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-   -   SBC 327 with Vortec heads (http://www.hotrodders.com/forum/sbc-327-vortec-heads-222419.html)

jexrod 08-01-2012 09:34 AM

SBC 327 with Vortec heads
 
I have just started to rebuild my first engine and in need of some guidance. I have a 66 Impala with a 327, powerglide combo. The engine began smoking heavily and after some investigating... a rebuild was the only option. I would like to increase performance all around as much as possible during this build. The major dilemma is what cam to use and why? Every where I go and call people will never recommend the same cam specs actually, most of the time it's not even close. The car is a weekend driver and it's will keep the powerglide trans. Fast off a roll would be the most fun.

Here is what I have so far,
HEI distributor
Vortec Heads 062 casting, stock rockers (refurbished by local machine shop)
Holley 750 CFM
ProComp PC22026 Air Gap Intake
Speed Pro +.030 Pistons Flat top
Hasting Rings
Stock Rods
Stock Crank, polished and tapped for center bolt
Cleavite Bearings
Melling Oil Pump
Felpro Gasket Kit

I would prefer to buy a Compcam or a Lunati kit to include cam and lifters. I would like to get to 400hp/400tq whether it's realistic or not is why I'm here posting for answers. Thanks!

ap72 08-01-2012 09:44 AM

A 262 or 268 voodoo cam is a very popular match for those heads. You'll need new springs and possibly new rockers.

oldbogie 08-01-2012 05:53 PM

Quote:

Originally Posted by jexrod (Post 1579078)
I have just started to rebuild my first engine and in need of some guidance. I have a 66 Impala with a 327, powerglide combo. The engine began smoking heavily and after some investigating... a rebuild was the only option. I would like to increase performance all around as much as possible during this build. The major dilemma is what cam to use and why? Every where I go and call people will never recommend the same cam specs actually, most of the time it's not even close. The car is a weekend driver and it's will keep the powerglide trans. Fast off a roll would be the most fun.

Here is what I have so far,
HEI distributor
Vortec Heads 062 casting, stock rockers (refurbished by local machine shop)
Holley 750 CFM
ProComp PC22026 Air Gap Intake
Speed Pro +.030 Pistons Flat top
Hasting Rings
Stock Rods
Stock Crank, polished and tapped for center bolt
Cleavite Bearings
Melling Oil Pump
Felpro Gasket Kit

I would prefer to buy a Compcam or a Lunati kit to include cam and lifters. I would like to get to 400hp/400tq whether it's realistic or not is why I'm here posting for answers. Thanks!


Getting 400 horses from a 327 is a little more difficult than from a 350. It'll take a bit more cam and some 1.6 rockers.

The flat top pistons might get you into more compression that pump gas is comfortable with but to compute that I'd need clearance from the piston crown to deck, head gasket thickness, and exactly which pistons to get at how many ccs are the valve reliefs. You need to work both the static and dynamic compression ratios especially with a bigger cam which tends to bleed compression under the torque peak RPM. To recover this requires extra compression, so all of these dimensions need to be worked out before buying pieces.

With parts roughly the same as what you sight a 350 with a Comp XE268 and 1.6 rockers would tease the 400 mark. Since power and displacement walk hand-in-hand for an equivalent configuration one could assume a 327 would make about 380. It's not quite that simple but close enough for two engines with only a 33 cubic inch difference.

The big problem is to get that 20-30 hp out of the 327 will take revving the engine to a higher RPM. To do this the Vortec heads need some work as the valve springs on these things are a small diameter and enlarging the pocket sometimes weakens the port roof if not actually breaking through. So the safer bet is the same size spring but one of better quality and strength. Beehives work best as they use a smaller thus lighter retainer so they have better valve control with less spring. Otherwise single wound 1.28 with damper will fit and provide upwards of 340 pounds of open pressure without having to carve out the pocket.

The next problem is the top of the valve guide, the stock 062 type casting will not tolerate lifts beyond .45 inch and you will need more so the guide needs to be machined down.

The stock Vortec rocker is self guiding and the rocker stud is pressed in. The spring pressure needed for a better cam is going to push the limits of the press in studs, these really need to be replaced with screw in studs which require machine shop milling down of the existing pads and tapping the hole for the screw in stud.

The 1.6 rocker should be a quality piece with at least a roller tip. If you use the self guided rocker then push rod guides are not needed. However the Vortec head is not configured for push rod guides so if the rocker selection is not the self guiding type then guides need to be used and accommodated under the screw-in rocker studs and hardened push rods used.

Making no bones about it, turning a rebuilt Vortec head into a performance piece is fairly detail involved and rather expensive. This is why aftermarket and GMPP's performance versions of the Vortec are so popular, as they can be had ready to support a high output engine for about the same cost as rebuilding production Vortecs into performance pieces.

