Dyno test info on spacers and timing

Hi Gang,

Just though I would share some useful info on the motor we dynoed this afternoon. Seems like we could all use a little more tech talk lately.. :laugh:

Anywho..

The motor is Brian Garrett's (Gold 72 GS) and it's going in his GS. Full street car with all options.

A little background on the motor first, and then we can look at the dyno numbers and their effect on power, with some timing and spacer and no spacer pulls.

Brian wanted a little more umph than my standard Level 1 motor, but we still had to maintain a good idle and driveablity. So we ported his STG 1 heads to our latest combo for the iron head, which is a full port on the intake, and a street/strip port on the exhaust. WE have found that we can reach those high 190 cfm number on the exhaust with this somewhat "less" porting job (read that cheaper) yet still make some good power. We coupled that with a new custom cam grind, and TA's new SP-1 manifold, and came up with some interesting numbers.

This motor is a departure from my Level 1 and 2 iron stuff, because we went with the better SP1 intake, instead of the Performer, and then made a cam to compliment it.

Here is a rundown on the motor specs

Full compliment of machining. Bore/ Deck plate Hone (.030), Line hone with main studs, zero deck height, engine re-fit for deck height dimension change. All our "usual" oil mods to the block.

Speed Pro Pistons with valve reliefs
Stock rods and crank
10.0-1 compression
'73 Iron heads, flowing 280 intake, 195 ex
Rollmaster Billet T-Chain
Stock Steel Rocker arms, with TA Roller Rocker holdowns and studs.
Custom Comp Cams Camshaft. 231/237 @.050 .496/.499 lift 110 LC installed 3* advanced.
New TA Sp-1 intake, with portmatch and very mild Plenum blending.
950 Holley HP prepped by Biggs Performance, jetted 85/88
TA timing cover
Stock oil pan, windage tray, and 5/8 pickup.
TA Hardened 5/16 pushrods.
1 7/8 full length headers

Nothing super fancy, just a good solid street performance deal.


Ok.. first thing I noticed was a higher level of performance than I had seen with the 950 sitting right on the Sp-1. In the past, the old versions of Mike's manifold really wanted a 1" spacer. This test was performed with 36* timing, and then we backed off on the timing in the next test..

 

averages of test 1

Averages are always important to look at, in testing..

 

Test 2

Now, as usual, we fooled with timing a little. We bumped up 2* and saw vitually no difference.

So we bumped it back a little, and saw very little change. That lets us know that this combo, with this cam, and the cylinder pressure it's making, wants the timing right there.

I gladly gave back a couple degrees, as it is a "safer" deal on pump gas.

Here is that test, with the timing now at 34*, with no other changes.

 

Test 2 Averages

I will give back a number or two, in an application like this, to go with a little less spark lead. With the cylinder pressure we are making with this thing, it just smarter. Knowledge like this is one of the reasons we dyno test every motor, as it takes the "guesswork" out of the equation. I have seen 2* timing changes in the past cost us 5-10 numbers..

 

Spacer 1

Ok, onto the spacer testing..

In the past, the SP-1 on a 500 HP motor has really wanted a 1" spacer. I have seen 10-15 HP on a similar motor with a bigger cam.

This is the smallest cam iron headed motor to date we have built, that made 500 HP on pump gas.

But this motor really is not spacer dependant, which is a good thing, since that extra 1" can really hurt the hood clearance issue.

Here are the results with our normal 1" Dart Cloverleaf spacer. The cloverleaf spacer, which looks like a 4 hole spacer with the center cut out of it, has always proven to be stronger by a few HP than an open spacer.

 

Averages

Up 5-6 numbers in HP/Torque, but not as much difference as there used to be. This combo likes the SP-1 better than it would if it had a bigger cam in it, without the spacer. Also the new SP-1 is superior to previous versions, out of the box. I could make an old SP-1 perform like this, but it was an easy 4-5 hours of work. I had about 1/2 that in this manifold.

