1970 Z28 intake, carb, heads and air cleaner find

[Furback]

Found and purchased 1970 Z28 matching carb, intake and air cleaner. All off the same car. Also a pair of 492 2.02 heads, straight plug. The strange thing is the dates on the heads are 1971? Guy told me everything came off the same car. A 1970 Z28.

[68moz28rs]

492 Heads are over the counter double hump heads, I don't think they ever came on a car stock. They should all have angled plugs. 70 Z/28 should have 186 heads.


Brandon

[Furback]

Three head casting I have seen on 1970 Z 186, 492 and 041. They are straight plug.

[Lynn]

492 and 041 heads could have found there way on to a 70 Z motor, but the only ones from the assembly line would be 186.

[68moz28rs]

186's are Original Z/28. 041 Heads are 350/295 and 350/300 heads. 492 were over the counter from GM which is why they have the 71 date code.

[Furback]

Three head casting I have seen on 1970 Z 186, 492 and 041. They are straight plug.

[Furback]

492 was a common head casting in the 1.94 and 2.02 versions. If they are actually a 71 date then they would have to be under the counter. There are 70 Z cars with 492 heads, they were used in 69 and 70.

[68moz28rs]

I can guarantee you that No car came from the factory with 492 heads. They were over the counter and Racers used to buy them and throw them on 327's all the time. It was Grumpy Jenkins favorite head. The only possible way is if somebody ordered a CE replacement lt-1 block and maybe a set of 492 heads. They are also all angle plug, so something is fishy with those heads.

[Furback]

I think you should do some research. LOL

[bigsixman]

^^^^^I agree, no 492 angle plug heads on a 70 Z/28. They came in several versions thru the years produced.

[Furback]

Who said that 492 angle plug heads came on a 70 Z??????

[Furback]

Who said that 492 angle plug heads came on a 70 Z??????

[Furback]

Actually, 492 straight plug heads were used in late production 1970, part number 3987376, this was also the superceded part number for the discontinued "186" 1969 Z28 head. Early production 70 Z28,s/Corvettes had "186" heads before the "492" was used. The Z28 and Corvette LT1 had 2.02X1.60 valve size and screw in studs. The "492" head was also used in 350/300hp but was a 1.94X1.50 with pressed studs.
71,72 and 73 used "487" casting, it was a large chamber 2.02X1.60 on the Z28 and Corvette LT1. Low horse passenger cars also used this casting but as a 1.94X1.50 and pressed studs. A friend has some M dated 1.94 492 heads, he got them off a 300 HP Taxi.

[SuperNovaSS]

Are you having a conversation with yourself?


Jason

[Furback]

LOL, no it is a quote. Seems that way though.

[68moz28rs]

I think you should do some research. 186 heads were 1969-1970. 487 were 71+. Use some google if you want to argue. They're all over the counter. And post some pictures if you really have 492 heads with straight plugs. They didn't make them.

Brandon

[supercomp 8.90]

when did they come out with the 292 turbo head? I remember years ago seeing a set of turbo heads that a circle track racer had a machine shop turn the angle plugs into straight plug style to pass tech lol!!

[Schonyenko2]

I believe there were some 186 angle plug heads floating around. OTC only. 186 heads ran into late production LT/1s My deuce has them. Colvin's book is not always 100% correct.

We ran 292s on a small blk 406. They make a lot of power.

[x77-69z28]

I have a set of 292 angle plug heads on my 69 Z. They do make a lot of power. It is a peanut plug as well.
Buddy

[68moz28rs]

Jenkins used a set of 492s on his 331 sbc and made somewhere around 700hp. I bought the heads from Jenkins and they're in a museum. They have a huge amount of meat in them for porting and the build quality tops those other fuelie heads in my opinion. I've personally never used 292s but hear a lot of good stuff about them!

Brandon

[Furback]

OK so here are the photos. January of 1971. Straight plug 492 heads that do not exist. LOL

http://www.yenko.net/ubbthreads/pics/usergals/2016/01/full-13540-37615-492_heads_002.jpg
http://www.yenko.net/ubbthreads/pics/usergals/2016/01/full-13540-37616-492_heads_003.jpg

[marxjunk]

my uncle raced some 292s in the 90s..he bought them new sent them out for some work and bolted them on..i dont know what a diff they made but he was really impressed and bragged about them all the time..at that time he said they where the most powerful upgrade he had ever made

[68moz28rs]

Casting number should be 3991492, and the Date screws are two different ones. Somethings not right with those. Never seen them as straight plug heads.

