Thread: 327 mods?

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I'm sure this has been discussed at length and I should do a search before asking, but I'm lazy. I'm wanting to hop up my stock 327/275 (L30). I'd like to not spend thousands, I'm thinking more like hundreds up to 1000. Car is a 68 Malibu, M21 4 speed and a 4.11 12 bolt. Engine is box stock. I'm thinking carb/intake, headers, and cam. I'd like to stick with the stock heads (1.94/1.50 Camel Humps). I know there are better flowing heads available for little cost, etc. I'd like to keep it a period correct "day 2" type car (with modern intake/cam). Keeping the points distributor as I'll never rev it over 6 grand. This car will never see the track, just a cruiser with some attitude. Looking for cam and intake/carb suggestions.

I'd advise that the first line in your plan needs to be for a hydraulic roller lifter conversion if you keep the 327. IMO if you choose to stick with a flat tappet cam you're just throwing your money away, or at best gambling when it will fail. There's simply too much evidence out there to chance investing in new parts and then staying flat tappet.
A good article on budget builds using OEM parts here - Chevy Small Block - Car Craft Magazine

Don't overlook an HEI dizzy.

Even if you don't need the extra RPMs, stock coils run 12K volts, HEI are 30-70K.

with todays oils and fuel you have two areas that are problems----oil for flat tappets and UNleaded fuel killing the valve seats------your best bet for some pep under $1000 would be to do Edelbrock aluminum heads/manifold and maybe a ss shorty header set (under $100 on Ebay)--------if you don't have any cam/lifter related issues you can keep it as long as you keep lifters in same holes/lobe as they are now and use Brad Penn or Joe Gibbs race oil.

An option for folks like you that have one of these era cars that I suggest is to remove the present oem numbers matching engine and replace with an later factory roller lifter block(I'd use Dart SHP 4.180 bore, ), stroker crank, for 427 inches with roller lifters, alum heads( there are some super iron heads out there for spec class racing with hardened seats) ------------you'd be at 427 inches, 450-475 HP

As usual, very good advise from these folks, I too strongly suggest spending the money to go with a roller cam set up; with today's oils, it's extremely easy to destroy an engine because of a flat tappet camshaft wiping out a lobe. Myself personally will never do another flat tappet engine for that reason.

The engine isn't a #s unit, so preserving its originality really isn't a must. There's also a filling station close that sells 110 leaded race fuel. By my calculation, a 4:1 mix with oxy free 91 puts me at 94.8 octane. Not enough lead for the valve seats, but some is better than none. As the roller vs. flat tappet debate, I've heard the pros and cons from both sides. I do run Brad Penn oil, so I know about that part of it. I'm in the information gathering stage for this future endeavor, so nothing is happening to this engine at the moment as it runs like a Swiss watch. Just would like a little more power for the butt dyno and the smile factor.

Butt factor dyno and smile factor equals cubic inches----------that other stuff happens at high rpm----------

Originally Posted by 327275

The engine isn't a #s unit, so preserving its originality really isn't a must. There's also a filling station close that sells 110 leaded race fuel. By my calculation, a 4:1 mix with oxy free 91 puts me at 94.8 octane. Not enough lead for the valve seats, but some is better than none. As the roller vs. flat tappet debate, I've heard the pros and cons from both sides. I do run Brad Penn oil, so I know about that part of it. I'm in the information gathering stage for this future endeavor, so nothing is happening to this engine at the moment as it runs like a Swiss watch. Just would like a little more power for the butt dyno and the smile factor.

Using leaded fuel on the street is AGAINST THE LAW.

The most important part of camshaft timing is the intake closing point. You must coordinate that point with the static compression ratio of the motor in order to get the correct amount of mixture trapped in the cylinder to make the proper bang when the plug fires. Too much mixture trapped and you can have detonation. Too little mixture trapped and you have a pooch. So, it's a fool's errand to try to choose a cam without knowing the exact static compression ratio of the motor. If you'll pop a head off to see that the piston crown configuration and the piston deck height are, we could have a better chance of helping you to determine the correct camshaft profile by mathematically figuring the static compression ratio. As far as intake manifold, go on craigslist and try to find a Weiand 8016 Stealth or Holley 300-36 Street Dominator used. Go to local swap meets and find a 650 carburetor and rebuild it. That's all the carburetor that this motor will need.

You need to spend a little more money to get a good set of long tube headers. Buy units with at least a 3/8" flange thickness. Less thickness than that can curl up like a potato chip under the heat of operation and spit the gaskets out. You will always be fidding with them to prevent leaks.

.

Welcome to CHR!
I agree with most all of the above – especially the information about roller cams and the input from Tech, re; compression ratio and cam timing. Is this the original engine that came in this car? If so you may be sitting on a pretty sweet deal and not realize it. The reason I ask is that you also reference “L30” – which is the 275 HP 327 from 1968 and the prize is it had 10:1 compression ratio.

The rear end that would have come with the RPO L30 engine was RPO G94-15 which is a 3.31 radio (code DD). The highest numerical ratio available from GM for the 1968 Chevelle was 3:73 so in all likelihood the 4:11 is aftermarket.

