whats the difference between red and blue 253

[Kingsandman]

Ive got a qr block blue September 74 , are they different to the red motor.

[Innuendo]

September 1974 has to be RED.

[davegmh]

I don't know all the technical stuff but I'm sure the blue motor had electronic ignition fitted.

[HK1837]

With regards to the title which red 253 are we talking about? There are a few:

HT-HJ, LH-early LX high compression.
HT-HJ, LH-early LX low compression.
HX-HZ, late LX and VB high compression.
HX-HZ, late LX and VB low compression.

And there are minor variations amongst some of these as well with regards to auto vs manual (carbies on some, dizzys, no EGR valve on manuals etc). Aircon versions got different fans and in some cases different rocker covers and air cleaners. Rocker covers varied along the way too, and there were different oil filler locations and heater hose attachment points The last few years of red 253 construction also got a different block. The inlet manifold design also changed during the later style red 4.2. The water pump design changed late in red V8 as well, and the last design red 4.2L block and water pump carried on into the blue 4.2.

The main differences between the last of the red 4.2L and a blue 4.2L are:

Lower compression.
Heads have different exhaust crossover ports.
4BBL manifold and 4BBL Quadrajet.
HEI distributor.

However a HX style 4.2 is probably almost as different to an earlier 253 than a blue 4.2 is to a red 4.2.

[Calum]

My question is... Can you determine high or low compression by the lettering on engine number? if so can you give us examples??

[Sandaro]

My question is... Can you determine high or low compression by the lettering on engine number? if so can you give us examples??

QR prefix would be high comp. Low comp got QS prefix during the years relevant to Sandman production. Holden achieved the different compression by the shape of top of pistons.

[wbute]

Blue 253 will have the prefix WR or VR.

[Kingsandman]

This motor came out of a hq panel van build date sep 74 qr high compresion stamp on engine prefix looks to be painted blue from factory or someone has rebuilt it and done a good job of repainting it.did high comp 253s come out of factory painted blue.

[Sandaro]

This motor came out of a hq panel van build date sep 74 qr high compresion stamp on engine prefix looks to be painted blue from factory or someone has rebuilt it and done a good job of repainting it.did high comp 253s come out of factory painted blue.

No, someone has painted it. What's the date code on the motor? Will give some indication if was original to that van.

[Kingsandman]

It came out of 1974 hq panel van sep build engine casting date matches build date 14j4 I didnt record engine no but its a qr block.ill post up engine no after work cheers.