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1922
United Kingdom
549 Posts |
 Posted - 29 Nov 2011 : 21:32:22
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My Marathon engine you mean? 
Well it was mine, I've sold it since.
It's 1840 cc, about 130bhp, Holbay E128 cam, enlarged inlet points and matching inlet manifold. Very nice to drive with bags of mid range - I remember spinning the back tyres on a wet dual carriageway in 3rd gear at 60. I put wider wheels on it after that!
The Avenger pistons are used for the Swaymar engine - that is 1922 cc.
Don't actually need the liners. This has enlarged ports and big valves.
Got mine at Coltec Racing http://www.coltecracing.com/
Not in the car yet - it's still next to the telly!
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moditup
United Kingdom
83 Posts |
Posted - 29 Nov 2011 : 22:11:28
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Wow not seen that turbo charged engine build before, even after a internet search looks an expensive piece of kit and the work thats gone into it !
I do also have a standard fastback engine with dished pistons if this can be built to the same spec, dont fancy wrecking an original holbay engine (even tho seized) i know the cam will be different but i am sure i can get one from Coltec either reground maybe ?
What cc are the Avenger pistons or size i need to look out for, by the way i am trying to do this build with shallow pockets ! |
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1922
United Kingdom
549 Posts |
Posted - 29 Nov 2011 : 22:49:21
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Avenger 1500 pistons, 86.121mm bore.
If your pockets are shallow your best bet is stick with a 1725 - my Marathon cost me nearly £800 back in 1991. The 1922cc Coltec/Swaymar was a lot more money - and this doesn't include building the engine.
Standard engines can be converted to Holbay spec, new pistons, cam regrind and a lot of head work. This is expensive.
If your are on a limited budget I would use the Holbay head, flat top pistons, Holbay cam and the best block, crank and rods of your two engines to make one good one engine. Then chuck all the bits in the back of a car and go to see Coltec to see what you can get for your money.
The H120/GLS use bigger clutch (8.5 inch) but Mr Holbay himself (John Reid) told me that this was not necessary - the factory were just being cautious and you can probably get away with using the standard 7.5 inch clutch.
If you need a manifold and webers they appear on ebay every once in a while.
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moditup
United Kingdom
83 Posts |
Posted - 09 Dec 2011 : 19:05:22
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Is the hillman hunter 1500 engine the same has the avenger engine,
there is somebody selling pistons has a NOS set. |
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1922
United Kingdom
549 Posts |
Posted - 10 Dec 2011 : 09:31:37
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Nope - it's a short stroke version of the 1725 engine. Same bore but different crank and rods. Pistons are the same as the 1725 but with a flat top instead of dished.
They look like H120 pistons but those are 10mm shorter.
The Avenger enine was an all new design - daft as it seems to create a new pushrod engine for a car introduced in 1969/70 when the rest of the world was moving to overhead cam!
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Edited by - 1922 on 10 Dec 2011 09:32:19 |
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moditup
United Kingdom
83 Posts |
Posted - 10 Dec 2011 : 14:21:25
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| Just stumbled onto some info that to use the avenger pistons i also need con rods from an hunter 1500 engine ? |
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1922
United Kingdom
549 Posts |
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moditup
United Kingdom
83 Posts |
Posted - 11 Dec 2011 : 13:13:07
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| So in effect if i get hold of a hunter 1500 engine i could in effect also use the block to have a play about with obviously with change of crank/pistons. By the way thanks for all your help much appreciated. |
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1922
United Kingdom
549 Posts |
Posted - 11 Dec 2011 : 14:18:10
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Yup, if you can find one, it would get you a spare block and the rods you want.
The head (iron), crank and cam would make effective paper weights I suppose 
Speedy Spares list new Hunter 1500 rods for £5 each.
You'd better find out how much the head work and rebore, balancing etc will cost though. It might put you off the idea 
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moditup
United Kingdom
83 Posts |
Posted - 11 Dec 2011 : 15:24:38
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The block machining and balancing is fairly reasonable pricewise £25.00 per cylinder and around £200 for a full balance inc flywheel going off a local company (if there any good), its the pistons that are expensive tried Coltec but couldnt get through.
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1922
United Kingdom
549 Posts |
Posted - 11 Dec 2011 : 17:29:18
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The head work could be the killer.
For a 1922cc engine you will need the combustion chambers increasing.
You've got to do this even if you leave the inlet ports and valves standard.
Try Coltec again, I usually get through first time.
There is also Chris Draycott, has a good reputation but I've no personal experience.
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moditup
United Kingdom
83 Posts |
Posted - 11 Dec 2011 : 17:51:14
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I agree the head work is the most expensive i was quoted for the below.
1.unleaded head.
2.3 angle valve seats with larger inlet valves.
3.tig weld to head/re-skim (slight corrosion around waterways)
4.uprated double valve springs.
5.full ported head included chamber enlagment.
6.motorbike plug insert reducer (due to high compression)uses smaller bike plugs.
This little lot is a few pence out of £800.00 !!!! |
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arrocuda
United Kingdom
501 Posts |
Posted - 11 Dec 2011 : 18:17:01
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| Good Holbays are getting hard to find outside of buying a whole car these days.... so I started collecting Holbay bits a couple of years ago. 1922 is correct in that your best bet and most cost effective way is to try to find a good condition standard block and transfer your Holbay bits over. At least you'll know when completed that it's been done to a good standard. |
Edited by - arrocuda on 11 Dec 2011 18:30:29 |
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moditup
United Kingdom
83 Posts |
Posted - 11 Dec 2011 : 19:32:25
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| Quite agree with what 1922 has said, but its spurned me on to build a high spec engine, mine needs machining anyhow so it would only probaly cost the same has waiting for decent Holbay bits to turn up and build a standard spec engine, i will hopefully be posting a build in the next few weeks |
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bigt80
United Kingdom
1052 Posts |
Posted - 31 Dec 2011 : 19:06:42
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quote:
Originally posted by 1922
Hunter props are usually one piece.
The Sceptre, Rapier, Alpine & H120 and some Hunters are split with a UJ, bearing and rubber mount in the centre.
The gearbox itself is strong, they were also used in Ginetta G21 and the Jensen Healey (this had a 144bhp Lotus twin cam).
The end of the gearbox mainshaft where the gearbox joins the overdrive is thinner than the rest of the shaft. I found a small twist in the shaft on one of mine at the point that it connects with the overdrive. I put this down to dropping the clutch at 6000 rpm a few times and smoking the back tyres.
Since then I've driven thousands of miles with an 130bhp Holbay Marathon engine and had no trouble. Howard Johnson claims 160bhp with his H120 (I think he has nitrous) but I don't remember him reporting any gearbox trouble.
I'm hoping for 150bhp or more when I get my Rapier back on the road but gearbox, overdrive and axle will be standard H120/Hunter GLS.
Interesting thread: just a couple of minor notes-
Alpines used the 3.89 diff regardless of o/d or not, so longer-legged than Rapier, but due to different internal ratios did not quite have same gearing as H120; which had closer ratio box.
Split prop used with 'D' type o/drives to help cushion wiplash effect as 'D' types were known to be weak on mainshaft. When stronger 'J' type came in they went to one piece props. |
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H120 axle ID