The RPO M21 is the close Muncie with a 2.20 first gear versus RPO M20 with the 2.52 low gear.

You also said she runs like a watch – so… if it were mine, I’d not mess with the cam because the heads are truly a limiting factor here. I would do the following:
1. Holley Street Dominator – like this one on ebay for $75 - USED Holley Street Dominator intake Manifold 701R-28Z 300-28Z FREE SHIPPING
2. Remanufactured Quadrajet like this one from Summit: https://www.summitracing.com/parts/jet-35002/overview/ with a free breathing 3” air cleaner
3. HEI from Davis Unified Ignition – like this one: https://www.summitracing.com/parts/d...make/chevrolet
4. New 8mm wires and spark plugs – gapped at .050
5. Hooker Super Competition Headers like these - https://www.summitracing.com/parts/h...make/chevrolet with 40 series Flowmasters and 2-1/2 inch pipe all the way back to the rear bumpers (with nice chrome or stainless tips!)
6. Set timing at 12 degrees initial and 32 degrees all in.

I know it’s a bit over your budget, but it will bring a nice smile to your face when the Quadrajet secondaries come to life. If you drive this for six months or a year and find you want a bit more pizazz you can save your money for a big block.

Remember to have fun and be sure and let us know what you come up with. Pictures are good too..

Best,
Glenn

Originally Posted by glennsexton

Welcome to CHR!
I agree with most all of the above – especially the information about roller cams and the input from Tech, re; compression ratio and cam timing. Is this the original engine that came in this car? If so you may be sitting on a pretty sweet deal and not realize it. The reason I ask is that you also reference “L30” – which is the 275 HP 327 from 1968 and the prize is it had 10:1 compression ratio.

The rear end that would have come with the RPO L30 engine was RPO G94-15 which is a 3.31 radio (code DD). The highest numerical ratio available from GM for the 1968 Chevelle was 3:73 so in all likelihood the 4:11 is aftermarket.

The RPO M21 is the close Muncie with a 2.20 first gear versus RPO M20 with the 2.52 low gear.

You also said she runs like a watch – so… if it were mine, I’d not mess with the cam because the heads are truly a limiting factor here. I would do the following:
1. Holley Street Dominator – like this one on ebay for $75 - USED Holley Street Dominator intake Manifold 701R-28Z 300-28Z FREE SHIPPING
2. Remanufactured Quadrajet like this one from Summit: https://www.summitracing.com/parts/jet-35002/overview/ with a free breathing 3” air cleaner
3. HEI from Davis Unified Ignition – like this one: https://www.summitracing.com/parts/d...make/chevrolet
4. New 8mm wires and spark plugs – gapped at .050
5. Hooker Super Competition Headers like these - https://www.summitracing.com/parts/h...make/chevrolet with 40 series Flowmasters and 2-1/2 inch pipe all the way back to the rear bumpers (with nice chrome or stainless tips!)
6. Set timing at 12 degrees initial and 32 degrees all in.

I know it’s a bit over your budget, but it will bring a nice smile to your face when the Quadrajet secondaries come to life. If you drive this for six months or a year and find you want a bit more pizazz you can save your money for a big block.

Remember to have fun and be sure and let us know what you come up with. Pictures are good too..

Best,
Glenn

It is not the original engine to the car. I've run the #s and it came from an Impala. As far as the exhaust goes, I'm pricing headers and the cost it'll take to fit my current pipes to them. From the manifolds back the exhaust is brand new and exits in the stock location (no chrome or stainless tips for this guy). Part of the reason I'd like some more power is because the 4.11s have to go. Being that I live in the middle of nowhere, getting to a cruise or show involves highway driving. 4.11s with a 26" tall tire at 65mph is no fun at all. It's cheaper for me to buy a new posi carrier and new ring and pinion than to buy a LGT 700 5 speed transmission. I was thinking 3.55, 3.42, or 3.31. It'll kill the acceleration but it'll give me a tolerable cruise rpm.

Just so you know, you're going the wrong way by using a tamer rear gear and a wilder cam. Once you change to a rump-rump cam, you're going to need that gear that's in it now.

It’s difficult to build a seat-of-the-pants launch in a 3,500 pound car with a small block without using the tall gears.

Highway speeds are certainly different than typical cruising. With the 26” tires you’re turning 3,452 RPM at 65 with the Muncie 4 speed. A TKO 5 speed with a .68 5th gear would drop your RPM to 2,348 – that’s huge (over 30%) and would make things a lot nicer in the car at freeway speeds. The 5 speed swap (done correctly) could set you back $2,500-$3,000, depending on how much you’re comfortable doing yourself.

All this is good discussion but it sounds (to me) that if you want to have a cruiser with a lot of stoplight snap that sounds wicked and yet still can do the freeway you need to look at dropping big bucks on a 5 speed or installing a big block if you want to get the rear end down in the mid-3.xx range.

More than $1,000 needs to be on the table with whatever you do