400 Small Block Build. 500+ HP

[Winston Wolf]

Yes, you can feel the extra torque on the street. I'm certain I'll run better E.T's But I am concerned about the drop off after 6300. This s.o.b should be running out up to 7k in my opinion. I am now thinking I probably have 2 issues after the big heads and cam, my standard Performer RPM intake and my small 1 5/8" headers. I think they are choking it off on the top end. I can easily try a 1" spacer on the track to see if I pick up anything by opening up the plenum, but the headers is a different story.

 

Time to do some research....

[CrazyDavey]

you certainly have a lot of good parts in there and have done a meticulous job. My comments/observations would be these...

 

as Mark mentioned you picked up the lowend torque which you felt when you first drove it...a good and often overlooked thing.

 

With more cam and those heads I'm thinking it's running out of breath with that intake and carb. I can't tell which manifold that is but it should at least be a RPM or even a Victor Jr. I think there is also something on the table with the Eddy carb. They are a nice street piece but the go fast carb's are BG, Holley or a custom like Prosystems. There's just more adjustability in them.

 

Also did you play with the timing at all? 34 seems a little conservative, I would kick it up to 36/38 and see if it likes that. Just some thoughts, I wouldn't worry too much, that's a great motor and it will fly. It's just a new combo and you'll sort it out. Dave

[Winston Wolf]

It's a regular Performer RPM. Do agree that there are better race carbs out there, but I have that 800 AVS leaned out a bunch from stock settings and it still likes to run on the rich side. It should certainly be good for 500 HP.

 

I'm sure the intake is an issue, how much of one I don't know yet. I'm almost thinking that getting the air out is my problem, I don't know how much differance 1 7/8 headers would make????

 

We couldn't play with the timing because of the blown thermostat gasket, but I can do that on the track where it really matters.

 

I did lower the compression from 11.95 to 10.45, so I can expect a 3-5% loss in HP there.

[CrazyDavey]

I think you've built a motor that's going to like to breath, especially if you want it to operate at 7000. RPM is a great manifold IMHO but with your new stall and motor upgrades it could probably handle a Vic Jr which should work better up that high, the RPM is good to about 6500.

 

That's kind of what I meant about the adjustability, just more things to play with on a Holley for example. I would really, really suggest you at least talk to Patrick at Prosystems and see what he thinks. I picked up 3 1/2 tenths just switching from a stock 850 Holley to one of his carbs.

 

With some more air/fuel coming in and the 7/8's headers those upper numbers will pick up a bunch I'm thinkin'. There's no question you have a 500hp motor sitting there....I also think you're still good at 10 1/2....hope you don't mine these thoughts, I just love to brainstorm this stuff..Dave

[Winston Wolf]

I think you've built a motor that's going to like to breath, especially if you want it to operate at 7000. RPM is a great manifold IMHO but with your new stall and motor upgrades it could probably handle a Vic Jr which should work better up that high, the RPM is good to about 6500.

 

That's kind of what I meant about the adjustability, just more things to play with on a Holley for example. I would really, really suggest you at least talk to Patrick at Prosystems and see what he thinks. I picked up 3 1/2 tenths just switching from a stock 850 Holley to one of his carbs.

 

With some more air/fuel coming in and the 7/8's headers those upper numbers will pick up a bunch I'm thinkin'. There's no question you have a 500hp motor sitting there....I also think you're still good at 10 1/2....hope you don't mine these thoughts, I just love to brainstorm this stuff..Dave

 

Indeed, I appreciate the comments. It helps everybody learn. I think the number one thing is I need to get it out to the track and see how fast it's running. There will be no need or point to change anything if it is running at that 11.50 mark. Unless I have a revalation and figure out a problem, I think I'll try it on the stip first. Then change the intake, see what that does, then the headers after that if I'm still not where it needs to be. Changing all this stuff at one time isn't good practice, that I know.

[CrazyDavey]

nothing like the track to tell you the real deal....looking forward to hear how it does.....it's the sum of a lot of little stuff that makes the difference, that's how it worked for me...Dave

[Winston Wolf]

an interesting read in regards to stall converters on the dyno....

 

Truth about stall converters and the dyno

 

I'm just going to the track and settle this.

