Discussion Forum - Northstar Chevelle Club

67ss · 1K+ Club

302 or 327 ???

Bowtieman427 · Active Member

Do you have the block already ? If yes what year ? Do you plan Flat tappet cam or soid roller? what heads ? You want to run on pump gas ? How much money do you have ?

400HP may be a little be optimistic if you trying to keep original is doable, but running a flat tappet cam will be a real challenge.
302 would be 1.32 HP/Ci
327 would be 1.22 HP/Ci

I think I would go 327 easier to reach 400HP goal. It will be no cake walk and will be $$$ to be different.
I know you will hate me saying this 383 make look like 327. I will not tell anyone if you do not : )

Lost in the 60s · President

67ss wrote:
So I am trying to decide which engine to build for the chevelle. Yes I know bigger is better but I want something different. So I am thinking either an aluminum headed 302 or an iron headed fake L79 327 350 horse. Either motor will most likley be in the 400 horse range. Yes I know I will have to spin the 302 higher to get that horsepower but the car is a 4 speed so no big deal.
Guess I am asking more of what everyone would think is cooler to open the hood and see.

What would distinguish one from the other
Obviously aluminum heads are going to stand out but the rest all looks the same.
My vote would be the L79...

Dave Seitz · Mega Poster

377 badged up as a 327 would be the least noticed your hiding power. Grind the names off a Performer have a Oil fill cut into the manifold and go for a sleeper look. Dressed up as a stock 327 or even a 283 your golden, the 50 more cubes will help hide any cam that would make a 327 or 283 sound snotty. Just what you need along with a 5 spd trans from an Fbody nobody but the skilled will notice. You could even hide a fuel injection system under a stock appearing air cleaner. With a conversion on the stock distributor to hei system it will run like a dream.

-- Edited by Dave Seitz on Monday 7th of November 2011 06:10:38 PM

Bowtieman427 · Active Member

The one way I am assuming the iron headed will be "double hump" heads to pass off the L79 327 350 people always look for that. If he is going stock look with "double humps" it will cost some to make them flow enough to get to 400HP. If he went Vortec it may be easier and aftermarket better yet. But the no "double humps" would be a dead give away. Also running ram horns will be hard to get it there also. headers, Vortec heads with work (or aftermarket iron), roller cam (or super solid flat tappet), and headers would be an easier route.
The 302 would hard to do but if he went aftermarket it could be done will not be cheap and the bottom end will have to have the best stuff too.

If we had good gas today it would not be that hard as he can bump CR up and get free HP. I am assuming he wants it to run on pump gas on the street so the CR will have to be down a little.

I have a good friend that has an original '65 Vette L76 365HP he has to detune it to drive it today but it is radical. He drives it like he stole it.

http://www.superchevy.com/features/chevellemontecarlo/sucs_0732_chevy_l79_engine/viewall.html

Tony Hoffer · Moderator

Go with as many cubes as the sanctioning body permits... a 302 would be cool in a Vega or Monza.. but given your choices Id go with the 327 in a Chevelle... If I had to do it again for a street engine Id go this route and disguise it .. http://www.hotrod.com/techarticles/engine/113_0312_dart_450ci_small_block_engine_build/viewall.html

67ss · 1K+ Club

I have at my disposal a set of aluminum GM fast burn heads or some 461 double hump heads that are 2.02/1.60 with mild porting. Either set of heads should support 400 horse. I was going to go roller cam with what I have for the 302. The 327 would be flat tappet most likely. I will be running headers not manifolds.

I know I can make any small block look like I want but I really want to keep it small displacment. I have always thought 302's were cool but I know they really don't make for a good street motor.

Here is was my initial build that I starter collecting parts for: 4bolt main block, the fastburn aluminum heads, solid roller cam, and was thinking the new offenhauser cross ram intake. All not really good things for a street motor.

This is when reality kicked in and I thought I should build a milder 327 thats 350-400 horse that would be more easily street driven and make the car look like an L79 built car.

Lost in the 60s · President

OK, I was thinking the 302 would be single carbed. I didn't know you were looking at '69 style dual quads on a crossram. Yeah, that would look killer under the hood but I think you would be happier in the long run and drive it more if it were more street friendly. I would still consider a hydraulic roller cam, just for the lack of oil concern. There is a guy in the Camaro Club with aluminum heads that he had powder coated Orange and to look at the engine, you would never know they aren't stock heads. You could even get a repro dual snorkel air cleaner and really have the L79 look...

bowtie · Secretary

Since you beat me to Cross Ram, I vote for 302 on an Edelbrock C-26 manifold with dual TBI units on Vortec heads that are painted orange with some slight work to the casting triangles. Round the tips over and call them "triple humps".

Bowtieman427 · Active Member

what 4 bolt block do you have ? I am assuming it is an original 4 bolt 302 or 2.45" main SBC 350 not aware of 327 in 4 bolt varity ? If you have an original 302 I would be scared to run it.
Fast burns yes 461 maybe
what were your flow numbers on the 461s after porting ?
2.3" or 2.45" mains I am assuming 2.45" SBC 350 with 4 bolt mains block if you going 327 you will need a 327 large journal crank ?

what cam(s) do you have you mentioned a solid roller and flat tappet ?

with the L79 look a like you plan to run stock intake ?

