alum edelbrock heads

AJ/FormS said

BTW, AJ and others, when you say lower DCR with AL heads, I presume you mean the AL heads have the effect (of) reducing detonation tendencies,(to) the same (as) an iron head with (a)lower DCR, is that right?

Yes, to some extent. The aluminum heads suck heat out of the chambers,and deliver it to the cooling system,and the surrounding underhood air--big time.When I originally put my combo together, It was 11.2Scr,9.2Dcr, and ran 87E10 full load WOT, without detonation at 32 to 35*timing. I quickly found out that on the street,MY a$$dyno couldnt tell the difference in output anywhere in that range, so it has run on the low end most of its life(32/34*). To exploit this effect, I have always run a 205*stat. The heads do require a longer than normal warm-up time tho.I combat that with a fat idle circuit and PLENTY of advance in the Vcan. I think the effect varies with load.
This would not be possible with iron heads, which seem to top the Dcr out around 8.5 on 87, 8.8on 91, and tickling 9 on 93 (from what I have gathered here from members). And with timing limited in some cases.

Click to expand...

OK, good numbers. I just wanted to make sure the new folks knew that DCR does not change with AL heads but the effect is like it gets lower.

'Back in the day' talk was of 'effective CR', I suspect only the likes of the big race teams and factories really worked at all with DCR numbers; all one knew as that a bit over 10:1 CR was safe on the new-fangled low-lead hi-test in general. All iron heads of course. I dug out my old cam card and dredged my memory for the CC's I set in the head and for the set static CR, etc., for my 351C build in 1974, and used the Pat Kelly DCR program and out popped the DCR for that old build: 8.48 !! LOL, was I lucky without knowing it! (All from studying Car Craft and Hot Rod magazines; the www was a generation away...lol).

For the OP, that engine had the stock high flows in the 351C-2V heads, similar to what you are looking at with the Edelbrocks out of the box, with a 10.3 static CR and quench dome pistons; you can do good quench with your engine and the new heads with flat top pistons and adjusting the deck height to somewhere near zero. The cam was a stump-puller cam, 114 LSA, 113 intake LCA (1 degree ground in cam advance), 445/471 lift and 254/264 duration. With large tube headers, a good intake and 600 cfm vacuum secondary carb, it would pull steady torque from 1500 to 6500; my 1-2 shift point was 55 mph and the 2-3 shift was 85 mph, with a 3.08 or thereabouts rear gear. Stock 440 Mopar B-bodies did not stand much of a chance in regular street races in Chambersburg PA and Roanoke VA. (My Ranchero was 3300 lbs so that helped; a rear gear like 3.55 would be even better but mileage would suffer). Stock torque converter on a C4 3 speed, and got 19 mpg on the interstate at 65-70 mph. Mild idle and rumble, excellent street manners with good torque across a wide RPM band, and would pass all mid 70's emissions except for NoX. And I used it to tow a 2500 lb race car all over the eastern US 3-4 time per year for several years....

So that is is an example of what you can do with lower duration, moderate lift, good breathing, and paying attention to the CR's. To me, that is the street engine you can drive all over and enjoy any time; at any RPM when you put your foot into it, it will be there ready to go. It will not set the ultimate drag times..... So what you want to do with the car is important to decide. Hope this helps you understand and make a good decision on how to go forward.