double hump head
Thread Starter
Burning Brakes
Joined: Aug 2005
Posts: 751
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From: Lufkin Texas
double hump head
A few years back someone told me they put a set of 68 double hump heads on a 78 engine. They said they drilled the holes for the Acc. such as ac etc. Has anyone done this?
Instructor
Joined: Nov 2005
Posts: 207
Likes: 34
From: raleigh N.C.
seen it done
they used washers to shim the top hole since
the heads have no boss cast in
only thing was it leaked oil from the top hole
since it is drilled all the way through
if you can find a set of 041 castings,
they are the same as the double hump heads but
with the extra holes already there
they used washers to shim the top hole since
the heads have no boss cast in
only thing was it leaked oil from the top hole
since it is drilled all the way through
if you can find a set of 041 castings,
they are the same as the double hump heads but
with the extra holes already there
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
For what it'd cost to get the humps and have them fully-rebuilt ... you can just about buy a brand new set of gm vortecs, darts or sportsman2's ... either of which will outperform the humps ... all 3 have tapped accessory holes too.
Just what are you working on and ... what are you trying to accomplish?
Just what are you working on and ... what are you trying to accomplish?
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
041 casting heads are actually BETTER than camel hump heads as they seem to have more meat in the casting. The combuston chambers are the same as the 186 and 492 style heads but, you will have to open up the chamber wall if you put a set of 2.02 intake valve in them. The MAJOR drawback is th elack of unleaded exhaust valve seats in any of these old heads (although the GM over the counter 492 heads sold new DO have induction hardened exhaust seats in them.) Go with some aftermarket heads and make some reliable HP that will live.
Pro
Joined: Jun 2005
Posts: 660
Likes: 4
From: Fredericksburg VA
I have a set of double hump heads that had the accessory holes added. I never had any oil leaks from the hole. I also had them opened up to 2.05 from 2.02. I loved the stock look they gave and the great increase in performance they provided. I run aluminum now because that is what the engine I got came with. Now the double humps are just sitting in my garage.
Safety Car
Joined: May 2001
Posts: 3,758
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From: Surrey
An old school mechanic that used to work next to where I do was always trying to sell me a set of 041 heads that he had "to give that Vette of yours some proper power". I did some checking (as he was offering them at a reasonable price) & the cost of buying them and then getting some port work done, new valves, etc, was about the same as buying a pair of new ally heads (like TFS). Further checking showed that, while the double humpers were good in their time, the modern design of performance heads is better. How much better "better" is, I'm not sure. Hope I didn't turn down a bargain! 
Team Owner
Joined: Sep 2001
Posts: 30,958
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From: Middletown Connecticut
Cruise-In IV Veteran
Originally Posted by UKPaul
An old school mechanic that used to work next to where I do was always trying to sell me a set of 041 heads that he had "to give that Vette of yours some proper power". I did some checking (as he was offering them at a reasonable price) & the cost of buying them and then getting some port work done, new valves, etc, was about the same as buying a pair of new ally heads (like TFS). Further checking showed that, while the double humpers were good in their time, the modern design of performance heads is better. How much better "better" is, I'm not sure. Hope I didn't turn down a bargain!
I had them worked over a bit and helped free up some extra horse from the last time I was at the dyno
Race Director
Joined: Aug 2000
Posts: 18,478
Likes: 3
From: Quincy IL
a friend has four of these heads, has offered to sell them to me a few years ago. i declined because of no acc holes and can get better heads with the holes already there. I know 2 of the heads were rebuilt by a machine shop and ready to go, the others are out in the barn on the shelf over all of our "hot rod"motors. they need to checked for cracks and rebuilt.These are good heads for hot rod guys building "T" buckets or cars that aren't going to have accessories, if acquired at the right price.
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Safety Car
Joined: May 2001
Posts: 3,758
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From: Surrey
Originally Posted by Corz
Actually, the 041 heads (that are on my car) were copyed by dart I believe and flow some pretty good numbers
Pro
Joined: Sep 2002
Posts: 541
Likes: 5
From: Epping NH
I guess it depends
on which double hump heads you have. If you are talking about 186 or 187 heads, 68 dated heads did not have predrilled holes for accesories while 69s did.
Also, the 186 / 187 heads came in two flavors, both 1.94 / 1.5 and performance 2.02 / 1.6 valve specs.
I guess it depends what you hope to accomplish with your engine, but if you are working with an original setup, those 64cc heads are more than up to the task for a street car.
Mark
Also, the 186 / 187 heads came in two flavors, both 1.94 / 1.5 and performance 2.02 / 1.6 valve specs.