I was going to do my 327 over but cost is pretty high to do the heads and what performance you get out of them Hmm not ready for that right now : )
Vortecs probably flow better.

So I switch gears and thinking and keep malling over what to do on it. Probably keep original. Still on fence building a Vortec block to look like 327 but that damn Fuel pump thing and Vortec heads. I wish had some Fast burn heads it would make that decision easier. So I have some parts and time.

This sounds fun and interesting build

Derek69SS · Founding Member

More bigger.

Dave Seitz · Mega Poster

Chris I really don't care if you go with a 302 or a 327 I would say this either engine built to 400HP is really going to $uck on the street. It WILL COST MORE to hit that magic # on either of those 2 compared to 350 377 383 406 and above displacements. Hitting that #and more on pump gas can be done with turbos or blowers just getting more expensive. The idle quality on a high HP small displacement get a tick funny so does fuel consumption. You do live a bit outside the metro area so that might be something to consider as well. Neither of the smaller displacement engines have loads of TQ and really like rear gears so without an OD unit long trips get cut short for fuel stops.

jim larson · 2K+ Club

If you are going to keep it stock looking, interior, etc. I would like to see a L79. Wasn't this engine the same as the 365 HP corvette engine in 65? You can always get it to run on avaiation gas or something like Octane Supreme 130. Are you really concerned about milage?

Chris R · 2K+ Club

327 engine fit that era back then so thats what I would go with.

Lost in the 60s · President

I don't think 400hp out of a 327 is unrealistic on pump gas. Look at the numbers people seem to be getting from engines with modern technology today. Cam profiles and especially the ramps have taken huge gains in lift and duration without the poor idle and low end characteristics of years past. I do encourage a full roller set-up to utilize a fast ramp. I agree it will be more difficult with vintage heads. Aluminum heads produce higher gains and help suppress detonation, so disguising them as stock at first glance may be in order. Then there is always the stealthy NOS plate as a "power adder" too.

Bowtieman427 · Active Member

Jim, I think you are right they are the same accept for the cam. A good friend of mine has a 65 Vette with the 365HP and drives it around he has to detuned it and mixes gas to run it. He bought it new in 65 and has redone it a couple times. His is a keep it "all original fanatic" it is super cool sounding. He has a lot of mile on it too. Radical SBC
There is a write up on L79 and variants in the artical I posted (got to copy and paste)
Today anything is doable = TIME & MONEY. The harder a SBC has to turn to make power the more it will cost in better parts. Keeping it all original looking at the same time using 40+ yr old stuff is a little harder. A little more money.

jim larson wrote:
If you are going to keep it stock looking, interior, etc. I would like to see a L79. Wasn't this engine the same as the 365 HP corvette engine in 65? You can always get it to run on avaiation gas or something like Octane Supreme 130. Are you really concerned about milage?

67ss · 1K+ Club

The flow numbers on the 461's were 220 on the intake and 150 I think on the exhaust. It was pretty comparable to a vortec head. They were on my buddies 383 in a nova running 11.80's till he blew it up.

I know this is not going to be cheap. I have both a 4 bolt old block and 4 bolt one piece block that is roller capable. I found a forged 327 crank on ebay for a resonable price that I might get. I think my thoughts are to use the aluminum heads and have the face done to look like a double hump. Runner the later roller block with a hydraulic roller cam, the newer lifters are capable of 7000 rpm now without to much trouble. I should be able to run 10:1 compression on pump gas with no problems and with the roller cam it should make the 400 mark I think with out to much trouble.

Bowtieman you can bolt those vortec heads to any vintage SBC so you can have a mechanical fuel pump. If you use an 88-95 block you can swap all the internals from your vortec motor to that block and again have a mechanical fuel pump.

Lost in the 60s · President

67ss wrote:
I think my thoughts are to use the aluminum heads and have the face done to look like a double hump. Run the later roller block with a hydraulic roller cam, run 10:1 compression on pump gas.

Sounds like a PLAN.....when do we get started ???

bowtie · Secretary

You can also punch and tap the fuel pump area on a later block (like a vortec era one) to use a mechanical fuel pump.

67ss · 1K+ Club

Here is some good reading comparing old motors 302,327,and 350. They made 350 horse with old technology. Can't be hard to make 50 more horse with newer stuff.

http://superchevy.automotive.com/116127/sucp-0909-chevy-small-block-testing/index.html

67ss · 1K+ Club

Lost in the 60s wrote:
Sounds like a PLAN.....when do we get started ???

First step is to try and get the crankshaft I need. Will have to watch the one on ebay.

Bowtieman427 · Active Member

bowtie wrote:
You can also punch and tap the fuel pump area on a later block (like a vortec era one) to use a mechanical fuel pump.

I do not want to steal this post. Is the punch out expensive to do ?

Also do the 88-95 blocks have provisions for OEM roller ?

Not up on the newer stuff : ) I am more of a BBC guy never really did to much with SBC. willing to learn.

