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I’m pretty sure you’ll need the larger combustion chamber and the spring diameter would be based on whatever Comp Cams recommends but I notice all of Trick Flow’s 351C heads are out of stock! Since you don’t know your piston specs, I’d have your engine builder measure the volume of your current combustion chambers, just to be safe. Do CHI or Scott Cook have heads that might work for you?

The best way that I know of is to measure the CC volume of the area between the top of the engine deck and the piston.  Add the volume of the head gasket and the volume of the head chamber that you wish to buy and plug it all into the CR calculator formula. I do this when I mock up an engine to check static CR.

I find the TDC and then drop the piston into the hole one inch.  I add grease between the piston and the cylinder to keep the measuring fluid from oozing out then use a piece of plexi glass with grease on it.  I then pour light oil into the the volume with a burette thru a hole in the plexi glass so it can be measured by CC.  Don't forget to calculate the volume of your cylinder 1" tall and subtract it from the total CC you just poured in.  This if done accurately will give you the cylinder CC taking into account and piston dish and position of the top of piston as it relates to the top of deck.

Hope this makes sense.....

Please leave politics at the front door. Thanks!

Have you tried some of the smaller online  companies? eBay, Racing Junk, etc. You might find a pair but you will need to know what you want first.

BTW, I have Edelbrocks on my all aluminum Clevor. After some port and chamber work they flowed very well and everything fit nicely. Very happy with the quality.

Good luck.

I emailed Mark Connor at CHI and he told me this:

They take about 10 days to go thru the process from casting to finished heads.
We can airfreight them direct, last pair was to NC and shipping cost was $548 AUD. Cylinder head price to supply direct from here is $1708.00 each AUD.
There would also be US tax and possibly duty payable on arrival before US customs release them.

-
That's about $2900 US shipped which isn't bad.

But I'm not even that patient. I bought this thing a month ago and want to DRIVE the thing!

I think Larry Stock at Pantera Parts Connection (www.panteraparts.com) in NV still has an unused NOS pair of aluminum Ford/SVO A-3 heads at his shop. These were pro racing Cleveland heads in the '80s and were quite popular until Ford stopped supplying nearly all Cleveland parts decades ago. The A-3s were the largest port volume (but still smaller than any iron heads), with 2.19" intakes & 1.73" exhausts. They feature relocated ports, Boss 351 architecture and use a specific open plenum 4bbl intake or Weber/EFI. Good luck.

@bosswrench posted:

I think Larry Stock at Pantera Parts Connection (www.panteraparts.com) in NV still has an unused NOS pair of aluminum Ford/SVO A-3 heads at his shop. These were pro racing Cleveland heads in the '80s and were quite popular until Ford stopped supplying nearly all Cleveland parts decades ago. The A-3s were the largest port volume (but still smaller than any iron heads), with 2.19" intakes & 1.73" exhausts. They feature relocated ports, Boss 351 architecture and use a specific open plenum 4bbl intake or Weber/EFI. Good luck.

I am running A3 heads and if you can get a set, highly recommend them. There are only two intakes for them though.

The M331 single 4 "Torker" and Halls High port Weber manifold.

I tried both and stayed with the Webers.



If you go that route, be advised that the exhaust ports are raised about 1" and the bolt pattern for the exhausts is a little different then the iron heads.

You would be bolting on an easy 30hp gain over the best iron heads. The intakes flow 330 out of the box so you need a 600 lift cam with them and 2" primary tubes on the headers. I went with 180's on those.

The combination of the heads, induction and cam change is likely closer to a 150hp gain.



If you can get the A3's, go for it.

I noticed a guy selling a set of closed chamber iron 351C heads on eBay. That might be a good option, for a mostly stock engine. If I recall, closed chamber heads give approx. 1-1/2 points higher compression than open chamber heads but are less likely to detonate because of the better combustion chamber.

I don’t see the value in SVO heads unless they are cheap or you are into nostalgia. I run modified C302B’s but I’m the first to admit, technology moves on! The current offerings from companies like CHI and Higgins are superior in every way.

Last edited by davidnunn

If you don't need to save 65 lbs off the Cleveland engine weight w/aluminum heads, +15 more from an aluminum intake & 10 more from an aluminum water pump (100 total), there are some sets of Australian 302 Cleveland iron closed-chamber heads floating around. They were never sold in the US, look like 2V- port-size 351 heads as used on their Falcon 302 V-8, with slightly smaller valves. Work very well on street engines.

As mentioned, the SVO heads relocate the exhaust ports 1-1/2" up and 3/4" back towards the deck lid so there are fitment issues with bolt-ons like headers, header-to-fuel-tank clearance and some 4bbl air cleaners to the deck lid. The SVOs used two different header bolt patterns, too. The iron 302 Cleveland heads had zero fitment problems. Larry had some of these, too.

@jmardy posted:

Agreed!
I got the feeling that the SVO heads are in the "if you have to ask how much they are, you can't afford them" category.
And I asked how much he wanted for them.

He wouldn't say.

Those heads are not gold bars. They are worth basically what any set of BARE aluminum heads are going to be.

That should be about $1,200. BARE!

I got mine for $450. They came off a circle track race car.

We can debate all night about which are better but the best offering the Australian heads can offer is their jewellery appeal. The Australians don't know any more then we do here.

If the A3's are junk then explain to me why so many are looking for them?

Last edited by panteradoug

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