rebuild 455

T

The Deuce

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I have a 455 from 1970 which is rebuild, but i like to know howmany hp it will produce with these items:
TRW Hypereutectic pistons 9.2:1
Stage1 equivalent camshaft (206/224, .419/.465, 112/118)

Everything is new, new bearings, pistons, piston-rings, distributor etc.

I think it will be around 370 hp, or am i wrong?
 
Originally posted by Buick_Freak:
I have a 455 from 1970 which is rebuild, but i like to know howmany hp it will produce with these items:
TRW Hypereutectic pistons 9.2:1
Stage1 equivalent camshaft (206/224, .419/.465, 112/118)

Everything is new, new bearings, pistons, piston-rings, distributor etc.

I think it will be around 370 hp, or am i wrong?
Click to expand...
A guy I know did a similar rebuild, and got 275 rear-wheel HP, which would be about 330 HP if measured at the crankshaft.

Of course it depends on how well tuned your engine is, too- if your carb is misadjusted and your timing is off, then you will not be near that.

-Bob Cunningham
 
You've dropped the compression, so you will loose some there, but it should be a nice motor. You can gain some performance over the stock engine by curving your distributor and improving the exhaust system so if you are hoping to have original performance or slight improvement, it is possible.
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Well, I have the original rochester 4bbl carb, i don't know if it's still in good condition, i have to find out when the engine is back in the car, and with the exhaust,i have the original headers with 2.5 inch pipes with cherry-bombs and the pipes exit just before the rear wheels and just before the autobox there's a balance-pipe , original it was a singel exhaust of 1 3/4 inch or something so this one must be better.
The timing have to be adjusted offcourse to be perfect.

Since my engine is now allmost brand-new, when i first start it, it has to break-in, is there a good method to do that, somebody told me i have to rev the engine to 2000rpm and keep it there for 20min. and then vary the rpm a lot.
Has anyone an idea??

(sorry if my englisch is not really good)
 
Freak,

Break-in is absolutely crucial to the life of a camshaft. If you don't do it right, you greatly increase your chances to flatten a cam lobe.

I like to break in a cam like this:
- Be sure that the cam is installed properly, with the proper cam break-in lube
- Use a known induction setup- in other words, don't try this with a new setup (a new carb, etc., that you aren't sure it is tuned properly). If you are going to switch to a new carb, do that *after* break-in so you don't have to stop halfway through and risk ruining your cam
- Start the motor and set the timing at idle (as quickly as possible)
- After the thermostat opens, top off the radiator and put the cap on (don't try the break-in without the cap)
- Raise the engine speed to 2000 RPM and hold it there for 20 - 30 minutes
- If you are going to use a mechanical fan, that should be "okay" for cooling- if you use an electrical fan, you should keep the radiator cool with a garden hose (electric fans will not keep the engine cool at 2000 RPM)
- Have a second person around just to keep an eye on things- make sure no oil is dripping, make sure your radiator doesn't start to overflow, watch a clock, etc.
- A couple times vary the engine speed- I like to keep it between 1700 and 2300 RPM
- After you've run for 20-30 minutes, shut the engine down and don't touch it for 12-16 hours

That procedure will break in the cam. To properly seat the piston rings, you will need about 500 miles of driving. Best is a heavy load about 2000 RPM, for example climbing a mountain. Vary the engine speed during this driving, as you would during normal driving (don't just get on a motorway and go straight for 500 miles at 65 MPH).

Make sense?

-Bob Cunningham
 
Thanks Bob for your reply,correct me if i'm wrong but when I have set the timing at idle I have to keep the engine idling untill it's at operating temperature and then after topping the radiator up rev it up to 2000RPM?
And do I have to vary the RPM within the 20-30 min of keeping it at 2000RPM or after the engine has ran for 20-30 min.

There's one thing, I bought the engine a while ago, installed it in my car and then fired it up for the first time to discover it was totally worn (a big hammering sound from the crank can't be good), so I took the engine out to be rebuild, but the engine never run longer than 10sec. or so, so i don't know if the carb is adjusted well.
I have to take the guess.

First I have to pick the engine up at the machine-shop, build it together and install it in my big-*** car and then, fire it up!!!!, I can't wait!!
 
Originally posted by Buick_Freak:
Thanks Bob for your reply,correct me if i'm wrong but when I have set the timing at idle I have to keep the engine idling untill it's at operating temperature and then after topping the radiator up rev it up to 2000RPM?
Click to expand...
Nope-

Bring try to set the timing within the first 30 seconds - minute (but don't hurt yourself with the fan!). Then bring it right up to 2000 RPM.

During the 20-30 minutes, you could vary the RPMs from 1800-2300 RPM or whatever.

Also during break-in, I like to have a garden hose handy- the engine creates a LOT of heat, so I keep a steady stream of water spraying on the radiator. The engine won't get too cold (as long as your thermostat is working) and usually I find that even with the water the engine gets nice and toasty. In my opinion, air cooling is not enough during break-in (especially if you've switched to electric fans or something).

-Bob C.
 
Bob, thanks.

When i've putted everything together i do what you have written and i'll let you know how it went.
Thanks again.

Koos
 
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