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2V Open Chamber Head Shave
#1
I have the 73 2V engine with open chamber heads. i think the compression is way low like 8 or 9:1. Like to get it up to around 9 to 9.5:1 range. Considering a .030" head shave. Anyone else shaved 2V heads? If so how much is needed and at what point do issue with manifold match, valve piston clearance and detonation emerge? Any one done .030" if so is rocker arm shim or longer push rod required?

Memphis "I'm a little tired, I'm a little wired , and I think I deserve a little appreciation"
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#2
Hi
I shaved my heads on the intake side 1.3 mm on the pistons side 0.95 mm that should give you 67-68 cc. Used with flat pistons gives you around 9.5.1
No decking of the block.

Regards Rob

For knowing your limit you have to pass it thumb
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#3
My 351C is bored .040 over. No changes for that bore to the rockers (stock) or the push rods.


KT-69;282806 Wrote:I have the 73 2V engine with open chamber heads. i think the compression is way low like 8 or 9:1. Like to get it up to around 9 to 9.5:1 range. Considering a .030" head shave. Anyone else shaved 2V heads? If so how much is needed and at what point do issue with manifold match, valve piston clearance and detonation emerge? Any one done .030" if so is rocker arm shim or longer push rod required?

Thanks

Tim
Tucson, Az
1973 SportsRoof
351C bored .040
Crank .020  and Stock cam
Flattop pistons
Edelbrock 4bbl CARB 800 CFM ELEC CHOKE
Edelbrock Performer 2750 Intake Manifold

[Image: NewPrimedHood_zpsw2jaj0cu.jpg]
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#4
Robsweden;282809 Wrote:Hi
I shaved my heads on the intake side 1.3 mm on the pistons side 0.95 mm that should give you 67-68 cc. Used with flat pistons gives you around 9.5.1
No decking of the block.

Regards Rob

.051" on the manifold (side) and .037" on piston (bottom). As I was wondering about the shave on the manifold....between bottom and side to maintain correct manifold fit. That is great information as I had not laid it out or done the math to check.

Did you modify rockers for adjustable or stay with non-adjust pedestal mount rocker arms? I plan to stay with pedestal mounts using high grade ARP 5/16 bolts then either shim the rocker or adjust the rod length as needed to compensate for the .030"-.037" shave job. Some have told me the head shave will not effect hydraulic lifter adjustment unless a large amount is shaved off.

I plan to match the manifold ports to the head ports as I am running a 4V/4V Edelbrock Performer manifold with the 2V heads. My cam grinder told me the 4V/2V Edelbrock manifold ports would be to small to take advantage of my extra cam lift above 4K rpm. The 4V/4V is a close match to the 2V heads ports only a little grinding will be required to achieve a match. I am looking at pulling up to 5.6K to 6.0K rpm with this cam, head, manifold and Holley 4bl carb combo.

Memphis "I'm a little tired, I'm a little wired , and I think I deserve a little appreciation"
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#5
113mm/.051" on the manifold (side) and 95mm/.037" on piston (bottom). As I was wondering about the shave on the manifold....between bottom and side to maintain correct manifold fit. That is great information as I had not laid it out or done the math to check.

Did you modify rockers for adjustable or stay with non-adjust pedestal mount rocker arms? I plan to stay with pedestal mounts using high grade ARP 5/16 bolts then either shim the rocker or adjust the rod length as needed to compensate for the .030"-.037" shave job. Some have told me the head shave will not effect hydraulic lifter adjustment unless a large amount is shaved off.

I plan to match the manifold ports to the head ports as I am running a 4V/4V Edelbrock Performer manifold with the 2V heads. My cam grinder told me the 4V/2V Edelbrock manifold ports would be to small to take advantage of my extra cam lift above 4K rpm. The 4V/4V is a close match to the 2V heads ports only a little grinding will be required to achieve a match. I am looking at pulling up to 5.6K to 6.0K rpm with this cam, head, manifold and Holley 4bl carb combo.

Memphis "I'm a little tired, I'm a little wired , and I think I deserve a little appreciation"
  Reply
#6
KT-69;282814 Wrote:Did you modify rockers for adjustable or stay with non-adjust pedestal mount rocker arms? b combo.

Hi I put in Crane guideplates and studs so that I could mount Howard Roller Rockers, new geometri and new pushrodlenght.

   

Regards Rob

For knowing your limit you have to pass it thumb
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#7
Just shaving the heads is only one part of the equation for increasing power. Just increasing the compression will likely gain you very little, if you stay with the stock camshaft. The stock camshaft was designed and timed for emissions and low compression.

Shaving the heads lowers the intake manifold mating surfaces and requires milling the head to intake surface or the intake manifold flanges. It also reduces the distance between the bottom (ends) of the intake manifold and the top of the block at each end of the lifter valley. The ends of the block or the bottom of the intake may also need milled.

This article should help some:
http://www.crankshaftcoalition.com/wiki/...nder_heads

You also need to take into consideration the condition of the rest of the engine, pistons, rings, crankshaft and bearings, as well as your valves (one piece or stock two piece) and the valve guides. Raising compression will also increase blow-by if your rings don't seat well.

Getting the heads off is a big part of rebuilding the engine.

Having the heads at a machinist is also the ideal time to have the pedestals machined for adjustable lifters.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#8
I was running some 73 CJ heads on my 351C - big ports, small valves originally. They had been cut around 60 thou I think as the chambers were down to 63cc.

I had the intake side of the heads cut as I expected to change manifolds in the future. This worked out ok. There was no issue with manifold to block contact, used instant gasket not the rubber seals anyway.

I had a mild perf cam in it with BBC rockers so I had to get custom pushrods. It ran ok but the previous rebuilder had used the 74 forged flat tops which have a small dish. Even with the small chambers this gave about 9.5:1 CR and would not take much timing on 95 RON unleaded premium.
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#9
Why not just scrap the crappy 73 2V heads and pick up a good set of 70-71 4V cc heads, or if available get Aussie heads. ( I'd love a set of those on my engine!!). D0AE-N heads are 69 -70 11:1, D0AE-GA are 70-71 and are 10.7:1, supposedly if you believe Ford compression numbers.
It would save a boat load of work and money in the end. Even just adding studs is very costly according to my engine shop, but then that's a Canadian shop!
Just a suggestion.
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#10
Stanglover;282883 Wrote:Why not just scrap the crappy 73 2V heads and pick up a good set of 70-71 4V cc heads, or if available get Aussie heads. ( I'd love a set of those on my engine!!). D0AE-N heads are 69 -70 11:1, D0AE-GA are 70-71 and are 10.7:1, supposedly if you believe Ford compression numbers.
It would save a boat load of work and money in the end. Even just adding studs is very costly according to my engine shop, but then that's a Canadian shop!
Just a suggestion.

+1 I just got a set of Aussie 2V heads complete done ready to go for under $1,500. Got them from Power heads. I also opted for the cam kit to go with them so they installed the correct valve springs for me as well.


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73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

- Jason


[Image: 082-hot-rod-power-tour-2017-1970-1970s.jpg]
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