Race Engine project planning

[1961BelAir427]

For when I order pistons in a few weeks:
I understand the measurements involved in calculating compression ONCE you have your pistons in hand and your block machined.....rotating assembly together...etc. It is how does one go about knowing how to order the pistons for a given target CC with a 348/409 that I do not understand.

From looking at the numbers, I need about 52 cc's (ballpark) to get in the 13.5:1 range with Edelbrock heads, Fel Pro (or Cometic) .040" compressed thickness gaskets (used 4.380" for gasket bore diameter.....anyone know the actual size?) and a 4.350" bore x 4.000" stroke @ zero deck.

How does one go about ordering custom pistons to achieve a certain chamber size?

It's not as simple as saying "A 54cc dome on my L88/ZL1 style pistons to get 13.5:1 with 113cc chambers in the heads in my 433."
I am totally lost on how to get what I want here......do I just tell them what the target compression is and HOPE for the best?
I don't even see how I can know what size the single valve relief I'll need to cut into the cylinder will be before I get the pistons and do a mock-up.......so how would I have that figure to give the piston manufacturer? Guess?? From looking at a few pictures I'd guess 3 to 4 cc's maybe? (Not the factory truck notch, but a new small notch for .730" lift in a passenger block.) My guess is based off of knowing the 4 valve reliefs in a 327 or 350 small block total about 6 cc's altogether.

 

[MRHP]

I would guess my notch is 6cc or so. When I did it, it dropped my compression .53 down to 11.97.

 

[1961BelAir427]

Thanks for the info. Sold some more stuff and bought some more parts.....updated the list near the bottom of page 5.
Awhile back I posted up about Ebay sending an offer to my wife for 10% off any single item and you could save up to $100. A lot of you posted that you didn't get the offer.....and in fact I never got it on my Ebay account either, but was able to use her's. Well this time they sent an Ebay Bucks bonus to us both. Mine was double ebay bucks ..... while hers was quadruple!!! Needless to say I used her account to buy the parts again. Hope some of ya'll were able to cash in on that little deal too.

 

[Skip FIx]

I found my JE piston sheet for my 470" if you need some specs as a starting point. They were 698 gms. The omnly thing I didn;t like was the intake notch wasn't deep enough.

 

[1961BelAir427]

I found my JE piston sheet for my 470" if you need some specs as a starting point. They were 698 gms. The only thing I didn't like was the intake notch wasn't deep enough.

Thank you. That would be very much appreciated!! Is there any reason why I couldn't use the Isky cutter to make the valve relief in the pistons a little deeper after I use it to cut the notch in the chamber? I know people use them to cut piston valve reliefs in non-W engines. Also I would need to make sure the crown was thick enough to allow for the notches to be deepened. Although minimal....that would take a few grams off as well.

 

[buildit]

Thank you. That would be very much appreciated!! Is there any reason why I couldn't use the Isky cutter to make the valve relief in the pistons a little deeper after I use it to cut the notch in the chamber? I know people use them to cut piston valve reliefs in non-W engines. Also I would need to make sure the crown was thick enough to allow for the notches to be deepened. Although minimal....that would take a few grams off as well.

It is very difficult to cut valve notches deeper with the Isky cutter, if the width of the valve relief is more than about 1/4 of the valve diameter. Better to have the machine shop deepen them with a flycutter. The amount of weight removed to deepen the relief .050" is pretty much insignificant.

 

[jim_ss409]

I kind of lost track but are you aiming for a "race only" high compression engine?
I was thinking, if the car's not too heavy, you should be able to make it into the mid tens with 11 to 1 compression. That's if you wanted to make it a strip/street kind of car.

 

[1961BelAir427]

I kind of lost track but are you aiming for a "race only" high compression engine?
I was thinking, if the car's not too heavy, you should be able to make it into the mid tens with 11 to 1 compression. That's if you wanted to make it a strip/street kind of car.

From the beginning around 13.5:1 has been my target....and "race only" but the more I get to thinking about it.....I may aim for about 11.5:1 instead. It seems this is much easier to get to compression wise.....and hopefully I could still run the number @ about 3500 pounds including me (170#). It would really be nice to drive my car on the street again. It's been off it for over ten years. Just hope some idiot on a cell phone doesn't bump me and the insurance total it out.

 

[Ishiftem]

Just hope some idiot on a cell phone doesn't bump me and the insurance total it out.

That's the #1 reason we re-lettered our car and made it drag only. Ever see how people drive in Chicago?

 

[1961BelAir427]

Never been up that way yet. I'm in a small town in middle Georgia so it's not so bad here, but still a concern.

My goal is to be able to run the 1/8th mile @ 6.50's even during hot/humid GA weather. Not making light of those numbers, but that is all as in - I'm not hoping to run that and then go a little faster and a little faster. I'll be content with that.....or even a best of 6.50 and 6.70's in the heat. I think that is mid 10's in the quarter. I'm also not expecting to run that number right out of the gate with no tuning. I'm sure I'll have to whittle down to it over a few trips to the track.
While most of my friends have always had the goal of going as fast as possible....setting goals of 7's....mid 6's....then high 5's...etc. to neverending. My goal has been to run that 6.50 number (don't ask me why that particular time, but it's what I picked out 15 years ago or so) and then once I'm there....work on being able to maintain that ability while making the car nicer/more streetable.

