455 swap maybe???

[H/O84]

So my plan with the engine will be to do new bearings and rings and regasket most of it. I only plan to change to a performer intake, cam, carb and headers. I know headers wont do very much but I read that the hedman sbo headers I have will fit if you make them fit (this is cause im cheap and dont want to pay for the manifolds if I dont have to). I have a holley 650 double pumper that was going to go on the sbc. Is this big enough for a 455? What lift cam should I be looking for, naturally I want to go big lift but I don't think that is the best idea for this application. What is max lift for stock parts? Does changing the rocker arms add to the amount of lift I can do?

 

[MrSony]

Get a good SBO or BBO quadrajet from 1975-80. Best carb you can have on a GM engine. Although, the 650 would be fine enough. Better throttle response due to the smaller cfm, better fuel mileage as well. but, I still recommend a qjet.

 

[MrSony]

Max lift for most GM stuff with 100% stock valvetrain is around .500. You wouldn't need much more than that for a hot street motor. Hell, with the way the BBO and SBO are designed, they make great power even with the sub 8:1 compression with just a cam with lift in the mid 4s and nothing else. They were a product of the smog era for much of their lives, and they worked. Higher ratio rocker arms essentially increase the lift and makes it almost like you put a slightly bigger cam in. It's not really worth all the extra expense and hassle imo, but if you want to wring as much as you can out of it go for it.

 

[olds307 and 403]

Olds rocker arm geometry is 1.55 so...way off, not so much. The rocker arm studs are like 5/16 on the bottom and 3/8 on top. If you have never used them? Why bash and be negative? Of course one can drill and tap them to whatever size. I was just sharing first hand knowledge.

But, Thanks!

They are not right, even the Ford ones are slightly off and some claim premature wear from using them. Personally on a mild, near stock build I prefer the stock non adjustable rocker arms. I am well aware of the conversion studs. I am not a fan of the Comp roller tips, they are loud even when properly adjusted. The SBF 1.72 Scorpion true roller rockers were whisper quiet in comparison.

 

[Canon_Mutant]

At least 750cfm on the big block and especially if you actually intend those headers to do any good at all? Though I was young once in a previous life too, I never have understood the passion some have for headers, in most cases, just to have headers. Putting headers on a stock small block will not do squat. This gaining 40HP nonsense is real similar to what the cold air intake folks claim adding their products to a stock motor will do.

You always have to consider what the limiting airflow is in your design? Putting them on a built small block that does its thing at higher rpm when you have air intake, carb/FI, cam, and heads to take advantage makes sense. Likewise, putting them on a big block that has enough cfm in the rest of the design and is going to be living on the strip or auto-x or other race application is worthwhile. Putting them on a big block street rod that due to the premium lack of space in turn makes every single thing you do from now on under the hood and under the car a royal PITA because the headers are in the way does not make sense. Then there is the gasket leaks, noise [which maybe you like], burnt oil smell no matter how careful you are changing the oil, additional heat under the hood and the problems that can cause . . .

Though mine has been scattered long enough with my suspension/brake swap I would frankly love to take a ride in my big block 442 too, I wish you were in the neighborhood so I could take you for a ride and show you why headers don't matter on a big block street rod. Torque is a wonderful thing . . .

 

[1bad79]

I'm not sure on limits of stock valve train but under .500 like the others have said I see quite a bit on other forums, on my 455 I run a quadrajet from an olds 403 800 cfm and got the parts from cliff ruffles works great electric choke starts and warms up nice

 

[olds307 and 403]

At least 750cfm on the big block and especially if you actually intend those headers to do any good at all? Though I was young once in a previous life too, I never have understood the passion some have for headers, in most cases, just to have headers. Putting headers on a stock small block will not do squat. This gaining 40HP nonsense is real similar to what the cold air intake folks claim adding their products to a stock motor will do.

You always have to consider what the limiting airflow is in your design? Putting them on a built small block that does its thing at higher rpm when you have air intake, carb/FI, cam, and heads to take advantage makes sense. Likewise, putting them on a big block that has enough cfm in the rest of the design and is going to be living on the strip or auto-x or other race application is worthwhile. Putting them on a big block street rod that due to the premium lack of space in turn makes every single thing you do from now on under the hood and under the car a royal PITA because the headers are in the way does not make sense. Then there is the gasket leaks, noise [which maybe you like], burnt oil smell no matter how careful you are changing the oil, additional heat under the hood and the problems that can cause . . .

