Howdy

Has anyone took a standard 390 and stroked it to a 428 CID? What I mean is to have the crank welded and stroked. The real problem is probably getting the bore, I think that the cylinder walls get pretty thin, but i wanted to here if anyone else has tried this mod. 428 motor's are getting hard to find and cores are real expensive! I have 2 engines I want to do this to. Any help would be great

Thanks Bill

 

I'd just go .030" over and call it good. You'd get a 416ci engine with a .030" overbore and a 428 crank. Exteranally nobody would be able to tell the difference, so why?

If you absolutely must have 428 bore dimensions, I think a late D3TE through D7TE block would be your best bet, as I've heard that they can go to 4.13" bore safely. As always, have it checked for wall thickness.

As for welding and stroking the crank, I think it would probably cost more than a used 428 crank.

 

Rusty70

Thanks for the reply, What years or vehicle types supported these engine types or block numbers. I reviewed my 6 blocks and none of them are these numbers ( D3TE - D7TE). Is this a group of castings or two specific block casting types? Also do you have a source for used 428 cranks?

Bill

 

The way they're numbered, D designates 1970's, and the number following it means the year in the '70's. Also, the following letter designates what the casting was originally intended for. A would be a ford automotive block, M would be Mercury, T would mean truck. So a D3TE block would be 1973, originally intended for truck usage. So when you go to the junkyard, focus your search on trucks.

DSC has used 428 cranks.

 

Thank You Rusty70
You have no idea just how helpful you have been!
Bill

 

A quick way to check for a candidate for a 4.130 bore
block is to remove a care plug from the side of the block and use an allen wrench as a
gauge
to check the distance between the bores. Use the following chart reference.

If an allen wrench fits between the bore._.

SIZE WRENCH SIZE RESULTS

375 3/8" No Good
312 5/16' No Good
281 9/32" 4.080 Max
218 7/32" 4.160 Max
187 3/16" 4.18 Max (in a
406
or 428, good block)
187 3/16?(427) 4..293 (68 C8AZ?6010?G)
125 1/8?(427) 4.310 (Marine Block & some early 427's)

7

http://www.doveperfonnanceparts.com...O7jpg 8/19/2003

 

Thanks Randy
I'll get the allen wrenchs out and see what happens. Hopefully out of six blocks i'll find one thats borable to the 428 (4.130+).

Bill

 

My not so humble opinon is this, Bore it enough to clean it up use the crank and go from there. The performance gains to be had from over boring is minimal at best. You may only see 10 hp difference by going to the 428 bore and stroke, I doubt it would be even that high. Save the block for future builds. then throw it out when it is all used up. All that being said.

Do not bore any motor more than nessecary with out sonic test.

Scotty

 

Hi Scotty
Thanks for your honesty regarding this subject. I have six good blocks to chose from provided they meet specification. I was looking at the longer stroke because of the torque increase. To be honest, I wanted a wild thing under the hood so i'm looking at a custom grind rolled cam. I like the the benefits that rollers and associated valve train do to free up HP and reduce rotational friction. The big draw back is the cost. If you or any of the other replyers have any recommendations it would be great to here from you.

Bill

 

Scotty is correct to a point. There is a reason Ford created a 428 and it wasn't just for more cubic inches. You don't get lots of horsepower gain with an increase of just 20-30 cubic inches.

There is a fork in the road where people have built average engines and others have built elite engines. There is just more clearance with a larger bore engines for larger valves. If you add the largest valves that will fit in a set of heads, then you will get a wakeup call on why your heads won't work with your 390 bore size. Now doing the same thing with a 428 bore size engine and you are looking at minimal problems in clearance issues.

No doubt that you can use a higher CFM capable set of heads with larger valves when your engine has a larger bore to accommodate them. There are many books on that issue alone when it comes to racing engines. But we aren't talking about racing.

I agree 100% that the cylinders should be cleaned up using the smallest bore you can to have more future rebuilds. Unless you are into racing and do all of the performance tweaks, then you are really going to see small performance gains from building a 390 into a 428. The performance gains will be minute when compared to performance gains from the other performance options out there.

