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Members thoughts on mild 186s engine build

Started by _186sHK_ , Feb 27 2017 07:08 PM

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#26 _186sHK_

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Posted 06 March 2017 - 07:03 PM

Thanks for all the reply's, Here are some flow figures I have been able to compile, the first three sets of figures are from a cylinder head shop that posted them online,(I have adjusted the figures from 25" water as tested to 28" for the sake of comparison) The last two are my standard head test and the modified head test. My throat diameter (smallest diameter below the seat leading to the bowl) is probably a lot smaller than most using 1.68 inch valves at 1.42 inches but this, combined with the seat geometry is what makes it flow so well at low lifts. This will however start choking the port and limiting the outright flow above about 550 lift. The seat geometry is close to the picture below, I tried a lot of other profiles but this seemed to work best.

Clearly despite all of the pissing around the motor hasn't really gone that well, but I don't think there is a problem with the head, as TK383 has said it might just need a little more duration and tighter lobe centers to wake it up.

I am more than aware that there would be a lot of other combos making better power with less cam and less flowing heads (the HQ race engines are a good example) but without knowing the exact specs of the entire engine its hard to compare.

What hp figure could you gain from a decent balanced bottom end with tight clearances, low tension rings, thinner oil etc etc. 10-20-30hp?

Extractors over cast manifolds?

Delete the engine driven fan?

Setup a cold air box?

Insulate the carb from manifold heat?

If I can get to 150-160 with just a cam swap I would be pretty happy, and that's most likely what I will be doing.

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#27 gtrboyy

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Posted 06 March 2017 - 08:02 PM

What makes you think it doesn't go well when clear objective was to modify yet keep factory look?

Personally think you've done well with big heavy car...sure can make more power but that's simple trial & error.

Don't forget when quoted figures on these it was usually inflated figures no fan etc

186s casties if they're same as xu1 then they'll flow decent enough,TK cam suggestions be well worth a shot.

Edited by gtrboyy, 06 March 2017 - 08:03 PM.

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#28 _imj411_

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Posted 06 March 2017 - 09:53 PM

The fastest 2 barel stromberg car I have seen is a 15.6 quater. In a much lighter LJ with a 202. I think this GTS goes really well for what looks like a stocker. It's probably making 170 flywheel hp nothing wrong with that.

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#29 LC-GTR-1969

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Posted 09 March 2017 - 05:00 PM

I agree- the figures are pretty stout all things considered... and the build seems to meet your desired objective, so all good I say...

However, a cam with about 240 odd @50 duration on 107 LSA would really wake it up- as long as you could tolerate the choppier idle... I would say there is about 30-40hp to gain with a more aggressive cam. In saying that- I quite like to stocker look and would leave this beautiful machine as it is!

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#30 DMLC71

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Posted 09 March 2017 - 08:03 PM

Hi Dave
I have a 186s in my lc and i done 3 runs and got 16.1 consistently. I think factory LC XU1 was 16.2?
Her I go. 186s 60 thou over (192), flat tops machined to suit ULP, anti pump up lifters, stage 3 nine port yella terra decked , wade XH 373 grind XU1 cam, elec dizzy set at 16 deg adv, triple 150CD XU1 carbies, gtr headers, trimatic auto, dominator 3000 stall, 336 banjo lsd.
Cheers Daz

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#31 _186sHK_

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Posted 10 March 2017 - 08:27 PM

What makes you think it doesn't go well when clear objective was to modify yet keep factory look?

Personally think you've done well with big heavy car...sure can make more power but that's simple trial & error.

Don't forget when quoted figures on these it was usually inflated figures no fan etc

186s casties if they're same as xu1 then they'll flow decent enough,TK cam suggestions be well worth a shot.

The fastest 2 barel stromberg car I have seen is a 15.6 quater. In a much lighter LJ with a 202. I think this GTS goes really well for what looks like a stocker. It's probably making 170 flywheel hp nothing wrong with that.

I agree- the figures are pretty stout all things considered... and the build seems to meet your desired objective, so all good I say...

However, a cam with about 240 odd @50 duration on 107 LSA would really wake it up- as long as you could tolerate the choppier idle... I would say there is about 30-40hp to gain with a more aggressive cam. In saying that- I quite like to stocker look and would leave this beautiful machine as it is!

Hi Dave
I have a 186s in my lc and i done 3 runs and got 16.1 consistently. I think factory LC XU1 was 16.2?
Her I go. 186s 60 thou over (192), flat tops machined to suit ULP, anti pump up lifters, stage 3 nine port yella terra decked , wade XH 373 grind XU1 cam, elec dizzy set at 16 deg adv, triple 150CD XU1 carbies, gtr headers, trimatic auto, dominator 3000 stall, 336 banjo lsd.
Cheers Daz

Cheers for the feedback guys....

