393 stroker stock block?

[Hizzle]

I was going to freshen up the 5.0 in the 'Stang but I have a good portion of the parts to make a 393 stroker. For the 5.0 I purchased pistons, rods, AFR205 heads, and a new cam. I know I will have to use the 351w rods for the stroker. I have a late 70s 351w block that was just cleaned and if it tests out o.k., I want to use it. I took a new Scat stroker crank in on trade for some tools. I keep reading different things about building a 393 stroker useing a stock block and it supposedly splitting if you have anything over 400 rwhp. I do not plan on using any power adders, just going all motor for now with this setup. Has anyone else done it or can tell me what they know? Please no I heard from a friend's friend that his friend did this or that. I know there's a lot more to it than the parts I have listed above and yes I know it's going to be expensive. I'm just interested in what you have to say about the engine itself holding up. Thanks

 

[5spd GT]

What year model is the block? They varied a few times in strength...

 

[Hizzle]

I've had it for a long time, it was either a 78 or 79. I'd have to go out and find the numbers off of it, will do this afternoon.

 

[5spd GT]

Well the 351 blocks can handle 450-500rwhp minimum from what I have read and seen from many combinations.

Now, typically the most sought after blocks are the '71-'74 blocks with them being stronger than the other popular factory blocks and they maintain the typical 9.500" deck height.

The '69 and '70 blocks are 9.480"...

Normally most tell you to stay away from the '75-'84, but I think with your goals you should be okay if you don't rev it to the moon.

The 94+ roller blocks are nice with hydraulic cam provisions already built in them...

Talking to an engine builder is your best bet...

 

[Hizzle]

I've talked to a few builders locally and while they have done strokers, only one has ever done a 393 stroker like this and has never heard back from the guy.Maybe no news is good news. I want to talk to some guys here who have done it. Experience is the best teacher IMO. I don't want to rev this thing sky high, another reason why I think a stroker is the way to go. I never have been a fan of overrevving (I consider anything over 6k overrevving, just the way I was brought up). I want something with a lot of low end snort. I have a lot of the stuff to start this project and it just seems like the way to go. It will be a bit before I get this thing in there. My dad and grandpa are going to build this thing while I'm in Iraq for another tour. When I get back, that's when the fun is going to begin. I figure while the engine is out, it would be a great time to do a k-member, and while that's apart, control arms, and while those are out, swap it to 5-lug, and since the rear will be apart I should do gears, you see where this is goin???? Build it once. Gonna be using a lot of that combat pay.

 

[5spd GT]

Yeah, you'll be getting that 'hazard pay' every month right? As a 'bonus'...be careful.

Sounds like you got plans for sure! Maybe hitting up Rick91GT on here can help answer some questions for you

 

[Hizzle]

Here's are the numbers off of the side of the block: D9AE-8015-ED 16.

 

[5spd GT]

Yep, it's a '79...

Your engine D9XX indicates its a 79 block. D is for the 70's, and 9 is the year...

 

[Hizzle]

I don't know anything about the different years and their quality. What am I working with here?

 

[5spd GT]

You could get a better block of course, but I think you should be fine with the power you are looking to put down and the block you are using.

I imagine the differences are in block content (lower nickel content for the 'weaker' blocks) and small areas of strength where other blocks may have more material on it, aka: 71-74, 94+, etc.

Someone more adverse to 351's will hopefully help you out...

 

[BlooDReigN]

69-70 are the strongest, with the highest nickel content and beefiest webbing. 71-74 is not far behind. Anything after that is weaker than the early blocks but they are all about the same strength wise from 75+. The 94+ blocks aren't any stronger, just have the (minor in my opinion) advantage of being set up for hydraulic lifters. It's pretty easy to convert an old style block to use roller lifters, or just use the tie bar lifters (roughly double the price) and not have to worry about the conversion at all.

 

[vristang]

Even the weakest 351w block should handle 600-700 hp, assuming the tune is right. (Once a motor starts to detonate, things break... it doesn't matter how much power is being made)

Your n/a 393w plans will work very well in the stock block.

As mentioned by BloodReign, the block castings changed several times. I have not been able to confirm the nickel content (this will probably require some pretty expensive analysis...), but it does seem reasonable.

The main thickness in the block is the major factor in block strength, as most seem to fail in this area.

This may help with some other questions you have...
http://www.freewebs.com/vristang/fox351wswapfaq.htm


jason

 

[Hizzle]

cool site, thanks

I'm not sure what kind of HP I will be running but a good tune is definitely in order. Here's the combo between stuff I have and want to run. 351w block, scat stroker crank, keith black .030 forged pistons (still need rods), AFR205 heads (may go with the Twisted Wedge CNC R heads), need a cam (looking for one with a lower end power), either trick flow or systemax intake. I will probably be at about 11:1 compression. As far as exhaust, I was thinking of some 1 3/4" to 3" long tubes with dual 3" pipes and x-pipe. Does anyone know if those pistons will work with the twisted wedge heads? I'll probably just wind up using my AFR heads.

 

[408gt91]

the twisted wedge heads need an offset valve relief if using a cam larger then 525lift.if you already have the pistons i would go with the afr heads.

 

[vristang]

There is more to it than just max lift.

By the time the piston reaches TDC, the valve should be closed. So what impacts the p-v clearance the most is the timing of the valve events.
This number can be hard to find, as most cam companies just provide lift, duration, and LSA.



Most good machine shops should be able to clearance a piston for the TW heads.


jason

 

[5spd GT]

Yep, I'm with vristang.

By the way, a piston is heading down the cylinder bore a good 2" when the cam lobe is at peak lift.

Duration, ramp rate, overlap, individual valve timing, etc, all play a roll in piston to valve clearance.

The stock cam peak lift of .444 could hit the piston if it is had a serious ramp rate and very early intake event or late exhaust events. Lift is the minimum to consider when seeing if p-v clearance problems will occur.

 

[Hizzle]

I think I probably will just keep the AFRs. I'm probably not going to run to big of a cam due to them being rated for higher RPMs