Building a new motor..

[69vettester]

Looks like weve been through a war since Ive posted on the forum..Ive been real busy and havent even had time to log on for quite awhile..
At any rate, I hope all the CACC oldsters are well, ditto to any new folks also.

Moving on....
Ive been planning a new motor for my car, but the specs have changed alot now that I have a Richmond 6speed doing the gear multiplying. The problem is how to get power to the .62OD gear??
Here's what I know at this point..
First gear through 5th has similar power as the Muncies gears.
but the OD gear is dead!!
Its like this...I shift from 5th 1:1 gear 3500rpms @ 80mph and still pulling strong ... to 6th .62 gear and all the torque disappears!! It still climbs up to 100mph fairly quickly and then struggles to 120mph and no then no more. The throttle is only 1/3rd open but there is nothing left even when I open it all the way up!!
My objective is to get a new motor built that will let me shift into 6th , find torque there and accelerate up to 140-150mph under power all the way. Im thinking 140mph would be around 5000rpms in that OD gear??

Here's the point.......
Anyone have any cam spec. ideas to make this plan work??
Ill be using edelbrock 170cc intake heads/64cc chambers. Edelbrock EPS Manifold(hood clearance problem .

Ive found out already that the larger the intake runners , the more difficult to get power in a OD gear Hence the trick flow and AFR ect..200+intake heads appear out of the picture now.

Has Anyone been through this?? or know about how to do this??
Any info is appreciated..
Thanks in advance..
Tom

PS Its not that Im going around hauling ass at 100+mph, Its that this is a awsome tranny and these doors have just opened up. I didnt even really expect it. I just wanted some gas mileage .
Oh Well onward and upward..

 

[69autoXr]

With your 27" tall tires and I'm calculating about a 3.55 rear end, 5000 rpm with the 0.62 OD will get you to approx. 183 mph!

This is the formula:

(rpm x tire dia")/(trans x rear end x 336) = mph

If 5000 rpm is what you're shooting for at 140 mph in sixth gear, you would need about a 4.62 rear end. I think the closest to that is 4.56. My question is, why not just change the rear end ratio? You'd probably get the "pull" you want out of the motor then. Unless of course you're generally unhappy with the power/torque of your engine?

Chris

 

[1979toy]

It'll be tough to give you any suggestions for a camshaft without knowing your engine specs and rear gearing. The type of driving that you intend to do is also important.
Just looking at the RPM's that you've posted it looks like you intend on having a low revving engine. The Comp XE262 is a good choice if you've got 9 to 1 compression on a 350.

 

[69vettester]

Yes it appears that to get what I want out of that gear, Anything else but a big torque in the low end cam wont work. My motor pulls great as it is now in 1st-5th, the problem is my present cam doesnt power the ".6 "OD" gear well, the power dies at 120, the rear gear is not the whole solution , dealing with an OD gear, Im finding out.

Its not necessarily that I need a new motor, its that a new motor is part of my 3 year gameplan for my car, and the time has come
Tom

 

[69MyWay]

I think you really need to consider EFI. By switching over to one of the many EFI brands out there, you get port fuel injection that allows you to run at lower RPM and still get a solid amount of controlled torque out of the motor because the intake is no longer as much of a deciding factor at the low end.

I s/w ROD about the .62 and told him about my motor. He actually warned me NOT to ever do any WOT shots while in sixth. He said that is the weakest part of the trans, and it can't handle and amount of torque being showered down on it. Thus, my thinking is, stick with the basic concept that you have, switch to EFI, then just sit back and take it easy in sixth, and down shift if you want a burst of acceleration.

 

[69vettester]

Hi Chris..OK I hear what you are thinking. That is what was confusing to me and that will make a cam selection much more flexible for me. The EFI part is out though, Ive got top upgrades for a carbed car allready installed, and they will be transfered to the new motor, Plus a new Carb and Manifold sitting on my shelf waiting for me to take this new Plunge
Tom