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Wes's Burb build/update/maintance
- Thread starter Wes Harden
- Start date
there is a set of 14096188 bbc cyl heads on market place for $750 pair. big valves open, chamber, 118cc comb chamber, rectangle ports. Supposed over the counter ls6-7 heads.
Can these be used on a gen vi ? I saw mention that the water jackets doesn't match a gen v
Can these be used on a gen vi ? I saw mention that the water jackets doesn't match a gen v
Don't take make head gaskets to block off the ports so you can use the heads?
Well I see there are gaskets to do this, looks like it is common. Now what does the tribe say about those heads ? better than peanut ports for my burb ? I know loaded question, not wanting to make lots and lots of Hp, prob gonna run cast iron exhaust manifolds on dual 2.5 into single muffler one 3" tail pipe. maybe even cast iron intake. for sure q jet and hei. If I were to go efi it would prob be a throttle body system of some type.
I mean they are rectangular port. They are high performance heads. But they are from a marine application. But still big block chevy ls7 heads. Better than my 781's lol
Wes,
A set of “188” heads are generally replacements for original casting “990” heads that were LS-6/7 rectangular ports - basically a superseded part number newer casting type of thing.
They are considered good ( as far as factory stuff goes ) flowing ports with fairly thick castings but today’s aftermarket heads offer so much more.
Now here is the kicker - they are just about the opposite of your peanut-port castings in the flow department.
Meaning that they are most likely not what you are looking for to power your Burb’n - Q-jets, lower compression numbers, very little to low cam numbers, exhaust manifolds and low speed trail riding mixed with freeway speeds and towing just ain’t what these heads were made for.
A set of “188” heads are generally replacements for original casting “990” heads that were LS-6/7 rectangular ports - basically a superseded part number newer casting type of thing.
They are considered good ( as far as factory stuff goes ) flowing ports with fairly thick castings but today’s aftermarket heads offer so much more.
Now here is the kicker - they are just about the opposite of your peanut-port castings in the flow department.
Meaning that they are most likely not what you are looking for to power your Burb’n - Q-jets, lower compression numbers, very little to low cam numbers, exhaust manifolds and low speed trail riding mixed with freeway speeds and towing just ain’t what these heads were made for.
Those “781’s” would work out GREAT for Wes’ Burb application - only downside would be the cost to rework a set v/s a newer aftermarket set. Investigate all costs and options before ya’ commit.
At that cost I would hold off, by the time you fix everything you could of likely bought new heads., especially if they need new guide or hardened seats. What year are they, pre lead? Or those are newer replacements?
In general, for your application, you are best off with a good flowing oval port, it will have higher velocity and make more power and torque in your intended RPM range.
A rect port BBC head is generally for higher RPM HP, it has lower velocity and less torque in the lower RPM range.
With that said, for compression, cost, and available parts reasons, GMPP puts the iron rect port heads on the HT502. Which I aways thought was backwards compared to the AL oval ports on the ZZ502. I think they did it because the larger combistion chamber knocks the compression down for lower grade gas, and they are cheaper. But the BBC still makes torque, it's a BBC. Essentially rect ports are not ideal for a torque motor, but they will still work. I wouldn't pay that much for them though.
I fixed it for you...
In general, for your application, you are best off with a good flowing oval port, it will have higher velocity and make more power and torque in your intended RPM range.
A rect port BBC head is generally for higher RPM HP, it has lower velocity and less torque in the lower RPM range.
With that said, for compression, cost, and available parts reasons, GMPP puts the iron rect port heads on the HT502. Which I aways thought was backwards compared to the AL oval ports on the ZZ502. I think they did it because the larger combistion chamber knocks the compression down for lower grade gas, and they are cheaper. But the BBC still makes torque, it's a BBC. Essentially rect ports are not ideal for a torque motor, but they will still work. I wouldn't pay that much for them though.
I fixed it for you...
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Im sure he can find a good set of used 781's they are much better for his application.
New big block info. T06087XW serial number with a date code E106. May 10th 2006. According to a Mercruiser pdf this might just be a 496
Should have it in my possession this week sometime. Then I will be able to really dig into it.
Should have it in my possession this week sometime. Then I will be able to really dig into it.
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Big Block part Deux.
Spent the afternoon playing engine shuffle. My buddies gararge door mechanism is non functional atm, so out the side door to small for engine stand to fit. 1st the 68 327 and power glide from the Impala I was fixing earlier had to be removed from buddies truck.
Lot a work in a warm garage and afternoon sun.
Date codes on heads even look 06, still thinking thisvis gonna be a 496. Have to pop pan and look for crank casting number. Got 1 more engine to shuffle before that happens.
For sure going to pop pan and intake, for inspection and reseal. On the fence about pulling heads. Dampener looks suspect, so it will be replaced. Timing chain will be replaced.
Maybe I should put some cheap oil in it and run a compression test/ leak down. Just need a flex plate.
Any opinions on that intake other than it's heavey?
