not sure on what heads to go for?!?
currently building blown rover 3.5 running low boost
and have been offered a pair of buick 300 heads,
they have,
53cc chambers
standard valves
ports raised
shoretened springs will have to change to double i reckon
inlet sz 39mm-40mm
exhaust sz 32mm
are these the right heads for me?
cheers guys.
buick 300 heads
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Re: buick 300 heads
maybe i'm better of with stage 2 or 3 heads i reckonminter wrote:not sure on what heads to go for?!?
currently building blown rover 3.5 running low boost
and have been offered a pair of buick 300 heads,
they have,
53cc chambers
standard valves
ports raised
shoretened springs will have to change to double i reckon
inlet sz 39mm-40mm
exhaust sz 32mm
are these the right heads for me?
cheers guys.
-
CastleMGBV8
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Compression ratio would be approx 7/1 with tin gasket 6.5/1 with composites.without skimming the faces.
I have these heads on a 4.35 engine I built recently and you would still need to have quite a bit of work done to make it worthwhile.
Are these alloy heads as they were only alloy for 1964, 65-67 were cast iron.
Also I'm not sure they are such a good idea on a small bore engine as you would have no or very little squish, although I have heard of therm being used on 3.5 engines but I think that welding was done to fill in and reshape the combustion chambers.
Also don't forget that these are 43 year old heads and the valve seats will probably need work to get all the valves level. you really need to have them recut for a set of big valves.
Kevin.
I have these heads on a 4.35 engine I built recently and you would still need to have quite a bit of work done to make it worthwhile.
Are these alloy heads as they were only alloy for 1964, 65-67 were cast iron.
Also I'm not sure they are such a good idea on a small bore engine as you would have no or very little squish, although I have heard of therm being used on 3.5 engines but I think that welding was done to fill in and reshape the combustion chambers.
Also don't forget that these are 43 year old heads and the valve seats will probably need work to get all the valves level. you really need to have them recut for a set of big valves.
Kevin.
Last edited by CastleMGBV8 on Wed Jul 01, 2009 11:25 pm, edited 1 time in total.
Wouldn't there be a problem with the valve placement and bore size? I was looking into a set of Buick 300s for my 3.5 turbo build but never got to the bottom of it. And don't the buick 300s already have very large valve sizes when compared to 'standard' or waisted stem Rover V8 heads?? I don't think you can increase the valve size in Buick 300s with a 3.5 inch bore.CastleMGBV8 wrote: Also don't forget that these are 43 year old heads and the valve seats will probably need work to get all the valves level. you really need to have them recut for a set of big valves.
Kevin.
cheers
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CastleMGBV8
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Olly,
The valve spacing as I only found out recently is the same as the Rover, the inlet valve from memory is 1.625" so bigger than the standard rover size but not waisted, and not quite as big as the 1.63" waisted stem valves normally used to up grade rover heads. The exhaust valves are only 1.312" so quite a bit smaller than the normal 1.4" upgrade and where quite a bit of power can be found.
Kevin.
The valve spacing as I only found out recently is the same as the Rover, the inlet valve from memory is 1.625" so bigger than the standard rover size but not waisted, and not quite as big as the 1.63" waisted stem valves normally used to up grade rover heads. The exhaust valves are only 1.312" so quite a bit smaller than the normal 1.4" upgrade and where quite a bit of power can be found.
Kevin.
Aha now I see. Fountain of knowledge as always Kev, you ahve Buick 300s right? What's your spec? Do you think you could upgrade the exhaust valves using Rover 1.4" exhaust valves relatively easily? I know they flow a lot more than Rover V8 heads, and when fettled they far outreach Stage IV Rover heads. It's just so hard to find a decent set nowadays as they are soooo old.CastleMGBV8 wrote:Olly,
The valve spacing as I only found out recently is the same as the Rover, the inlet valve from memory is 1.625" so bigger than the standard rover size but not waisted, and not quite as big as the 1.63" waisted stem valves normally used to up grade rover heads. The exhaust valves are only 1.312" so quite a bit smaller than the normal 1.4" upgrade and where quite a bit of power can be found.
Kevin.
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CastleMGBV8
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Olly,
It's just a simple recut of the seats to take the waisted stem 1.63" In, and 1.4" Ex, valves.
The same sort of work needs doing to enlarge the inserts to seat size and then blend in the bowls as you would on Rover heads,
I left the much larger port runners as standard apart from a gentle clean up of any very rough spots to maintain good fuel suspension at low RPM which seems to have worked well as the engine will pull 4th gear at 35MPH and pull away smoothly without changing down.
