Head suggestions (runner volume & valve sizes) for 327.

I finally decided on a 327 for my 66 Vette. But I need some info on heads.

-I plan on using a cam more radical than the L79 cam (222 int & exh @ .050 and 447-ish lift). Not sure how radical, but I'll be getting suggestions from cam manufacturers to help me choose.
-I plan on running between 10 and 10.5 to 1 compression.
-I plan on running the stock L79 Dual plane intake & early Corvette 2 1/2" ram horns exhaust manifolds.

The heads I'm leaning towards have 1.94 int & 1.6 or 1.5 exh valves and an intake runner volume of 170-180cc. Would these be big enough?

Saying that, is it really necessary to have 200cc intake volume and 2.02 valves on a 327? Is it possible to do more harm than good with big head numbers the same way it is to "over-cam" or over-carb"?

where are you going to drive the car and how nasty do you want it???
I built the 327 in my car im running a set of 81 smoger heads
76cc 194 150 valves
cam is ex284 240 246 512 514
9.6/1 compression
long tube heddars
my car runs 12.9 1/4 times but next to no vacume at an idle
but the manifolds are going to impeed everything

You can "over head" an engine just like over camming and over carbing. You're on the right track with the 170cc intake runners. Some SR torquers would work very well on there. The key is to have the highest velocity ports able to supply a given engine displacement at the desired rpm level. You have many choices available in the aftermarket head department. Anything up to 185cc will make some serious hp out of the 327

where are you going to drive the car and how nasty do you want it???
....................the manifolds are going to impeed everything


The car is going to be a "driver" with an occasional trip down the 1/4 track.

As far as how nasty, about as nasty as I can get it without affecting driveability too much. I should have said earlier that it has a 3.36 rear, is a manual (Muncie 4 Speed), and if you're not familiar with Corvettes, it's a relatively light car weighing in @ 3,050lbs. I think I should be able to get away with a fair amount of cam, but like I said, I don't plan on just throwing a big ass cam in, but actually checking with a few different manufacturers for their recommendations.

I know I'll be at a disadvantage without headers, but for the most part I want to keep the stock look under the hood.

Even though the 327/350hp 66 Vettes had a 2 1/2" exhaust, the rams horns manifold outlets were only 2". The exhaust pipes had 2" pipes that widened to 2 1/2" before the pipes made the turn to the back. :rolleyes: ...........what kind of sense does that make?

The earlier small block Corvettes with the 2 1/2' exhaust had "true" 2 1/2 manifolds but they ended this in '64 or '65. By using the earlier "true" 2 1/2", I'll be a bit better off than the 2" rams horns and a HELLUVALOT better than the crappy stock "log" manifolds usually on small blocks.

The old style rams horn exhaust flow very good. They are the next best thing to headers. You won't notice a measureable difference between them and headers with a semi mild combo such as yours.

I would say 180-190cc or so. A used set of iron bowtie heads would be a good choice or vortec heads as well. The vortec heads will flow slightly better than the bowties but will require a new manifold and might not have the right look for your vette. 2.02 1.60 is a proven combination. I mean the factory did it on their 4" bore performance engines. Its not going to cost you low end on a 327 to go to a 2.02 head.

I tryed to talk comp cams and crane as well as edekbrock about cams
all they could tell me is that what i was trying to build would not work?????
like i said before the car runs high 12s to low 13s on 8 year old street tires
makes me wonder why I phoned any of them??????

-I plan on using a cam more radical than the L79 cam (222 int & exh @ .050 and 447-ish lift).
-I plan on running between 10 and 10.5 to 1 compression.
-I plan on running the stock L79 Dual plane intake & early Corvette 2 1/2" ram horns exhaust manifolds.

The heads I'm leaning towards have 1.94 int & 1.6 or 1.5 exh valves and an intake runner volume of 170-180cc. Would these be big enough?

Saying that, is it really necessary to have 200cc intake volume and 2.02 valves on a 327? Is it possible to do more harm than good with big head numbers the same way it is to "over-cam" or over-carb"?


You know, that soundls like a pretty good combo with the smaller heads. I personally might want a bit more lift... maybe up around 460. Just a gut feeling.

I do wonder if you have the M-21 or M-22 though. Do you know? If it helps, the 22 is the loud one.

If it was MY car, I'd go for those 2.02 heads, put in a slightly bigger cam, use shorty headers (The Ramshorns are worth too much anyway. ) and talk myself into side pipes. Performer RPM too.

You've got an early vette with a stick shift. Live a little.

I would lean towards a set of Dart Iron eagles maybe the 180 cc runners. They flow pretty good and have a modern combustion chamber design.The SR Torquer heads are just copys of old dbl hump fuelie style heads which were great 35 years ago. the SR stands for stock replacement btw. Im not sure of the avalability yet but RHS (Comp) bought the old pro topline co that had some killer sbc heads. you could also go aluminum pro1's or whatever and paint them. 50 pounds lighter and they look the same.

DJ

I considered the Vortecs due to their relative cheap cost and they seem to work pretty well. Only problem is, I would have to get adapters to use my "Corvette" script valve covers and I couldn't run my stock intake. (Aren't Corvette guys a pain in the A$$?? ;) ).

I've also considered the Iron Eagles, but I want to run 10:1 to 10.5:1compression on premium pump gas, and am afraid I'll have detonation problems if I use iron heads.

I have a Muncie M20. The M21 and M22 (on a 66 Vette at least) were "close ratio". One (21 or 22) was "heavy duty" and the other was not.

The specs I posted are for the L79 cam, so yeah, something around the 460 lift (or maybe even a little more?) might be what I'm looking for. I filled out a Comp Cams help sheet with all my numbers and will be curious to see what they suggest for a cam.

I didnt suggest the Vortecs because most of you vette guys wouldnt want to change to a vortec style intake but you would like them if you tried them. I ran my old 406 with vortecs at 11.3 to 1 compression on 94 sunoco for several years with no trouble. Im not so sure that aluminum heads really allow you to run more compression. I think it has more to do with them having a better designed combustion chamber.` The Iron Eagles have the same heart shaped chamber as the Pro1 heads. there are precautions you can use during the build up to make it less detonation prone. like stay away from pop up pistons, smooth all sharp edges, have an excellent cooling system, cam selection ect. I think they might offer the IE's with a smaller chamber now which is a better way to gain compression than bumps on the pistons :-)

theres a ton of good stuff out there for the sbc motors.

Doug