According to one of the leading mail order suppliers, these heads are not compatible with my 78 L48 with stock cam because I don't have the correct cam installed. These heads list for hydraulic cam only, he said I have a flat tappet cam. I responded yes, but it is still a hydraulic cam. This guy is full of crap....correct?
I chose these because they will accept the performer intake and perimeter style bolt valve covers.

Brand:
PROMAXX Performance


Manufacturer's Part Number:
2151


Part Type:
Cylinder Heads


Product Line:
PROMAXX Performance Vortec 185cc Iron Cylinder Heads


Summit Racing Part Number:
PMX-2151




Cylinder Head Style:
Assembled


Cylinder Head Material:
Cast iron


Cylinder Head Finish:
Natural


Combustion Chamber Volume (cc):
64


CNC-Machined Combustion Chamber:
No


Intake Runner Volume (cc):
185cc


Exhaust Runner Volume (cc):
60cc


CNC-Machined Intake Runner:
No


CNC-Machined Exhaust Runner:
No


Intake Port Location:
Standard


Exhaust Port Shape:
Square


Exhaust Port Location:
Standard


Spark Plug Style:
Straight


Intake Valves Included:
Yes


Intake Valve Diameter (in):
2.020 in.


Exhaust Valves Included:
Yes


Exhaust Valve Diameter (in):
1.600 in.


Valve Springs Included:
Yes


Maximum Valve Lift (in):
0.575 in.


Outside Diameter of Outer Spring (in):
1.270 in.


Damper Spring Included:
Yes


Retainers Included:
Yes


Retainer Material:
Steel


Locks Included:
Yes


Lock Style:
Stock


Valve Stem Seals Included:
Yes


Rocker Arm Studs Included:
Yes


Rocker Arm Nut Thread Size:
3/8-24 in.


Rocker Arms Included:
No


Rocker Arm Nuts Included:
No


Guideplates Included:
Yes


Guideplate Pushrod Size:
5/16 in.


Valve Cover Mounting Style:
Center and perimeter bolt


Accessory Bolt Holes Drilled:
Yes


Valve Guides Included:
Yes


Valve Guide Material:
Manganese bronze


Valve Seats Machined:
Yes


Valve Seat Machine Style:
5-angle


Valve Seat Material:
Ductile iron


Steam Holes Drilled:
No


Oiling Style:
Through pushrod


Machined for O-Ring:
No


Heat Crossover:
No


Quantity:
Sold as a pair.


Notes:
For use with hydraulic cam and lifters only.

 

Unless you've changed the cam, you have a hydraulic flat tappet cam.

 

yes, stock cam so these heads will be compatible?

 

The specs list a 1.270 spring for .570 lift....so yes, these heads will work for flat tappet.

Jebby

 

Thanks Jebby

 

Something to consider

I built a small journal 1967 327
Steel Crank only needed polishing, tough old cranks.
Rods, I used Eagle I Beam
Pistons. Forged 30 over Kieth Black 10.5:1
Cam, better than stock but not too loopy.

On top I use factory yet ported, double Hump heads and factory Aluminum Intake and valve covers.

I done several build such as this to Chevy and Fords of the 60’s

so that the outside looks totally stock while the inside is anything but.

 

in the summit description is plainly states hydraulic flat tappet, so I dont know what the tech guy was thinking. THe other 2151 head is a 2151HR which is probably for hydraulic roller lifters but they dont provide a description for it

 

the applications page lists it ...must be some gen z kid
https://www.summitracing.com/parts/P...ions/year/1978

 

it lists those as unavailable but heres some aluminum heads that are similar
https://www.summitracing.com/parts/e...make/chevrolet

https://www.summitracing.com/parts/b...make/chevrolet