[Jared Richey]

Well if you run below 11.50 theres always a thing called a Roll Bar

And I agree after some track time, call Patrick at Pro-systems, I really think that would wake your engine up a good bit.

 

This has been a great post to read so far, and it keeps getting better!

[Heckeng]

Hey Winston, which AFR heads are those?

 

I think the RPM may be holding you back just a hair, but not too horribly. I do think a Vic Jr. would be nice like mentioned above.

 

Is there any possibility of valve float or bounce on the closing side? That would kill you at a certain rpm as well.

 

I would be tempted to go up to 36 degrees as well, since you have aluminum heads, but I'd hesitate to go higher because you do have some decent compression there.

 

I'm not a fan of the edelbrock carbs, but I'm pretty much uneducatedly biassed there! Never used one, I just like my Holley style carbs.

 

What were your cam specs at 0.050"?

[Winston Wolf]

Hey Winston, which AFR heads are those?

 

Eliminator Race Heads, 210cc runner, 75 cc chamber, 2.08/1.60 1.550"diam springs

 

I think the RPM may be holding you back just a hair, but not too horribly. I do think a Vic Jr. would be nice like mentioned above.

 

I may try an RPM Air Gap..?

 

Is there any possibility of valve float or bounce on the closing side? That would kill you at a certain rpm as well.

 

To me it did sound like it was missing at the top of the runs. I was really surprised, but I honestly think it was floating. I changed out the dist cap and rotor when I did this stuff because I thought I may have ignition problems. I really am having a tough time believing it's a valve spring/cam issue. These are some BMFing springs and it's a solid roller cam.

I would be tempted to go up to 36 degrees as well, since you have aluminum heads, but I'd hesitate to go higher because you do have some decent compression there.

Really, I don't think the compression is an issue with the big chambers. I went from 63 to 75, that drops it around a point and a half... I will be trying this at the strip

 

I'm not a fan of the edelbrock carbs, but I'm pretty much uneducatedly biassed there! Never used one, I just like my Holley style carbs.

 

What were your cam specs at 0.050"?

 

•Advertised Duration (Int/Exh): 279/285

•Duration @ .050 (Int/Exh): 249/255

•Gross Valve Lift (Int/Exh): .585/.600

•LSA/ICL: 110/106

•Valve Lash (Int/Exh): 016/016

•RPM Range: 2800-7200

[CrazyDavey]

I wanna say the AFR's come with roller rated springs with some good seat pressure, I know the BB one's do. I did my best to measure the RPM vs the RPM Airgap version and I didn't see any difference other than the airgap feature, it should support the Vic Jr just fine. It's kind of hard, you're right on the border for both intakes by their specs. For a SB that's not a radical cam but being a soild roller should make 7000 okay with power.

 

Maybe Scott can elaborate on the timing vs compression, I've never heard that but that sure doesn't mean anything. I've run BB motors with 11 1/2 as high a 44 degrees (with steel heads) with no ill affects, I give the motor what it wants and so far that's worked. Every motor I've had seemed to like its own thing, there are so many variables in a motor I don't think you can cookie cutter the timing...you've got the right idea, play with it and see what works....it will be interesting to see what feedback you get from the Chevelle guys...Dave

[Winston Wolf]

Here are the springs Lunati wants

 

Lunati Intro Series™ valve spring set

 

•Spring Type: Dual

•Outside Diameter: 1.500 in.

•Inside Diameter: 0.800 in.

•Seat Load: 197 lbs @ 1.850 in.

•Open Load: 533 lbs @ 1.250 in.

•Coil Bind: 1.110 in.

•Spring Rate: 560 lbs/in.

 

Part Number: 73899

 

 

Here is what is on the AFR heads.

 

AFR-8000 1.540 OD

225# @ 1.950

600# @ 1.250

Chrome Silicon

Bind Height 1.155

Rate 550 lbs

Max Lift .710 in

orange .800 ID

 

If these springs are allowing valve float then, they aren't what AFR says they are....

[wallaby]

It's kinda fun to speculate on what would make the biggest difference at this point, so I'll add my gut reaction.

I suspect that you have reached the limits of a dual-plane intake. As far as I know, the RPM and the RPM air gap are the same except for the air space beneath them, so I don't see any point in going that route. The RPM is considered one of the best performance dual-planes already, so I'm thinking it's time to step up to a single-plane intake.

