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PostPosted: Wed Jan 31, 2018 4:51 pm 
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4 BBL ''Hyper-Pak''
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Hi all,

I have been here for the last few years while I worked on my turbo build. Your guys' wisdom has been key in me getting this far.

Right now however, I find myself at a crossroads.

I want to keep my /6 in my truck, but I've been told by a lot of people that /6 turbo setups lack longevity, and there is no way to build it to last.

I don't want to believe that, but here I am...going on engine 3...and I want to build it out with LONGEVITY as my #1 goal.

Heres a parts list I'm using:

Holley 500 modified for blow thru application. (Percy metering plate for external on the fly jet adjustment.)
Lokar linkages (well tuned)
Holley Blue fuel pump
Holley 12-879 Fuel pressure regulator with 1:1 boost ref. port (set to 6.5PSI)
Garrett GT25R(2554R) Ball bearing turbocharger (Oil/water cooled)
AEM AFR gauge (tuned to 12.5-13.5 cruising)
Glowshift Charge Air temp sensor (130-160F temp generally)
Homemade methanol injection system with Shurflo pump (boost activated)
Air/Air intercooler with 2" piping and Spectre bonnet
727 Torqueflite G/RG - Fully Rebuilt
Fixed blade fan
3" Stainless exhaust

Latest Motor Failure:

1971 /6 with forged crank - history unknown - claimed to have been rebuilt? - pulled from 1971 Charger project car

Cruising gently at 85mph at 0psi (-1 vacuum), started going up hill, load on system produced 5psi boost, engine rattled and lost compression in cylinder 6. Presumably a ring failure. Haven't taken it all apart yet.

SO!

I want to rebuild this motor out so it can take low boost, and last me a long time. I have the $$$ to do so...but I'm lacking the specs.

Who can help?

I don't want to rebuild this motor for another decade. Sick of the pipe dream. If what I'm asking is a pipe dream, just tell me now and save me the misery. hahah

Thank you,

-Greg

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PostPosted: Wed Jan 31, 2018 5:41 pm 
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Supercharged
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Location: SW Washington
Car Model: 1965 Plymouth Barracuda, 1954 Dodge C1-B8
If you broke a ring land then it's almost certain that the ring end gaps were too small.

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PostPosted: Wed Jan 31, 2018 6:57 pm 
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4 BBL ''Hyper-Pak''
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Might you be able to suggest a selection of rebuild parts, and specs that I could use to avoid this, as well as other known maladies?

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PostPosted: Wed Jan 31, 2018 9:53 pm 
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Supercharged
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Location: SW Washington
Car Model: 1965 Plymouth Barracuda, 1954 Dodge C1-B8
Bigger valves and pocket porting help power a lot. Most oversize valves are stainless which handle heat well, but also expand a bit and may stick if the guides are too tight. SI Valves, according to a recent discussion, is currently out of stock of their oversize /6 valves, but I would go with a lighter 5/16" stem valve anyhow like an early Ford 289 valve.

Venolia, Ross and others will make you custom forged pistons, but the stock replacement pistons do well so long as detonation doesn't break them. Ring end gaps need to be opened up so that the ring ends don't butt together, stick in the cylinder and break the ring lands. Chances are that tight ring end gaps is the only thing that kept your current engine from living a long time.

Oil pump driven gears can fail. Stay away from high volume pumps.

Head studs help keep the gasket intact.

There is plenty to read on all these topics here. The search function is your friend.

What are you using for timing control?

The blue pump will only work to about 7 psi boost. With a bypass regulator I'd switch to an EFI pump.

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PostPosted: Wed Jan 31, 2018 11:50 pm 
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Quote:
history unknown - claimed to have been rebuilt?


I'm fairly sure I see the problem.

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PostPosted: Thu Feb 01, 2018 2:59 am 
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The biggest thing I see is that you do not discuss timing control/retard. You need to run less timing than stock under boost. I have the MSD 6AL-II digital programmable on my turbo car and I run about 20-23 deg timing at 5 psi boost (I need to double check this) down to 18 deg at higher boost levels (up to 15 psi so far and nearing 400 HP).

What is your AFR under boost? 12.5-13.5 is too lean. 12.5 is probably OK for 5 psi, but not above that. What is your max boost level? I run 11.0-11.5:1 under 6 psi and higher boost and try not to see the gauge above 12.0 ever under boost.

I also agree with Josh that the rings need to have larger gaps. The tiny amount of compression you lose by having large gaps is insignificant compared to blowing your engine.

Get a knock sensor. Rattling is probably detonation, which will kill your engine quickly.

Hope this helps and let's continue the discussion. I'll have limited internet for the next 4 days, but otherwise can discuss...

Lou

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PostPosted: Thu Feb 01, 2018 8:31 am 
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4 BBL ''Hyper-Pak''
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SlantSixDan wrote:
Quote:
history unknown - claimed to have been rebuilt?


I'm fairly sure I see the problem.


Most definitely. Just wanted to test it until it failed (inevitably)

Dart270 wrote:
The biggest thing I see is that you do not discuss timing control/retard. You need to run less timing than stock under boost. I have the MSD 6AL-II digital programmable on my turbo car and I run about 20-23 deg timing at 5 psi boost (I need to double check this) down to 18 deg at higher boost levels (up to 15 psi so far and nearing 400 HP).

What is your AFR under boost? 12.5-13.5 is too lean. 12.5 is probably OK for 5 psi, but not above that. What is your max boost level? I run 11.0-11.5:1 under 6 psi and higher boost and try not to see the gauge above 12.0 ever under boost.