Kevin.
It's just a simple recut of the seats to take the waisted stem 1.63" In, and 1.4" Ex, valves.
The same sort of work needs doing to enlarge the inserts to seat size and then blend in the bowls as you would on Rover heads,
I left the much larger port runners as standard apart from a gentle clean up of any very rough spots to maintain good fuel suspension at low RPM which seems to have worked well as the engine will pull 4th gear at 35MPH and pull away smoothly without changing down.
Kevin.
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CastleMGBV8
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CastleMGBV8
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Dimitri,
Thats interesting as I asked this question on one of the US forums recently and was told it was the same as the Rover valve spacing.
I didn't think to measure my 300 heads when they were off the engine so wanted to know purely for academic reasons.
I know that without moving the guide position that the biggest valves you can fit to the 300 heads are 1.775 In. and 1.5" Ex.
Any idea what the additional spacing is?
By the way the TA Performance heads for the Rover should be available I believe at the end of this month.
Kevin.
Thats interesting as I asked this question on one of the US forums recently and was told it was the same as the Rover valve spacing.
I didn't think to measure my 300 heads when they were off the engine so wanted to know purely for academic reasons.
I know that without moving the guide position that the biggest valves you can fit to the 300 heads are 1.775 In. and 1.5" Ex.
Any idea what the additional spacing is?
By the way the TA Performance heads for the Rover should be available I believe at the end of this month.
Kevin.
Kevin,
yes largest valves in Buick 300 heads without offset valve guides are 1.775" In. and 1.5" Ex.
On Rover heads maximum is 1.7" In. and 1.5" Ex. without offset valve guides.
I remember I tried to install Ferrea Valves in an pair of RV8 heads I had just to see what's it look like and see which chamber reshaping needed in case of small combustion chamber... The valves overlapped.
There is something around 0.125" of difference between Rover and Buick valves spacing.
But there is an major problem with Buick valve guide : the bore of the guides may not be concentric with the OD because of the production process where the seat pocket and the guide were machined at the same time but not indexed on the guide OD.
yes largest valves in Buick 300 heads without offset valve guides are 1.775" In. and 1.5" Ex.
On Rover heads maximum is 1.7" In. and 1.5" Ex. without offset valve guides.
I remember I tried to install Ferrea Valves in an pair of RV8 heads I had just to see what's it look like and see which chamber reshaping needed in case of small combustion chamber... The valves overlapped.
There is something around 0.125" of difference between Rover and Buick valves spacing.
But there is an major problem with Buick valve guide : the bore of the guides may not be concentric with the OD because of the production process where the seat pocket and the guide were machined at the same time but not indexed on the guide OD.
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CastleMGBV8
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But there is an major problem with Buick valve guide : the bore of the guides may not be concentric with the OD because of the production process where the seat pocket and the guide were machined at the same time but not indexed on the guide OD.
Dimitri,
Yes I was aware of that, fortunately didn't cause a problem when fitting the larger valves as presumably they centred the cutter on the existing guide bore.
To answer olly's question, will the larger valves in a 300 head work on the smaller bore 3.5 engine or will they be overshrouded or possibly touch the cylinder walls?
Kevin.
Dimitri,
Yes I was aware of that, fortunately didn't cause a problem when fitting the larger valves as presumably they centred the cutter on the existing guide bore.
To answer olly's question, will the larger valves in a 300 head work on the smaller bore 3.5 engine or will they be overshrouded or possibly touch the cylinder walls?
Kevin.
About shrouding factor it is not really easy to reply as it depends of your objectif and engine configuration.
Before all we increase valve size to increase low lift flow but which is particulary affected by shrouding factor in small bore engine. But in case of high lift flow is less important as the most important is the port design.
The key is to find the correct port diameter depending of optimum port diameter and shrouding factor.
Also in Olly case it was for an turbo engine where the most important is the exhaust valve. So Buick heads with 1.5" Ex. valve would not have been an problem.
Before all we increase valve size to increase low lift flow but which is particulary affected by shrouding factor in small bore engine. But in case of high lift flow is less important as the most important is the port design.
The key is to find the correct port diameter depending of optimum port diameter and shrouding factor.
Also in Olly case it was for an turbo engine where the most important is the exhaust valve. So Buick heads with 1.5" Ex. valve would not have been an problem.
