I have the low buck 350 chevy crate engine. I'm wanting to put a little more power out of it.

I purchased some World S/R heads. These have 67 cc chambers as apposed to the stock 76 cc chambers. Stock compression is suppose to be abotu 8.1:1 . How much will this change increase the compression ratio?

Also World recommends a .041 thick head gasket. But I was thinking about using this gasket, which is .015. To give me a little more compression.

http://store.summitracing.com/partdetail.asp?part=FPP%2D1094

Anyone see a problem with the head gasket? Or any suggestions?

I take it you are talking about the Goodwrench 250 engine right? Which is their low dollar, all new, 350 long block.....

Let me know before I say anything.

Yes, the low buck 350 small block.

Ok, it starts out as an 8.5:1, 250/260 rated horse power long block. Adding the 67cc S/R heads woud put you around 9.4/9.5:1. Which will work great if you use a cam shaft that isnt too big or too small for that matter.

CHP did a GM 250 with a pair of TFS 23* heads, a Comp Cams XE 268 and a Edelbrock RPM manifold. The combo made 412hp on 87 octane. Uhm, not bad.

With the heads you currently have, you could do something right about the same. You have the bottom end and the heads. Now its down to selecting a camshaft, manifold and proper carb.

The head gasket required will be the one that nets you the compression ratio that suits you camshaft selection. I myself use FelPro 1010's which are thinner than 0.041" but thicher than 0.015".

By the way, there is nothing low buck about that engine. My last GM 250 went 273,000 miles without a hickup. Damn good engine if you ask me.

We'll carry on later, I gotta split ..........

Thanks for the info.

I already bought a cam, it's the Extreme 268 that you suggested. I couldn't pass the deal up, $350 for the heads and cam/lifters, both with less then 1000 miles for $350.

So which gasket do you think I should use? Do you put your head gaskets on dry?

The .015's ought to work just fine. It'll help reduce your quench height a bunch, which'll be good, too - it'll help offset any penalty from increasing the compression ratio - though you should be in o.k. shape there anyway. One issue with steel shim gaskets (anything under about .025 or so is too thin to make a composite gasket of) - you need flat heads to seal well. My heads came from the factory about .006 out of flat, and my machinist recommended milling them off to get them flatter to seal decently with a shim steel gasket. Flatness of the block deck may be an issue, too. You want to consider that before you go to a shim type gasket.

Smokin deal Mark! I just hope the lifters were marked to cam position.......

Once again, Huck deserves a feather in the cap. I agree with this. It would be a good move to tighten up the quench but the stated thickness might be a problem with the shim type gasket. It has to be FLAT in order to surive. If you were to surface the head or block (if either required it) the FelPro 1010 would be a good choice to make up the difference. It would be even better if it were the block that had to be machined, but I take it the engine is still in the chassis and a head and cam swap are the evident mods by themselves...... If the block were out, I find something closer to 'zero deck' and go from there.

As for the FelPro 1010's that I use they are installed dry and have a compressed thickness of 0.039".

In June, CHP did an article on pretty much the same bottem end with similar sized production Iron heads , a RPM air gap and made 336hp @5300 / 377ftlbs @3700.

With the better head that you already have, I could see another 60 or so hp and it would easily make 400 ftlbs. Something that would run all day and night.......

Thanks for the great info guys.

I've been reading these build up articles CHP did;http://chevyhiperformance.com/techarticles/index6.html

They used a stated as "rubber-embossed steel shim gasket" that compresses to .015". Is this the same gasket as I mention above? They never give a part number to the gasket though, :confused: .

I am about 99% sure that it is Fel Pro part number 1094.

Mark,

That cam should rock in your motor after you get her up to the CR. you want, imho...

pdq67

Thanks.

I'm still not sure on which head gasket to use. I might try the .015 one.

Also, will my stock rockers work okay with these heads/cam?

Would you run a 600 or 750 cfm carb?

I think you should consider using the springs that go with the cam or at the very least a cheap set of Z-28 springs.

As for the 600 vs the 750 thing.

A 3310-, 750cfm carb. will only let your motor use what it needs, being vacuum secondaried so if it is tuned to your cobination, it will be fine.

And the 1850, 600cfm carb. is also fine at this power level. You may give up just a schosh on the very top-end, but more then make up for it in better gas mileage, He, He!!

As always, jmho.. pdq67

I would think the springs that came with the World heads would be good enough. I'd have to check the specs though. You think?

You can get the spring specs of the World heads off of their web site. Just make sure that they are shomewhat close to what the cam manufacturer recommends. If within acceptable means, I'd say run it.

As for a carb a 650 would be choice. I guess it depends on what the rest of the package is and what you plan on doing with the car. The 3310 vaccume secondary is a great street carb. As PDQ stated, it only takes what it needs and would be a great carb with an auto. But if a mechanical were your flavor, a 650/700 DP would be fun.

But a 3310 750 would be great on a 350/automatic. You havent said what this was going to be used with and I dont want to assume only because your sig shows a 468 and a 700R4......is this going in the Camaro?

No it's not going in the Camaro. My brother and I are building a '59 Brookwood (two-door Chevy wagon) and this thing is huge. Which is why I wanted the heads and cam so it might be able to get out of it's own way.

The tranny will be a TH-350. I'll probably just go with a 600 carb. I've always liked to run Edelbrock carbs, so that's probably what I'll get.

The engine came with a Performer RPM intake, so I'm good there.

I'll also try to run the stock rocker arms that came with the engine. Unless anyone sees a potential problem with that.

Opps, forgot to cover that in my last.....

I dont think you will have any problems running stock rockers.

The stock rockers will be fine with the xe268 cam. Also, the springs that come with the sr torker heads will work fine with that cam too. If you havent bought an intake and carb yet, I would seriously consider a performer/650 spread bore holley vs carb. Unless you have 3.42 or lower gearing, the performer/spread bore combo works much better in a heavy vehicle with relatively tall gears. I have a very similar setup in my 4500 pound truck w/3.08's. I recently switched from a 750 edelbrock/performer rpm (vortec heads) to a 650 spread bore/performer and the difference was night and day on the low end, with only the very slightest loss in top end power (over 5K rpms). I got my carb thru www.sdpc2000.com (http://www.sdpc2000.com) ...it is a late Lt-1/L-82 calibration carb that works beautifully with this combo right out of the box. Also, unless you have really tall gearing (like 2.56's or something), I would use at least a 2000 stall convertor. The head gaskets the chp used was the fel-pro 1094's...rubber embossed .015 shim gaskets. Overall an excellent combo for all around use.

Thanks. I already have a Performer RPM, so I'm going to run that.

I think I'll try the .015 gasket.