Brandon

[Furback]

So now they are fake? LOL

[Furback]

I must admit that these are odd. But the casting number has not been played with. The guy I bought the parts from had these parts for over 30 years and he is the one that junked the car and knew the car from new. Small town here in NB. He is a car guy , says there were two 70z cars there. One orange? and the other Citrus green. The parts are from the orange one. I am no expert on the 70 Z cars, but I do recognize when something like a casting number is played with. All the other 492s I have or have had are the 3991492. And this number was used in 2.02 or 1.94 versions. Go figure. I have not checked the intake or carb numbers which I will do shortly and post..

[67ssonly]

Back in the early seventies I worked for Cal Corp aero marine.We raced cigarette boats with twin LT1s.The heads we used were straight plug 492 right from the gm parts counter.They made great power.We switched to 292 angle plug they made a big difference.

[Charley Lillard]

Am I the only one that thinks it reads 388 482 ?

[markinnaples]

No. That's what it looks like to me Charley. :smh:

[Mr70]

...I see 386 482.
Which were used on 283cid. & 307cid. small blocks from 1968-1973.

[Furback]

Holley # is 3972121 and the intake is 3972110. The original throttle cable bracket and lines are still there. The dirtiest parts I ever purchased. One head is 388 492, the other is 3991492.

[Furback]

Here is an old ad for a pair of 3881492 heads. I think the 1 in the casting number is missing and there is a space there for it.




street stock 77 is offline 100 Post Senior Member


Join Date:Aug 2010Location:chillicothe ohioPosts:36


Default SMALL BLOCK CHEVY HEADS



1ST SET CASTING NUMBERS 3911032

1968 1969 307CI. OR 327CI.

70CC 1.72 INT. 1.5 EXT. STRAIGHT PLUG 75.00 MAKE OFFER THEY ARE NUMBERS MATCHING



2ND SET CASTING NUMBERS 3881492

1970 LT1 CAMEL HUMP 350 CI.

SCREW IN STUDS AND GUIDES

64 CC ACESSARY HOLES STRAIGHT PLUG 225.00 MAKE OFFER THEY ARE NUMBERS MATCHING
LOCATED IN CHILLICOTHE OHIO CALL 740 703 6451

NEITHER SET OF HEADS HAVE BEEN ON RACE MOTORS OR HOGGED OUT
THEY ARE STOCK SO WHAT YOU DO WITH THEM IS YOUR CHOICE

THANKS.

[luzl78]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Charley Lillard</div><div class="ubbcode-body">Am I the only one that thinks it reads 388 482 ? </div></div>. All three 8's in the photo are the same. Doesn't look like a 9.

[Furback]

The throttle cable bracket part number is 3980982.

[ted]

I have a straight plug head 3991492 dated K30 1 with 1.94s, pressed in studs and acc. bolt holes.
Looks like Mr. Furback is from New Brunswick and I am from Quebec. Could these somewhat similar geographical locations have anything to do with this topic?? Just an idea, maybe a bad one, eh boys??
I have 3991492 and the head below 3973370 as camel humps on my parts listing.

Here is another one, 3973370 dated D23 0 straight plug 1.94s was on the same 355 engine I bought years ago.
Obviously they are not date-matched, but 3973370 is that a popular U.S. head or an oddity of some sort??
Thanks!
Ted

[68moz28rs]

Hey Ted, those are good heads. The 370 were a Canada only production head. Not sure but I think they were over the counter and came on some 350/300 or Z/28.?

[Furback]

The 370 head is a &quot;Canada&quot; casting. Commonly found on Canadian built Pontiacs like the Paressien 2+2 cars, on the 350 / 300 horse engines in 1969 and 1970. I have had lots of those. They are very good casting to port as they are cast on the heavy side. 492 straight plug castings are quite common in the 1.94 valve version. I have heard that some 370 castings have been found on Canadian built Chevelles that were sold in USA. That would be cars with the 300 horse 350. Never saw any 370 castings in 2.02 version.

[Furback]

Another pair of those 492 straight plug heads that were never produced. LOL



http://www.ebay.com/itm/492-heads-/291257551038?hash=item43d04d88be:g:0eMAAOSwEK9ULKG G&amp;vxp=mtr

[Lynn]

I believe the 3991492 casting came in straight plug and angle plug. The better angle plug heads (especially if porting) are the 292.

[Hotrodpaul]

The 492 heads were primarily an over the counter and warranty replacement head. My 70 Z28 has a CE warranty replacement short block and one original 186 and 492 replacement head. Second owner said the engine was overheating around 1972 so he brought it to the local Chevy dealer and they installed the warranty short block and head.
The 492 angle plug head and 292 Turbo heads are different castings. The 292 head has an improved Intake port with additional material and volume for porting, and was the best head for racing use in the mid to late 70's. I have both and plan to flow test them on my Superflow bench sometime in the future. I will post the results when I get the time.

Paul

[Lynn]

Thanks Paul. Is the full casting number on the 492 replacement head different from the 492 angle plug head? Perhaps that is where the confusion lies.