Do ya'll really think I can get there with my current parts list and around 11.5:1 compression??

 

[Clyde Waldo]

............... Just hope some idiot on a cell phone doesn't bump me and the insurance total it out..........

I don't know if the Frito-Lay truck driver that rearended Ellen and me while in our 409 powered 55 T-Bird was on the cell phone but take it from me those idiots are out there and they seem to zero in on nice old cars.

It's said that most accidents crashes happen within a few miles from your home but we were about 700 miles from home.

I now have lots of insurance on the car!!!

 

[Ishiftem]

I don't think your expectations are unreasonable and it would be a bitch'n ride!

 

[1961BelAir427]

I don't think your expectations are unreasonable and it would be a bitch'n ride!

So for occasional street use (limited also by the life of the lifters/valvesprings) stay under 12:1 then? I'm pretty confident I can get by with over 11:1 on 93 octane with the size of the cam I'm planning. Then I can mix in a few gallons of race gas at the track.

 

[Ishiftem]

I think you can accomplish your goal with a max of 11.5:1. The only thing that kills as fast as rpm is detonation.

 

[1961BelAir427]

I don't know if the Frito-Lay truck driver that rearended Ellen and me while in our 409 powered 55 T-Bird was on the cell phone but take it from me those idiots are out there and they seem to zero in on nice old cars. It's said that most accidents crashes happen within a few miles from your home but we were about 700 miles from home.
I now have lots of insurance on the car!!!

That is terrible Clyde. I'm glad that you and Ellen made it out of that. Your car as well.

 

[jim_ss409]

Just to give you an idea, the 437 ci 348 stroker we got from Joe Sherman had 11 to 1 compression. Here's a link to the article... http://www.hotrod.com/techarticles/engine/hrdp_0911_chevy_w_series_engine_build/
The 55 Chevy weighs about 3,300 lbs with a driver and it ran a best time of 10.37 with that engine. (that was in fairly warm weather)
We had a cam failure with that engine and we transferred all the stuff onto 476 ci 409 stroker with 11.2 to 1 compression and ran 10.17 (that was in good but not great weather)
The cam on the 409 stroker was the same except that we had to go with a 110 lobe separation angle instead of the 108 that was in the 348. The piston notches were not deep enough for a 108 lsa.

The thing is, you may find it difficult to get your car down to 3,400 lbs. If you had an engine similar to the 476 ci you should get to 10.50 or quicker at 3,400 lbs but if your car ends up at 3,600 or more, it would be tough.
Of course if you build it as a strip only car, it wouldn't cost any more to raise the compression to 13 to 1 or so and it would make a noticeable improvement in the horsepower department. The engine could also use more cam. If you added ten degrees to the intake and exhaust you'd be making even more power.

As I think about it, I guess I could run the engine in the 55 Chevy on the street if I just wanted to take it to a cruise night a few times a year, but really, it would be a really lousy street car. Another thing I think you already mentioned is that a racy solid roller cam doesn't usually live very long on the street.

 

[1961BelAir427]

It is around 3500 with me (170#) in it now. I still have to get the rollbar installed which should add around 50-75 pounds. Not a full cage, but an 8 point rollbar with swing-out door bars. I'd like to add a rear anti-roll bar and also some re-enforcements to the lower control arm frame brackets, and that will add another 25 pounds or so. The aluminum headed 409 should be good for around 80 pounds off what the iron headed 433" weighs I think.....plus I am swapping to fiberglass fenders and hopefully both bumpers.....so I am really hoping to stay right around that 3500 or less mark.

 

[benchseat4speed]

Can you use all of your existing drivetrain from the flexplate back? My slide rule says you're gonna be tachin 7,027 rpm @ 120 mph, and 7,320 @ 125 with a 28" tire and 4.88's, not including converter slip. Can a stock block 482 with stock main caps take that rpm over and over?

 

[1961BelAir427]

Can you use all of your existing drivetrain from the flexplate back? My slide rule says you're gonna be tachin 7,027 rpm @ 120 mph, and 7,320 @ 125 with a 28" tire and 4.88's, not including converter slip. Can a stock block 482 with stock main caps take that rpm over and over?

All of that will bolt right up to the W motor just the same as a SBC or BBC. I bet the stall will even flash close to the same RPM as it did behind the 433" big block since I think TQ peak / rpm will be close between the 2 engines. Not the same.....but close enough to not effect the stall rpm greatly.
As far as the block holding up to 7500 or so RPM with only main studded 2 bolt caps..... I don't know. I am pretty sure that they got ran up to those RPM's back in the day by all the racers and that would have been with much heavier pistons, weaker rods, etc. Mine will not see that RPM in the lights very often however. It will mostly be run in the 1/8th mile. There is a 1/4 mile track about 60 miles away, but they only run 1/4 on some nights....and 1/8th the other.....so not sure I'd make it there much. I also plan on moving my rearend back about 1" from stock the way Brian (BLS409) and others did sometime in the future. That way I can also run 29.5" tall slicks. I think they would be tall enough to allow me to go through a full quarter without too much stress.
All of that is just speculation so far of course. Hope I will find out for sure around early spring. Also hoping to have the engine running by the end of the year. Depends on how well all my other stuff sells off, but it's going okay so far.

 

[Ishiftem]

Depends on how well all my other stuff sells off, but it's going okay so far.

I hear ya man!