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merlin heads ID

General engine tech -- Drag Racing to Circle Track

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prairiehotrodder
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merlin heads ID

Post by prairiehotrodder » Sun Feb 09, 2020 5:00 pm

i just bought a set of World merlin BBC iron heads. I bought them second or third hand but they have never been used. I'd say they are older castings that have sat around for a number of years. The casting numbers do not jive with the current merlin heads on the website. I'm hoping someone here can tell me more about them.

They are cast 1-043D which is the 269cc oval port head
They have 2.19 / 1.88 valves 3/8 stems
double springs 1.51 dia.
stamped on the end 30645 (this is the number i can't figure out)
also cast in is "Bill Grumpy Jenkins"
stamped 6-3004
and one head is stamped 901041 and the other is 812302

Also they were wrapped in green sticky wrap like is used at a machine shop so i wonder if they were maybe purchased bare when new ? Unless World wraps them in that stuff ? Maybe somebody has an old catalog ? The 30645 should tell me everything i think
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PRH
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Re: merlin heads ID

Post by PRH » Mon Feb 10, 2020 9:51 am

I don’t mean to sound like a smart ass....... but if you have the heads in your possession....... what info would you get from a catalog that you can’t get by just checking the heads out?

I can offer this tidbit though......
On a pump gas 496 with a Dart single plane intake, 850dp carb and a Comp 292H cam.......
Bowl blended factory big ovals with 2.19/1.88 valves made more power than bowl blended Merlin ovals.
Somewhat handy with a die grinder.

pdq67
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Re: merlin heads ID

Post by pdq67 » Mon Feb 10, 2020 11:45 am

I want to say that my bought new from Summit Merlin cast-iron oval port 2.19"/1.88" heads have something like, "010", (or some such), very lightly stamped on one end..

I figure it meant, "oval", is all?? I got them back about 2001 or 2 or so. I think back then they might have 261 cc instead of 269 cc chambers, but don't know for sure. Don't know when the 269 cc chambers came out.

If I had it to do over, I would have bought the Merlin, "VR", heads with 290 cc oval intake ports.

I don't know if they are even sold anymore??

Oh, and btw, I bought them because a local guy said that if I had my good -781 heads redone, that it would take a lot of time and cost a lot of money! To me, cheaper to buy the Merlin's then to deal with him..

pdq67

prairiehotrodder
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Re: merlin heads ID

Post by prairiehotrodder » Mon Feb 10, 2020 11:58 am

thanks guys. I got these heads for $1200 canadian dollars, rebuilding a set of 781 heads recently cost me $1800 so it seemed like a good deal. These heads came with a dual spring so i'm thinking they were setup for a hyd roller cam. I'm using a small comp flat tappet thumper cam so i changed out the springs. I see on the merlin website that the new heads come with 2.30 intake valves and mine have 2.19 so they must be an older model. I think they should work fine for what i'm doing.
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Re: merlin heads ID

Post by PRH » Mon Feb 10, 2020 12:06 pm

The earlier heads had 3/8” valve stems....... newer ones are 11/32”.

That test we did would have been about 20 years ago, with whatever the current Merlin ovals were at the time.

It wasn’t an intentional test.

I reworked the stock heads, and while on the dyno the engine developed a misfire.
Upon pulling the plugs during the trouble shooting, water came out of one cylinder.

Pull the heads and pressure tested them and had a leak coming out from behind one exhaust seat.
Out of curiosity I removed the seat, since I was sure it didn’t break through when machining the seat pocket.

There was no hole...... just some invisible porosity.
The air bubbles just emanating right through the casting.

Rather that screw around with another stock head, we just put the new Merlin’s on.
And we were pretty surprised when the motor was making less power with the new heads.
Last edited by PRH on Mon Feb 10, 2020 12:16 pm, edited 2 times in total.
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Chris_Hamilton
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Re: merlin heads ID

Post by Chris_Hamilton » Mon Feb 10, 2020 12:06 pm

Seems to be a fair bit of discussion on them around the web. Maybe it'll help.

https://www.google.com/search?q=Grumpy+ ... irefox-b-1

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