87 Octane Pump Gas 350 Cruiser

Discussion in 'Small Block Tech' started by YoDesigner, Oct 18, 2017.

  1. YoDesigner

    YoDesigner 69 Skylark

    To me it seems most members on here encourage 10+ compression to get the most power out of their motor which is fine, but I don't want to buy high-octane fuel or mixes and I am not concerned about getting higher horse power. I want to continue using the cheap fuel for my cruiser on my future build. So what is the ideal compression ratio to run on 87 octane? I intend to put the TA212 cam in my motor (from what I have read here seems to be a good all around cam regardless of compression and sounds good). What should the cam be degreed at for this combination? Other info: TA Stg 1 intake, Rochester carb, No headers (using exhaust manifolds), TA down pipes. No port or polish on 73 heads, dual exhaust, 200r4 trans, 4.10 rear-end, TA HEI distributer.
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

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  3. alec296

    alec296 i need another buick

    Personally,even with overdrive trans, 4.10s are too much. With the 212 cam your better off with headers. You need the higher rpm range with 4.10 gears. With that 212 cam you could run 8.2-8.7 static compression depending on tuning. Of course it would run better on 89-93 as do most engines. You will want to recurve the hei . I would get piston closer to zero deck and ported heads with big valves. Again, with 4.10s you need more upper rpm power. You need to address the oiling upgrades as you will be spinning engine in the upper rpm range very regularly.and same reason, setting the cam at zero or retarded 4 degrees would probably be considered.
    Consider a custom cam from Scott Brown and heads flowing atleast 255cfm.
    If your 69 is a factory 4 barrel car, you have about 9.25 compression already.
     
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  4. MrSony

    MrSony Well-Known Member

    I had a comp 268 cam in my '76 engine. Sure there was a little power left on the table, but it set at Zero let a lot of pressure build in the cylinders and it sounded freaking great. It was just .030 over, three angle VJ on the heads, TA HEI, and Accel 8mm Spiral Wound Wires with R45tsx plugs gapped at .050, TA stock replacement balancer. The one in the pic was my old one I used to set the rope seal before the TA one shipped. Other than that it was mostly stock. Stock manifolds, intake, stock (rebuilt) 17058241 800cfm qjet. LOVED 87. The KB/Silvolite pistons I had had a shorter comp. height so actual SCR was about 7.8:1 lol It had tons of torque though, butt dyno and 1/4 times suggest 260ish hp. Not bad for a DD. Was a great peppy motor, would've been a LOT better with something other than 2.41s my Regal had. That poor 195.
     

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  5. 8ad-f85

    8ad-f85 Well-Known Member

    Gears do reduce the load on the engine, giving much needed margin for octane tolerance.
    Rpm and acceleration rates do help against load induced detonation, so do higher cruise rpms when the throttle is opened.
    Don't be afraid to rpm them some at cruise, it doesn't hurt any.
     
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  6. Golden Oldie 65

    Golden Oldie 65 Well-Known Member

    I've had a 200-4R and 4.10 gears in mine for years and I couldn't be happier with the combo. I usually don't shift it into OD until around 50-55mph but I've got 270/60 tires which are about 28" tall. At 70mph I'm right around 2,500rpm. Couple that 4.10 with the 2.74 1st gear and you've got a 1st gear that is absolutely unbelievable. I personally don't think there could be any more inexpensive amount of work that could be done to a stock engine that would equal this type of performance increase.
     
  7. 8ad-f85

    8ad-f85 Well-Known Member

    I would bet the cost of good head work including flow bench based port work would come in less than an OD swap, and I would without a doubt put that up against a stock headed but OD combo any time.
     
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  8. Golden Oldie 65

    Golden Oldie 65 Well-Known Member

    I guess the obvious question would be, is there anyone who is willing to spend the money on some good port work and swap them onto their otherwise stock 350 and go make a few passes at the dragstrip, then remove them, reinstall the stock heads and install a 200-4R and some 4.10 gears and head back to the track for some comparison results. Just curious, but how much would some good port work cost on a pair of 350 heads?
     
  9. alec296

    alec296 i need another buick

    Sort of. I have 3.90 gears to go in my 65 special.I have a 2004r supposedly out of a grand national. I have a set of home ported 71 heads. A 71 short block. A 71 350 transmission.
    If someone wants to help with a major port job, freshen up shortblock or 2004r. Or tuning? We could try this. Just use some shorter tires to simulate the 4.10s on the 3.90 gear. It's close enough to compare.
     
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  10. Fox's Den

    Fox's Den 355Xrs

    I ran the 268 Comp Cam on a totally stock engine a 71 engine with 8.5 comp I would guess. Had those stock 260 gears or so and it ran good. A 410 gear with the 2004 trans would have kicked butt. I would do the 212 cam and when you are ready to upgrade do so. You don't need all the other engine work to make the cam work, but will wake the engine up a lot more if you do.

    I ran the regular gas too no problem. Do Larry's timing tune and you will be ok. Go check out what Larry said on the DCR stuff and then you can maybe make a decision on your cam choice. The 212 will work fine, it is the go to cam for most over stock builds.

    I wish I had all this info in 1983 when I put the 268 cam in. It worked just fine though and I kicked a lot of butt on the street too.

    What you should do though is the little mod for the oil pump to freshen it up. Then later on you can do the major oil mod where the oil holes are drilled bigger.

    You should also at least put in a new front cam bearing when installing the cam.

    The engine is so strong that I drove 40 miles with the engine knocking back in 93 and what had happened was the crank was cracked in half.
     
