FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
||||
|
||||
Milled heads?
How can you check if the cylinder heads have been milled before?
Are there any reference points to measure against? Are there any blueprint drawings for reference? IMWTK |
#2
|
||||
|
||||
Kenth I have used the distance from the deck to one of the end accessory bolts and compared to a known "virgin" head. If you have an identical virgin casting you can try measuring chamber depth but getting the exact same location can be difficult , even on the same head!
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#3
|
||||
|
||||
Skip, thanks for your input!
I was thinking measure from deck surface to an intake bolt hole with a bolt mounted in the hole. Wouldnīt all 1965-79 heads have the same distance? Factory blueprints would tell if thatīs the case. |
#4
|
||||
|
||||
youll want to be sure the Intake side is equally milled so it all fits and you dont have to make it a 1 off engine.
__________________
"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
#5
|
||||
|
||||
Absolutely, but if you bought used heads that you have no history on, how do you know how much is milled, if anything?
|
#6
|
||||
|
||||
Quote:
dry assembly "might" be able to tell if intake will be leak free too.
__________________
"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
#7
|
||||
|
||||
Quote:
Looking at the depth on the countersink on the intake bolts that accept the gasket retainers will give you a good idea if the intake side of the head has been milled. If the head was milled correctly the step for the valley pan to seal to will be the giveaway. |
#8
|
|||
|
|||
Could just cc the chamber’s.
|
#9
|
||||
|
||||
What heads are you working with?
The later heads with the stamped letter/digit would differ between each one. The early ones like a 12 probably are the same, but different than a 13 head. CC's would give you an idea if they are milled if one knows what they were stock.
__________________
John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." Socrates |
#10
|
||||
|
||||
In this area of any production iron head ( as in my first photo)I have always found to be .300” plus or minus .020” if the head(s) have not been milled .
If the heads have been run you should aways see minor rust pitting around the heads water passage holes in the deck, if not then that’s a sign that they have been milled. The factory machining of the chamber is very Accurate. This means that if you CC one chamber in each head and then measure it’s depth as in my second photos, checking the depth of the other chambers in the same manor makes things easy. If the depth of all the other chambers are .006” or less in variation then all of you chambers will be between 1 to 1.5 CC of each other.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 01-18-2024 at 04:35 PM. |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#11
|
|||
|
|||
Quote:
We've always used chamber depth, measured like you, as an indicator of milling. Like you said, Pontiac heads are VERY consistent with chamber sizes/depths. |
#12
|
||||
|
||||
Steve I will disagree with you. Here are similar measurments but to ne consistent at the edge of the intake vale to the deck on the heads I had at the house that day.
#614/SR 0.073 72cc E head 0.104 #16&62 0.137 #670 0.140 6X-4 0.225 6x-8 0.282 4X-1H 0.345 So all totally different. Using the depth at intake bolt is assuming every casting is the same from the bottom and around the heat crossover. I would bet there are variables there. To keep accessorizes the same form head to head form deck(assuming not a 301) it should be the same
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#13
|
|||
|
|||
to me anyways its pretty easy to tell by the pits near the coolant passages and overall look of gasket surface exactly how deep the mill is hard to tell but virgin vrs worked? no coolant pits or very shallow? dead giveway
__________________
If your not at the table you're on the menu A man who falls for everything stands for nothing. |
#14
|
|||
|
|||
Are Pontiacs broached like other GM heads from that era?
Not hard to mistake a virgin head if broach marks are present. |
#15
|
|||
|
|||
Are Pontiacs broached like other GM heads from that era?
Not hard to mistake a virgin head if broach marks are present. |
#16
|
||||
|
||||
The late Jim Taylor (Phillipsburg, NJ) at one point told me he had some Pontiac cylinder head blueprints. The length of the head bolt bosses was called out including the nominal along with the tolerance. It'd be nice to have access to those numbers.
|
#17
|
||||
|
||||
Here is what i have found on some of my heads measuring from a long intake bolt unthreaded upper surface to deck surface.
Seems like 1.665" is the magic number for an untouched head deck surface. Pontiac-heads Date mm / inch #191 L080 41,3 /1.626 Been on a racing engine #191 L080 41,3 /1.626 #191 A081 42,3 / 1.665 Original single #191 L080 42 / 1.653 Clean planed surface #191 A081 42 / 1.653 #614 ?041 41,7 / 1.641 Been on a racing engine #614 No date 41,7 / 1.641 #7F6 A052 42,3 / 1.665 Original pair #64 I089 42,3 / 1.665 Original pair I would still like the see the Pontiac blueprints on Pontiac heads dimensions. Canīt believe they are so hard to get! |
Reply |
|
|