Bogie

vinniekq2 08-01-2012 05:55 PM

A 400 HP 327 with power glide and heavy car? what gears would this daily driver have? a 325 HP daily driver 327 makes more sense to me,because,the power will be at a lower RPM that is more user friendly.Heavy cars need torque to have peppy acceleration.A power glides first gear is like everyone elses second gear.Put a 4 spd auth with a 3:1 first gear for offline help and use O/drive for fuel economy.

F-BIRD'88 08-01-2012 06:48 PM

Its not going to happen with the powerglide.

jexrod 08-01-2012 11:13 PM

Thanks, for the input guys. Sounds like 400 is a stretch, however if I can maximize the potential of what i have and keep it close to 350, it would be nice.

Piston is +4cc valve reliefs
Piston to deck is .029
Head gasket in kit is .041

Vortec heads are fitted with screw in studs, but the seat of the stud and valve guide height is stock. Not knowing I requested the screw in studs but no additional machine work. I have a screw in stud but it cannot accomodate guides. Live and learn.

Just picked up a set of headers, I will add to the project.

Rear gears are stock 3.08's

vinniekq2 08-01-2012 11:31 PM

a 350 horse 327 is not a tough job at all,its just not a very good match for the powerglide and street use in a heavy car.a 350 or 375 HP 327 with a 3 spd or better a 4 spd auto is great and easy.A turbo 350 is almost a simple bolt in. turbo 400 or 700r4 will need the X member moved back
a couple inches,drive shaft shortened and yoke changed.

to get 400 pounds of torque from a 327 will probably net you closer to 450 HP.Still not a problem,just need different parts.When you picked HP/torque numbers how did you arrive at those figures? What do you want the car to do?what does the car weigh? I understand using a 327 for nostalgia

jexrod 08-02-2012 12:59 AM

Car and engine has been in the family for years, so trying to keep it going.

I local guy has an aggressive 350 in a Nova he says reaches 500hp at the crank.

That being said i wanted to build this one myself, with some lofty aspirations. If he can hit 500hp, I figured hitting 400hp would be possible. Having spent all day reading blogs and looking at similar set ups, its a stretch that i will reach 400hp.... or that he actually makes 500hp.

So for now, I would prefer to wrap this one up with the most HP and TQ reasonably possible and slowly start building towards a 383/700r4 set up.

I spent a few minutes chatting with a local performance engine builder and he stated using Comp cam 12-206-2 or 12-210-2 will cause pinging with my current build.

Back to the original question, will a 262/212 @50 duration or 268/218 @50 duration cause pinging?

Jexrod

vinniekq2 08-02-2012 01:09 AM

what fuel are you using? Are you willing to use a solid flat tappet camshaft?You can use more compression with aluminum heads.9.5 is a safe CR for cast heads.400 HP is easy,its the drive ability issue using a power glide and near stock convertor.A turbo 350 will make it easier.high horse power+heavy car+plus not much gear+higher RPM camshaft+starting in what most people consider 2nd gear (1.72:1 low gear in power glide)makes for a gas burning slug. first gear in t 400 is 2.5:1,turbo 350 2.7:1 and 4 spd auto is 3:1.

a 400 hp 327 will rev 7,000 rpm with moderate priced cylinder heads and not make much power until hitting 3,000 rpm,so idle to 3,000 rpm will be a slow process with 1.7 first gear ratio.passenger can get out and push,,,

jexrod 08-02-2012 01:20 AM

93 octane, would switching the torque converter help?

vinniekq2 08-02-2012 01:33 AM

swithching the convertor would make it worse for a daily driver. 92 octane will work fine with 9.5: 1 CR with cast heads.a bigger camshaft with more overlap can help you get away with a little more CR. I have 10.72:1 CR in my stroker small block I use aluminum heads though

BigEd36 08-02-2012 04:57 AM

jexrod, using the parts specs you've given us (64cc chambers, 4.030 bore with 4cc dish pistons .029 in the hole, .041" FelPro head gasket), I'm coming up with a static CR of 9.17:1, with the HE 260H #12-206-2 a dynamic CR of 7.774:1, with the HE 268H #12-210-2 a dynamic CR of 7.57:1 so I don't see a problem with pinging using either of the cams you've mentioned. One thing I notice is with the .041 head gasket and .029" in the hole your quench/squish distance is .070", which is too wide to be effective. Changing the head gaskets to GM #10105117 (.028" thick with a 4.10" bore) would reduce the quench to .057" (better but still not "best") and increase the static CR to 9.48:1, Dynamic CR would be 8.03 with the 260H #12-206-12, 7.821 with the 268H #12-210-2, still within range for 93 octane. Changing to a FelPro #1094 shim head gasket (.015" thick, 4.10" bore) would reduce quench to a much better .044" and raise the static CR to 9.79:1. You might even want to consider going to the Comp Magnum 270H #12-211-2 with this combo (dynamic Cr of 8.01).

