[Lildave]

I'm working with a 454 block dated around 1974, so I think that is MKIV? I have square port closed chambered iron GM heads. 11:1 TRW pistons...... I went into a local speed shop the other day to buy some Felpro head gaskets, intake gaskets, exhaust gaskets, and head bolts. I was going to go with GM bolts and regular gaskets. I have zero idea what the correct part numbers are, and am pretty new to BBC stuff. He was trying to sell me ARP bolts because they are "only $10 more than GM", and some "race" head gaskets from Felpro that have a special metal ring? Is this NECESSARY, or is he just upselling a little more expensive parts? This deal will probably only see 5800 rpms in short bursts, and it'll spend most of its life at 2800 or so cruising the lake in a jet boat. If it truly NEEDS something more than stock, then I'll buy it, but I don't want to just blow money on stuff it doesn't need.

 

[gn7]

I'm working with a 454 block dated around 1974, so I think that is MKIV? I have square port closed chambered iron GM heads. 11:1 TRW pistons...... I went into a local speed shop the other day to buy some Felpro head gaskets, intake gaskets, exhaust gaskets, and head bolts. I was going to go with GM bolts and regular gaskets. I have zero idea what the correct part numbers are, and am pretty new to BBC stuff. He was trying to sell me ARP bolts because they are "only $10 more than GM", and some "race" head gaskets from Felpro that have a special metal ring? Is this NECESSARY, or is he just upselling a little more expensive parts? This deal will probably only see 5800 rpms in short bursts, and it'll spend most of its life at 2800 or so cruising the lake in a jet boat. If it truly NEEDS something more than stock, then I'll buy it, but I don't want to just blow money on stuff it doesn't need.

Use the Felpro 1037 Stock head bolts are fine if you have them. If you're buying bolts, I'd go with the ARP.
Use the 8081PT2 at your own peril.



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[Lildave]

Peril generally means RISK or DANGER to me....though I'm definitely not an English major. I read that....

Use the "race" gaskets (what the speed shop guy referred to them as) at your own risk?

I take it ARP bolts, Felpro 1037's, regular intakes......isn't there a few exhaust gasket choices too?

 

[gn7]

The 8081PT2 is not a performance gasket. It is a econo rebuild gasket. People use them in performance boat engines and claim they are OK, But IMO, at that compression in a boat, you are taking your chances with them.

The 1031 is a stainless steel core marine gasket designed for high compression. Its your money and your choice.



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[andyc]

The 1412 Felpro is what I use for header gaskets if you are running a round header flange. What closed head are you running? 291's?

 

[Lildave]

Gn7... If it was your boat, and your money..... 1037 or 1031? My budget is pretty tight, but I've got all winter. I'm not trying to half ass it with those econo ones.

 

[Lildave]

The 1412 Felpro is what I use for header gaskets if you are running a round header flange. What closed head are you running? 291's?

If I'm reading these casting numbers correctly, one says it is a 3919840 and the other says 3964291..... I don't know what a 291 head is.

 

[TNYoungblood]

The 291s are a closed chamber head usually 109 cc. I've got a set 4sale that came on a engine that was in my winger.

 

[andyc]

I found one that way

If I'm reading these casting numbers correctly, one says it is a 3919840 and the other says 3964291..... I don't know what a 291 head is.

You should have a matching pair for starters. Different chamber sizes, 109 and 107 plus runner volume is probably different too. You should try to stay away from these heads due to what you tend to use the boat for. These 2 different heads are good at high RPM-hugh plenums. I bought a boat once that had 1-291 and 1-391 (I sold the 391 for double what I bought the boat for) and the 291 replaced a cracked 291 that I had. Look for a 049 or a 781 oval head for your build, I believe you would be happier with the finished product and be pump gas friendly. Just my .02!!

 

[Lildave]

Just looked that up, that one is 107cc and one is 109cc.... This engine has been running for years with these heads. Long before I bought it in 2010. Not saying it's right, just how it's been.

 

[SoldHondaBoughtHondo]

I'm working with a 454 block dated around 1974, so I think that is MKIV? I have square port closed chambered iron GM heads. 11:1 TRW pistons......

About same combo as mine. While i don't recommend it i use steel shim head gaskets, the same 'junk" gm put the motor together with in the first place.I have 'inspected' them 5 times now, other than a little corrosion around the water ports they are fine. Basic mr gasket intakes with the sealing compound around the ports, the ones that don't use the 4 upper bolts, light spray glue to the head, water corrosion on the intake repaired with JB weld, silicone only on the end rails. Nothing special exhaust gaskets, no idea what brand, they came with motor when i got it...been on/off a few dozen times. I am anal about re torque. 3-4 times with new gaskets is normal for me, used gaskets get checked about once. No lock washers either.
Everybody has their own way of doing things, my way being less than the absolute minimum for most people, but it works for me.

New head bolts would be nice, used are fine as long as threads aren't damaged....been using teflon paste on the threads....seems to cut down on corrosion. Make sure block/heads are clean flat and smooth too.



291 head? same as mine....first design ls6 11.0-1 with steel shim gaskets from the factory....make sure the pistons are at least .015 down the hole.... Brown sealer both sides..$24......for 2:happy:

Well you said you were on a budget lol

Or do what GN 7.0 says, his way works to, but he doesn't have a budget:stir:

 

[gn7]

Stock shim gaskets work and add a bit of compression over the composite Felpros ...IF.the piston is at least .018 to .020 in the hole and the head and deck surfaces at flat a smooth.
If the block has been decked, you better know how much it was decked. Standard factory "in the hole" is about .020. Doesn't leave a lot for decking.



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[SoldHondaBoughtHondo]

Just looked that up, that one is 107cc and one is 109cc.... This engine has been running for years with these heads. Long before I bought it in 2010. Not saying it's right, just how it's been.

You have heard of split duration cams? Those are split compression heads. lol
Can't hurt to much, i have the 291's @109 cc except one was milled .030.....ya, i fix it next time motor is apart.

 

[67weiman]

How much is 2 cc really gonna hurt anything unless its an all out build for max hp?

 

[gn7]

How many GM heads have you guys even measured? Most of the time the claimed CC is less than the actual, and its not uncommon to have 2 CC difference in the same head from one chamber to the next.



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[Lildave]

Gn7...So what you're saying (hopefully) is it's no big deal on a low hp application like mine and just run em?

 

[gn7]

Gn7...So what you're saying (hopefully) is it's no big deal on a low hp application like mine and just run em?

They will be fine.



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