Author Topic: Any minor modifications that can have slight benefits to power?  (Read 1236 times)

CDB

  • Newbie
  • *
  • Posts: 7
    • View Profile
Any minor modifications that can have slight benefits to power?
« on: February 03, 2017, 09:13:29 PM »
I tried searching, but the keywords I was using just brought up irrelevant threads. If there's one, I'd appreciate a link.

I have a numbers matching 350. I'd obviously like to keep it that way. But are there any super minor modifications I can make to increase performance? I'm not looking for huge gains, just things that wouldn't really affect the history of the car. I'd keep any part I replaced for posterity.

I'm assuming my only real choice would be to buy a Z or 396 or take the engine out, put it on a stand, and replace it with something more powerful.

bcmiller

  • CRG Member
  • *****
  • Posts: 1786
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #1 on: February 03, 2017, 09:17:43 PM »
Cam, intake and carb change come to mind.

What year?

What transmission and rear axle ratio does it have?
Bryon / 1968 Camaro SS 396 - now 468 ci, M21, 12 bolt
Looking for 68 Camaro with body number NOR 181016

CDB

  • Newbie
  • *
  • Posts: 7
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #2 on: February 03, 2017, 09:24:32 PM »
1969, 4 speed M20 with 3.31 gears, 12 bolt

1968RSZ28

  • Hero Member
  • *****
  • Posts: 6164
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #3 on: February 03, 2017, 09:37:10 PM »
Headers! :)

Paul

Mike S

  • Hero Member
  • *****
  • Posts: 1912
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #4 on: February 03, 2017, 09:38:32 PM »
Cam, intake and carb change come to mind.

Yep....those were the days when men were men!
Today, just change a chip..... No more bruised knuckles or oily hands.  :-\ No fun in that!
 Oh, the youth today don't know what they are missing out on.

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Under restoration

KurtS

  • CRG Coordinator
  • *****
  • Posts: 4447
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #5 on: February 03, 2017, 11:06:46 PM »
IMO.
Focus on distributor timing first. Free power there......
Intake - some gains
Carb - not much if it's tuned right.
Exhaust - yup!
Kurt S
CRG

ko-lek-tor

  • Hero Member
  • *****
  • Posts: 1465
  • someday I'll get one finished
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #6 on: February 03, 2017, 11:30:42 PM »
This was my last attempt at a power mod ::)
James to strangers, Bentley to friends
1969 SS/RS 396 coupe Hugger Orange X22 712 bought in 79
1969 SS 350 coupe LeMans Blue 713 bought in 79
1969 307 4spd. coupe Daytona Yellow 711 bought in 85

bcmiller

  • CRG Member
  • *****
  • Posts: 1786
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #7 on: February 03, 2017, 11:54:23 PM »
Cam change is still your best bet if you don't want to change the look of things. An older non GM aluminum intake can be painted orange to have a stock-ish look.

I guess I assumed timing would have already been optimized with what you have. Carb may or may not help much - depending on what you do.

Headers and better exhaust, yes that would help too. Just depends if that is ok for the look you want.

Or you can go the route of putting the original engine on a stand - and building something else.
« Last Edit: February 04, 2017, 03:57:58 AM by bcmiller »
Bryon / 1968 Camaro SS 396 - now 468 ci, M21, 12 bolt
Looking for 68 Camaro with body number NOR 181016

KurtS

  • CRG Coordinator
  • *****
  • Posts: 4447
    • View Profile
Kurt S
CRG

jeff68

  • Member
  • ***
  • Posts: 423
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #9 on: February 04, 2017, 09:19:43 PM »
I guess I assumed timing would have already been optimized with what you have. Carb may or may not help much - depending on what you do.
If the original engine had (or has) a smog system, then there is a lot to be gained from re-mapping the timing (assuming the smog system has been removed or 'gutted' so it doesn't function).  The original timing on the smog equipped cars was really weird.

