Edelbrock 340 High Compression RPM Performer Alloy Heads?
- Thread starter hux340
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dano
Evil Handy Man
If your referring to the ones with the milled openings to clear the 68-71 above deck pistons then they are not overly recommended to use. Best bet is remove your heads, measure your pistons height (if there is any as production tolerances will vary wildly) and order thicker head gaskets (if needed) and the non-340 heads. Get a gasket thickness to give the best quench distance. Most shoot for about 0.038" (someone correct me here if I'm wrong) This is all based on your engine is assembled and possibly in the car. If your building a new get your block sonic checked, squared, and have the piston brought to zero deck, then use the non-340 closed chambered heads.
Then jump into rocker geometry and push rod length...
Then jump into rocker geometry and push rod length...
dano
Evil Handy Man
And in all honesty us knowing more about what you want to do and have will help a lot, because there are several ways to skin this cat.
The open chambered Edelbrock Head (?) is designed for the stock piston in the early high compression 340 engines.
Is that the head considered for use?
If that is what I had, a stock high compression 340 and it actually checked out OK which would be a near miracle so many years later, then that head could be considered for use.
A rebuilt 340 with the same replacement pistons would need to be carefully checked against the stock piston. And then double checked against the heads chamber for fit and clearance.
Over all clearance of piston to head on my zero deck/flat top pistons with OE connecting rods use a .038 head gasket for safety. This obviously puts the piston at a safe known distance away from the head. Also take into consideration that the rod & piston assembly will stretch under stress and get slightly closer to the cylinder head. How much this stretch is also a consideration of the parts used.
On my street and street strip rides, the above pattern of building (flat top @ zero deck) is maintained no matter the cubic inch size because it is a tried and true safe path that can and will perform safely and repeatable over and over again.
Addding a dome must just simply have the clearance in the pistons chamber. I have just not found a reason that run a dome on the street with the available fuel octane and camshaft sizes dropping the dynamic ratio for pump gas. Or race fuel if that is what the engine is designed for. Head gasket selection and availability these days provides final adjustments.
Again, for myself I have had no need for a domed slug. Head chambers for stock heads are generally in the 72 open cc area and the closed chambered sizes down to about 58 cc for stock or most high performance heads provide enough of a ratio swing to do most of what is needed ratio wise.
Looking forward to your build.
Is that the head considered for use?
If that is what I had, a stock high compression 340 and it actually checked out OK which would be a near miracle so many years later, then that head could be considered for use.
A rebuilt 340 with the same replacement pistons would need to be carefully checked against the stock piston. And then double checked against the heads chamber for fit and clearance.
Over all clearance of piston to head on my zero deck/flat top pistons with OE connecting rods use a .038 head gasket for safety. This obviously puts the piston at a safe known distance away from the head. Also take into consideration that the rod & piston assembly will stretch under stress and get slightly closer to the cylinder head. How much this stretch is also a consideration of the parts used.
On my street and street strip rides, the above pattern of building (flat top @ zero deck) is maintained no matter the cubic inch size because it is a tried and true safe path that can and will perform safely and repeatable over and over again.
Addding a dome must just simply have the clearance in the pistons chamber. I have just not found a reason that run a dome on the street with the available fuel octane and camshaft sizes dropping the dynamic ratio for pump gas. Or race fuel if that is what the engine is designed for. Head gasket selection and availability these days provides final adjustments.
Again, for myself I have had no need for a domed slug. Head chambers for stock heads are generally in the 72 open cc area and the closed chambered sizes down to about 58 cc for stock or most high performance heads provide enough of a ratio swing to do most of what is needed ratio wise.
Looking forward to your build.
My questions was more about, is he trying to make the 340 into a high compression engine with his choice of cylinder heads, or, is he looking at cylinder heads that are to be used on the factory high compression 340 engine?
I see a difference between a high compression 340 and 340 High Compression RPM Performer Alloy Heads.
Are we talking about Edelbrock Small-block Chrysler or Small-block Chrysler 340 or even Edelbrock Small-block Victor?
Everybody is saying it............we need more information.
I'm going to season my evening meal. What spices should I use?
I see a difference between a high compression 340 and 340 High Compression RPM Performer Alloy Heads.
Are we talking about Edelbrock Small-block Chrysler or Small-block Chrysler 340 or even Edelbrock Small-block Victor?
Everybody is saying it............we need more information.
I'm going to season my evening meal. What spices should I use?
stixx
Well-Known Member
High density NOS salt'n'pepper.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Flat-tops, .034Q , closed chamber heads,and Scr adjusted to 185psi, with whatever cam you run. I ran about that on 87E10 at 34* power-timing at 3400, in a 3650 pound blob, me and the car together. It will take 32*@3200, which is all those aluminum heads need on the street.
A) My 367
Static compression ratio of 10.9:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 8.91:1 .
Your dynamic cranking pressure is 183.76 PSI.
V/P (Volume to Pressure Index) is 162........................................ 162
Unbelievable power in a 367.
If you don't know about VP,read about it here; V/P Index Calculation
B) a stock 1969 440 Magnum makes about;
Static TRUE compression ratio of 10:1.
Effective stroke is 2.83 inches.
Your dynamic compression ratio is 7.79:1 .
Your dynamic cranking pressure is 154.44 PSI.
V/P (Volume to Pressure Index) is 154........................................ 154
Some of us might remember these as the things to beat in the GTX/ Roadrunners......with our little 340M/T As... back in the day.
_________________________________________________________
I tell you what, even the 383Magnum GTX-4-gears were tough; gear for gear, and only to about 85 mph.Then they were catching up......sometimes, FAST!
But after I blew up the 3.55s,I lied about the 4.10s in there,lol; and tried not to beat 'em by too much. Those GTX owners were all the same, after they got beat by a puny Dart.
A) My 367
Static compression ratio of 10.9:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 8.91:1 .
Your dynamic cranking pressure is 183.76 PSI.
V/P (Volume to Pressure Index) is 162........................................ 162
Unbelievable power in a 367.
If you don't know about VP,read about it here; V/P Index Calculation
B) a stock 1969 440 Magnum makes about;
Static TRUE compression ratio of 10:1.
Effective stroke is 2.83 inches.
Your dynamic compression ratio is 7.79:1 .
Your dynamic cranking pressure is 154.44 PSI.
V/P (Volume to Pressure Index) is 154........................................ 154
Some of us might remember these as the things to beat in the GTX/ Roadrunners......with our little 340M/T As... back in the day.
_________________________________________________________
I tell you what, even the 383Magnum GTX-4-gears were tough; gear for gear, and only to about 85 mph.Then they were catching up......sometimes, FAST!
But after I blew up the 3.55s,I lied about the 4.10s in there,lol; and tried not to beat 'em by too much. Those GTX owners were all the same, after they got beat by a puny Dart.
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May be he is talking about 340 Buick heads.
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