Needs MORE POWER!!! (Tim Taylor Style!!!)

[Edelbrock]

Specs:

78 K5
400 SBC
4 Speed granny
4x4
410 axles
37" tires
Edelbrock intake
1407 Edelbrock Carb with manual secondaries
New distributor (complete), plugs, wires, PCV, Air filter.
Headers with relatively free flowing exhaust.
Throttle opens the butterflies all the way.
Probably has an aftermarket cam, but unconfirmed.

Need MORE POWER~

I want want to improve my WOT acceleration performance between the range of 10 MPH and 40 MPH.

Any ideas?


I was thought about picking up a C3 with a blown 383 stroker to solve this HP deficiency problem, but I would rather put my energy into the old K5.

So what can I do to squeeze a few more HP out of this thing? Any ideas?

 

[legopnuematic]

4.56 or 4.88s if you are on 37s would definitely help the seat of pants feel.

 

[Shorty81]

You could just slow down there ole boy....appreciate these old trucks for what they are.

 

[Scott91370]

You could just slow down there ole boy....appreciate these old trucks for what they are.

BY reading his other posts, that ain't gonna happen. I think we got a young 'un here.

 

[Edelbrock]

4.56 or 4.88s if you are on 37s would definitely help the seat of pants feel.

Do you think that going down to 35's would make much of a difference on acceleration?

I like the 37's, but going down to 35's would be acceptable if there was a significant performance improvement. I have a spare set of 35's, but no spare rims - so it would be costly to swap the tires, and then swap them back if there was no improvement.

 

[Catbox]

If you haven't already, try installing a set of 1.6 rockers on the intake valves.
The exhaust is good enough already and won't really need them.

A little more lift, just might provide the pep in your step you are looking for.

Just roll the engine over by hand before you start it.
Only you know how the engine was built and what its clearances are inside.

 

[legopnuematic]

Do you think that going down to 35's would make much of a difference on acceleration?

I like the 37's, but going down to 35's would be acceptable if there was a significant performance improvement. I have a spare set of 35's, but no spare rims - so it would be costly to swap the tires, and then swap them back if there was no improvement.

In a basic sense it dropping tire size will, how much and if it would be enough for what you are wanting is hard to say.

Measure both the 37s and 35s to get their true diameter, some tires are really that diameter, most are smaller. My Dodge has 35x12.5x17s that are really 34.5” tall. That will give you an idea on what the effective difference would be as you can calculate the difference in rpm/road speed for both.

37s are also likely going to be heavier than a 35, adding more mass to get spinning.

 

[Edelbrock]

If you haven't already, try installing a set of 1.6 rockers on the intake valves.
The exhaust is good enough already and won't really need them.

A little more lift, just might provide the pep in your step you are looking for.

Just roll the engine over by hand before you start it.
Only you know how the engine was built and what its clearances are inside.

Thanks for the info, I might just have to try that.

I'm not sure about the engine build. I bought it the way is is, and had changed hands half a dozen times in the year prior.
But I think its has an aftermarket cam. I do have an intermittent lifter issue, so if I were to start taking any of that stuff apart to swap rockers, I would want to change lifters as well. Questions:

Can I swap the lifters without pulling the heads? (you can not on an LS engine).
Can I safely swap the lifters without changing the cam?
Should I go with OEM lifters or are there upgraded one?
Can you send a link to the 1.6 rockers (on Amazon)?

 

[Rickf]

Forced induction or NOx

 

[nvrenuf]

You don't have to pull the heads to swap the cam or lifters.

You said you have an intermittent lifter issue, what is it?

Assuming the cam and lifters are healthy, I would be very careful with disturbing the valvetrain. In the last 10 years or so flat tappet cams have become more and more notorious about wiping lobes, sometimes due to assembly and sometimes due to current oi formulas lacking lubricating ingredients that help those types of cams survive. If you're good at that kind of work - great. If you're not, you might want to leave it alone.

I agree that 4.10's and 37's is under geared, even 35's with 4.10's are less than optimal (especially considering GM considered 30's and 4.10's a good combo).

Lastly, if you're looking for acceleration the wide ration splits of the 4spd makes it a poor choice.

 

[Bextreme04]

There's only two real solutions to this problem.

The first one is displacement.. there really is no replacement for displacement. Drop a warmed over 454 in there and be done with it.

Unless you are willing to do the second option, which is the only acceptable replacement for displacement..... BOOST. Slap a turbo or supercharger of your choice on there. Then incrementally replace all the weak parts you break with all that extra power. Its a win-win really.

 

[Edelbrock]

You don't have to pull the heads to swap the cam or lifters.

You said you have an intermittent lifter issue, what is it?

Assuming the cam and lifters are healthy, I would be very careful with disturbing the valvetrain. In the last 10 years or so flat tappet cams have become more and more notorious about wiping lobes, sometimes due to assembly and sometimes due to current oi formulas lacking lubricating ingredients that help those types of cams survive. If you're good at that kind of work - great. If you're not, you might want to leave it alone.

I agree that 4.10's and 37's is under geared, even 35's with 4.10's are less than optimal (especially considering GM considered 30's and 4.10's a good combo).

Lastly, if you're looking for acceleration the wide ration splits of the 4spd makes it a poor choice.

Thanks for the info. The gearing has always been a little off with this rig. Learning curve to drive it smoothly.

I am hesitant to less with the value train.

As for the lifter issue:


Everything is fin if you drive it normally or even with frequent WOT acceleration up to 4 to 4.5K.


If you maintain an RPM for 3.5 or above for an extended period of time, then its develops a really loud lifter tick that you can hear over the sound of the engine and loud exhaust at 70MPH. Sounds like only 1 lifter though. When you go back to idle: tap tap tap tap really loud. Let it sit there for 5 minutes idling and the tap slowly goes away. So basically you just cant maintain high RPM for extended periods or the problem returns.

 

[Edelbrock]

There's only two real solutions to this problem.

The first one is displacement.. there really is no replacement for displacement. Drop a warmed over 454 in there and be done with it.

Unless you are willing to do the second option, which is the only acceptable replacement for displacement..... BOOST. Slap a turbo or supercharger of your choice on there. Then incrementally replace all the weak parts you break with all that extra power. Its a win-win really.

I agree with the replace/displace thing for sure. I have considered a 454. Also like the turbo idea a lot.

 

[nvrenuf]

Are you sure the 400 is above stock? I don't believe they were big power makers in stock form.

 

[Matt69olds]

Forced induction or NOx

Beat me to it!!!

Nitrous is by far the best bang for the buck.