Made up my mind for a 331 stroker.

stinger86 · Nov 22, 2010

OK i was leaning on a 347 for a while. Then after lots of homework and talking to a few people who i thought knew what they were talking about ive decided on a 331 because of the longengivity and what i want in my car. Now i ask the experts

OK there are sooo many freakin options here. Basic questions for now. I know i ask allot but i no where else to turn.

I'm looking at stroker kits and some things i see are confusing.

1. Comp ratio. what am i looking for into a the comp ratio for 331.
kits say something like

58cc 64cc 70cc
10.4 9.7 8.9
9.3 8.7 8.1
12.9 11.8 11.1

What does all this mean?

2. Waht kind of pistion do i want? Flat top, Dish top, Dome top?...probally forged right?

3. Since the kit inst replacing my heads, should i look into getting newer one or just replacing springs?

Thanx again for all your tremendous help!!!

lx5.0maine · Nov 22, 2010

DELETED

D.Hearne · Nov 23, 2010

stinger86 said:
I'm looking at stroker kits and some things i see are confusing.

1. Comp ratio. what am i looking for into a the comp ratio for 331.
kits say something like

58cc 64cc 70cc
10.4 9.7 8.9
9.3 8.7 8.1
12.9 11.8 11.1

What does all this mean?

2. Waht kind of pistion do i want? Flat top, Dish top, Dome top?...probally forged right?

3. Since the kit inst replacing my heads, should i look into getting newer one or just replacing springs?

Under the 58cc, each one of those numbers represent the compression ratio you'll get with each piston type. 10.4 will be with flat tops, 9.3 is with dished, and 12.9 is with a domed piston. Unless you're only going to be racing, rule out the domed pistons. You can then decide which you want flat topped or dished. Dished will run with lower octane fuel than the flat tops, but will make less power too. The numbers under the 64 and 70 cc column correspond to the compression ratio you'll get with those size combustion chambers, just like the numbers under the 58 ccs. What heads do you have now ?

stinger86 · Nov 23, 2010

OE Heads. This engine has minor upgrades. New distributer, tranny, and the headers and mufflers i put on. Does Flat top pistons work for pump fuel? I'm really just going to use the pony as street very rarely strip. But i want the speed. What kind of compression ratio do i want? 8.9 whats that? PSI? or air to fuel?

robbz28 · Nov 23, 2010

The compression ratio is a calculation based on how close the piston gets to the head (in so many words). The higher the compression, the more power can be made, but that can come at a cost. The ideal compression ratio for a street car is in the 9.5 to 10.5:1 range. If you get lower than that you lose power, if you get higher than that you have to start burning premium (sometimes special 110 octane) fuels. You can run 11:1 safely on 93. (Guys i know I am leaving a lot of stuff out but this is basics). A flat top piston is Ideal because it keeps your air flow smoother than dished or domed pistons and will most likely give you the compression you need. As far as the heads go, since you are stroking the engine I would get some aftermarket heads. You could port your factory ones, but I feel on a stroked engine you will want something with higher horsepower potential in the future. Just my thoughts.

stinger86 · Nov 23, 2010

I knew you were going to say new heads. Those things are damn expensive. BUT cost alone should not deter me. Theres no point in stroking the engine to have the heads fail or what not. Is there a rating or a type of head ie aluminum or whatnot thats is prefered street/stip? I dont want to get ones that are merely the same or overpowered. Thanx! That was a great explanation!

stinger86 · Nov 23, 2010

What if i get the stock remanufactured heads and "port" them. I just dont know the condition of my current ones.

PoppyMod · Nov 23, 2010

Hi fellow 331 seeker..

Two years ago, I did a blue-print build of a 331 w/.040 bore , pistons are Probe flat tops with dual valve reliefs (important for TWs). The heads are 170 Trick Flos, (milled for 56 CCs), the cam is a custom billet hydraulic roller, intake is Eddy Performer RPM, headers are coated TRY-Ys. The CR 10.6. It will idle at 800-900. Has 17" vac. Runs on 93 octane. Running a custom built 680 CFM Holly, it was dynoed at 392 RWHP at 6100 w/400 RWTQ at 4400.
As I assisted in the design and assembled it myself, I have many details and pics, I can offer.
BTW, out of boredom, I'm currently running dual DCOE 40MM Webers.
Happy Motoring!....Happy Thanksgiving!

D.Hearne · Nov 23, 2010

stinger86 said:
What if i get the stock remanufactured heads and "port" them. I just dont know the condition of my current ones.

You don't have to buy new aftermarket heads. Nor do you need to stick with ported O.E. heads. There are lots of good used aftermarket heads out there, all you have to do is look. I bought a used set of Ford Racing GT40Y's a couple years back for $600, and at that same time ran across two other sets for the same price. One of the others was a set of Edelbrock RPM's. All you've got to do is keep your eye out and be patient. I bought the Canfields I have on my 331 7 years ago for $1000 new, but secondhand, at that time these were $1400 heads.

robbz28 · Nov 23, 2010

You can port your original heads and they would do fine, but those things were designed to flow for 289 cubic inches, not 331. To port the new ones they have to be totally torn down, hogged out and built to accept new bigger valves and screw in studs and new springs. You are going to invest at LEAST 800 bucks in that. That would go a long way toward some new heads that can handle more horsepower. If you arent attached to your original heads you can probably fetch a couple hundred bucks for them and regain some of the cost of the new heads.

65FBE2 · Nov 27, 2010

Like D says, keep your eyes open for good used set. I scored a rebuilt set of Canfields for $800. They don't make them anymore so you can find them a little cheaper sometimes. I would not even consider putting the stock heads on a 331. It would totaly defeat the purpose of stroking it

PoppyMod · Nov 28, 2010

+1 for the Canfields. Beware, if you proceed, unless you get the matching cam, factor in new springs and setup for a new cam. Also, I think the Canfields have raised ports, so, depending on who's headers your running these heads may have issues with your shock towers.
Good Luck.

rrenie · Nov 28, 2010

D.Hearne said:
You don't have to buy new aftermarket heads. Nor do you need to stick with ported O.E. heads. There are lots of good used aftermarket heads out there, all you have to do is look. I bought a used set of Ford Racing GT40Y's a couple years back for $600, and at that same time ran across two other sets for the same price. One of the others was a set of Edelbrock RPM's. All you've got to do is keep your eye out and be patient. I bought the Canfields I have on my 331 7 years ago for $1000 new, but secondhand, at that time these were $1400 heads.

Look in the classifieds I have a set of Edelbrock Perfomer RPM heads with roller rockers on there at a great price right now.

D.Hearne · Nov 28, 2010

PoppyMod said:
+1 for the Canfields. Beware, if you proceed, unless you get the matching cam, factor in new springs and setup for a new cam. Also, I think the Canfields have raised ports, so, depending on who's headers your running these heads may have issues with your shock towers.
Good Luck.

New springs aren't a given with aftermarket heads. It depends on what springs are on them. I used the springs that came on mine with both a B303 (on the first build, a 306) and the Z303 cam I'm running now in the 331. And the raised ports aren't an issue at all. As a matter of fact, I ran only ran into problems in my Ranger when I pulled the 306 out with the Canfields and went back in with an E7 headed replacement motor. Then I had to chamfer the bottom of my Tri-Y's so they'd fully seat against the E7 heads. The exhaust bolted right up with little effort. I now have the Canfield headed 331 in a 77 Comet and the Hedman long tubes bolted right up and cleared everything just fine. The Comet's got a tighter engine bay than even a 65-66 Stang has. It's more comparable to the early Falcon/Fairlane in dimensions.

Made up my mind for a 331 stroker.

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