As usual, there are a lot of choices...if you like Edelbrock there is the Torker or the Victor Jr, and Weiand has the X-CELerator or the Team-G intakes.

I always prefer to build for torque, so personally I'd choose the smaller offering in hopes of gaining power in a useable range insted of fixating on upper RPM limits.

 

A day at the track will probably make you feel better.

[Winston Wolf]

Wallaby, I tend to agree with you.

 

Here is an interesting read and awesome comparo video about the manifolds.

 

SBC Manifold Test

 

 

 

I am also thinking I might need to switch to 1.6 rockers on my intake. I think these AFR heads would do better without a split cam. 1.6's would bring my intake lift up a bit (.585/.600 with the 1.5's, .624/.600 with the 1.6/1.5)

 

At least I am coming up with some possible solutions and should have some things to test out. It's going to take me a few weeks to sort things out. Trips to the stip take some coordination and they dyno has a 2 week wait plus 100 bucks an hour....

[Sam (Bones)]

my big block with 12:1 likes 40 degrees of timing too

 

are you sure! you are getting enough fuel??? (as in the pumps/lines to the carb?)

[Winston Wolf]

my big block with 12:1 likes 40 degrees of timing too

 

are you sure! you are getting enough fuel??? (as in the pumps/lines to the carb?)

 

I posed the same question to the dyno guru at the shop. His comments were that we would see it in the a/f leaning out at the top end if it was running out of gas. I run a stock type pump and an electric pump back by the tank that "supercharges" it. I am still using the stock lines.

[Sam (Bones)]

if you have the 5/16" line...IMO it isn't not be large enough for the power level you're trying to achieve

 

did you "degree" your cam when it was installed?

[Winston Wolf]

Cam was degree'd. See first post.

[Heckeng]

My comment on the timing vs compression ratio is simply that I've always been told that the higher the compression, the less timing you can run. That will change with cam bleed-off though which I would guess is why Sam is able to run so much timing. Winston, with your cam being as large as it is, maybe you can also try something up a little higher, maybe 38 degrees?

[Andy's Auto]

Mr Wolf, you solve problems right?

 

This one just seems like a light build issue and a little tuning. My professional opinion is simple. You are leaving a ton on the table with that Thunder Series Eddy. Great carb for a light compression street car, but you built more of a weekend cruiser/track car. Love the cam, love the cubes, love the heads. Hate the carb and intake. The faster guys like the AEDs and Prosystems. I am an AED kinda guy. I am fundamentally a big block guy with emphasis on the mental aspect.

 

I have never asked a 468 to turn more than 6000RPM without the beni of at least a Victor Jr. I have installed dozens of Air Gap RPMs on dozens of 12 second 3500 pound cars, but those with the pockets to go 11's get the big boy stuff.

 

Your write up is awesome,Everyone on this forum thanks you. Now go solve the problem. That bottom end screams low 11's , but you do have a bit of a fight on your hands. Keep us pposted.

 

Andy

[Chevyss]

Replace the fuel line. We messed with mine for one whole summer trying to figure out why I kept running out of fuel. Kept burning up fuel pumps. Replaced the sending unit with one with large 1/2 tubbing and run 5/8 line to the regulator and 1/2 inch line back to the tank. A1000 pump and an 100 micro fuel filter.

No more problems. Good Luck

[Winston Wolf]

This one just seems like a light build issue and a little tuning. My professional opinion is simple. You are leaving a ton on the table with that Thunder Series Eddy. Great carb for a light compression street car, but you built more of a weekend cruiser/track car. Love the cam, love the cubes, love the heads. Hate the carb and intake. The faster guys like the AEDs and Prosystems. I am an AED kinda guy. I am fundamentally a big block guy with emphasis on the mental aspect.

 

I have never asked a 468 to turn more than 6000RPM without the beni of at least a Victor Jr. I have installed dozens of Air Gap RPMs on dozens of 12 second 3500 pound cars, but those with the pockets to go 11's get the big boy stuff.

Thanks for the comments. Are you recommending a Victor JR then? or another single plane intake? This still is not a big block, and with the heavy car I do worry about the midrange torque. I am planning to switch manifolds to something other than the standard RPM that I have, they all cost about the same, so the price is not a factor in my decision.

