Dyno of Edelbrock Heads

Mark, were these heads out of the box or did you polish and port, oversize valves? What other mods have you done to your motor? Still agonizing over CHI or Edelbrock heads with oversize valves.
Richard T.

Hello Richard,
I bolted these on straight out of the box.
My motor is stock 72 except for Crane H272-2 cam(216/228&519/524), airgap manifold, and 700 dp carb.
I, like you, debated on which head to run. This comparison is far from scientific but I'm happy with the results. I would be fascinated to try a comparable CHI and AFD for comparison but that's not practical.
I searched the internet extensively for dyno comparisons but only found people exchanging flow data. I hope this information helps you in your decision.

regards... Mark

Thanks Mark, I have a Comp Cams 292 duration, .56 lift to go in this spring. I am running an Edelbrock intake with a 600 Holly carb and headers. Not to much different than your set up. I'm hopeing for 400-450 hp. I have a 750 holly lined up. There are some pretty good deals on the Edelbrock heads vs the CHI.
Thanks Again
Richard T.

Mark, I would like to see this comparison better, could you make a PDF file or a better image file. I don't know if a PDF can be attached to a posting maybe someone else here knows a better way.
Thanks, Jon

Hi Mark,

I've been waiting for a post like yours. I just bought the Edlebrock heads and am rebuilding my engine but have not decided on cam/pushrod length and piston (flat/dished). I also am not going to use my torker and have the air gap also. What pistons do you have (flat/dished)? And what compression to you have? Did you reuse your stock puchrods?

thanks for the info and great to see how satisfied you are with the heads, now I'm ready to pull the engine out.

Hello Jon, I will try to rescan and get a better image. I don't know how to send PDF files.

74LQQKR, My motor has factory original pistons and crankshaft. I estimate my compression ratio to be a math challenged estimate of 10:1. Chamber volume dropped from 76cc to 60cc. I'm using Comp pushrods #7976-16. Guidplates are designed for 5/16 diameter and pushrods need to be hardened and a Boss length of 8.495 - 8.500. Bolt down rocker design of a CJ will only be a non-hardened 8.400.
I am considering going with the Comp hyd roller #32-541-8 that seems popular with others here.
Edelbrock has recently introduced a flat hyd #7168 with 230 dur and .578 lift. Althought the peace of mind at not flattening a cam may be worth the three fold price difference.
The Comp Cams power estimator program promises a 70 hp increase with this roller cam. Seems wildly optimistic but I'm intriqued.

regards... Mark

Thanks Mark,
I've got crane 1.73 gold roller rockers and am still trying to determine the cam. I'm partial to crane but their rollers are pricey. The Edlebrock heads have a limit of .600 lift and 320# spring pressure max. so I'm working with that. I am actually thinking that with the oil problem and flat lifters I may go to synthetic oil. What do you think of a solid cam? I had one in an old mustang and it was not too bad adjusting. The P car might be a bit of twisting when adjusting. Thanks again

Since my goal is not a high rpm motor and the fact that I am lazy, I'm not considering solid lifters. As I recall the Edelbrock heads have a coil bind max of .600. The limit to effective flow is more like .580. Going more than that won't give more flow and will only decrease bottom end power. Also we are dealing with 2v size valves: intake 2.05 and exh 1.60. I'm confident that with the cam upgrade I'm planning 450hp flywheel is not a problem. Next step is an income tax return supported 408 stroker.
74LQQKR, I see by your signature line that you were originally from San Francisco. Did you ever make it across the bay to Vic Hubbard Speed and Marine in Hayward. That's where I work. I might have sold you some speed equipment at one time.

regards... Mark

DSC Motorsports built my Edelbrock heads. They have 4v sized valves for more flow and were bowl ported. The smaller 2v ports give better low and mid range. They made a huge difference over the stock 4v open chamber heads that were on my engine. Most flow tests show the comparison between stock Edelbrock heads vs. the more expensive heads which is why the Edelbrock flow numbers are so low. They are supposedly a lot better with the bigger valves. I paid under $1800 shipped to Hawaii for my ready to bolt on pair, to me that was a deal! In any case, they look cool!

Dennis,
What kind of intake manifold have you got there?

Nice job Dennis, they do look cool.
Mark, I do remember Vic Hubbards. I had been there before for stuff for my stang and jet boat.. Thanks again for all the info..

quote:

Originally posted by larryw:
Dennis,
What kind of intake manifold have you got there?

Edelbrock RPM Airgap, designed to run with their heads.

I have a feeling that the intake contributed to some of the HP increase. Too bad that intake does not have injector bosses cast in.

Dave, can't speak for Dennis, but my increase involved heads only. I already had the airgap prior to the test.
Dennis, give us more info on your engine, cam choice etc. Have you had a chance to dyno?

regards... Mark

I did the heads, cam, roller rockers and intake at the same time. Never been on a dyno but the butt dyno says dramatic increase. I'm runnning a comp cams extreme energy 262H hydraulic flat tappet. I think .519/.524 lift.

Dennis & Mark,

I'v decided to go with a Crane roller cam #529541 but calculating the pushrod length with the Edelbrock heads. The difference between the pushrods recomended for the cam with stock heads is 7.781" which is a .627" diff from stock. So, Mark if you used 8.495" and I substract .627 I get 7.868" to work with the Edelbrock heads and the roller cam. Does this sound correct to you guys?

Thanks

74 LQQKR,
Crane will want you to use #52631-16 pushrods(heat treated because of guide plates), they are 7.781. Crane seems to gloss over the fact that there is an approx .090 difference between adjustable rocker (boss) and non-adjustable bolt down pushrods. I personally would not sweat the difference. In my opinion .090 , once adjusted for, is not enough to affect the function of your valve train geometry. If you call Crane they will tell you to use a pushrod checker. I've never known them to put their necks on the line when non stock components are used.

regards...Mark

I'm running hydraulic flat tappets. Never been a measuring guy, I ran the stock pushrods, then checked the alignment on the valve tips. All were centered well and I've never had a problem with them.

Another question Mark. Did you have to modify your headers or muffler attachment at all when you put the heads on?

Thanks

No exhaust changes necessary. Port height is stock. You can bolt up 2v or 4v headers. There is added machined gasket surface to accomodate both. Of course just use the gasket appropriate for your header.

regards...Mark