Building a new 327 - Chevelle Tech
Engine General Engine Discussion.

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post #1 of 10 (permalink) Old Oct 28th, 19, 9:06 PM Thread Starter
 
Join Date: Nov 2011
Location: Canada
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Building a new 327

Starting the build of a 3791362 Nova block that I have. It’s for my 66 2 door hardtop. Muncie, 12 bolt with 3.73:1 posi

Going with the Trick Flow double hump heads. Flow is 258/200 At .500” lift.
Pistons are Wiseco forged flat tops with 3cc valve reliefs.
Heads are 60 cc so the compression with good quench will run right at 10.5:1.
I have a 350 forged crank ground to small journal that I considered running but the compression with those heads and flat top pistons gets to be over 11:1.
I’m thinking with that compression the cam would have to be very large and make for lousy street manners. That’s why I’m back to using the 4577 forged 327 crank. I have Eagle rods with good bolts. Bore is 4.040”
Rotating assembly will be balanced.

Plan is to use my z28 intake rather the the 3890490 L79. Carb is a 600 Holley double pumper. Headers are 1 5/8 full length, H-pipe, 2 1/2” pipes.

I’m going solid flat tappet. Called Comp and Lunati today. Both recommended small cams. I’m good with that. I want street manners, a good sound and power to 6200RPM.

Comp said XS262s. 262/268 adv. 224/230 @ .050”. .477”/.488” lift

Lunati 266/276 adv 233/241 @ .050” .505”/.520 lift

I run a 10.3:1 327 with 461 iron heads and a comp 280 Magnum presently. Engine runs well but needs good gas to run a good advance curve.

Will a real 10.5:1 engine with aluminum heads and good quench run a cam as small as comp suggests?



Thanks in advance
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post #2 of 10 (permalink) Old Oct 28th, 19, 10:46 PM
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Richard
 
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Re: Building a new 327

Nice, I always loved the 327! I've got one in a 65 SS, Muncie. I'm thinking of selling the car though. I still have a 65 SS convertible and 55 210 I haven't finished yet. Might let the 55 go to. I'm getting too old, lol.

Richard

65 Chevelle SS Convertible 350 4 speed Muncie...hopefully complete in another year or so
65 Chevelle SS hardtop 396, 4 speed
65 Chevelle Malibu Convertible, 350/TH350
64 Chevelle Malibu 2dr hardtop
64 Chevelle SS, 350/450hp, Muncie M21
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post #3 of 10 (permalink) Old Oct 28th, 19, 10:48 PM
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jeff
 
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Re: Building a new 327

I have a 350" with 10.87 compression and smaller than 58 cc heads I have ran the 268H in it ground on a 106LSA which closed the intake valve sooner than the 260H cam.
225 psi cranking pressure. over 10 years on that engine and I pull my 20 foot pontoon with it.
35 total timing makes 3 less HP than 38 total.

Well I did recently change the cam to a 280H because I needed more top end power. seems these LS deals pull me on the big end.

You can't just willy nilly slap stuff together with high compression and make it work.
I remove all sharp edges on or in the chamber and on valve reliefs of the pistons and the outer edges of the piston tops.
My intake runners are not smooth.. they are roughed up starting from under the carb all the way to the first valve seat cut.

Rough like hard stone rough.
Keeps fuel atomized.
I have ran just under 12:1 with 91 octane gas and smallish cams like the 280h [email protected] .050 on a 110 lsa.
They lived and they made excellent power.. but the attention to details.
Cars were not loaded up in gear and coolant temps stayed below 180 for the most part.

Daily drivers.

I recently did a 327 small journal ..right after pulling a 385".
Disappointing to say the least . I left it in for 2 days and pulled it and stuck a 357" in.
Much better.
I was only around 9.5 compression on the 327.. not enough I ran the 230-230 cam the 280H.

your heads flow much better than mine and more compression also.
Should work well.

I ported my cousing 461 heads on his 327" and stuck the RPM intake on it with an old crower cam on a 108LSA .
It had a 4 speed and 336 gears in a 67 camaro.. went 13.8 et. 20+ years ago

I run 13.5 et easy with a 350" and 268H today with ported 601 iron heads. Better MPG quieter and much more TQ out of the hole.

