Holbay

[dodgealpine]

Just bought a Holbay1725 engine, bottom half, for £87! Rebored to 1789 (+0.060). Going to refurb it with my big valve Holbay head. Going to be busy. Just had to tell someone!!!!

[nickbrad]

Great bargain, piccies always help to rub it in

[Davenger]

Nice one, top work!

[dodgealpine]

Heres some pics as requested:-



Shown some of the sparkly bits I've refurbed & chromed. Will be stripping the block for inspection & cleaning. will keep you posted as I go on.
dodgealpine.yolasite.com

[dodgealpine]

Well started to do a few checks, the pistons come out as 0.003" variation on height, pretty good.Did a bit of stripping got down to the timing chain sprockets. They were a tooth out so the engine was probabaly running rough after its last rebuild.
I bought new sprockets & chain about 6months ago on ebay for a tenner Bonus!

[dodgealpine]

Got it painted, looks good, couldn't resist trying some goodies on. need to get it on the bench then I can check the bottom end.

[dodgealpine]

Well, fit new front plate, new timing sprockets & chain then got some bits back from chroming

All new gaskets fitted with blue hermatite, Also fitted a new sump & polished water pump. things going well. Any comments?

[dodgealpine]

Managed to fit the modded inlet manifold & Solex sidedraught carbs.


Just a few probs, head bolts 3mm too long, no backplate with the water pump. Thinking of getting the rocker cover annodised red, have to price it up.

[dodgealpine]

Bits comming in slowly, red rotor arm fitted, chrome fan tried on & core pluks arrived today. Will pop the old ones out & clear any blockages in the water ways - Fun!


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[nickbrad]

Looking very tasty, should be all sorted and ready to rock the last days of summer at this rate or are you planning on installing over winter ready for next year?

[lemansvk]

I have a question about Holbay heads. How different are they to standard alloy heads? Is it just the combustion chambers, or does the port size differ?? The reason I ask is that a friend with a Hillman Hunter Royal 660 (alloy head, twin Stromberg engine) has just arranged to buy a set of twin 40 Webers on the Holbay manifold and wants to know if he'll have any fitting issues.

Thanks, Vic

[dodgealpine]

The Holbay head does have different 'kidney' shaped chambers, but also smaller inlet ports, to aid smoother tickover for the GLS & H120. I enlarged mine to match. They also have nimonic ex valves to cope with the higher temperatures of the higher compression. The webers & manifold should fit nicely.

[lemansvk]

Thanks. So I guess that means he will have to enlarge the ports in the manifold to match the stock head. Is there much difference in size? Hopefully there's enough 'meat' in the manifold.

Cheers, Vic

[dodgealpine]

The manifold should be the same size ports as the standard head, It was the ports on the Holbay head that were smaller. Weird I know!

[dodgealpine]

Waiting for bits for my rebuild so went back to an earlier project, forced induction. Made the airbox from some stainless, cant fit the electric fan unit yet so am using a free flow filter I bought at Tatton park - £ 3.00 Bonus!!