Topic: Is a 455 HO engine for 1975 any good?

[TAFEVER]

I am thinking about buying a 1975 455 HO engine for $400. The block casting number is 500813 and it has 6H heads on it. The block is stamped Y4 on the front.

I plan on building a mild street engine capable of 500-550HP for my 1979 TA/SE.              Will this engine be any good for that or should I keep on looking?

It seems 455 engines are very,very few around here. But I have been reading that the 1974-1976 engines are no good as being "thin wall" castings.


I could also buy a 1968 400 engine from a GTO for the same money but I heard it would use different engine mounts to be able to work in my TA.

[72blackbird]

A 455 for $400 is a good deal. The 500813 75-76 455's were part of the 500 series lightweight blocks, but had additional stiffening built into them to handle the 4.21" stroke. Despite their thinwall design I've never heard of them having the same problems as the 500557 400's when stroked, even when built up to around 500 hp.

The 6h heads on that 455 do have cavernous 124cc chambers- ideal for a boosted or turbo application but not much else.

Geno

[TAFEVER]

A 455 for $400 is a good deal. The 500813 75-76 455's were part of the 500 series lightweight blocks, but had additional stiffening built into them to handle the 4.21" stroke. Despite their thinwall design I've never heard of them having the same problems as the 500557 400's when stroked, even when built up to around 500 hp.

The 6h heads on that 455 do have cavernous 124cc chambers- ideal for a boosted or turbo application but not much else.

Geno

I plan on swapping out the heads for some 6 X4 heads that I already have.
Does edelbrock make the only aluminum heads for Pontiac? Is there anybody else who makes a cheaper head?

[brian c]

KRE makes AL heads for Pontiacs as well. The difference a while back were Edelbrock were round port only while KRE's were D port. I thought I read that Edelbrock brought out D port heads as well.

[trentonmakes]

Both have d port from what ive read and with blocks with 557 are they not just as good unless your going for obscene hp?
You can stroke and bore them blocks with no isseues assuming its in good condition.
even with the thinner walls they should be fine for a street strip car.
If your building an all out strip car, especially over 500hp then yes you would want the older blocks

Sent From My Fancy Little Thinking Box

[72blackbird]

Forget about using a 500557 400 for a 4.21" or 4.25" stroker build- the Pontiac forums are filled with plenty of 500557 owners telling tales of woe when their 500557-based stroker cracked, or worse, let go of the rotating assembly. Performance internals and machine work are too costly to trust to a block that should only be used for stock or mild builds- use a 481988 or 979xxxx block and give yourself one less thing to worry about.

E-heads or KRE D-ports are both good choices for performance builds- by the time you buy D-port cores, clean, mag, and install stainless valves and bronze guides, you'll have spent $900-1200. Plan on getting some porting done as well to even get near what stock aluminum heads flow out-of-the- box. Either Edelbrock or KRE heads cost around $2k/set, but used ones can be found for around $1500-1600/set if you shop around. Either style of head will make about 500 hp with the right cam.

I bought 325cfm CNC ported e-heads from SD Performance for my 455. Those heads, along with a Holley 850 cfm on a T-II and SD's "Road Paver" HR cam, will make around 600 hp on a 455 or 461. Of course it takes more than just a bunch of parts to make that kind of power, but those parts are the main ingredients.

Geno

[scrapinainteasy]

Geno, what years and models were the "good" 455 blocks in?

[72blackbird]

Geno, what years and models were the "good" 455 blocks in?

455's were made from 1970-1976. The 1970 No.9799140 can come with 4-bolt caps, depending on the model the engine was in and the hp rating. 71 455 HO's no.483677 came with 4-bolt caps. 1972-1974 no.485428's came with 2-bolt caps, but are drilled for 4-bolt caps. The 75-76 no.500813 455's came with 2 bolt main caps.

 Any 455 is a good performance Pontiac engine to rebuild, thanks to the 4.21" crank- with good heads (like any 96-102cc head) it will make 400 hp/ 450 lbs.-ft. even with a mild cam.

Geno

[scrapinainteasy]

Guessing the 70-71 455 blocks are hard to come by? I want a 455 450-475hp motor really bad! I want durable and as reliable as possible. You wanna build one for me?  With cast iron heads and a stock looking intake. Is this even possible?

[72blackbird]

Guessing the 70-71 455 blocks are hard to come by? I want a 455 450-475hp motor really bad! I want durable and as reliable as possible. You wanna build one for me?  With cast iron heads and a stock looking intake. Is this even possible?

There's a demand for the earlier blocks, as anyone wanting a 455 also wants one with 4-bolt main caps. But don't stress about it- the later 2-bolt 455 blocks can handle 600 hp when you run ARP main studs. A 450 hp 455 with iron heads and stock intake is not only possible, but can be done running pump gas and a regular flat tappet cam. The factory intake is also an excellent piece and can be used- the only drawback is it's weight.

I do build engines for customers- PM me and I can discuss it further with you.

I'm currently building a 73 455 for myself, but will be breaking open the piggy bank and running ported aluminum e-heads and a roller cam (SD Performance is currently working on my heads). Check out my build here.
http://www.78ta.com/HTAF/index.php?topic=39126.0

Geno



 

[scrapinainteasy]

sent pm

[eviledolean]

A 455 for $400 is a good deal. The 500813 75-76 455's were part of the 500 series lightweight blocks, but had additional stiffening built into them to handle the 4.21" stroke. Despite their thinwall design I've never heard of them having the same problems as the 500557 400's when stroked, even when built up to around 500 hp.

The 6h heads on that 455 do have cavernous 124cc chambers- ideal for a boosted or turbo application but not much else.

Geno

I plan on swapping out the heads for some 6 X4 heads that I already have.
Does edelbrock make the only aluminum heads for Pontiac? Is there anybody else who makes a cheaper head?

I took this engine block code off my project car.   

0169516
YY

Date code was L245, December 24th, 1975.

Can anyone tell me what Block I have? 

The heads are marked with a 6X

[jmurray878]

Best bet would be to find the casting number on the rear of the engine near the distributor. 

[eviledolean]

Dang, wish i could come across a deal like that.   But for now ill just focus on restoring the interior.