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67 396 valve job. Not sure about Machine Shops Answer

3K views 29 replies 9 participants last post by  cdminter59 
#1 ·
Hi all.
Had the heads from my 67 396 to a machine shop for a price on valve seats and/or guides. Price for the 3 angle valve job is $ 530.00. New seats, $ 30 - 40 per. His suggestion was to only change the exhaust side.
I don't really know where to go with this. Any suggestions are greatly appreciated.
Thanks,
Dom
 
#6 ·
The valve job price is way out of line..

Here is a tip. The 50+ year old heads are going to need guides or better yet properly installed liners. Have hard exhaust seats done at the same time. That way when the valve job is done. You get three angle valve job done for no extra cost.
The seats have to be done that way anyways.

So when you get your quote... Ask for guides/liners and hard seats+ valve job and you will get a three angle valve job without the "added" cost. All part of the work correcting the seats after the guides and seats are installed..

Some of these shops consider you "fair game" when you mention "three angle valve job".. When in reality it is an included part of a regular service guide and seat install.
 
#10 ·
I was thinking that as well but didn't know what that price was including. Does that price include any parts? cleaning, magnafluxing, surfacing an assembley? Drop off a set of greasey big block heads and pick them up full of new parts ready to bolt on an you easily have $500 in them. I did find it strange that he was quote an hourly rate rather than a flat rate for seat replacement.
 
#11 ·
Tresi:
His quote was for the seats only. I think the work was included in the 530 price.
Although I could have misunderstood him. But, the 3 times I have been there, he was sitting in the back office watching tv, and the place looked too clean, so I don't have much confidence in him.
 
#15 ·
This is a busy time of year for a good machine shop. People have their tax refund in hand an want to get their race motors done. If he has time to set around give him some more time to set around by finding another shop. Even are local parts store that sen all of their machine work off to it's corporate machine shop an hour and a half away would give you a better deal.
 
#18 · (Edited)
67 396 valve job. Not sure about Machine Shops Answer

Dom, Check out these new aluminum heads from GM Parts Direct. They have 110 cc semi-open chambers. Also the valves are 2.19/1.88. GM Parts Direct: Search results The only other manufacturer that has a 100 cc chamber is Edelbrock 350-604719 from Jegs. The only problem I see is you don't know what camshaft you have to get the right springs. Take the camshaft out inspect it for part numbers if none take it to a machine shop to be measured.
 
#20 ·
Dom, Check out these new aluminum heads from GM Parts Direct. They have 110 cc semi-open chambers. Also the valves are 2.19/1.88. GM Parts Direct: Search results The only other manufacturer that has a 100 cc chamber is Edelbrock 350-604719 from Jegs. The only problem I see is you don't know what camshaft you have to get the right springs. Take the camshaft out inspect it for part numbers if none take it to a machine shop to be measured.
As vinnykg2 suggests, I think I'm going to leave the can of worms closed.
The engine worked well before I put it to sleep and it's getting more and
more expensive to wake up. I think I'm going to do the least that I can, but make sure it's reliable, and wait on going bigger.

Thank you for the GM site. It is a very good site to look through.
I'll save it for hopefully going bigger in the future.
Dom
 
#23 ·
Don't know where you live but if that's 530 dollars just for shooting 16 seats at 3 angles that's about twice the price. If it includes 16 new guides and 8 exhaust hard seats plus cleaning and magnaflux it's actually a darn good price.

Bogie
Bogie:
Would you be able to explain a little for me ?
cminter59 uggested newer heads. My understanding is/was, if I change the cc's from my original 98.4 to 11_ whaterver, I would be losing compression.
I can understand that. But, is that true ? Or, can I go with a set of heads with a higher number of cc's ?

Anyone else's comments are most certainly welcome also.

Thanks,
Dom
 
#24 ·
One of the pitfalls of building a 396 based engine is the lack of availability of small chamber heads. The aftermkt is supplying heads based on the 112-122 big bore chambers. The 396 requires the small chambers to make compression/power. Larger chambers on a small bore require huge domes that then screw up flame travel and open up another separate can of worms.

Take a lesson from small block engines.. 76 chamber/big dome vs. 58 chamber/flat top pistons. Same approx. compression ratio, but different fuel/air/timing requirements.
 
#27 ·
One of the pitfalls of building a 396 based engine is the lack of availability of small chamber heads. The aftermkt is supplying heads based on the 112-122 big bore chambers. The 396 requires the small chambers to make compression/power. Larger chambers on a small bore require huge domes that then screw up flame travel and open up another separate can of worms.

Take a lesson from small block engines.. 76 chamber/big dome vs. 58 chamber/flat top pistons. Same approx. compression ratio, but different fuel/air/timing requirements.
Eventually, I will go bigger. For now, as buzz suggested, I'm going to put it back together and enjoy it. That will give me more time to build a 454 correctly sometime in the future.
Thank you !
 
#25 ·
. Yes, you lose compression ratio, MPG, and possibly power with bigger cc heads, depending on how well the new heads flow air... and whether 'fast burn' combustion chambers... but bigger chambers may allow running on lower priced pump gas instead of race or boosted gas...

. Someone hinted $500 will nearly buy a pair of new aluminum big block heads... LOL! ... Way off! ... Maybe a great swap meet score...

. So far, you really don't know what you're comparing... would need to get an itemized list of just what the guy will do for X price... just because he's slow in winter doesn't mean he doesn't know what he is doing... although it's often good to ask where your buddies went and if they are satisfied...

. And, like you say, if it's running OK for now, passes compression gauge testing, no oil smoke, not fouling plugs, maybe let it go for a few more years... just enjoy it...
 
#30 ·
67 396 valve job. Not sure about Machine Shops Answer

Dom, I am thinking that your pistons are the old seal power or speed pro domed pistons. They probably have a piston head volume of -21.00. If I run some figures thru the KB calculator https://www.uempistons.com/index.php?main_page=calculators&type=comp) with your 98cc heads I get 10.254 for the Static Compression Ratio. You definitely would have to mix racing gas to keep from detonating. With either of the aluminum heads you could run 93 octane pump gas. With the GM heads and a .027 thick head gasket you would have 9.155 S.C.R. You could use 87-91 octane gas. Edelbrock 100cc chamber heads would give you 10.051 S.C.R. which you would still run 93 octane pump gas. BTW you would have to choose a new cam with an intake closing point to give you a 8.2- 8.5 DCR. Your quench on your engine is probably .054-.066 which isn't good. Most engine builders set the quench at .035-.045. You mill the top of the block and choose the right thickness head gaskets to get this.
 
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