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post #1 of 12 (permalink) Old 09-27-12, 10:23 PM Thread Starter
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Cleveland 351 heads, Changing to Unleaded?

Hi Guys

If anyone read the intro section I'm new here and I've recently inherited my dad's F100 Custom.

A little background: The F100 was converted to a Cleveland 351 when my dad bought it has 4 valve heads with a mild cam and runs a Holley 650 4 barrel carby.
Back in 1995 or 96 I helped my dad recondition the engine ( i would have been 14 or 15) and I cant remember much except helping him carry the block and doing the valve timing.
I'm certain that we had the valve seats lapped but I have no idea if they are soft seats or hardened seats in the head.
She had done less than 5000k's since the rebuild and has only done about 20k's in the last 10 years. Still runs beautifully.

I would like to be able to run unleaded without the use of additives, So i ask Is there a way to tell whether the valve seats are hardened without pulling the heads?

And secondly, what would the impact of running an ethanol blend unleaded fuel in this old beast?

I'm definitely not a fan of ethanol in cars that weren't made for it, but it is a lot cheaper. (sadly not for my daily driver which gets 100k's less per tank)

Thanks, Roy.

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post #2 of 12 (permalink) Old 10-05-12, 06:45 PM
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Re: Cleveland 351 heads, Changing to Unleaded?

4 valve heads? If they are Arao Engineering can I buy it off you for 100 dollars?
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post #3 of 12 (permalink) Old 10-06-12, 01:03 PM
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Re: Cleveland 351 heads, Changing to Unleaded?

How old are the heads? After about 1978 or 79, all heads were built with hardened seats as far as I know.

As far as the ethanol blend, you may have to adjust timing and rebuild the carb with gaskets compatible to ethanol, but it shouldn't hurt the motor. You may notice a slight power loss, though.

Ever notice that there's so many high performance parts available for GM products?

Did you ever think that maybe they NEED them?
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post #4 of 12 (permalink) Old 10-07-12, 04:02 PM Thread Starter
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Re: Cleveland 351 heads, Changing to Unleaded?

Quote:
Originally Posted by Reverb View Post
4 valve heads? If they are Arao Engineering can I buy it off you for 100 dollars?
Hi Reverb, I'm gonna have to disappoint you, i wont be parting with the heads, sorry.

Quote:
Originally Posted by CatSkinner View Post
How old are the heads? After about 1978 or 79, all heads were built with hardened seats as far as I know.

As far as the ethanol blend, you may have to adjust timing and rebuild the carb with gaskets compatible to ethanol, but it shouldn't hurt the motor. You may notice a slight power loss, though.
CatSkinner

I couldn't say how old the heads are, The V8 world is beyond my experience, my forte lies with motorbike engines. Even though I do all my own mechanical work I've never had to touch the engine.

I think I'll just have to get a new gasket set and pull the heads off.

The question is once i get the heads removed, how to tell if the seats are hardened?

Roy.
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post #5 of 12 (permalink) Old 10-07-12, 04:26 PM
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Re: Cleveland 351 heads, Changing to Unleaded?

Good question, so I went looking for answers, some actually say that you can't tell if they're done right. However, some also claim that you might be able to see a seam on the edge of the seat or by looking down the bowl to the valve port. A hardened seat has to be pressed into the head and the metal will be different.

If the heads show sign of having been worked on (lead seal on the ports remade), odds are the seats are hardened. Also, if you can get a stamping that will indicate a year, that may also tell you.

Ever notice that there's so many high performance parts available for GM products?

Did you ever think that maybe they NEED them?
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post #6 of 12 (permalink) Old 10-07-12, 05:48 PM Thread Starter
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Re: Cleveland 351 heads, Changing to Unleaded?

Thanks for that, a few good points there that i'll have to check.

Roy
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post #7 of 12 (permalink) Old 10-15-12, 05:54 PM
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Re: Cleveland 351 heads, Changing to Unleaded?

Are they really 4 valve heads or 4V heads?
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post #8 of 12 (permalink) Old 10-16-12, 01:11 PM Thread Starter
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Re: Cleveland 351 heads, Changing to Unleaded?

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Are they really 4 valve heads or 4V heads?
Hmm... now you've got me questioning my memory.

When i get the time i will inspect under the rocker covers.
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post #9 of 12 (permalink) Old 10-27-12, 11:49 PM
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Re: Cleveland 351 heads, Changing to Unleaded?

the 4V stands for 4 Venturies in the carburetor as delivered from the factory. major difference between the 4V and 2V heads is the size of the ports. her you have 4V, 2V & Windsor

all are 2 valves per cylinder

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post #10 of 12 (permalink) Old 10-28-12, 06:02 AM
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Re: Cleveland 351 heads, Changing to Unleaded?

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the 4V stands for 4 Venturies in the carburetor as delivered from the factory. major difference between the 4V and 2V heads is the size of the ports. her you have 4V, 2V & Windsor

all are 2 valves per cylinder

I'd never heard of 4 valve heads for a Clevo before, but that's what you said, so I was just wondering.The hardend vs unhardend is a leaded/unleaded thing, not ethanol related, and doesn't seem to be a big problem at least not compared to the early predictions. Have had burned ex valves in my 302C, but don't know if that because of the no lead or what. Ethanol mainly affects rubber hoses, gaskets & such, unless in high concentrations
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