I do not think another small cube would make me happy.
But if you are light like 3000 lb race weight it might be good.
My vehicle was 3376 with driver and it was ho hum below 4500 rpm.
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post #4 of 10 (permalink) Old Oct 29th, 19, 8:54 PM Thread Starter
 
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Re: Building a new 327

Thanks for the replies. I have already worked all the sharp edges on the Wiseco Pistons.
Iíll check the heads for sharp spots when I get them. Iíll assume the runners shouldnít need any work???

Before I spend money on these heads maybe I could ask an opinion. I have a beautiful set of fresh 461 heads. They have 2.02/1.6 valves. Unshrouded chamber. Screw in studs, guide plates, new guides, hardened exhaust seats, posi seals, bowls have been cleaned up. These heads have a ccíd measurement of 61cc so they would make great street compression with my flat top pistons that have only a 3cc valve relief. I have these heads up for sale to help fund the new heads.

If I built the engine with these heads, optimized the compression with the right cam, how would it compare to the aluminum headed engine with a well picked cam. Both would be with headers, z28 winters intake, 600 double pumper.

Thanks
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post #5 of 10 (permalink) Old Oct 30th, 19, 11:26 AM
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jeff
 
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Re: Building a new 327

Cleaned up bowls is not the same a bowl ported.
You need to make the bowl larger to take advantage of the larger valves.
You mentioned the chambers have been unshrouded but in the picture it only looks relieved a little on the side where the intake valve is.

Many hardened seat inserts hang out into the bowl and need much massaging.
The chamber between the relieved area and the spark plug needs to be kicked out like a heart shape or peanut shape to get the power out of those larger valved heads.
Even the 1.94" valve responds to kicking the chamber out in that area.

Pushrod pinch needs to be opened up also on most heads to make the thing rev better and make more power.
I find this dyno a little sad really for the cam and the trickflow heads.
Good TQ but lower RPM than my smaller cams..That is what I find odd.

Upgrade the power of your Gen I small-block Chevy


They made max wheel HP at 5300rpm. and max TQ just under 4000.

Makes me ask what was left on the table.. was it the heads cross section was the engine too tight.
That was the comp magnum 280H cam.
Max HP on my 268H cam with 601 305 heads with 1.84-1.50 valves comes in at 5700 rpm and max TQ at 4500.

I had one car on the wheel dyno with the 280H cam and max HP came in at 5850 RPM.. little 305 heads on it.

Something is not right with the above superchevy deal.

you can read all of this
https://www.chevelles.com/forums/18-...ad-thread.html

around page 4 I show some 492 angle plug heads and if you look close you can see a lot of gold in the chambers kick that area out and make more power.
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post #6 of 10 (permalink) Old Nov 1st, 19, 12:11 PM
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Re: Building a new 327

Use those trick flow heads for sure they are leagues better than the iron ones..no comment on the cam but its good youre not getting carried away. Love sft cams
Sounds like a fun combo to me that ought to have some decent torque for its size.

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post #7 of 10 (permalink) Old Yesterday, 8:21 PM Thread Starter
 
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Re: Building a new 327

Iím switching gears on my build and considering a smallish solid roller like the XR268R or XR274R

Opinions?
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post #8 of 10 (permalink) Old Yesterday, 9:03 PM
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Re: Building a new 327

Even better a SR really makes power!! Forget all about ported sbc camel humps.
Youll love it they run super hard. No risk of HR issues

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post #9 of 10 (permalink) Old Yesterday, 9:16 PM Thread Starter
 
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Re: Building a new 327

Well......the 461 hump heads are gone. I sold them this week and Iím all in on the Trick Flow DHC heads.
Block is at the machine shop. Full machine work and balance. Rotating assembly will be installed and the rest I will do.
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post #10 of 10 (permalink) Old Yesterday, 9:44 PM
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Re: Building a new 327

I love 327's. In the late 70's I had a 11 to 1 327 in a 68 Camaro with 4.88's that would run 12.70's all day long and scream to 6800 rpm. Was a fun ride, good luck with the build and yours should go good with the Trick Flow heads.
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