454 casting mark question

I just picked up a 454 engine from I think a 77 truck, so I know the heads and compression are no good for performance, but in the position that the block is in I can't get a good view at the number on the block but I did see that it said Passenger on the back of the block, which didn't surprise me, but it also said
Hi-Per which I have heard about but don't remember what it meant, and would like to know what it means.....possibly the 4 bolt block? I can't get to the engine enough to take off the oilpan...not to mention it is still full of oil, I can't get to the casting number on the block yet, the manifolds are still on and its covered in grime....but in most cases the casting numbers will only say 2 or 4 bolt. SO....what does Hi-Per mean?

anyone know?

It is common for 454 2-bolt blocks to say Pass Hi-perf on the block casting. This just tells you it is not a hi-deck truck block.

Hmm, since there is no sure way to tell from the casting numbers if it is a 4 bolt block or not, I'll just have to rip off the pan to find out. Thanks for the help, I did get the casting number off the block which was 361959, just a 73-85 casting, same with the 113 cc smogger heads. The engine has no EGR and its carbureted at the moment. I had heard it mentioned before on other sites, just couldn't remember where. I know what Hi-perf means....just not what it meant on this block; mains, steel crank, good rods, etc.

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Originally posted by 1stGenCamaro
Hmm, since there is no sure way to tell from the casting numbers if it is a 4 bolt block or not, I'll just have to rip off the pan to find out. Thanks for the help, I did get the casting number off the block which was 361959, just a 73-85 casting, same with the 113 cc smogger heads. The engine has no EGR and its carbureted at the moment. I had heard it mentioned before on other sites, just couldn't remember where. I know what Hi-perf means....just not what it meant on this block; mains, steel crank, good rods, etc.

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Unfortunately HiPerf does not necessarily mean it. Nor does it mean you get forged cranks with 4 bolt mains or hi performance rods, heads, yada.

It sounds as if you have the engine in a vehicle. These things make a ton of torque up to 4500 rpm which is fine for a street vehicle around 3500 lbs. If you want more performance you'll have to take it out and tear it down. Then you'll know what you have and what needs replacing from a worn or performance standpoint.

High Perf. Doesn't really tell you what the main bearing's are it was written on 2 and 4 bolt block's. A Mark IV is a excellent street or race motor , they weigh about 750 Lbs but can make ton's of torque. Even a 2 bolt will rev to 6500 R.P.M.'s they have an excellent oiling system . Good luck with your Rat motor. If your going to rebuild it you have to take the pan off anyway so you can check it then.

Been a while since I replied on this post, but the current news on the Rat is that it is a 2 bolt, which I may or may not modify to use splayed caps. The heads were the 'better' heads of the day, but still far below current aftermarket quality. I checked it all out inside and it looks good to use, not too much wear and the bearings were still good. I am giving it a full hop up rebuild anyway, but it is good to know that it was in good shape to start. Thanks for the help, I had spoken to a machine shop that told me that Hi-Per on the back of the block meant nothing because they all had it cast in.

HUH! Very Interesting;


~ Vegas ~

Not all BBCs have this but because it has it does not mean you get "high performance" parts. Many of these have 2 bolt mains with cast cranks and truck heads or peanuts which make plenty of power to 4500 rpm but that's about it.

Unless you are racing the 2 bolt block is fine. Use ARP bolts on the rods and you are good to 6500 rpms. If you want to radius cut the crank fine and certainly check the crank, block and align bore it. Polish the crank at the least.

Check the rods and resize if necessary. Use the 3/8's bolts to 6500 rpm unless the motor will live there all the time. They are fine for street use.

Keep your flat pistons if they check out fine. You don't normally want more than 9.5 to 1 and you can't hardly go above this with stock pistons without at least angle cutting the heads or going to older closed chambered heads.

Stay with oval open heads. You will make more streetable power unless you are restoring something that calls for closed heads or you are racing. 049s and 781s are good but talk with your machinist or someone on here who does head work for a living. You don't need expensive heads again unless you are racing. You can get all the street power you want for $500 or less for your head work.

Keep your cam streetable. Talk with someone who knows your assembly and application or just talk with Summit yada and they can hook you up. They will want to know your entire powertrain including rear end, trans yada.

Keep your carb as small as possible but it needs to be able to deliver fuel up to your maximum cfms within reason. If you are going to drive at 4500-5500 at most 98% of the time or less stay with a smaller carb. You'll get more bottom end and spend less time at the pump. If you are going to live at 6500 rpm enough then go 750.

If you want faster I honestly believe you'd be better off with a real drag car. If you want bragging rights and can drive safe just build what you want.

im a power junkie....i don't think i can get enough, I can't stand the feeling of putting the pedal to the floor and feeling nothing or being disappointed by the lack of acceleration. I want a big block for the torque for street driving, i was seriously contemplating blown, and specifically turbo(s) for the adjustability and driveability, minding the cost of efi, which would be good anyway, i might upgrade to a merlin or dart block just for the security, durability and the CUBES OF COURSE, planning on a 540 or so...something big for unkillable torque and keeping it under 600 cubes for at least 5 mpg hehe.

Oh and sorry Streets, the machine shop didn't say that they ALL had it cast in, he said that it meant nothing because lots of them had it and it didn't mean a thing. I might just go with a mild (or wild) rebuild of the 454 but i doubt it...the car is mini tubbed and i'm likely putting a streetable 4 link back there to keep the 9 inch planted, plus i already have a t-56 for the cruisin and racin so I already overshot the ability of a mild 489 with better driveline parts..which is good, i would rather have a driveline that could easily handle the power of the engine than one that was on the ragged edge or broke all the time. thanks for the help, any input on the 4 link or ratio in the back or the engine in the front would be greatly appreciated, it will likely have power rack and pinion steering and some drop springs, upgraded shocks and steering links, it already has polyurethane body mounts and steering bushings etc, the idea is what i guess the magazines call a g-machine, but with some wild power that i could adjust from practically all motor (maybe for town?) with maybe 2 psi boost and up towards 10 psi boost with adjustable wastegates for some track power

just above oil filter,,5/8 plug 2bolt 7/8 plug 4bolt comon id. for 60s and 70s blocks