.I've got a couple sitting around(dry and covered) and someday plan to build one for a 68-70 mustang and shoot for the low 11's. hee,hee.
 
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Old 09-26-2003, 02:05 PM
FE 390
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Well if you heard right, I'm in luck then, because the block I just picked up has "105" cast into it (on the front though, where the "352" usually is). It came out of a '74-'75 Ford F250. I picked it up complete with Holley/Ford 4 BBL. I guess I'll keep it for that Bigger, Better, Badder FE I want to build some day....
 
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Old 09-26-2003, 08:51 PM
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I've got one of those "mirror image" 105 blocks, and after doing the drill bit test, the walls are actually thinner than an older 390 block out of a 64 T-bird. If you really want the straight lowdown on FE's then log on to the FE Forum on network 54. Those guys will dispell a lot of what's been posted here. I've got 2 -68 390 blocks that would be hard pressed to bore to .030, let alone at .060. If you've got the money to spend then locate a 427 block and start from there, 428 blocks are just about getting as scarce as the 427's now-a-days. I had a 427 powered 67 fastback in the 80's and let me tell you, that car scared me. I'm satisfied with a 390 now.
 
 
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