[ROVERNET - UK] 3500s head compatibility

Kent Kinard kkinard at swbell.net
Sat Feb 18 15:07:53 GMT 2006

Hi James,
Time for a history lesson:
These do appear to be Olds 215 heads. They use eighteen head bolts (or 
studs) each to hold them to the block.  They will NOT bolt to the 
Buick/Rover blocks and require an Oldsmobile block (or, curiously 
enough, one of Ian Richardson's Wildcat cast blocks).  The extra row of 
head bolts go all the way through the rocker pedestals and shafts, 
through the heads and into bosses that protrude from the deck into what 
would be valley space on the Buick/Rover blocks.  These "extra" bolts 
are very long, but make all the difference as far as head gasket sealing 
is concerned.  OLds engines do not have the "tilted head" syndrome 
common to Buick/Rover engines.

IF you could bolt these heads to a Buick/Rover block, you would lose 
some compression.  Olds used a wedge type combustion chamber and flat 
top pistons whereas Buick used a hemispherical chamber and dished 
pistons.  You can use Buick/Rover heads on an Olds block. Hot Rod 
magazine did a side by side test of the two versions in 1961 and the 
technical description makes an interesting read. All Olds engines use 
the same pistons but compression was varied by using two different head 
castings, one type for high compression and another for low compression. 
You must cc your heads to determine which ones you have, 51cc or 38cc. 
All Buick 215 heads are the same. Compression varied according to the 
piston used.

Olds heads use different valves, valve springs, valve spring retainers, 
pushrods, rockers, rocker shafts and even a different route for bringing 
oil to the rockers.  Their valves are on the centerline of the cylinder 
bores as compared to the Buick/Rover valves which are slightly offset. 
This allowed Olds to use slightly larger valves for any given bore size. 
  The  valve stem diameter and length are also different.

I have one set each of the Olds heads, two Olds Jetfire blocks (larger 
main caps) and many sets of Olds rocker shaft/rockers and some special 
tubular pushrods.  Hammill says that Olds used pressed in cylinder 
liners.  I think he is wrong, but I intend to have a set bored out just 
to see.  It wouldn't be his only technical error related to US versions 
of the engine, but all seem very minor.

One other thing I need to check out are the lengths of the oil pump 
gears.  The oversized pump gears and spacer plates sold in this country 
for Buick V8 and V6 engines are longer than SD1 gears.  Hammill says 
they are SD1 size.  There may be some oversize pump kits sold in the UK 
that are that size, but the ones sold here are bigger.

Everyone but James probably quit reading three paragraphs back.

Kent K.

James Dean wrote:

> Kent,I respect your knowledge, as always, and have a head question. I 
> have a set of heads for sale on my eBay store, item# 4537403229, that I 
> thought were 215 Buick. Someone just informed me they were 219 Olds; I 
> believe F-85, so I changed the description. He told me they will bolt 
> ontoa 215 Buick, a Rover 3.5, 4.2, 3.9, 4.0, or 4.6; but it will result 
> in a loss of performance. Could you enlighten me further? I like to keep 
> my ebay descriptions accurate.
>        Also, you were right with your comment my P5B parts car probably 
> was the last one left with original factory air. I sold the system , and 
> on removal, found the evaporator was made by Smith's. I did photograph 
> it, in case anyone needs a reference; though I only had the body, no 
> engine  . James Dean
> ----- Original Message ----- From: "Kent Kinard" <kkinard at swbell.net>
> To: <rovernet at lyris.ccdata.com>
> Sent: Friday, February 17, 2006 9:34 PM
> Subject: Re: [ROVERNET - UK] 3500s head compatibility
>> Hi Peter (and anyone else contemplating a rebuild of a P6B engine)
>> You can have the heads for the cost of shipping.  I will never use 
>> them since I prefer the later two types, but it will be at least three 
>> weeks before I can ship.
>> General suggestions:
>> Use an SD1 block or have the early block and crank machined to take 
>> the SD1 type rear crank seal.  There are similar lip type seals 
>> available to convert the P6B front cover.  I have done this on Buick 
>> 300 V8 covers.
>> Use 9.35:1 pistons and run regular unleaded gas.  Install the cam 
>> bearings as per Des Hammill's instructions ( I'll send them to you you 
>> if you don't want to buy the book)and oil restrictors in the passage 
>> that feeds the rocker shafts.  This has been common Buick V6 practice 
>> for twenty years and it makes using a larger oil pump unnecessary on 
>> the street.  But,there can be NO wear in the oil pump cavity or on the 
>> gears.
>> Use the later Range Rover Cam (to '95).  It has the same lift and 
>> duration as the P6B cam but is slightly advanced. Use a true roller 
>> timing set. Install hardened valve seats.
>> Don't even think about using a block until you have checked the main 
>> caps for fretting.  If you can lift off the main caps with the bolts 
>> out they probably aren't properly registering in the block and the 
>> block is therefore junk.  After you are sure the main caps still 
>> register properly in the block make your final assembly using studs 
>> instead of bolts.
>> There has been a lot of discussion about head bolts, studs and stretch 
>> bolts.  Torquing steel bolts into aluminum castings invites stripped 
>> or pulled threads.  I use studs on the heads and studs are a must on 
>> two-bolt mains. Milodon makes head studs, main studs and true roller 
>> timing sets.
>> I've pontificated enough.
>> Roverly,
>> Kent K.
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