The other simple mods that will help and will not really change the car are:
- plug the "hot slot" exhaust crossover on the intake manifold and replace the heat riser with a 'blank' piece (or just remove the valve disc for a stock look)
- change to an electronic ignition like the Breakerless SE   http://www.breakerless.com/
- have the old Quadrajet rebuilt and set up for ethanol fuel (IMO, go right to Cliff Ruggles - he's the man for Q-Jets)

Now, I can't quote any horsepower numbers, but I did all of the above on my L30 327 and it was very noticeable.  I wouldn't call re-mapping the timing "super simple", as it took a lot of time & patience to get it just right.  Everything else was quite easy.  My car now drives beautifully, with instant throttle response and more power than I can ever remember.

For more info on setting up the timing, here is what I did:
http://www.camaros.org/forum/index.php?topic=10925.msg89071#msg89071
68 L30/M20 Convertible, Ash Gold
N10, F41, N34, Z21, ZJ9, Z87, D55, G80, P01, U17

TRLAND

  • Member
  • ***
  • Posts: 70
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #10 on: February 04, 2017, 10:51:52 PM »
I agree that timing and tuning are the easy and cheap things to do that can make a huge difference if they aren't right.  Most of it can be done with minimal tools and a clear understanding of what you're doing. If you're new to this as I was a few years back you can get up to speed by reading JohnZ's timing papers on this site (including the one Kurt posted above) or Lars Grimsrud's papers on timing and tuning.  I ended up sending out my carb and distributor for rebuild and setup to Lars because I wanted them done right by an expert. My old 327 performs way better than it ever has.

I also just replaced the timing chain and based on how loose it was, come springtime I'm expecting some improvements from that (not as simple) project. Might be something else you want to check before doing major mods.
Mike in Northern Illinois
1967 RS 327

X33RS

  • Hero Member
  • *****
  • Posts: 891
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #11 on: February 05, 2017, 12:00:28 AM »
Funny when I read that.  I've had discussions with Cliff about this and he is dead set on ported vacuum only.  He doesn't understand the benefits gained with manifold vacuum and how it works.   So the only way he knows how to deal with excessive vacuum advance is to just remove it from the manifold and stick it on a ported source from the carb.

Best way to deal with it and still reap the benefits of manifold vacuum advance is to install an adjustable vacuum can.  A small allen inside the port nipple can be turned to tighten the spring tension and make it less sensitive.
  If that's not enough I make a breaker plate stop out of a penny that screws down behind the vacuum canister rod and limits movement.

Takes a while to get this all dialed in, every car is different.  But once finished you'll find better gas mileage and throttle response, and a smoother idling engine (if you have an aggressive cam) and you'll find the engine will run cooler in slow traffic idle situations.

Only reason the factory stopped setting them up this way is because the vehicle produces more hydrocarbons with this method.  So ported vacuum was used simply for emissions reasons starting some time in the 60's.

L78 steve

  • Hero Member
  • *****
  • Posts: 780
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #12 on: February 05, 2017, 12:43:51 AM »
Ported vacuum is not really a performance killer because the moment you touch the throttle you will have signal to the advance can.
The disadvantage with ported is you need more throttle plate opening for idle which can cause run-on at shut down and a labored idle.
Best to go full Vac.
69 Z/28 Dover White. SOLD
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C. SOLD
70 Nova L78 Blk. Cherry,Sandalwood,M21,02B

X33RS

  • Hero Member
  • *****
  • Posts: 891
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #13 on: February 05, 2017, 02:05:38 AM »
I would categorize manifold vacuum as a drivability improvement.  With better off idle transition, more engine vacuum, smoother idle with large overlap camshafts, and I find cooler running conditions while idling in traffic, and generally picks up a slight amount of gas mileage.   Something else this does is it also allows a leaner idle AFR which cleans the plugs up a bit if idling around a lot and can also help to boost mpg a slight amount if doing a lot of slow stop and go idle type situations.

I hope I didn't come across earlier as this being a performance boost.   The link provided made me chuckle reminding me of a long forgotten conversation, so I shared my thoughts.

CDB

  • Newbie
  • *
  • Posts: 7
    • View Profile
Re: Any minor modifications that can have slight benefits to power?
« Reply #14 on: February 05, 2017, 02:33:16 AM »
Some good info here. Thanks all. Timings are definitely something I'm interested in as they won't affect the originality of the car. I'll have to read all this information and get a better understanding of it.