Mini Mania
Est. 1974
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Gt17 Longman Race Cylinder Head Assembled

Gt17 Longman Race Cylinder Head Assembled

Gt17 Longman Race Cylinder Head Assembled
The stock 1275cc Spridget and many later Mini Cooper heads have 1.31" intake, 1.15" exhaust valves and porting that means valve lift after about .350 is a waste of reliability! The heads supplied by Longman have huge valves: 1.48" intake and 1.15" exhaust valves. The porting is such that .500 valve lift is still on the curve of performance gains. This head not only works fantastic but looks like it belongs on display rather than in a car. The GT17 head from Longman is complete with extra long valves, special springs and rotators. These rotators help insure the valve is free to rotate as it goes up and down, thus greatly increasing the life of the valve seats.
Mini Mania is the exclusive direct importer of genuine Longman cylinder heads. As such we are also able to have heads modified to our specification, and we are directly involved in the ongoing development of the SCCA GT5 spec. head. All Longman heads are fully ported and polished and come assembled with Longman's exclusive valves, guides, springs and retainers.
Technical Information:
Competition Cylinder Heads
A selected range of modified cylinder heads are available to suit a wide variety of applications. All port and chamber modifications are carried out by experts to current state of the art specifications. Therefore, actual specifications may alter slightly as gas flow and port velocity efficiency improvements are developed. Where large bore heads are used on small bore engines (i.e. 12G940 casting on 948/1098cc block), it is necessary to check full lift of exhaust valve, and pocket the block as necessary. All heads have EN214N steel valves, hidural valve guides and hi-grade valve springs. REMEMBER: Highly polished ports reduce atomization and DO NOT increase flow.

SPEC: 35.6mm In. 31mm Ex. Combustion Chamber Volume 21cc
12G940 casting recommended for most road use engines having higher velocity ports to retain torque.

SPEC: 37.2mm In. 29mm Ex. Combustion Chamber Volume 24cc
12G940 casting. Larger ports and inlet valve make this suitable for highly modified road engines and especially the big bore 1380/1400 type.

SPEC: 37.2mm In. 31mm Ex. Combustion Chamber Volume 21cc
12G940 casting. Very modified head suitable for race applications and extensively modified big bore and long stroke engines. Exhaust valve is offset to minimize cracking between the valves

SPEC: 31mm In. 26.4mm Ex. Combustion Chamber Volume 24cc
It has the biggest valves fitted that produce maximum flow figures, and is suitable across the entire small bore range from relatively standard to fast road applications.

SPEC: 33.3mm In. 29.2mm Ex. Combustion Chamber Volume 24cc
12G295 casting. The ultimate small bore head. Modified to suit all fast road/rally engine specifications.   Suits race small bores.

Lead free head. As C-AHT87 but with exhaust valve seat inserts.

C- AHT134
SPEC: 35.6mm In. 29.2mm Ex. Combustion Chamber Volume 20cc
A budget 12G940 head using standard iron valve guides and standard heavy duty material valves. Ports and chambers are modified for maximum efficiency considering the valve sizes. This head is suitable for fast road applications where a limited budget is available.

SPEC: 37.2mm In. 29mm Ex. Combustion Chamber Volume 17cc
Same as the C-AHT221 but has been fully flow tested and balanced. It has longer valves (.140" longer) & special springs (with rotators) to work better with high lift cams.

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