I guess it depends what you hope to accomplish with your engine, but if you are working with an original setup, those 64cc heads are more than up to the task for a street car.
Mark
Race Director
Joined: Sep 2004
Posts: 11,874
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Burgundy 69
on which double hump heads you have. If you are talking about 186 or 187 heads, 68 dated heads did not have predrilled holes for accesories while 69s did.
Also, the 186 / 187 heads came in two flavors, both 1.94 / 1.5 and performance 2.02 / 1.6 valve specs.
I guess it depends what you hope to accomplish with your engine, but if you are working with an original setup, those 64cc heads are more than up to the task for a street car.
Mark
Also, the 186 / 187 heads came in two flavors, both 1.94 / 1.5 and performance 2.02 / 1.6 valve specs.
I guess it depends what you hope to accomplish with your engine, but if you are working with an original setup, those 64cc heads are more than up to the task for a street car.
Mark
Thread Starter
Burning Brakes
Joined: Aug 2005
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From: Lufkin Texas
Originally Posted by bobs77vet
i have the 186 small valve heads and i like them....you can get the summit version with big valves, screw in studs, and acc holes for like $$550...
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Originally Posted by toupstrio
Thanks for all the response just trying to wake an L82 up to around 350 hp on a budget.
Drifting
Joined: Apr 2005
Posts: 1,743
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From: Hawaii
Originally Posted by Corz
see if you can get ahold of 041x heads, they're the same heads WITH the acc holes already built in
Check out the archives on the C2 forum concerning flow potential of the double humps. Once worked over by a knowledgeable porter they actually outflowed the aluminum Edelbrocks and compared very favorably to ported vortecs. The I/E ratio was an eye opener and literally blew away the flow claims made by many aftermarket brands. Check it out
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
In most cases it is true that by the time you get finished fixing up an old set of heads you could have had new ones for the same or slightly more $$$.
It depends on if you are the type of guy that enjoys doing that sort of thing, if you have access to the proper tools, etc.
SBC Cylinder Heads by Casting Number
It depends on if you are the type of guy that enjoys doing that sort of thing, if you have access to the proper tools, etc.
SBC Cylinder Heads by Casting Number
Thread Starter
Burning Brakes
Joined: Aug 2005
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From: Lufkin Texas
Originally Posted by jackson
True dual exhaust will do A LOT. Freshen your Qjet & OE HEI. GM Vortec 64cc heads, SpeedPro hyd flat tap cam P/N CS1062R (.468/.480-220*/231* 110* cl), Victor composition head gaskets P/N 5746 (0.026" thick x 4.1" bore), professional products cyclone vortec intake P/N 52007. Right at 10:1 CR w/ your L82's OE forged flattops ... easy 350hp on pump premium ... parts around $1K. Your rings & bearings need to be in good shape when you stuff more compression on top of 'em.
Instructor
Joined: Jan 2006
Posts: 143
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From: Aiken SC
From what I recall the x after the head number like 041x or 462x denotes the intake port flows about 10 cfm more than the casting without the "x". I don't remember it denoting weather the head was cast with or w/o acc. holes.
I have had the 041x heads on a 355 before and they were awesome. However as noted in above posts, the vortecs, darts, or edelbrocks will beat them. If you have the same port work done on any of those verses any older head I think the newer heads would win out. I have been informed by those with dyno tests that the vortecs will improve an honest 20-40+ over any older production head. For the street they are hard to beat with cams ~480-510 lift. A little port work on the exhaust or a split cam with a little more duration and lift on the exhaust is the ticket with the vortecs.
I have had the 041x heads on a 355 before and they were awesome. However as noted in above posts, the vortecs, darts, or edelbrocks will beat them. If you have the same port work done on any of those verses any older head I think the newer heads would win out. I have been informed by those with dyno tests that the vortecs will improve an honest 20-40+ over any older production head. For the street they are hard to beat with cams ~480-510 lift. A little port work on the exhaust or a split cam with a little more duration and lift on the exhaust is the ticket with the vortecs.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Originally Posted by toupstrio
Will that cam give me a lopey idle? Thats whay im looking for just dont know how much duration or lift I need.
Team Owner
Joined: Jun 2000
Posts: 38,923
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From: Southbound
Cruise-In II Veteran
Originally Posted by Gary79
....These are good heads for hot rod guys building "T" buckets or cars that aren't going to have accessories, if acquired at the right price.
Also good for restorers looking for OEM parts. I have an original pair on my '68.