I have a 428. It is a frankenstein engine. It has parts from two or three engines. There is know doubt that this happened from someone wanting more horsepower. It is built with .030 over 428 pistons even. I know that made some people cringe. Well let me say that I have had the rpms pretty high and the worst thing that has happened is a piston had a hole develope in it from the engine going lean. I repaired that and have been driving it for years without a single problem. Obviously The story may be different if this 428 were to be used for racing. I really couldn't see it lasting too long under the stress of racing. The cylinders probably aren't thick enough for that. The point I am getting at is an overbored engine can be durable and have little or no problems. But why risk it if you don't need to?

 

In other words, it's how you add those cubic inches that determines what you get from them.

Stroking an engine is always going to add torque. In the case of the 428 vs. the 390, the gain is notable. The trade off is a larger reciprocating mass that won't rev as high. This is a desirable combo for a street engine - not so for racing.

In the case of the 390 vs. 428, you gain a large amount of torque and a decent horsepower gain. I agree that the slight amount of horsepower you'd gain by increasing the bore to 4.13 is not worth jeopardizing the integrity of your block. In this case, all the gains come from adding the longer stroke of the 428 crank.

If you were racing the engine, it would be a different story. Then, you'd want the biggest bore possible and a short stroke. That's the difference between the 427 and the 428. The 427 is a high revver that makes most of it's power at 5000 RPM and above. For street driving, we want our power and torque down around 3000 - 4000 RPM.

Look at the modern engines that boast 400 and more horsepower. They never talk about torque. That's because the don't have any. That's why a Honda has to rev 7000 RPMs to make it's power. That's why they have 5 and 6 speed transmissions.

Sorry, got carried away.

 

First off Thank You all for the excellent advice.

I have read about some of the problems the are inherent with the FE engines and am curious about your take on these potential problems.

1. Why did the Ford engineers setup the main bearing oiling ports the way they did ? I mean the main inserts cover approximately 50% of the port.
2. I understand that the cam oiling galleys have a restriction near the 3-5 main transfers.
3. Over oiling to the valve train so a restrictor needs to be installed.
4. The oiling transfer port from the oil filter to the main journals need to be enlarged.

Please add to this list if I have missed any, because I'm sure I have.

Thanks Bill

 

SledBill, sure, you can stroke to 428, or thereabouts. You have several options. You can use a crank with 3.98 stroke and keep the 390's 4.050 bore, you'll then have something like the 66-67 mercury 410 engine. That would mean buying a differant crank. You can offset grind a 390 crank, to 4.00 stroke ( easy ) or you can weld on a cast crank and then re-grind ( almost impossible ) Or you can get an FT forged steel crank and weld and grind on that, do-able but time consuming and exspensive. The easyest current option is to purchase a new crank from Scat with 4.125 or 4.250 stroke, use aftermarket rods and have some pistons made to fit you new combination. If you can find someone with a few old copies of street rodder magazine, you might be able to read about their 390, stroked with a 4.125 crank, that ripped out an easy 520 lbs-ft of torque. Now on to those questions....#1, the oilports are where the are so that the drill that made them could make a staight shot to the cam saddle when the block was made. I use a die grinder and open the holes up a bit so the oil can pass through better. #2 There is a restriction cast in front of the #5 main bearing to keep more pressure on the lifters. Mr Ford ( Henry 2 ) was coming ungluded when T bird owners complained of noisy valvetrains. #3, more valvetrain noise cover-up. #4, lazy or uncaring line managers at the block machining area. That should have been drilled to 7/16ths, that is the size the blueprints call for. DF

 

Thanks DF
Quite a history involved here - Hmmm - Who is a supplier of custom pistons and I like the Idea of the "Scat Crank" Torque is what I'm loo looking for.

Bill

 

With the 4.125 or 4.250 Scat cranks you'll need new rods too. They should have a 2.200 big end. Lunati, Oliver, Crower and Manley ( and Scat them selves ) all make nice rods. I would use a 6.800 long one if you have room. For pistons, there is Venolia, Arias, Wiseco and JE. I like the JEs, but that is just my personal preferance. DF