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389-400ci power/torque gains?


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Hey there,

We're back on the road again after the head job 😆, however I have some technical questions to ask those who know @64 kiwi boni @Fitzy @JUSTA6 @Frosty @Wrongway

Full disclosure...I don't have all the necessary information to achieve an accurate answer, so I'm hoping that there are some experts on here that are willing to make an educated guess for me?

I don't really want to dyno (I know this is the only true way to know exactly what I have) the car because (a) it's just a street cruiser, so the results aren't critical just for my interest (& maybe a little bit of boasting🤷‍♂️), and (b) the original Hydramatic is fine just now, & I don't want to accelerate its wear by flogging it on a dyno.

The original 389, cross-referencing all the numbers ('60 heads, '59 block), seems to sit at 303HP/425ft/lb @ 10.25:1 CR. Quoted cylinder head volume of 69cc. Fitted with original Carter AFB.

It's been bored + .060", fitted with forged 14cc dished pistons. Bore size 4.122" (not standard 400). Now running a Melling "068" 285/298 212/225 115 Hyd W/.408 lift Cam, with standard Butler hydraulic lifters,  Edelbrock Performer 600cfm carb.

So, using all the attached data (see photos) I've calculated the new static CR at 9.73:1.

Assuming this is true, approximately what HP and torque should I be expecting now?

 

Screenshot 2024-05-17 at 09.09.12.png

Screenshot 2024-05-17 at 09.09.34.png

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I have a good idea of the horsepower/Torque with the combination that you're running...But first I have a  couple of questions...Before I divulge any numbers...

Have the cylinder heads had any Port/Combustion chamber work done...??  Multi angle valve grind..?? Or were they just cleaned up and have a stock type valve job...??

Has the rotating assembly been balanced...??

Are the cam specs advertised or @ 050...??

What is the typical pump gas octane ratings and ethanol percentages in your part of the world...???

TLBT...

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15 hours ago, Frosty said:

You didn't mention exhaust, which can kill HP. However, I will assume you have stock log style exhaust manifolds.

I would believe that this engine could make 380-425 HP at the crank. Assume 25% parasitic loss at the wheels due to the transmission and diff. I would wager 425-475 lb-ft of torque at the crank as well.

Ah yes, sorry.

Standard manifolds, then 2 ½" from there.

Thanks for your input 🙏

13 hours ago, JUSTA6 said:

Since the purpose of the dyno is tuning the car to max performance, we will never know.  Take a baseline, adjust carb, timing until max results are attained.  Thinkin Frosty is being a lil generous on HP.  I would guesstimate round 375hp tops and somewhere within Frosty's torque range with a mild cam and carb changes.  Justa my :my2cents:  glad she's ready for some street/show action. We want pic's.  Congrat's.  Both of mine are down right now.  Seeing so many rides out showin off N havin fun.

Thanks for that, and yes - pictures will follow 🤙

 

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2 hours ago, TWO LANE BLACK TOP said:

I have a good idea of the horsepower/Torque with the combination that you're running...But first I have a  couple of questions...Before I divulge any numbers...

Have the cylinder heads had any Port/Combustion chamber work done...??  Multi angle valve grind..?? Or were they just cleaned up and have a stock type valve job...??

Has the rotating assembly been balanced...??

Are the cam specs advertised or @ 050...??

What is the typical pump gas octane ratings and ethanol percentages in your part of the world...???

TLBT...

Ok...

Cylinders heads themselves standard, just decked for straightness. Valves too - seats done for ULP, but nothing special otherwise.

Rotating assembly balanced, yes.

Cam specs are as provided, but from what I gather that is pretty close. Apparently those cams come pretty highly recommended for the expectations of our build. Butler themselves suggested it to be a good choice for a "warm" street build. Not sure what you meant by "050"?

Fuel availability is 98, 94/95, 91, Ann a 10% ethanol blend. When built I tried both 98 & 95 - the car seemed to run a little cleaner on the 95, so I've stuck with that. ice the heads have been done though, the car is much sharper than it was (obviously the new rocker gear has made a big difference), so I guess I'll do the trials again & see what the performance/mileage balance is.

The distributor (OEM style) has also been recurved, to give a total (vacuum and mechanical) advance of 32-34 º, which I've been advised is how it should run best. Plugs changed from NGK BP5S to B4's, again upon advisement. And I've fitted a 160 º high flow thermostat, to assist with cooling.