67ss · 1K+ Club

Yep most 88-95 blocks have the provisions for roller cams. The block I am going to use for the 327 build is of that vintage.

To use your vortec block you would have to go to a good machine shop to have them bore the hole through the block for the fuel pump rod. It can be done but I don't know what they would charge.

Chris R · 2K+ Club

67ss wrote:
Here is some good reading comparing old motors 302,327,and 350. They made 350 horse with old technology. Can't be hard to make 50 more horse with newer stuff.

I was just going to say the same thing. Ill bet you can get a good chunk of HP on top of that with the heads you plan to use already.

Bowtieman427 · Active Member

67ss sent a PM.
So you looking for large journal forged crank. Is there a way to make that 2PC work in 1PC block that is cost effective. If there is & not to bad on build cost then total cost should not be that bad. It sure will be eaier to reach your goal.

50HP even with todays great stuff in 327 is a lot in original form would be hard to do. Now we are talking with the Hyd roller cam mods to the heads and running headers it will sure help get there. (imagine if he was building a big SBC 383 we would be talking 470HP and torque)

What cam were you thinking ? Once you figure you DCR and heads you want to use and see what is out there for pistons. You may find you can run 10-10.5 with the iron and 11-11.5 AL depending on cam etc. If you iron flow just as good as fast burns then you may want to go with iron keep it original looking even to the educated observer.
All being = iron and AL perform the same. It is disipation of heat that is the issue that leads to detonation. Running tight quench it will help and keeping it cool will help. Keep the chambers hot not the cylinder walls.

-- Edited by Bowtieman427 on Tuesday 8th of November 2011 01:37:55 PM

67ss · 1K+ Club

Yes there is an adapter to use a 2 piece crank in a 1 piece block. So if I can find a forged large journal crank it will drop right in. I could use a small journal also but I would rather stay away from using crank bearing spacers.

The iron heads I have don't flow as well as the aluminum fast burns. The fast burns are better then vortecs though.

bowtie · Secretary

here's the adapter form GM: 10051118

http://store.gmperformanceparts.com/store/SelectProd.do?prodId=7900&redir=true&manufacturer=GM&name=Rear%20Crankshaft%20Seal%20Adapter&model=

not cheap, but doable. Maybe Northern in IA has a crank that would work? Otherwise Chris Straub (Straub Technologies) might have a vendor he can get one from.

Dave Seitz · Mega Poster

I do have a steel 350 crank if you need one, also remember some of the ratings back in the day were not all that acurate.

67ss · 1K+ Club

So I was talking to the machine shop last night about what I want to do. It so happens he has a 327 that he has been playing with for awhile. The last version of it had vortec heads with a solid flat tappet cam. It made 412 horse at 6200 rpm and 400 ft lb at 4000 rpm. He has since put a set of ported 292 turbo cast iron heads on it but has yet to dyno it again. The cam has 239/249 duration with 517/543 lift, that will run on the street just fine.

Lost in the 60s · President

67ss wrote:
So I was talking to the machine shop last night about what I want to do. It so happens he has a 327 that he has been playing with for awhile. The last version of it had vortec heads with a solid flat tappet cam. It made 412 horse at 6200 rpm and 400 ft lb at 4000 rpm. He has since put a set of ported 292 turbo cast iron heads on it but has yet to dyno it again. The cam has 239/249 duration with 517/543 lift, that will run on the street just fine.
Perfect !! get the block over there and have him build it. You should be able to find a similar cam in hyd roller. He must have connections for a forged crank at a competative price too.
400 lb ft torque at 4k is awesome...

Bowtieman427 · Active Member

That cam is close to waht I was going to put in a BBC. 239/249 with the lash would be like a 230/240 ballpark cam in HYD roller, but the total duration may be longer depending on lift. That is a pretty healthy cam for a 327. I like it. I would be interested to know what the rest of the cam numbers are. Is his cam a wide LSA 110-112 or something ? Are those his peak #
torque at 400ftlb@ 4000RPM then peak HP 412HP@6200RPM that is a 2200RPM spread which is pretty wide band which is awsome. usually HP peaks 1000-1500 after torque. Sure 400ftlb is at 4000RPM and not 5000RPM ?

Scott Parkhurst · Super Poster

Don't ask me because I will recommend you get an internally-balanced 400 crank to make a 383. The Fast Burn heads are a good match on a street deal and will make solid power with the right solid roller. The cross ram will also be more effective, since it'll have more vacuum down low and more stroke means more torque too. It would outperform the 302 or 327 everywhere- down low, midrange, and top end.

So, don't ask me because that's what I'd tell you, and you probably don't want to hear that.

67ss · 1K+ Club

I bought the forged crank on ebay last night, time to make some horsepower.

Lost in the 60s · President

67ss wrote:
I bought the forged crank on ebay last night, time to make some horsepower.

bowtie · Secretary

1.5hp per cube is standard now......... you already have a blower car, so now you need a snotty n/a car. Imagine if you had that Monza from high school again!

67ss · 1K+ Club

Crankshaft done, now to save up to get things rolling on the rest of it.