Though mine has been scattered long enough with my suspension/brake swap I would frankly love to take a ride in my big block 442 too, I wish you were in the neighborhood so I could take you for a ride and show you why headers don't matter on a big block street rod. Torque is a wonderful thing . . .

A 650 cfm could be made to work with tuning but the 455 as said needs a 750 minimum to reach it's potential. What are you saying, my mighty 260 didn't gain 40 HP with headers and duals🙂. It would be lucky to have gained 10 HP which is still a big deal when you start out at 105 HP. I am just going off Bill Travato's dyno number. I would bet the stock spindly exhaust also contributes a lot to that number as well. The Olds builder I deal with figures more like 30 hp, still nothing to sneeze at. As said the 455 is different than the 350 or 403 with those awful regular manifolds. I know one guy showed pictures of the G body SBO Hedman header's on a 455. They only needed minor tweaking, hopefully you get that lucky. One the builder I deal with for parts told me unless you push big power, like 500+ HP, according to his dyno tests, your 1 3/4" headers are plenty big.

 

[H/O84]

I never have understood the passion some have for headers, in most cases, just to have headers.

The only pashion I have for headers is that I already paid for them. Otherwise I would do the manifolds but I will try to take use of what I already have.

A 650 cfm could be made to work with tuning but the 455 as said needs a 750 minimum to reach it's potential.

I didn't think it was big enough. Looks like it's time to search Craigslist

 

[Kennybill]

If you are re-ringing a standard bore low compression 1973 Olds 455, the last thing you want to do is "over" cam & carb this engine. Get a torque RV Comps Cam 0.456/0.456 lift. Stock rockers and bridges will be fine, 650 CFM also will be fine. When in doubt, under cam and carb. Your not building a National Record Holder here. I did a similar 455, J heads with that cam and similar carb. It was a fun tire shredder street car. 1981 Regal. Jmo.

 

[Canon_Mutant]

And, to the OP, I am not ragging you man nor do I know how old you are? I look at these threads as a general discussion of the issue. That said, younger folks like I was once, do have a passion for headers that you tend to learn the hard way are often completely unfounded. Does it got headers on it? Yeah, I have been there. I put a set of headers on an otherwise stock 327 back in the mid-70s which did nothing and then put a big lopey camshaft in it when I was running an old Carter AFB tiny 4 barrel [like 400cfm if I recall??] again with stock 1.76 tiny valve heads. But, of course, I could open the headers and people could hear that big lopey cam, and the thing "sounded" badass . . . ran like $hit. Finally, since I did manage to build the low end of that small block well, I got a set of 2.02 heads [1.94s probably would have been sufficient] and a 650 Holley with a Performer intake and boy did that change things. But, again, like from 3500-6500 rpm.

That big block with W/Zs will start pulling hard at only 1500rpm and you are effectively done by 5000rpm, less than that if it is a stock smog motor. My big block has mildly ported Edelbrock aluminum heads just to even out the inside and outside flow numbers in case I ever want to move to FI and headers [probably won't happen] but, with 750cfm on top, Performer intake, the W/Zs, and a .496/.512 224/234 cam, I shift at about 5200 where my HP really starts to fall off. So, for an all out race condition, I am limited. For a street rod, to date from a rolling start because those 15" BFGs won't begin to hook up, with all of that torque, this thing is so snappy quick [a well tuned CCC carb feels a lot like an FI car], I walk on just about everything up to a speed that is safe for street rodding where the HP limitation starts to become problematic. I am anxious to see what the ole girl will do lowered with a much improved suspension, brakes, hardened rear end internals, 1350 joint drive shaft, frame reinforcement, and 275/40/18 high performance tires out back both out of the hole and around auto-x and a few road course twisties just for fun? FWIW, I don't exactly intend to dominate the GTV circuit . . . just out to have some fun and show what even a G-body can do?

Anyway, I am just wanting others to learn from my mistakes and those I've seen others make in my nearly 60 years. That is all I am trying to do here.