Hope that helps - now please, reveal your secrets🤣

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5 hours ago, TWO LANE BLACK TOP said:

With all the accessories in place...generator..waterpump..power steering pump..etc.. With the 600 CFM carburetor...Log style exhaust manifolds...(fully dressed and wet) With your combination of parts...Realistically The engine will probably put out slightly less than 1 horsepower per Cubic of Displacement...Or around 355/360 (net) Horsepower...@ 5000/5500 RPMs...With 420/425 ftlbs of torque @ around 3400 RPMs...And a good Solid 300 maybe slightly more Horsepower at the wheels...

TLBT...

Well thank you for that information, kind sir. That'll do me...It seems most are around that range, too.

I'm as much interested in how people come to their conclusions, as the numbers themselves.

I believed I had some idea but that was really just a combination of (educated?) guesswork with some data comparison of similar engines.

Thanks again 😃

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8 minutes ago, Fitzy said:

You'll increase your triglyceride index by reformatting the deflobulator. Also, adding a couple of hamsters (in wheels) to the engine bay will increase torque. A little white powder in their water will give a turbo like boost. Apparently stuffing a tiger into the fuel tank helps too. You'll be a hero at the drag strip but the RSPCA won't like it.

Stuff the RSPCA - I'll just make sure the tiger is compatible with the fuel I'm using, & that should be ok?

The white powder upgrade may need a little more research though...

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9 hours ago, Bonne61 said:

Stuff the RSPCA - I'll just make sure the tiger is compatible with the fuel I'm using, & that should be ok?

The white powder upgrade may need a little more research though...

:rofl: you two are crack ups !

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16 hours ago, Bonne61 said:

Stuff the RSPCA - I'll just make sure the tiger is compatible with the fuel I'm using, & that should be ok?

The white powder upgrade may need a little more research though...

Where am I suppose to put the Tiger???  I've been doing it wrong for how many years?

 

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Captain.jpg

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  • 2 weeks later...

Further to this discussion, I have an issue that's raised it's head that has me stumped🤔

The engine is an early 389, that runs vested filler caps on each rocker cover, and the draft tube at the back of the motor.

Since rebuild, I removed the draft tube (just to tidy things up a bit) and fitted one of those small push in filter elements, so the engine can still vent but it's kinda hidden up under the distributor. It ran like this for 7000 miles, no probs.

Since the heads have been done up, I just can't top engine oil being pushed out through the vented caps, and making a bloody mess (not to mention a fire hazard, as it is coming in contact with the exhaust manifolds) of my engine bay.

The main difference that with the screw in rocker studs installed, the oil is now fed via the pushrods rather than the old hollow rocker studs. This seems to squirt more oil up into the rocker covers.

The motor is running really well so it appears to be nothing more than a nuisance, however it is problematic.

Will I create an issue if I just fit non-vented filler caps, as this seems to be the simplest solution?

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you will need to take your covers off Paul and add a good baffel to the under side of the vent holes.

also maybe consider getting rid of the draft tube and add a pcv to vacuum

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10 hours ago, Fitzy said:

Yep - what he said. I endured a similar problem, but that was 45000 problems ago.

Aye ???? Are you sure it’s 45000 problems ago ? I count 45007 ? :rofl:

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On 5/30/2024 at 5:43 AM, 64 kiwi boni said:

you will need to take your covers off Paul and add a good baffel to the under side of the vent holes.

also maybe consider getting rid of the draft tube and add a pcv to vacuum

I've ended up just fitting non vented caps, and the issue seems to have been resolved (without causing any other problems-that I've found yet, anyway 🤷‍♂️). Oh yeah, I painted them black too, for aesthetic purposes 😊

Another question...I've even checking out methods to adjust the valves. I used 2 different static methods, and both left me with zero compression (obviously valves too tight). So after the second fail I became convinced I wasn't the problem here. Just as a guess I backed off the +½ turn to +¼ turn and straight away I had compression and it started.

Sooo, I ended up doing it while running (yes, as messy AF but at least I could tell what was going on!). Backed off each until they rattled, then down slowly until they stopped. Then I slowly added only ¼ turn instead of the usually recommended ½ , and all seems to be good.

What say you all 🤔

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