Also now flip flopping about exhaust manifolds or headers
Spent the afternoon playing engine shuffle. My buddies gararge door mechanism is non functional atm, so out the side door to small for engine stand to fit. 1st the 68 327 and power glide from the Impala I was fixing earlier had to be removed from buddies truck.
Lot a work in a warm garage and afternoon sun.
Date codes on heads even look 06, still thinking thisvis gonna be a 496. Have to pop pan and look for crank casting number. Got 1 more engine to shuffle before that happens.
For sure going to pop pan and intake, for inspection and reseal. On the fence about pulling heads. Dampener looks suspect, so it will be replaced. Timing chain will be replaced.
Maybe I should put some cheap oil in it and run a compression test/ leak down. Just need a flex plate.
Any opinions on that intake other than it's heavey?
Also now flip flopping about exhaust manifolds or headers
Wes, I would so very much wish you came across a GEN-7 496 but that motor looks to be a GEN-5/6 ( GEN-6 if it has a mounting boss for a fuel pump - the GEN-5’s did away with that and it was brought back revamped casting after that series even though it was not used on production motors ).
The GEN-7’s have different heads ( amongst much much more differences ) as a dead giveaway for quick reference.
That intake is absolute grade-A crap ( notice how low the carb mounting pad surface is ) and that is a dead giveaway away that it’s a high-torque peanut-port 454 or 502 crate motor if it’s an ‘06 model year casting.
The GEN-7’s have different heads ( amongst much much more differences ) as a dead giveaway for quick reference.
That intake is absolute grade-A crap ( notice how low the carb mounting pad surface is ) and that is a dead giveaway away that it’s a high-torque peanut-port 454 or 502 crate motor if it’s an ‘06 model year casting.
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Is definitely a gen 6. No fuel pump boss.
Is also a mercruiser block. Still got the tag on it.
I know it's not the gen 7, isn't that the 8.1? Have one of those in my 01 Burb.
Sitting here thinking 3 big blocks in my possession now, and that Tom is a bad influence
Shuffled done
Draining oil, no water in oil so win.
Black as sin though
Pulled dampner and compaired it to a mark 4
Mark 6 on bottom. Appears to have a larger weight. Tdc marks line up with key way on both.
Is also a mercruiser block. Still got the tag on it.
I know it's not the gen 7, isn't that the 8.1? Have one of those in my 01 Burb.
Sitting here thinking 3 big blocks in my possession now, and that Tom is a bad influence
Shuffled done
Draining oil, no water in oil so win.
Black as sin though
Pulled dampner and compaired it to a mark 4
Mark 6 on bottom. Appears to have a larger weight. Tdc marks line up with key way on both.
If it does not have a F/P mounting boss it’s a GEN-5 block casting - GEN-6’s brought it back.
Good news is that all those motors came as a 4-bolt main block.
Dig into it because they offered 502’s with the same heads.
Those “156” casting heads are definitely peanut-ports that are used very heavily in marine applications.
You are off to a great start in your conversion into big-block life style - I am proud for ya’ !
Good news is that all those motors came as a 4-bolt main block.
Dig into it because they offered 502’s with the same heads.
Those “156” casting heads are definitely peanut-ports that are used very heavily in marine applications.
You are off to a great start in your conversion into big-block life style - I am proud for ya’ !
Third picture from the top in today's post shows Mark VI cast in number 8 water jacket.
Very odd - not doubting you at all but just curious about the casting area; can you get a good pic of the fuel pump area?
Maybe newer M6 castings deleted it at some point.
so this block has a weird machined spot on lower right front. In an article I just read they are calling that a fuel pump pad.
picture from article, same as what I have.
Also says the mark 4 and 5 have 10 bolt timing covers
picture from article, same as what I have.
Also says the mark 4 and 5 have 10 bolt timing covers
Alright, I should have said that the pad wasn’t drilled on a GEN-6 but is absent all together on a GEN-5 - sorry about that.
And the quantity of timing cover bolts are a dead giveaway too - I’m gett’n slow in the head. The G6 has the plastic/phenolic cover with only six ( at least I think it’s six ) retaining bolts on it and the G5 has a tin cover with ten retaining bolts just like a Mark-IV does ( I don’t know why GM tried to get all fancy and started calling what should of been the Mark-V engines GEN-5 ).
I should’ve mentioned the cover differences from the start and looked at your pics better - man, all these medical drugs are slow’n my brain down…sorry for the confusion Wes.
And the quantity of timing cover bolts are a dead giveaway too - I’m gett’n slow in the head. The G6 has the plastic/phenolic cover with only six ( at least I think it’s six ) retaining bolts on it and the G5 has a tin cover with ten retaining bolts just like a Mark-IV does ( I don’t know why GM tried to get all fancy and started calling what should of been the Mark-V engines GEN-5 ).
I should’ve mentioned the cover differences from the start and looked at your pics better - man, all these medical drugs are slow’n my brain down…sorry for the confusion Wes.
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