Harv's Repco HighPower crossflow head thread

Includes fuel system, cooling system and exhaust.

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FireKraka
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Re: Harv's Repco HighPower crossflow head thread

Post by FireKraka »

I bet you can't wipe the smile off your face Harv
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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

FireKraka wrote: Wed Mar 30, 2022 11:04 am I bet you can't wipe the smile off your face Harv
smiling.jpg
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Cheers,
Harv
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Re: Harv's Repco HighPower crossflow head thread

Post by BS »

How good!!


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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

Thinking a little more about the cooling for both the meth monster project and the FED. Real estate is going to be sparse at the front of these engines, so need to use my noggin and plan.

The meth monster will see mostly drag use, but will be street registered (just…). It needs some form of cooling system. It will run on methanol (runs cold), but also petrol (runs hot). Some form of radiator, a fan (somehow… don’t like electric if I can avoid it) and the standard water pump. I’ll run one of the improved-cooling head gaskets. The original Repco guidance notes:

When the engine is installed horizontally in special chassis a small additional water outlet pipe from a hole drilled in the head adjacent to the rear most head-bolt on the exhaust side is essential to prevent the formation of steam or air pockets. The normal water pump is quite satisfactory and should be run at normal speed with no restriction plate as is sometimes thought to be necessary.

It’s likely that I’ll use the original Repco head for this one. It has been drilled for two additional water outlets drilled midships, as per the blue circles in the diagram below:

Repco cooling.jpg
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The water outlets at the front and rear of the head (purple and green circles) have been blanked off with ally plates. This setup (two additional holes midships) is not quite what Repco indicates above (one additional hole aft, as per the red circle) but should be OK for this setup. When it’s up and running I’ll run an IR temperature gun over the head, and see if the cooling is relatively even. Can add an additional cooling hole to the rear (red circle) relatively easily.

The FED will have no radiator. Plan is to use the traditional process and fill the block with water (no glycol). The front water outlet (purple circle) gets a radiator neck and cap, with the overflow going to a catch-can. Prior to a run, the motor is warmed up (to 160-180C), then the water around the block used to absorb any heat during the run. After a run the block is allowed to cool, with some people draining the block and flushing with cold water to bring temperatures down (gently, to avoid cracking). This should be fine, as the engine only runs for 12 seconds at a time (scary… the crank only turns 1000 revs per run), give or take a little staging time.

What has got me a little cautious though is that the FED will get the reproduction head, which is ally. I suspect it is going to be more susceptible to temperature changes than the cast iron heads. A little worried about ending up with more cracks than a plumbers convention. Whilst I’m not running a radiator, I’m wondering whether I should retain the water pump and at least circulate the block/head. This will help to keep temperatures even, though comes at the cost of having to run the pump. Perhaps run the thing with the pump belt off as a test, and see if there is much difference.

Cheers,
Harv
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Re: Harv's Repco HighPower crossflow head thread

Post by BS »

Have you looked at an elec water pump at all? I initially ran the mechanical water pump on the grey ghost with an electric pump to help cool it/circulate water when it was not running back in the pits. I have since converted it to purely elec water pump as it made the mechanical pump redundant. Penrite also make a coolant race inhibitor which is glycol free. Not necessary but I’m running an ally radiator so wanted the extra level or corrosion protection. Might be worth considering if you are running an ally head?


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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

Trying to avoid an electric pump... the stubborn part of me keeps trying to make this thing (relatively) era correct.

Good idea on the coolant though. Between the methanol in the carbs and an ally/iron mixture at the head/block, the corrosion potential is high.

Cheers,
Harv
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Harv's Repco HighPower crossflow head thread

Post by BS »

Makes sense if youre doing what you can to keep it period for sure.


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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

Before I get too serious pulling bits off the Repco head, I figured I should get a set of gaskets. After much ringing around, I have realised that HighPower gaskets are like rocking-horse poo.

Once upon a time, ACL did the gaskets as a valve regrind set (VRS), part number PBB2042:
ACL Gaskets PBB2042 VRS set to suit Repco head 2.jpg
ACL Gaskets PBB2042 VRS set to suit Repco head 2.jpg (124.16 KiB) Viewed 940 times
ACL Gaskets PBB2042 VRS set to suit Repco head 1.jpg
ACL Gaskets PBB2042 VRS set to suit Repco head 1.jpg (119.56 KiB) Viewed 940 times
ACL are long out of business, and the tooling was scrapped.

The gaskets are however being reproduced by Terry King:
Dominator Engine Reconditioning and Sales Pty Ltd
1/6 Scallop Street
Huskisson, NSW 2540
0405479906
Repco crossflow head gaskets.jpg
Repco crossflow head gaskets.jpg (1.23 MiB) Viewed 940 times
Terry does not make the cork sideplate gasket, but a standard GMH one (with the top cut off and a bead of silicon along the top) will do the trick (Permaseal KV171, Rare Spares H1081).

Cheers,
Harv
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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

So knowing that the Repco head has to go onto another motor, I figured it was time to bite the bullet and unbolt it from the speedcar block. There is a real sense of unease pulling apart a working motor, and worse when the bits are not exactly common. Was worried a few weeks back about the head gasket. I reckon the head will have to come on and off a few times, so the head gasket will end up shagged. I’ve since managed to source some replacements (see last post), so all good on that front.

Rocker cover off, and evident that some of the rocker post studs have been replaced. No big deal.