As pointed out earlier, the real detriment to your street performance in your big Impala is the lack of "gear". With a 1.76:1 low gear PG and 3.08 diff your overall ratio is just 5.42:1. Changing to a 2.52 low gear T350 would increase that to 7.76:1 for over a 43% increase in torque multiplication to get your big Impala moving (about the same as changing your 327 for a 454 with equivalent specs!). Better yet would be a 200 4R with a 2.74 low gear, 8.44:1 overall, the OD would put you at 2.06 for highway cruising. A 700 R4 or 4L60E with 3.06 low gear puts you at 9.42 overall, a 74% increase in your "off the line" torque! (and still have OD for cruising) Combining some lower gearing with the increased HP/torque from your 327 build should put some :D:D on your face! As Vinniekq2 pointed out, with any of these automatics, 2nd gear will be nearly as low as the low gear in your PG.

454C10 08-02-2012 05:24 AM

Your biggest issue is the transmission. get a th350. Not even a 454 would like to pull on a powerglide with a 3.08 gear and heavy car.

For less than what you are spending on that 327, you can buy a used and complete, 350 vortec engine in good condition. These engines come with roller cams and vortec heads. They will make 300hp with a set of headers and intake. or 325 hp with a mild rv type cam. Plus you don't need to worry about cams going flat. Call your local used engine salvage yard.

Forget the rpm air gap intake. Very slow intake warm ups give it poor street manors. The regular rpm is better.

ap72 08-02-2012 06:53 AM

Quote:

Originally Posted by 454C10 (Post 1579364)
Your biggest issue is the transmission. get a th350. Not even a 454 would like to pull on a powerglide with a 3.08 gear and heavy car.

For less than what you are spending on that 327, you can buy a used and complete, 350 vortec engine in good condition. These engines come with roller cams and vortec heads. They will make 300hp with a set of headers and intake. or 325 hp with a mild rv type cam. Plus you don't need to worry about cams going flat. Call your local used engine salvage yard.

Forget the rpm air gap intake. Very slow intake warm ups give it poor street manors. The regular rpm is better.

Very good idea. Get the 700r4 while you're at the yard too.

oldbogie 08-02-2012 10:42 AM

Quote:

Originally Posted by jexrod (Post 1579334)
Thanks, for the input guys. Sounds like 400 is a stretch, however if I can maximize the potential of what i have and keep it close to 350, it would be nice.

Piston is +4cc valve reliefs
Piston to deck is .029
Head gasket in kit is .041

Vortec heads are fitted with screw in studs, but the seat of the stud and valve guide height is stock. Not knowing I requested the screw in studs but no additional machine work. I have a screw in stud but it cannot accomodate guides. Live and learn.

Just picked up a set of headers, I will add to the project.

Rear gears are stock 3.08's

Having read through many of the entries I would have to question why you’re keeping the Powerglide but putting a 327 in to it. The 327 isn't native to a 57 so why even hang onto the obsolete power glide. You can slip a 700R4 under the floor and pick up a deep low gear for faster launches or at least better in town gas mileage as it takes less throttle to get the car moving from a stop and this relates right back to fuel consumed. At the other end the 4 th gear overdrive lets you cruise the freeway using modest RPMs with a 3.08 ratio 70 mph would be about 2000 revs. And a lock up converter eliminates the slippage always present with a torque-converter this can be good for another 10% or better reduction in RPM for a given road speed with the converter unlocked. The 700R4 can be column shifted from what you already have in the car so from the casual viewer's point of view the car would look original.

As has been mentioned; the buildup of the piston crown to deck distance and the head gasket thickness is excessive for the best squish/quench. My calculator with your dimensions gives a fairly mild Static Compression Ratio (SCR) 9.1 to 1 which should be no problem for a Vortec head. You can lean on that a little and pull your squish/quench back toward the more desirable .040 inch by using a shim style head gasket these are available for .016 and .019 inch thicknesses. The .019 would bring the squish/quench distance down from .070 inch to .058 which is much more desirable for mixture agitation and detonation resistance. The .019 gasket would bring your SCR up to 9.5 to 1 which is quite good with these heads. The shim gaskets do require flat and parallel head and deck surfaces, it they aren't then some milling is needed and that depending upon the dimensions of material removed can drive a different gasket solution.

Bogie


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