Help with choosing heads

April 15, 2020, 11:29 AM

Fatboy81

Sorry for the late response guy and think you for all the input.

I’d love to just change the cam but my valves/springs will only handle .600 lift. By my estimate I’d be spending $600 to upgrade this on a set of heads that are truly just street heads. The engine was originally built for my streetcar. When I built this s10 for my daughter when we got her drivers license I didn’t expect her to need to go very fast so I didn’t change much on it. The truck ran 11.0s with the 355ci. We spoon a rod at the end of last season so I stroked it and put the domes and good bottom end. I knew the heads/cam where still street stuff but it worked good at the time. Now that the tracks are closed and we have some down time I want to go ahead and step up the top end. I didn’t see the point in changing the cam until I got a head to handle it. Her brothers(15)car runs 9.80 and we slow it down with a restrictor plate to keep it in the 10s. She makes comments from time to time about her truck being slow so I’m just trying to get hers to run about what his runs.

The truck traps in the 1/4 at about6900. If we increase power to run a low 10 that will increase to about 7200 which is way I built the bottom to hold 7500. Most races here are going to 1/8 so rpm limit shouldn’t be a problem.

Comp cam suggested a custom cam 276/.284 duration @ .050" and .672/.672 lift with a LS of 108

Giving piston to valve clearance. What do y’all think? Seams big to me. Also what are suggestions for heads? I contacted Chad but he said his heads would be overkill

April 15, 2020, 11:33 AM

Alaskaracer

You've got some good advice from some very knowledgeable people here...I'd take it to heart and decide from there....

April 15, 2020, 12:45 PM

TOP38

quote:
Originally posted by Fatboy81:
Sorry for the late response guy and think you for all the input.

I’d love to just change the cam but my valves/springs will only handle .600 lift. By my estimate I’d be spending $600 to upgrade this on a set of heads that are truly just street heads. The engine was originally built for my streetcar. When I built this s10 for my daughter when we got her drivers license I didn’t expect her to need to go very fast so I didn’t change much on it. The truck ran 11.0s with the 355ci. We spoon a rod at the end of last season so I stroked it and put the domes and good bottom end. I knew the heads/cam where still street stuff but it worked good at the time. Now that the tracks are closed and we have some down time I want to go ahead and step up the top end. I didn’t see the point in changing the cam until I got a head to handle it. Her brothers(15)car runs 9.80 and we slow it down with a restrictor plate to keep it in the 10s. She makes comments from time to time about her truck being slow so I’m just trying to get hers to run about what his runs.

The truck traps in the 1/4 at about6900. If we increase power to run a low 10 that will increase to about 7200 which is way I built the bottom to hold 7500. Most races here are going to 1/8 so rpm limit shouldn’t be a problem.

Comp cam suggested a custom cam 276/.284 duration @ .050" and .672/.672 lift with a LS of 108

Giving piston to valve clearance. What do y’all think? Seams big to me. Also what are suggestions for heads? I contacted Chad but he said his heads would be overkill

If low 10's is the goal, change the cam to the right solid lifter or roller cam for your deal. As Ed stated, Comp's is OTL! You likely talked to someone who knows little other than to read from a catalog. Ballpark, take 10 to 15 degrees off the duration and close the lobe separation 2 to 4 degrees. To fine tune the cam you need to know the real compression ratio, not the text book listing for that piston and how much lift those heads with the valves in them can take, ie max installed height. As far as piston to head goes, you need to check it no matter what you change which includes new heads also.

Low 10's with your heads is achievable! Good luck.

April 15, 2020, 01:20 PM

Mike Rietow

Ah ha ha ha ha ha! The cam is gonna improve the efficiency of the converter, at lower rpm at the stripe

oh my gawd what a cluster F!

April 15, 2020, 01:21 PM

1320racer

your way out of your league, step aside.

April 15, 2020, 01:29 PM

Mike Rietow

Proceed, ya'll are some entertaining mofo's no doubt!

April 15, 2020, 01:37 PM

Fatboy81

Yes that cam seamed a bit much. I’m going to get with my local engine builder and see what he would spec out for the cam

April 15, 2020, 01:38 PM

SpeierRacingHeads

I built myself a 3.48 stroke, 379 with a set of my 205cc CNC heads. 10-1, 750 carb, true 91 octane, 231/235 cam, .550 lift, for my street car. It made 510tq@4000 and 548@6300..

We didn't find every ounce of power because it got a elbow/EFI/throttle body in the car.

You can easily make the same power with an as-cast head and a much smaller cam than you were told.

April 15, 2020, 02:27 PM

"The Bender"

quote:
Originally posted by 1320racer:
Very achievable with just a cam change but depending on what the converter flashes to and drops to after the shift now, it may need a tweek. I'm guessing the converter is loose now so the right cam would only improve it's efficiency.

I'm with Ed on this one....

April 15, 2020, 03:22 PM

TOP38

quote:
Originally posted by Mike Rietow:
quote:
Originally posted by "The Bender":
quote:
Originally posted by 1320racer:
Very achievable with just a cam change but depending on what the converter flashes to and drops to after the shift now, it may need a tweek. I'm guessing the converter is loose now so the right cam would only improve it's efficiency.

I'm with Ed on this one....

2, 10 or 200 greenhorns in here who don't know what they're talking about agreeing with Ed, won't change performance fundamentals.

The only way the converter gets more efficient with a cam change, is if the engine makes more power, goes faster and cross's at higher RPM - MPH.

That's a fact, not an opinion.

Here's another fact for Mr Absolute! It would if it were modified to better fit the new cam or whatever, so that's a second way to your ONLY WAY!

Just saying!

BTW, I replied to you on this so not to leave you out and feeling lonely regarding this tread.

Got a question for you, since you are so smart, cuz you say u r, why are you wasting your time here, shouldn't you be working on a cure for the Covid -19????

This message has been edited. Last edited by: TOP38,

April 15, 2020, 04:28 PM

1320racer

Mike, I'm going to post over at YB, thanking them for chasing you and all your aliases out of there and with nowhere to go, landing here. Because of you, Top38, Bender and I now agree on performance advice and I suspect as long as you are around we will in many more threads.

April 15, 2020, 04:38 PM

Mike Rietow

Here's where we are greenhorns. Not opinion but fact.

Anyone else?

2, 10 or 200 greenhorns in here who don't know what they're talking about agreeing with Ed, won't change performance fundamentals.

The only way the converter gets more efficient with a cam change, is if the engine makes more power, goes faster and cross's at higher RPM - MPH.

That's a fact, not an opinion. This is not a subjective matter or I wouldn't be here.

April 15, 2020, 04:50 PM

"The Bender"

Does this mean that Mike has "out-Ed'ed" even Ed?

April 15, 2020, 04:59 PM

Mike Rietow

Generally speaking, people can't handle the Truth. That's where I come in.

April 15, 2020, 05:27 PM

Curly1

For Cam recommendation I would call all of the major manufacturers and get their opinions. You will quickly see a few are way out of line with others. Disregard them.

I called one big cam company one time for a recommendation. They asked me "Big Block or small Block Drag or Dirt track? Here is cam you need" Obviously I did not buy from them. They have went from a good cam company to sales team.

My last few cams have been from Bullet and they have been great. When you call them they will ask you a bunch of questions about what you have, what you want to achieve and will give you a good recommendation and how it will help you.

There are some who think they know more about cams than the people who do it for a living.

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