My motor is a 408 small block with indy edelbrock heads. I rebuilt it over the winter and spring when I bent a valve. Changed a lot about the motor, and finally caltracke'd the car and put on some 295's on the rear. OVerall the car is less streetable in terms of torque. Now that I have the fuel and timing tuned reasonably close, it won't spin them easily of the line, just seems to take of nicely and softly instead of blowing them away instantly. The old motor would hessitate then shokc the small 255's and blow them into smoke instantly. I have some friends in teh car last night for a free ride, and it didn't feel like it would smoke them if I really wanted to (I didn't want to smoke them, just plant my friends in the seat backs which worked very well. This just has me a bit puzzled. I didn't think I'd be losing much on the bottom end. I just want to confirm if the bottom end should have lost a bit, or if I should be looking for a problem that has robbed me of that RPM range.

Fro the street, I cant' just down shift to 1st and fly away due to the lack of a low band apply in first. And 2nd gear now feels a bit more sluggish than I'd have liked at those slower street speeds. Couple that with a 3000 stall converter and I've like the muscle car version of turbo lag which is changing my driving style from that sort of, leave it in drive and just use that torque, to downshift if I want to pick up quickly.

The old motor was:
Stock indybrock heads 9.8 comp
RPM Air-Gap intake
244/256@0.050 0.573/.584 solid flat on a 114 LSA 4 deg advanced
small 4 hole spacer throttle body adapter
~600CFM throttle body

The new motor is:
Well ported (300CFM range) indybrocks 10.8 comp
COM XR286R cam 248/254 @ 0.615/0.620 lifts 112CL (no idea on adv/retard)
Weiand Tunnel with roughly 2L of plenum area
1300CFM throttle body

Now to be fair I have actual tires on the rear now so it hooks and maybe that makes the car feel softer down low. But overall it fells significantly less torquey in the 100-3500 RPM range. In the 3500-6500 PRM range it just progressively pulls harder and harder and I'm thinking of bumping the rev limiter because it's still pulling harder at 6500 and I can probably still gain by 7000.

If this is just what that parts combo should be like, we'll I won't sweat it, but if it should be on par of better than the old combo, I'll need ideas on why and what to check.

I'll be on a chassis dyno on July 7th so ideas submitted to help me get the most I can would be appreciated.

Greg

More converter would help.

What is your initial timing now?

Well ported (300CFM range) indybrocks 10.8 comp
COM XR286R cam 248/254 @ 0.615/0.620 lifts 112CL (no idea on adv/retard)



This is most likely your problem... find out where
the cam is installed and try advancing it, advancing
it gives more low end grunt but knocks the high rpm
down

I'm going to phone my engine builder and ask what he installed it at. Probably whatever was the recommended from COMP. I know the first CAM was advanced for just that reason. I'd hate to give up that sickening high RPM power though.

As for converter, well this is still a steet car with 2600RPM highway cruising, and mostly 1500-2000 on the street. I don't want to go too loose for a few reasons. Heat being one, and the other being it will sound like I'm revving or racing it just to basically start moving at any red light. I'm sure a 4k convereter would make this lower RPM torque problem a non-issue.

Edit, forgot to mention the cranking compression is 165 PSI which is in the same range as my last build was.

Greg

That is a common misconception of how a stall converter works.

A quality converter will drive normally from light to light under light throttle.

Mine flashes close to 3500, and still loads up the motor even at idle speed.

Don't fear a stall converter. Just fear a cheap one.

My friend in calgary recently switched to one that stalls at 4200 on his 90% street driven 69 B body, with 440 (very similiar in cam and heads to your build) and he loves it. It really woke the car up.

A good trans cooler will keep it good and cool.

I'll second that, cheap convertors are exactly that , cheap!
My buddy runs a 5500 and you would never know it when he takes off from the lights easy. If he punches it from a dead stop, it easily flashes from 5400 to 5500.

Greg

It's such a pain to pull and install a converter mostly due to the impossible to get to bell housing bolts. My knuckles are still recovering from getting the car running this spring