[ignaro]

After a long coronavirus delay, my heads finally arrived. I know the speedmaster heads get a lot of hate around here but I didn't see a lot of evidence to back that up. The price is hard to beat!

I'm going to check the valves for leaks and don't see any problems out of the box.

I also got their single plane intake as part of a promotion and am debating between that and a used Edelbrock Performer RPM I have.

They're going on my 461 short block with dished pistons, a Barry Grant 950 Demon and Craigslist headers. I've got a super T-10 for now, I'll get a TKO600 when I break that!

--
My question is : if my cylinder bore is 4.155 and the combustion chamber measures the same, do I want the 4.16 Cometic gaskets that fit better or the 4.3" that were recommended to me by the sales guy? Seems silly to go bigger, right?

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[blueghoast]

Originally Posted by ignaro

After a long coronavirus delay, my heads finally arrived. I know the speedmaster heads get a lot of hate around here but I didn't see a lot of evidence to back that up. The price is hard to beat!

I'm going to check the valves for leaks and don't see any problems out of the box.

I also got their single plane intake as part of a promotion and am debating between that and a used Edelbrock Performer RPM I have.

They're going on my 461 short block with dished pistons, a Barry Grant 950 Demon and Craigslist headers. I've got a super T-10 for now, I'll get a TKO600 when I break that!

--
My question is : if my cylinder bore is 4.155 and the combustion chamber measures the same, do I want the 4.16 Cometic gaskets that fit better or the 4.3" that were recommended to me by the sales guy? Seems silly to go bigger, right?

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I would go with the 4.16 one's myself. I'm still waiting on my heads.

GT.

[lust4speed]

Very pretty heads.

I'd go with the FelPro 4.3". We've had a few engines where the block's deck finish was within the guidelines and the Cometic's still seeped a few drops of coolant. To me they are a little unforgiving. As far as the pure math, 4.3 - 4.16 = .014 difference in diameter which means about .007" difference around the rim. Pretty much filled in and smoothed over by carbon by the time the break-in is completed.

[Joe's Garage]

Unless they've changed they way they calculate using that 'new' math they teach over there in Kommie-forn-eye-aye......

Probably the same way your legislature balances their budget.

My vote would be for the 4.16 gaskets, presuming the surface finishes are correct.

Plus: 2x on the pretty heads!

Good luck!

[ignaro]

Oh man, I learned to carry the one like the rest of the Reagan-kids but the new grouping bull**** they teach kids is way better!
As an adult, if you wanted me to carry the one, I'd tell you to eff off. But making tens of it thousandths and triple it, I can do that! Thank goodness for progress!

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[ignaro]

Originally Posted by lust4speed

Very pretty heads.

I'd go with the FelPro 4.3". We've had a few engines where the block's deck finish was within the guidelines and the Cometic's still seeped a few drops of coolant. To me they are a little unforgiving. As far as the pure math, 4.3 - 4.16 = .014 difference in diameter which means about .007" difference around the rim. Pretty much filled in and smoothed over by carbon by the time the break-in is completed.

Oh that's a good point, thanks. Forgive my ignorance but why would the tighter bore size make it more prone to leaking coolant?
Thanks!

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[Mike Davis]

I'd go with the Felpro 1016. Had too many issues with the cometics on street cars if the surface was not perfect. I run the 1016's on my 66 race car and never had a problem @ 12:1 and even driving it on the street a bit. I got a pair of the Speedmaster heads but have been sidelined with other projects and haven't been able to complete my 421 build with them. My looked great out of the box.

[i82much]

kinda funny. i blew a fel pro head gasket on my street car, switched to cometics and have not had a problem - even reused them after having the heads off several times.

ya just never know i guess. i am not making a recommendation, just giving my experience. hope it works out great!

[Steve C.]

Is the single-plane intake shown the 'same' as the Hurricane/Tomahawk Intake others sell ?

https://butlerperformance.com/i-2445...tegory:1234847

Years ago I bought a Tomahawk intake when they first came out. On mine I found the intake ports as cast had small port openings for marketing reasons so they could be used on all cylinder heads, including stock iron heads.
They took quite a bit of port work including runner blending to match my Edelbrock heads with taller ports.

.

[ZeGermanHam]

No questions from me, but I am very curious to hear how they work out on your 461 build once you get everything together, since I will be building a 461, too. I've been impressed by much of what I've read about the Speedmaster heads so far. It's good to have options when it comes to Pontiac speed parts.

[ponjohn]

What camshaft are you using?

[Steve C.]

I went to the website, answered my question. A Tomahawk copy intake.

.

[lust4speed]

Well I blew that math problem, hopefully the spirits of the nuns that taught me don't come back to haunt. Yes .070" diameter and .035" around the circumference. Cometic gaskets require a particularly smooth finish. The finish of the block needs to be very smooth at 50 RA or finer and some shops just can't reach that finish. I haven't the equipment to measure the finish the shops provided, and not sure if too rough of finish wasn't the problem with weeping. Only thing I run Cometic's on is my aluminum block drag engine and only because FelPro doesn't make that large of gasket.

Check port alignment on the clones. Had a dual plane clone and it was far enough out that we couldn't correct it. Looked pretty until you through an intake gasket on it, then the ugly came out.

[Joe's Garage]

The .140" larger diameter split in half would give you .070" on each side.

To end up with .035" you would have to split in in half twice. The 2nd split is not needed.

But back on subject: It will be interesting to see how well these new heads perform and hold up. More aftermarket parts is better for all of us Pontiac addicts!

(fingers crossed for everyone who has bought them)

Good luck with the build.

[NeighborsComplaint]

How many cc's dish in your pistons and what is your SCR with those 72cc heads
?

[Formulas]

What does the oil drain back provisions look like ?

Also can 1.65 rockers be used without any work ?

[ignaro]

Originally Posted by Formulas

What does the oil drain back provisions look like ?

Also can 1.65 rockers be used without any work ?

I don't know how to check! Can you tell me how to check the oil drains?
My rocker studs are on their way, I have comp 1.5 Rocker arms, I'll measure how much room there is once I get them installed!

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[ignaro]

Originally Posted by NeighborsComplaint

How many cc's dish in your pistons and what is your SCR with those 72cc heads

?

25cc dish, gives me a 9.9:1 compression ratio

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[ignaro]

Originally Posted by ponjohn

What camshaft are you using?

Comp xr288hr hydraulic roller
Lift: .520''/.540''
Duration: 288°/294°
Lobe Separation Angle: 110°

I was looking at cams in that range and they guy I spoke to at butler said that's what he would run, good enough for me!
It's got Johnson lifters, Butler said the extra price is worth it to avoid issues.

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[ignaro]

Originally Posted by Steve C.

Is the single-plane intake shown the 'same' as the Hurricane/Tomahawk Intake others sell ?


... the intake ports as cast had small port openings.. .

.

I measured the port dimensions on the heads, E intake, and this single plane and they were all within 50 thousandths. Close enough, for sure, but not out of the box port matched.

I will say the Speedmaster intake was a little ugly, like the casting had issues and it required a lot of cleanup work - but the work was done and the gasket surfaces looked perfect.

I'll compare the intakes to the gaskets I have and post any meaningful discrepancies.

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