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Jun 11, 2015 11:36:15 GMT
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Have a pair of cast iron Mopar J heads I'd like skimmed, 38 thou on the combustion side and 76 thou from the intake side, so that the intake will still bolt up. Figures have been quoted on several different Mopar sites, though the intake side milling seems excessive.
This should drop around 8cc from the cylinder heads volume and give me a touch more compression.
Anyway, found a small local company who are quoting £10 per face to do the work.
This seems incredibly cheap to me, or is the amount I'm asking really not that much?
I'd rather not have to go get Edelbrock heads so soon...
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Jun 11, 2015 12:27:28 GMT
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Thats really cheap even for a tea money job! Can you go in and talk to them and confirm exactly what you need doing and double check the price?
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Jun 11, 2015 12:40:11 GMT
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I was intending to have a nose about anyway when I went down there, I think they're just starting up and trying to get their name out there a bit more.
Need more accurate figures for what I want first anyway, I've found different numbers for milling the intake surface. Irritating!
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,715
Club RR Member Number: 34
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Cylinder head skimmingDez
@dez
Club Retro Rides Member 34
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Jun 11, 2015 17:41:03 GMT
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30-40 quid is going rate round here, for a simple flat skim of a clean bare head. price goes up considerably if you expect them to strip or clean it or do anything fancy.
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Jun 11, 2015 18:58:13 GMT
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last time i saw a cheep head skim it was like the surface of a 40 year old vinyl record and covered in swarf. £40 to £50 each would be what i would expect from a decent firm.
Out of curiosity , why are you wanting them skimmed?
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'88 Cadillac Brougham hearse (white)
'91 Carlton GSi 24v
'72 Dodge dual cab pick up
'99 Mercedes S55 AMG
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Cylinder head skimmingslater
@slater
Club Retro Rides Member 78
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Jun 11, 2015 21:31:01 GMT
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He just said, he wants more compression!
As for the amount you need to take off the inlet face you can work that out with some simple trig. Might be worth getting the chamber volume measured so you can actually make sure too as I wouldn't trust the Internet
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Jun 11, 2015 23:16:31 GMT
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Aye, a cheap and easy compression boost. Heads are already completely disassembled, I'm just waiting on all the kit to arrive to accurately CC them myself as well as find out how far down the hole my pistons actually sit. I'd like to get as much compression as possible with the stock components, a small cam and then bung some Keith Black pistons and a set of Ali heads on/in.
I'd like to keep it fairly low cost until I can make 100% certain it'll all fit in my car.
Basically, as close to 9.5:1 as I can get with stock parts for now. Then bang the pistons in and the heads on, aim for 10:1+ and go for broke.
Unless I win the lottery and find myself in possession of a intake to suit a Weiand 6-71.
Trig was never my strong point, any pointers Slater?
Going to get some more accurate figures shortly and then play with a compression calculator and see what comes up.
Cheers for all the replies so far.
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Jun 13, 2015 21:23:32 GMT
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He just said, he wants more compression! ok, i saw that, but i was only curious as to the need for this? Its been my experience that this rarely achieves much on performance unless other work has been done on airflow such as porting,carb,exhaust and valve work. But there again sometimes just a new set of rings with a bore hone will lift compression the same amount as a skim would. However when i do engine work i will as a matter of course get a head skimmed to make sure it is perfectly flat befor refitting. The chap who does this for me will only take whats necessary off to make it flat and no more. fell free to educate me though as after a while i forget stuff that i should remember, like where i live etc etc  |
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'88 Cadillac Brougham hearse (white)
'91 Carlton GSi 24v
'72 Dodge dual cab pick up
'99 Mercedes S55 AMG
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Jun 14, 2015 10:53:20 GMT
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Stock compression on this small block is advertised at around 8:1, it's realistically more like 7.6:1 with the heads having massive chambers.
Most of the cam kits I've seen have recommended compression ranges starting at about 9:1
It'll be getting a new intake, carb and headers before its all bolted together anyway.
The heads allegedly flow really well in stock form, they're just a bit big and open.
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Jun 15, 2015 16:35:20 GMT
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Done some rough measurements today, seems my stock lump is around 7.9:1 with a very thin 0.027 compressed head gasket and if the heads are 72cc. Bumps up to 8.44:1 with 8cc chunked out of the heads. Also looks like I may already have big valves in the heads I have. Will need to have a measure of the valves when I remember where I put them. The compression goal wasn't random by the way. I do have the small block mopar bible. Which also does contain proper numbers for skimming to keep it all lined up. Handy.  |
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Jun 15, 2015 20:08:00 GMT
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Port matching works well
As do making sure the joins between all the inlet parts
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Jun 15, 2015 22:25:53 GMT
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It works well yeah, but not for gaining compression...
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