 

Most people in this HP/ET range with a big car like a Monte Carlo are talking big blocks. It's the same, to a point. You BBC guys don't need to worry about giving up any low end torque, you've go plenty to spare. When you can spin the tires for 2 blocks with your 468 or 496 or 502, 20 ftlbs less isn't a factor, you can't use it anyways. With the small block it's more of a big deal. I'm trying to show that it can be done with a mouse motor that you can actually drive on the street enjoyably.

 

Unless I can't get to that magic 11.50 mark, I am going to try and stick with the Edelbrock carb. The car runs great and pumping another 700 bucks at the carb doesn't sound awesome to me. I don't disagree with you at all though, I'm positive I would see gains.

 

I will head to the track on Saturday, weather permitting. I want to see what it will do now before I tear back into things. Who knows, maybe I am there already. With 25 more HP and the bigger stall I could have picked up the half sec I need and won't need/want to change anything.

 

[wallaby]

I imagine you have already done your research, but here is some more info that might help.

Hot Rod build

CHP build

CHP build II

I find these kind of articles helpful to learn what I did right, so I can focus on what's really important. Intake manifolds, carburetor sizing, and header tube sizes are all here. Crate engine specs can be helpful also, but are often vague. An advertisement for a 450hp engine that says "aluminum heads, custom-ground cam, and forged pistons" doesn't help you any if you are trying to duplicate their results.

The proof is in the pudding though...your dragstrip results will let you know if you're making progress. Like you said: your ideal combination might be under your hood already.

[Winston Wolf]

Thanks for those articles. I had stumbled across them.

 

Looking more at my dyno sheets, looks like peak HP is 385 and the peak is long, from 5400 to 6000, then drops hard after 6250.

 

In this article

Edelbrock manifold testing, ported vs stock

 

They are seeing the ported RPM air gap at 6400 rpms down only 4 hp from the ported victor jr and more power all over than an as-cast victor. I feel getting this monster rolling off the line is going to ET faster than trying to scream it at the end of the quarter. Plus, I just don't think giving up the 20 HP at 3800 RPM is going to make it fun on the street.

 

My biggest conflict is that as you roll on that throttle going 60 mph you want it to move. It's still only running 2500 at 70 with the converter locked...

 

It's going to be a battle of compromise, but I'm leaning towards porting a RPM air gap, and running the 3/8" open heat spacer to even it out. I don't have any more room than that, a 1" spacer won't fit with the 4" element.

[Winston Wolf]

Well, Got to Wisc today to test out the new stuff. Not too impressive.

 

Best time of the day with the new engine was a 12.04 @ 113.5

 

Best time on the other heads/cam was 12.02 @114.06

 

I did have one run that would have been in the 11's, but the timer did not record my 1/4 mile et or speed. That was a 7.673 @ 90.54 1/8th with a 1.701 60 ft. Drag strip doesn't lie, I had more power before.

 

The new converter did help a little on the 60 ft times. I was averaging 1.73ish and before it was almost 1.8's with the 2400 stall.

 

Played with the timing. Looks like it wants 37 deg. I am assuming this is from the lower compression.

 

I am still getting a miss on the top end, the same as with the other combo. I'm thinking it may be in the distributor, I'm just not sure. You will be able to hear it on the video below. On the last run it is really noticable. That is the 12.04 run. As I think back, I have fighting it on and off for years. I don't think it valve springs anymore. The car actually ran so terribly on the first run, I couldn't believe it. Seemed like it missed in every gear. Ran a 12.356 @ 110.76

 

You will also see the logs from a few runs. I can't seem to get this Edelbrock carb to put down a good a/f curve. I am done fighting it. I also see some leaning out at the top end rpms. I'm crossing my fingers that it is my fuel pump setup and stock lines.

 

The trans is still giving me a bit of fits too. I'm having a tough time getting my lockup timing correct. You will see some flat spots in the revs on the charts, that is the converter locking up. Everything happens so fast, it's tough to shift, lock up conterter, shift all in a second, I'm still working on that.

 

I guess the bottom line is I will be blowing some more cash this week: new intake, carb, distributor, fuel pump, and lines.

 

For those who haven't see logs before, the top line is the RPM's during the run and the bottom line is the air/fuel ratio.