    Last edited: Oct 19, 2017
  11. 8ad-f85

    8ad-f85 Well-Known Member

    My comment was fairly rhetorical.
    The OP already has the 4.10 gears and OD.
    I'm stating that if you don't have the OD and 2.74 then put the money into the heads first, it would only improve when the better gears and OD were added later ... if you don't have one.
    It's inferred that the 2.74 1st gear was the main improvement being described, yes?
    That makes it a question of the heads being less than the cost of an OD swap.
    The 8% difference in 1st gears should easily be overcome with good head work and cam (which both are being left vague intentionally).
    The top end guy can make the engine do whatever he wants, so there's an advantage there.
    The other aspect is that there are builds here already that have astounding performance and various levels of head work that run on pump gas...the OP is talking about a cam swap on a good condition engine.

    As far as describing a comparo, is that Granny Smith apple better than a Valencia orange?
    "Good port work" is incredibly vague. Most can hit hit whatever goals are presented... reasonable or not, therefore the question always refers back to what the owner is willing to plan and afford.
    The OP might not choose that cam knowing this.
     
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  12. 8ad-f85

    8ad-f85 Well-Known Member

    Sorry, generally speaking...if a person is paying for fairly spendy head work, it's usually for the purpose of a huge increase.
    It's usually considered wise to benefit from the induction person's abilities to put together good working packages, including considerations for cam and how it works with the rest of the package.
    It's both incredibly unfair to compare a bolt on trans swap to a +80hp or more head/cam swap, and at the same time assume the engine is in good enough condition for running full throttle for either method. It's probably not going to last either way.
    Not really comparable.
     
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Gears are multipliers of torque, so 4.10's coupled with a 2.74 1st gear will accelerate the car faster, but the trap speed would likely be the same or very close, despite the drop in E.T. I would expect that the better head flow would improve HP and TQ, and result in more of a gain than the gears. I think the gears would be much more of an asset on the street, than on the track, assuming you could hook the car on the street. Those are my thoughts, I might be wrong.:)
     
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  14. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    It would be simple enough to math out for a comparison. Bridges are built and rockets sent into space using this method. No need for a 'side by side' comparison in some instances, when you can do amazing things with mathematics.

    Gearing is simply torque multiplication. Use this as your basis for comparison.
     
  15. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    It would be much simpler and cost effective to do a trans and gear swap vs other major and highly involved engine work to make this comparison. Your engine will still run the same and have the same behavior and thus more predictable, reliable, and a myriad of other factors (or issues) that could arise from increasing power to make up for lack of gearing (when considering this comparison).

    Engines with less than big block torque will always respond best with better gearing (transmission as well as rear end), since there is less torque to work with, it needs to have as much multiplication as it can get and will make the most of the horsepower you have.

    There's just so many potential paths that making statements such as these are highly anecdotal; however, generally speaking would be accurate enough.

    That said, a low comp, regular gas burning cruiser would benefit more from a trans and rear end gearing change due to the limitations imposed on the engine itself to remain able to use 87 octane safely without too much work involved. The better gearing would also aid in detonation resistance (low RPM load induced detonation).

    There's a reason why GM decided to ditch transmissions such as the 2 speed ST300 and Powerglide in favor for more gears (TH350, and then later on the 200-4r) when compression ratios dropped and emissions were clogging up any chance at making power. The only way to go was either increase displacement (too much fuel used), or improve gearing.
     
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  16. Gary Farmer

    Gary Farmer "The Paradigm Shifter"


    Sorry I got caught up in the other responses so much that I failed to read your actual question...(!) lol.

    These threads can sometimes get derailed pretty quick.

    Well, detonation can arise from a great many reasons, but 'in general', here's some advice based on my limited and humble knowledge/research:

    A dynamic compression ratio ranging from 6:1-6.5:1 should be a safe margin for a street cruiser using 87 octane pump gas at sea level, and this assumes a 210* ambient temperature.

    This is for the Buick 350 and its smaller, albeit open, combustion chamber.

    Higher elevations and lower temperatures will allow a higher DCR to be used, among other things.

    You should be safe with about 8.5:1 static compression ratio and a 71* IVC point (I.E., the FM cs647) cam with little overlap and scavenging, with a 180* or 195* thermostat and good cooling system.

    Installing the TA 212 cam 'straight up' with no advance or retard will set this cam's IVC @70*, so it's similar to the above.

    Hope this helps.
     
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  17. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    Some quick math for ya: take 4.10 (rear end gearing) and multiply it by .67 (the .67:1 overdrive ratio for the 200-4r trans) to get 2.747. This is your final drive ratio, which is very close to the standard GM 2.73:1 rear end with a 1:1 final drive ratio, such as a TH350 or whatever.

    That final drive ratio is great for highway and even interstate cruising, while giving you an amazing 1st and 2nd gear for some spirited driving, making the most of the power you already have.

    Any reduction in parasitic loss will improve things as well, such as using electric fans instead of a mechanical fan setup.
     
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  18. alec296

    alec296 i need another buick

    You will want the driveshaft balance checked. It will be spinning about 3 times what it used to.
    Safety loop would not be a bad idea.
     
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  19. 8ad-f85

    8ad-f85 Well-Known Member

    Gary, not sure if you caught that he already has the gears w/ OD and is doing a cam swap.
    It wouldn't be overly complicated or unpredictable any more so than the cam swap would be (as far as how it ran).
    I definitely support the use of torque multiplying gears along with the fact that it's a bolt on.
     
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  20. Fox's Den

    Fox's Den 355Xrs

    and if you use a lockup convertor like I use with the 2004 that is another 200 rpm drop.
     
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