 

Next we moved up to the HVH Super Sucker Spacer.. it's basically a 4 hole that transions to a open spacer, and I have seen improvements on every motor we have had this on, over the cloverleaf spacer.

 

Averages

AS is typical with a carb spacer, it flattens the curve, and holds the higher numbers longer.. hence the higher averages.

This HVH spacer, although spendy, does a very good job of this.


Up 3 numbers in HP/TQ over the Cloverleaf Dart spacer.

 

And a graph of that last test..

 

So... my advice to Brian.. don't sweat the spacer for normal crusing, but when you take it to the track, break out your HVH spacer, and install the air cleaner in the backseat, to get your best times.

If he can hook it, this will be an 11 second GS, with the right conditions and supporting equiptment.


Also of note.. another one of our board members here sent me a brand new 850 CFM Edelbrock Q-jet.

Although far from optimum ( this motor has a Holley flanged manifold on it, and we had to install a spacer for the Q-jet, which left a "step" in the airflow from the secondaries), this new carb, straight out of the box, performed great in the part throttle test, and made 500 HP on this motor. I was impressed!

I very well may make this carb the "standard" carb on my Level 1 and 1A and the level 2 iron motor in the future.


We also video taped this session, and maybe we can get a few clips on here in the future, for your viewing pleasure..

JW

 

Jim,
Great job on the info to the group! Keep it coming. I like your tech talk.

 

Thanks Rick..

Your shiny new "present" left via Fed EX today..

 

Great tech article. I had just bought one of those HVH spacers for my car.

I just got the Stage 2 scoop installed and had been told by a Chebby guy that I was wasting my time with a spacer on my car. I was feeling uncertain, but now I feel a lot better, especially after what they cost.

As you said, it'll only be on the car for Norwalk and Quaker, but I'm always looking to squeeze what I can out of my car. My engine also seems to like 34 total timing best too.

 

Hey Jim Great info, on that 850 q-jet it works well out of the box? No changes are needed the secondarys open well? This carb on a performer should work well then.Any other thoughts on
what this carb can do i'am sure the board member would like to know.thanks Jim

 

I feel like a proud papa! That work of art will be here this weekend and I am excited as can be! I can't wait to see how it runs in my car. The great thing about it is that it is 100% setup and ready to run.... all I have to do is bolt it in! That way there is no guess work to do. It will be a thing of beauty sitting in my engine compartment! Brian

 

I'm sorry, but what is a HVH Super Sucker Spacer. Could it be used on a stock engineo No: ?

 

brian were going to need pics espically for me i have my pice of artwork soon to be completed.

 

Jim,

Great information!!!!

Is the HVH spacer under $200 these day? The information supplied here backs up everything that I have heard with the HVH spacer. As for being spendy?? Well... an NHRA prostock guy would love to find 8-10 HP for $200 bucks!!!

I also agree with moving back the timing and giving up a little bit of power for more reliability.

Great Job

 

You can get a super sucker for about $100 or so. Just surf the net. I'll try and post their website here later.

The super sucker website:

http://www.highvelocityheads.com/ss.htm

 

I'll definitely post some pic's when it comes back! Maybe Jim will strike a pose with it for me. Maybe something like Grumpy Jenkins half naked bear rug shot that was in Hot Rod last month! On second thought, maybe not!! In any event, the engine will look awesome, I popped for the billet mega fuel pump and braided hose with AN fittings at the last minute. I didn't really want to install an electric pump and having Jim assemble the fuel lines and fit the pump properly to me was the smart thing to do. Plus it will look better than whatever I would have come up with! As far as the fuel pump issue goes, I've been told that modifying the pump arm, not repositioning the pump mounting is the way to go. Apparently there can be some very nasty things that can happen if you aren't careful and check your clearances when you go to a double roller and or new timing cover. That billet pump can handle up to 800 horses I believe. Brian