Will most likely look into a new cam over winter, but as suggested I,m not going to get too carried away with it, as there are too many other limiting factors with the engine/driveline anyway.

One of the reasons I thought this thing might go a bit better was I had an LJ GTR when I was younger that had a pretty standard 202 in it, std low comp red head (std valve sizes), 350 holley, redline manifold, extractors, and mild cam (not sure on spec but probably close to what I have now in the Monaro, I clearly remember it would only pull about 4700, and sounded like the rods wanted to exit the block while doing it) drive line was M20 4 speed non lsd Banjo and 205 60 13s, the best timeslip I could find was a 16.28 @ 83.

Using the same HP calc as the one I have been using says 120hp to do that (at maybe 4500rpm) , so the Monaro with more compression and better head is only making another 20hp (and at maybe 5200rpm)

I dont think the holley/redline would be any better than my modded factory 2 barrell intake & Stromberg,

the extractors may have been better than the cast manifolds I have currently, and I guess the extra stroke of the 202 would have helped with a bit more torque.

Using that calc my current motor would probably do a 15.6 @ 87 (with a little wheelspin) in the Torana.

Like everyones been saying though, i guess i just haven't hit on the right head / cam combo for this motor yet.

If anyone wants to play around with some cool engine/car calculators here is a link to a really good site: http://www.wallacera...Calculators.htm

Also here is a link to the theory behind my home made flow bench, I'll probably start another thread and put some photos up of my specific setup, http://www.musclecar...r-heads-part-3/

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#32 8BALL

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Posted 10 March 2017 - 09:46 PM

How does it get off the line?
Does it just wheelspin? Or does it hook up?
Or are you "Driving" ot off the start then getting into it once ya going?

The start is where it all done and dusted.
One problem with a heavy car and small tyres is going to be wheelspin.

But i think you mentioned its lsd with 215's? So guessing its hooking up reasonably?
Bogging down off the line can then become an issue with low power and good traction.

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#33 _Bomber Watson_

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Posted 10 March 2017 - 10:52 PM

These engines do tend to enjoy a bit more camshaft than the general public will have you believe though...

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#34 LC-GTR-1969

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Posted 11 March 2017 - 08:47 AM

These engines do tend to enjoy a bit more camshaft than the general public will have you believe though...

yes, the asthmatic 202 loves duration and tightish centres. My observation is that 12 ports like around 250 degrees @50 but not uncommon for 9 ports to love a little more than that, like 260@50. Im running 266@50 in my rig, but to be honest 255/258@50 would probably work just as well but with less idle chop

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#35 _186sHK_

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Posted 11 March 2017 - 02:18 PM

How does it get off the line?
Does it just wheelspin? Or does it hook up?
Or are you "Driving" ot off the start then getting into it once ya going?

The start is where it all done and dusted.
One problem with a heavy car and small tyres is going to be wheelspin.

But i think you mentioned its lsd with 215's? So guessing its hooking up reasonably?
Bogging down off the line can then become an issue with low power and good traction.

Was getting off the line ok, I was loading it up against the handbrake slightly to take up the drive-line slack, revving it up to about 4 grand and letting the clutch out (not quite what i would call dropping it, but close) it would wheel spin for a couple meters, then drag the motor down slightly as it hooked up, but not by much.

You are right about the launch being critical, best et came with best 60' which was 2.515.

I guess ideally the best 60' for this HP and Weight would be a 2.3 something, but I'm not likely to achieve that with the current drive-line.

I didn't flat change on the 1-2 shift (I've dropped the small cross driveshaft out onto the ground doing that in this car before) but was flat changing the rest.

The rear uni flogged out over the course of the day and turned half the needles to dust, I was lucky to get home on it.

I'm planning to put a big cross shaft in it soon, then I suspect the axles will be the next weakest link.

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#36 8BALL

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Posted 11 March 2017 - 07:36 PM

Yeah being manual and quite heavy getting it moving is gonna be the issue.

I think back in the day the ol hx (?i think it was?) Ran a best of 16.9 with a 2.1 60'
It suffered uptop due to the old single barrel.
But being auto it left the line well with a Gemini converter. Although i think top gear was slipping near the end too.

But was pretty decent for a swap meet slap together (bought all the bits on a bet at a swap meet). this was about 20-25yrs ago.