Rocker cover off.jpg
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The rocker mounting blocks are nyloc nutted, though for some reason one had a split washer too. Mixed fasteners are becoming a signature on this thing. One rocker post (inlet side centre) is way bigger (3/8-16UNC) than the others (5/16-24UNC). Must remember to ask the Repco gurus if this is normal, or if someone has stripped and oversized the head. Appeared be a lot of sideways travel of the rockers along the shafts… perhaps the shaft spacers have been mismatched. The oil crossover was funky… some brass pipe (normal) and plastic compression fittings (not so normal).

plastic oil fitting.jpg
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There should be an ally block and bracket behind the sideplate to mount the oil feed line. Mine has been replaced with a pigtail. No drama, just different:

Curly oil pipe.jpg
Curly oil pipe.jpg (671.75 KiB) Viewed 836 times
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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

The rockers cover the head studs on the inlet side, so cannot remove the head with the rockers in place.

Those headstuds cannot be gotten at.jpg
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The inlet rocker shaft came out OK, but the exhaust hung up. The rocker post closest to No. 1 exhaust was tight… because the rocker post stud, which had been replaced, was poorly sized. Fight the stud out, Remove the rockers, then finally get to the head studs.

The stuck rocker mount stud.jpg
The stuck rocker mount stud.jpg (664.53 KiB) Viewed 835 times

Off with his head.

The open bores showed flat top pistons, with some half-moon shaped reliefs cut for the valves. The reliefs are only shallow, as expected for a flat top. So far, so good. Was running short on time, so didn’t run a bore gauge into it. Forgot to take a photo too.

With the head on the bench and sitting on some head stands, it was time to have a look see at the head. Hmmmm… ally retainers. Unusual, but standard kit for the Repcos. Valve tips have been ground, so spring tension has probably been set well. Find the spring compressor, pull the collets and out with the double valve springs. Some of the valve spring seats have shims, so again looks like the head has been built properly. Valves, retainers and collets back in to check installed height. Hmmmm… some of the retainers are a little sloppy, probably where the collets have started to eat the ally. Valve stem installed height not so even with the sloppy retainers either.
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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

Squeeeeeeze.jpg
Squeeeeeeze.jpg (667.29 KiB) Viewed 834 times

Valve stem installed heights inlet and exhaust measured from outer spring seat to tip of valve:

Valve stem installed heights.JPG
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No. 1 inlet was measured with a 0.030” shim in place.
No. 3 inlet was measured with a 0.040” shim in place.
No. 3 exhaust was measured with a 0.030” shim in place.
No. 4 inlet was measured with a 0.035” shim in place.

I checked the valve spring pressures over the weekend. My tester is an old one (uses a torque wrench), but is close enough for this rough check. Because my installed heights had so much variance, I used 1.28” as the installed spring height for the inlets, and 1.36” for the exhaust (note that spring heights are smaller than valve stem heights tabled above). Results below in lb:

Valve spring installed pressures.JPG
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A fair bit of variance, but more of a worry is that the values are low. I’ll need somewhere around 120 lb of seat pressure.

Methinks new retainers are in order. Measured valve springs, and will order some new steel retainers from Performance Spring (part number RET G1260).

Plan is to get the retainers (and perhaps new collets) in place, recheck valve installed height then recheck valves. New retainers will likely be a different height, so will have a different seat pressure.

Random photos I forgot to post earlier:
Valve springs (or at least half of them)

Valve springs.jpg
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Pushrod:

Pushrod.jpg
Pushrod.jpg (503.97 KiB) Viewed 834 times

Cheers,
Harv
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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

Some info on the ET G1260 retainers I am thinking of using. They are meant for a normal-headed grey motor with double valve springs:

Retainer OD: 1.250” (Repco ones are similar if not identical)
Outer spring inner ID: 0.975” (my Repco ones are 1” – this would give 0.0125” spring pocket clearance if I reuse my springs)
Inner spring inner ID: 0.700” (my Repco ones are 0.78” – this would give 0.040 spring pocket clearance if I reuse my springs… a little high, but perhaps not intolerable)
Stem diameter: 11/32” (same as the Repco valves)

Contact:
Performance Springs
Allen Waye
Telephone: (07) 3807 3882
Email: allenw@performancesprings.com.au
Address: Unit 4/13 Commerce Circuit Yatala Qld 4207

Cheers,
Harv
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Re: Harv's Repco HighPower crossflow head thread

Post by Errol62 »

Heady stuff this Harv. Boom boom. I’m surprised at the parts you can find. Cool as mate!


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Re: Harv's Repco HighPower crossflow head thread

Post by In the Shed »

Interesting Harv,

After what you have found you might be a little more comfortable you did indeed have a peek inside?

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Re: Harv's Repco HighPower crossflow head thread

Post by Harv »

The Repco heads are reknowned for being either porous or cracking. This one leaked water, and was "Loctite'd" back in the 80's. I assume this is done using this product:
https://www.eis.co.za/index.php?route=p ... ct_id=3151
Not sure if Loctite even make it anymore, but will contact them too.

Anyhoo, I really need to clean the head up. Needs the paint off it, muck out of the water passages, and grime off. I would normally give it to a machine shop to do, but am wary of stuffing it in the process. I assume the Loctite is some form of epoxy, and impervious to fuel and warm water. Not sure how it would handle caustic or acid if the machine shop decided to clean that way.

Anyone had any experience refreshing a Loctite'd head please?

Cheers,
Harv
327 Chev EK wagon, original EK ute for Number 1 Daughter, an FB sedan meth monster project and a BB/MD grey motored FED.
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