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1600 cylinder head chambers


Gadgetman
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OK I'm confused.... I have 2 1600 cylinder heads and the chamber shape differs on both. The first one has a defined straight port edge and the other is more scalloped out, also one has a lot more land around the plug thread than the other????

The first one  with the defined straight edge of the chamber has 28cc volume and the other 24cc

I would have thought the second is the better head due to chamber shape and volume, any thoughts????

I see in the parts book there are 2 heads specified, early engines and late engines, I assume these are the two of them and the second may have been skimmed!

head 1.jpg

head 2.jpg

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 from the back of the grey matter my   64  HB 19***  1600 had the lower version

the  8.75 CR   change was  upto   HB16301  used head 511122    from HB16302 used  512837

as usual theres no clues in the Spares or WSM about chambers 

just what changed  ????   the low compression was 7:1  that might be the upper one , but really only for export to low octane territories . so where did that come from  ???

daves the best bet on this 

do use HD nuts and washers on refitting to avoir distortion and torque loss.

 

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So with these chamber sizes the first one gives an approx compression ration of 9/1 and the second 10/1

C.R. = (V=C)/C = swept volume of the cylinder in c.c. and C=total chamber volume in c.c.

so for the 1600 engine V=1600/6 = 266cc

Therefor C.R. = (266+C)/C

With a head gasket and block an extra 4.5 cc is added to C so head 2 C= 24+4.5=28.5

Therefore head 2 has a cr of (266+28.5)/28.5 = 10.3 / 1

head 2 works out to (266+28+4.5) / (28+4.5) = 9.1 / 1

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The cylinder head was reworked and the  distributor was changed to a Delco-Remy D202 at Engine number HB16302, late 1963, which gave less advance and was due to a reshaped of the combustion chambers in the cylinder head to improve the combustion. This was similar to the work carried out on the Vanguard Six engine prior to it being fitted into the Triumph 2000 Saloon.

Dave

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maybe not  my 64 had the shallow head chambers and solex , fitting the strombergs  certainly ups the response 

think the strom's  upgrade was well after the head change .

and 1600 stroms dont have a damper spring but a heavy diaphragm weight

mine would howl up with the 631 and std 1600 needles ,  other needles (few) were hopeless

made a wonderful  crisp sound to die for ...i miss her .

Pete

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On 01/05/2018 at 2:48 PM, Gadgetman said:

So with these chamber sizes the first one gives an approx compression ration of 9/1 and the second 10/1

C.R. = (V=C)/C = swept volume of the cylinder in c.c. and C=total chamber volume in c.c.

so for the 1600 engine V=1600/6 = 266cc

Therefor C.R. = (266+C)/C

With a head gasket and block an extra 4.5 cc is added to C so head 2 C= 24+4.5=28.5

Therefore head 2 has a cr of (266+28.5)/28.5 = 10.3 / 1

head 2 works out to (266+28+4.5) / (28+4.5) = 9.1 / 1

Did you allow for the over piston volume and the volume of the gasket as I think you will find that will drop the comprestion ratio down from 10.3 to 9.5:1. You don't realy want a CR that is over 10:1 unless you are using AVGAS / 100 Oct fuel.

CR= (C+S)/C            

C=Clearance volume - which is chamber+ Gasket + Over Piston          

S=Swept Volume - (Bore/2)XPISquared X Stroke

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Algy,

I think you are a little severe in how high is a tolerable CR.     I use at a CR of 10.5 on Shell V-power at 99RON, a lot easier to get than AvGas .  A previous engine, I allowed to get to 10.9, and when installed and first run, it pinked!  But that was on a tank of old fuel.   A fill-up with fresh and it never pinked again.

JOhn

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Hi Pete,

Just had my pal around, to him there are some bits that are very much the same but a fair amount that is completly different (mainly in measurments and floor area), his was on a Burlington plan chassis. Typical though he has sold his last year, so will not get the side by side shot now until it is finished and take the car to a show (I don't do shows very often).

John,

Yes you are right 99 RON may just about be okay as long as you keep the fuel fresh. But unless you are using the car for competion the extra you get from the higher CR is, to me, not worth the extra strain on the engine and the loss of driverablity in hot weather and cost of fuel; lets face it most of us will be driving the cars in slow modern traffic and even if we tuned the car to an inch of its life, still would not keep up with a hatchback in the trafic light drag race. But a fair point anyway.

 

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I am only going on my experiance.

BSA 250 not good until dropped CR to below 10:1, wifes was okay just needed retarded ingnition but hers was a 9.75:1.

BRM Lotus Elan with 10.2:1 CR ran bad no matter what we did with ignition but loved high Octane fuel at race track or Octain boost added, converted to standard Lotus head and was driveable on public road and in trafic.

I supose it depends on the engine and the freshness of the fuel. It sounds likeTriumph engines are more tollerant, from the coments on here, can't think why though.

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and a steel shim Head gasket is used on the 1600  not a thick copper or such  and as with any triumph head be it 3/8"  or 7/16" studs  hd washers and  hd nuts to take the torque anything normal will strip and the washers deform.

Pete

 

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