I've decided to put a 331 in my car and have a question.

68EFIvert · Oct 8, 2009

I don't know anything about doing that but I assume my machinist does. The only problem I could see with that is the engine already runs on the warm side and I don't know if that would cause that problem to get worse. I assume when you fill the block you add some sort of dense material to water passages?

65ShelbyClone · Oct 9, 2009

Yeah, a common brand is Hard Blok block cement.

js66coupe · Oct 9, 2009

I was just wondering if others have tried this. I don't know anyone who has done a partial fill on their SBF.

rebel65 · Oct 9, 2009

i would put some more in the heads, every little CFM helps when it's boosted, and just to make sure you're going to supercharge this 331 right? otherwise i would probably spin it higher to make the power wanted.

68EFIvert · Oct 9, 2009

Well I have solved the block problem and purchased one on flea bay that a guy bought, machined and then changed directions. I got a good deal on it considering it is ready to bolt together. Of course I will have my engine guy look it over before I do anything. It is a new Boss block!

blown65 · Oct 9, 2009

classic boost said:
i made 500rwhp with those heads and turbos (stock cam & pump gas, too). they're an efficient head.
68efivert, check out the new dart 'shp' blocks.

Still doesnt change my mind, I wouldnt use those heads on a power adder car. Just my .02 cents.

10secgoal · Oct 10, 2009

I would. If 185's will get you into the 8's (<-----believe it), 165's should do OK. 500 should be easy peasy.

68EFIvert · Oct 10, 2009

I have always heard that the exhaust flow was more important flow wise than the intake. The 165 and 185's have the same flow on the exhaust and at the lift of my Trick Flow Stage 1 cam there is only a 17 cfm difference on the intake valve. On a dyno test listed on the AFR website the engines made very similiar power. The 185 headed engine made about 17 ponies more and 16 ftlbs more. The question is do I care about that for the price I would have to pay and does the difference get magnified when you use boost?

stonecoldtx · Oct 10, 2009

68EFIvert said:
Well I have solved the block problem and purchased one on flea bay that a guy bought, machined and then changed directions. I got a good deal on it considering it is ready to bolt together. Of course I will have my engine guy look it over before I do anything. It is a new Boss block!

You might want to measure the cylinder walls on that block before you buy pistons . . . in many (or maybe even most) cases, the pistons themselves are the specifiied bore diameter, and you will want to make sure that the pistons you buy have the correct clearance, or you'll have to have it re-machined for the next size larger.

For example, if you're going with an economy stroker kit that has hypereutectic pistons that are exactly 4.030" in diameter, you're going to need less piston skirt to cylinder wall clearance than you would with a forged piston, and vice versa.

Now, if' it's only bored 0.30" over, and it's one of those thick-walled blocks that can take up to a 0.125" overbore, then it would be one I'd consider but I sure wouldn't consider it if it can't take more than a 0.030" overbore, for the reasons specified.

Also, different forged pistons required different piston skirt to cylinder wall clearance figures, too.

IMO, a block that has already been machined isn't my first choice (except for the example above), simply because of this reason, and also because you don't know the quality of the machinework. It could very well be that the reason this guy sold the block is because the machine shop screwed up.

65ShelbyClone · Oct 12, 2009

68EFIvert said:
I have always heard that the exhaust flow was more important flow wise than the intake.

That's a tricky statement to address without being wrong in some way. I suppose the correct answer is that it's important for them to flow in the right proportions. Most commonly that is with the exhaust port flowing 80% of the intake. SBFs typically have wheezy stock exhaust ports, so that area gets a lot of attention. In contrast, single carb Honda XR600R/650L bike engines have exhausts that flow in the 95-98% range, so the intake port needs the improvement instead.

68EFIvert · Nov 4, 2009

Well I had my engine builder look over the block but he said that it was bored 4.032 rather than 4.030. He said that it would be a little too loose for his preference and suggested taking it over to .040. I thought why not do a big bore and go 4.125 to give me 347 cubes but that would not allow me to bore it again if I ever had a problem.

How realistic are the max bore limits they place on blocks? I have seen that the max bore on most blocks is 4.030 but they ofter go to 4.060. Do you thing kit would be a problem if I ever had to take the boss block out to 4.155?

stonecoldtx · Nov 5, 2009

68EFIvert said:
Well I had my engine builder look over the block but he said that it was bored 4.032 rather than 4.030. He said that it would be a little too loose for his preference and suggested taking it over to .040. I thought why not do a big bore and go 4.125 to give me 347 cubes but that would not allow me to bore it again if I ever had a problem.

How realistic are the max bore limits they place on blocks? I have seen that the max bore on most blocks is 4.030 but they ofter go to 4.060. Do you thing kit would be a problem if I ever had to take the boss block out to 4.155?

If that block has the extra thick cylinder walls, and can be bored to 4.125, I'd go for it! Chances are you probably wouldn't be doing another overbore on it anyway, since it will likely last for well over 50K miles, possibly 100K, and if it wears out by then, you probably would want to buy a new block anyway . . .

Plus, it will allow you to purchase the oversized pistons, and have your engine builder "fit" the pistons to the bores for closer tolerance control.

Just my humble opinion . . .

10secgoal · Nov 5, 2009

If it'll go 4.125, I'd just leave it. It'll cost you twice to bore it to get it that big, and if you go .040 or the minimum each refresh or rebuild, that block should last you forever.

68EFIvert · Nov 5, 2009

I ordered .040 pistons today. I decided it was better to be safe than sorry. I guess I'll be rolling with a 333 under the hood instead of a 331. I had the same thoughts as 10secondgoal on this topic.

rebel65 · Nov 5, 2009

half the devil?? 333 the new scary number ( especially since it's going to RIP around town!! can't wait to see it done man!

68EFIvert · Nov 5, 2009

rebel65 said:
half the devil?? 333 the new scary number ( especially since it's going to RIP around town!! can't wait to see it done man!

Very fitting though. Red car that is missing half of it (convertible). Maybe I'll name her "Christine".

rebel65 · Nov 5, 2009

hey, maybe some day i will name my stang too.. haven't found a better name than 'my baby' yet... lol

and ya i didn't think about the vert part.. very cool now .

dodgestang · Nov 6, 2009

68EFIvert said:
Very fitting though. Red car that is missing half of it (convertible). Maybe I'll name her "Christine".

The name 'Deathtrap' is taken.

I've decided to put a 331 in my car and have a question.

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