I also agree with Josh that the rings need to have larger gaps. The tiny amount of compression you lose by having large gaps is insignificant compared to blowing your engine.

Get a knock sensor. Rattling is probably detonation, which will kill your engine quickly.

Hope this helps and let's continue the discussion. I'll have limited internet for the next 4 days, but otherwise can discuss...

Lou


Of course I forget timing...

I have the initial timing set as far down as it goes, measuring at 4deg advance with a light. Stock dizzy with likely worn out innards, with vacuum advance plugged in.

As far as the ring gap, how do I achieve this?

I will tune the jets down to the AFR suggested once I get a system sealed enough to produce more than 5psi hahah

As far as the detonation goes, I'm definitely detonation free on 93 pump gas with the methanol kit...even on a hot day.

On my first motor I was detonating like crazy, so I became relatively familiar with the sound.

Did a 500 mile trip on the 1971 motor prior to the failure with no problems whatsoever fyi.

Any recommendation in specific parts for the build? Going to have to put a list of parts, as well as considerations for the local engine builder.

-Greg

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PostPosted: Thu Feb 01, 2018 8:33 am 
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4 BBL ''Hyper-Pak''
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I guess I should reiterate, I'm more concerned with longevity than power.

If I can cruise at 80mph max speed for highway I'm happy.

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PostPosted: Thu Feb 01, 2018 4:43 pm 
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Supercharged
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Car Model: 1965 Plymouth Barracuda, 1954 Dodge C1-B8
You file the ends of the rings to open the gap. Standard rebuild parts have survived a lot of boost. Longevity is mostly in the tune after the mechanicals are sorted and ring gap is about the only thing you need to change on a boosted engine. Oh, good valve springs are needed too.

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PostPosted: Fri Feb 02, 2018 4:07 am 
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Initial timing does not mean anything. You need to map the timing curve and shorten the advance "distance" between idle advance and high RPM mechanical advance. Shoot for roughly 5-10 deg at idle and 20 deg above 2000 RPM. Better yet, get the MSD programmable and used a locked distributor and you can play with timing easily on the computer.

Let's keep the discussion going...

Lou

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PostPosted: Sun Feb 04, 2018 5:47 am 
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4 BBL ''Hyper-Pak''
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Dart270 wrote:
Initial timing does not mean anything. You need to map the timing curve and shorten the advance "distance" between idle advance and high RPM mechanical advance. Shoot for roughly 5-10 deg at idle and 20 deg above 2000 RPM. Better yet, get the MSD programmable and used a locked distributor and you can play with timing easily on the computer.

Let's keep the discussion going...

Lou


I'm silly and forgot to mention that I installed the chevy hei system in the vehicle...with a new coil and wires.

Do you have a part number that would let me take it to the next step? I'm an infant when it comes to timing. Gonna have to do some reading once I find out what part I need.

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PostPosted: Sun Feb 04, 2018 8:36 pm 
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Supercharged
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Car Model: 1965 Plymouth Barracuda, 1954 Dodge C1-B8
To limit the centrifugal advance we've been welding up the slots in the distributor "governor" and filing them to the proper length. The easiest way to do the adjustable timing is a lean burn distributor and the MSD box Dart270/Lou suggested.

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PostPosted: Sun Feb 04, 2018 11:56 pm 
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4 BBL ''Hyper-Pak''

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yeah if you want to keep it simple get a digital 6 or a msd BTM even if you want to go older non computer control, i'd rather computer personally

as others have said, it is certianly not enough to just set your base timing low, besides the fact you're hurting your power everywhere else by doing that as well, and as an extra tip, i'd be working on running it RICH untill such a time you have it all sealed up and ready to play with mixtures for a boosted setup, not the other way around.... thats how you break things


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PostPosted: Mon Feb 05, 2018 8:07 am 
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The super dead simple thing is to get a locked (lean burn) distributor and run 18-20 deg for both initial and final advance. You could also lock the adv mechanism in your dist by JB welding the pins to the slots, assuming you clean everything well. Or, weld weld them. This would give you vac adv for street cruising, which will come off when you hit boost. If you go to the parts store, maybe a 1980 diplomat dist for a 225?? Maybe Charrlie_S could help with the right one to buy.

This is what I would probably do first before you do anything more complex. It will run pretty fine all around with that timing and you will have suitable timing under boost too.

Best,
Lou

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PostPosted: Mon Feb 05, 2018 7:36 pm 
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4 BBL ''Hyper-Pak''
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Dart270 wrote:
The super dead simple thing is to get a locked (lean burn) distributor and run 18-20 deg for both initial and final advance. You could also lock the adv mechanism in your dist by JB welding the pins to the slots, assuming you clean everything well. Or, weld weld them. This would give you vac adv for street cruising, which will come off when you hit boost. If you go to the parts store, maybe a 1980 diplomat dist for a 225?? Maybe Charrlie_S could help with the right one to buy.

This is what I would probably do first before you do anything more complex. It will run pretty fine all around with that timing and you will have suitable timing under boost too.

Best,
Lou


Ahhhh. So I am essentially disabling the mechanical advance, and just using the vacuum advance while off boost...

That is dead simple!

I actually prefer that solution over the MSD...because so far, the HEI is the only circuit board that is required for the vehicle to operate...and I find it fun that everything mainly relies on mechanical devices.

I think I'll weld the stock Dizzy. As long as I have your and supercharged's blessing.

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