Transam461

Hi, my name is Brian, and I am new here to the forum, and just acquired a 1972 455 Olds that I am going to freshen up for my 1979 Trans Am. I am also new to Oldsmobile engines, as I have always ran Pontiac stuff, so I'm still learning Oldsmobile. I have started taking apart this 455, and it seems it has some decent stuff in it, and it is in really good condition, so I'm just going to freshen it up with new rings, bearing, gaskets and so on. It is a 1972 455 block, it has 67-69 "C" heads on it, and after cleaning them up, it appears that have been "pocket ported". I also found ".020" stamped in them, so I would almost bet they have been milled .020" as well. They have ARP Rockers Studs and guide plates. The Pistons are SpeedPro L2323 dished forged piston, Summit says they are 18cc dish. The camshaft it a hyd flat tappet JM 25-28, 236/248@.050 .523/.544 lift 108* Lobe Seperation, pretty good sized camshaft, but it in excellent shape, so we will be reusing the cam and lifters(we marked everything when removed). It has Comp Cams 1.6 roller tipped rockers and Poly Locks. Head Gaskets were Felpro 8171PT1, .039" thick. Piston looks to be in the hole somewhere around .040"-.045" just measuring carefully with a hand caliper. Intake is a Edelbrock Performer with a 750 Holley. Ignition is all Flame Thrower. That's about all I know about it up to this point. I did use a compression calculator, and it appears that it may have somewhere around 9.25- 1 as it is now. I would like to increase compression a bit with a thinner head gasket if possible, to raise it up around 9.6 or so atleast, to compliment the decent sized Mondello camshaft a little better, without spending a bunch of money on it. I figured head gaskets would be a great way to do it, since I have to buy them anyway, but I don't need the expensive MLS gaskets. It will run on pump gas.

I can't seem to find any cheap composite head gaskets that are thinner than .039" In my search, I did read that Corteco used to make a .028" , 55661 gasket. I've searched, and can't seem to find any For Sale. Does anyone know where I can find a set of these gaskets? I did run across a member here on the forum that was telling another guy that he had a lifetime supply of them, but not sure if he was selling them or not. Also, overall, how does this combination of parts sound?

Any help would be greatly appreciated, Thank You

Battenrunner

I did the same search for the thin Corteco's and came up empty handed. If you can luck into the factory steel shim headgaskets for cheap or you must go with Cometic .027's.

We ended up with .027 Cometics and they seal very well on our build.


At this point, there is no cheap way to increase compression for you, as the thinner Cometic gaskets are ~$180 a set.

Your combo sounds pretty healthy to me for a fun street/strip combo. Watch out for scope creep and budget crashing events...

Make sure you have the bores checked for size carefully to the L2323 pistons. These pistons aren't the hottest and best new thing in pistons, but they will work fine for your use as a fun and affordable street engine. Ring gap is important, don't set them too tight. New,, modern-design pistons with thin rings are worth 10-15hp over these older style pistons, but also, keep in mind that you can't use the L2323 Speed pro pistons with a Bronze-bushed rod made for floating pins (like Eagle rods), so you will have to use stock rods, which can work up to a certain power level for so-long a time, especially with the correct sizing method for the big ends of the rods.

I think the best thing you can do is have your heads really checked out by a very good shop. You should have the valve guides inspected and tested for clearance and have the seats checked for runout.

Don't spend too much on the iron "C" heads, as you might just go with a set of Procomps and install some big intake valves (2.125 or 2.15's) and have them shaved down and spend almost the same if your C heads require much work.

The other improvement could be moving up to a Performer RPM intake, but if you don't do a lot to your heads, you really wouldn't be that limited by the performer intake that you currently own.

cutlassefi

A few additional things he missed;
Have the heads cc’d as well.
RPM Intake won’t fit under a TA hood. Even the Performer will be tight. You’ll need a big drop base air cleaner.
Carb is too small, needs an 850.
Ring Gap isn’t your biggest concern with those pistons, piston to wall clearance is, needs .004 MINIMUM.
Finally, buy a wideband and tune it right.

Hope this helps.

Run to Rund

While Corteco was alive, before being bought by ROL, I purchased a bunch of 55661, and can sell some of them. IIRC, they are in plastic bags inside of the boxes. so should remain fresh over time.

Transam461

Thanks for the good info everyone, it is much appreciated. Awesome Run to Rund, how much for a set(2 head gaskets), shipped to S.W. Missouri zip 65624? Thanks!

olds 307 and 403

Here is another option.
https://www.tapatalk.com/groups/real...ts-t16544.html

Transam461

Thanks for the help. Not really looking to spend that much on head gaskets at this point. I'm gonna purchase a pair of the Corteco from Run to Rund. I appreciate it though.

olds 307 and 403

I get that. Too bad the shim and .028" are no longer. I bought the last pair of .028" head gaskets from Rocket Racing which looked like the old Detroit or Mr Gasket head gaskets. Not everyone wants to pay $200 for a pair of head gaskets.

Transam461

I agree 100%.... I believe Run to Rund has quite a few sets of the Corteco .028" gaskets, as he bought a bunch of them when he found out ROL bought Corteco out. I'm purchasing one pair from him. They are packaged in sealed bags inside of the Corteco box, so they should stay fresh.

Rocketbrian

Are the Corteco and the Detroit .028" gaskets the same or completely different? I have a pair of Detroit that my builder may use in my current build.

olds 307 and 403

The old stock Detroit 260 head gaskets I have look a lot like the Rocket Racing and the Mr Gasket. 028" SBM head gaskets I bought from Hughes Performance. They are black in colour vs white for the Corteco, current Mr Gasket Oldsmobile and Edelbrock Oldsmobile head gaskets.

matt69olds

Deck the block to minimize the deck clearance, and mill the heads a little further to allow the use of standard head gaskets. A little more compression, cheaper gaskets, win win!

Run to Rund

I can bring some Corteco's to the OCA Nationals if others want some.

Gerald Nickels

Whats wrong with Felpro head gaskets the thin ones not sure on inches its been a long time on my 455 motor.
Gerald

Transam461

The Felpro are good gaskets, its just that they are .039" thick. The Corteco is only .028", so you can take advantage of a bit more compression if you can run across a set. The Olds 455's came from the factory with steel .017" shim gaskets, but are unavailable nowdays

bill-is-ready

Hi, Do you still have any sets on the Corteco 55661 head gaskets available?