Hi Everyone,

This is my first go at rebuilding an engine and I am building a 351W for towing torque and longevity on a budget. I want this engine to last 200,000 miles, I use this truck for towing a lot, up really big hills. I am going to stroke it to a 393 and I am trying to decide on a head. I want to run 87 octane gas, so lower compression ratio is important. I am looking at 3 options. What option will give me the most reliability?

1.) Should I rebuild my stock heads, get larger valves and get them port and polished? If I mill the head deck I am going to raise the compression ratio unless I get a thicker head gasket and I am worried about blowing a head gasket and having things leak.
2.) Should I buy some used GT40 heads (non P, 65cc combustion chamber) and just get them rebuilt. Are these better than option 1? Also have to worry about milling the head deck.
3.) Should I buy some cheap aluminum heads? Are they just as reliable as iron? I am worried about the expanding and contracting over time, are they more likely to crack? With the movement of the heads from thermal expansion, on the head gasket, will this make the head gasket blow prematurely? At least with aluminum heads I have some more options with compression ratio.

Any advice is much appreciated.

Cheers!
Alex

 

Alloy heads. Don't waste the time or money on iron. If you're porting/polishing to support the additional displacement then the time and money right there justifies alloy heads in itself. Just don't buy Chinesium heads. Edelbrock E-Street is probably a good compromise, but I'm way more familiar with the aftermarket offerings for Mopars, so someone else might have another brand in mind. Thermal expansion is not an issue anymore with quality castings. As for compression, alloy is more forgiving giving its thermal characteristics. Ultimately your compression ratio is going to depend on the cam selection, but the general rule is you can run anywhere between a half-point to a full point of compression over iron and still have the same resistance to detonation.

 

I did that once, started with a $2-$3,000 budget, went to $5,000, now, probably at $10,000.

So, your cheapest option is to home port the stock heads.
No point in spending money at the machine shop, might as well get decent aftermarket aluminum heads for the same price.

No point in buying cheap aluminum, you get what you pay for, and you will probably have to take them to a machine shop anyways.

I don't see how building a stroker is going to be a budget build. What is your budget?

 

Thanks for the advice, if I got aluminum heads, I would probably go with AFR heads, they are the cheapest heads that are made in the US I think.

How do you pick a cam? I know very little about cams do you have any threads you could recommend?

 

I called CompCams, they recommended my cam after me giving them all the information for what I was wanting to accomplish.
You can read for days, different threads, different opinions, different requirements, different outcomes.

I'd call the manufacturer of the product you think you'll choose. Heck, call a few of them, see what different cam profiles they recommend.

 

Any reason not going 408? Yah I know can use 302 comp height pistons (what 1.61?) but you still have to buy new ones...

You will have to recondition the stock rods anyway, may as well grab some new decent I-beams for similar cost.

Also, yep I would waste zero time with production heads. Look for some old GT40X, Edelbrocks, Systemax, whatever. Freshen them up and rock on.

 

I was originally thinking about going with a 3.75" stroke but decided to go for the 3.85". I don't want to get any bigger than that, more cubes means more fuel. Also, I read somewhere that the more you stroke an engine the more pressure you put on the sidewall of the cylinder because the crank is rotating in a larger diameter and can prematurely wear out the cylinder wall. Not sure how much merit there is in that argument. Also I read more than 3.85" and you have to modify things for clearance, just another step and I need to get this truck back on the road so I can use it again.

 

If that concerned about long term (and fuel use in a box on wheels), keep it stock stroke. Note piston rock at BDC is a deal on SBC with long stroke, as the deck is shorter around 9.0...351 is 9.5. That is how they get into trouble. SBF strokers similar.

Efficiency and power go hand in hand. I would put my money into heads and a modern camshaft than stroking this and using pathetic heads. Plus whatever supporting mods you choose.

Either way, enjoy the build

 

393W is the cheapest option because it uses stock-ish parts other than crank itself. Most larger-displacement strokers have rod journals that are smallerSBC size, so clearancing isn't the problem until you are well over 4.00 stroke (408). My 393W didn't need any clearancing. I developed a combo that is now offered by cnc-motorsports.com. https://cnc-motorsports.com/catalog/...category/1007/

There ARE good aftermarket iron SBF heads - just not very common any more. I used a set of $400 used professionally-ported iron 64cc World Windsor Seniors, when combined with KB364 302 22cc-dish 'blower pistons', gave a static CR of ~9.3:1 - and it ran just fine on 87 octane. I had also found a pair of TFS high ports for $400, but finding headers for those was a problem... Many circle-track engines are limited to iron heads, so check out that bunch for used heads...
I had intended to link a website with various stock/ported/OEM and aftermarket SBF head flow data, but it seems to be down... carbdford.com/tech/flowdata.htm

Anyway, that mild 393W, with a mild torque-grind/towing/'RV' cam gave me somewhere near 325hp - much better than the 180hp of the stock 351W-Variable Venturi...

 

Yep, no one really knows TFS made iron heads.

 

Just because it's US made doesn't guarantee quality. Whatever you pickup have your machine shop check them over for valve guide clearance and valve sealing.

Is your 351 block a factory roller cam block? If so, this is ideal. Use a roller cam and factory roller lifers. Comp Cams will probably have something for a truck in their catalog. It's going to depend on your intended usage. Give Comp a call and they'll guide you to something to use.

Also, I agree with the sentiment of others here: probably best to forgo the stroker route and go factory bottom end. Stroker pistons with shallow compression heights have a tendency to rock in the bore and it'll make noise. Not conducive to a 100k mile motor either. Drop the money in heads and intake. I say this as someone who built a stroked big block. They're hella fun, but it's a weekend fair weather toy. Definitely something I wouldn't daily drive.

 

You are absolutely right! I heard that 393s are cheaper than other builds bc you can keep your connecting rods and just get the crank and some aftermarket mustang pistons but now that I am getting into the details it just keeps going up! Going up and down the mountains of East Tennessee with a fully loaded trailer is super annoying and hard on my 302 I just want the longest stroke I can afford and I want to use it as long as possible. Maybe the stock 3.5" stroke of a 351 is all I can afford.

 

What is your budget in case I missed it....

 

At first it was $3,000 but now I am thinking $5,000. And at the end of the day my truck will still be worth $5,000 lol. Bury me in it!

 

Post #3, lol: