Cubic Inch Compression Chart

The LRFIX Cubic Inch Compression Chart lists compression ratios and corresponding cubic inch measurements for quick engine reference.

Cubic Inch Compression Chart
326 Block		Stroke
Bore		3.75	4.00	4.21	4.25	4.50
Stock	3.720	326	348		370
+.030	3.750	331	353		376
+.040	3.760	333	355		378
+.060	3.780	337	359		382
350 Block		Stroke
Bore		3.75	4.00	4.21	4.25	4.50
Stock	3.875	354	377		401
+.030	3.905	359	383		407
+.040	3.915	361	385		409
+.060	3.935	365	389		413
389 Block		Stroke
Bore		3.75	4.00	4.21	4.25	4.50
Stock	4.062	389	415		441	467
+.030	4.092	395	421		447	473
+.040	4.102	396	423		449	476
+.060	4.122	400	427		454	480
400 Block		Stroke
Bore		3.75	4.00	4.21	4.25	4.50
Stock	4.120	400	427	449	453	480
+.030	4.150	406	433	456	460	487
+.035	4.155	407	434	457	461	488
+.040	4.160	408	435	458	462	489
+.060	4.180	412	439	462	467	494
+.065	4.185	413	440	463	468	495
421 Block		Stroke
Bore		3.75	4.00	4.21	4.25	4.50
Stock	4.093		421	443	447	474
+.030	4.123		427	450	454	481
+.035	4.128		428	451	455	482
+.040	4.133		429	452	456	483
+.060	4.153		433	456	461	488
+.065	4.158		435	457	462	489
428 Block		Stroke
Bore		3.75	4.00	4.21	4.25	4.50
Stock	4.120		427	449	453	480
+.030	4.150		433	456	460	487
+.035	4.155		434	457	461	488
+.040	4.160		435	458	462	489
+.060	4.180		439	462	467	494
+.065	4.185		440	463	468	495
455 Block		Stroke
Bore		3.75	4.00	4.21	4.25	4.50
Stock	4.151			456	460	487
+.030	4.181			462	467	494
+.035	4.186			464	468	495
+.040	4.191			465	469	497
+.060	4.211			469	474	501
+.065	4.216			470	475	503

Our Compression Calculator can help you find the values of these and every other engine block (and bore), including yours!