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Compression ?


OWL
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Hello All

I am current restoring a 1961 Series 2a Project which I bought a couple of years ago, I'm just about to start looking at the engine and did a compression test today and the results from the fan backwards are 120, 95, 95 & 30 psi.

I want to keep the engine and wondered :-

1) What should the compression be?

2) What may be causing the low reading on the last cylinder

3) Whist I have the engine out and on an engine stand what else is worth doing to it before it goes back in , e.g. Electronic Iginition or Megajolt, complete refurb etc. etc.

Thanks

OWL

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I take it you are talking about a 2.25 Petrol? If it was diesel lump - the compression would be seriously pants :lol:.

120 is ok for a fairly worn engine, but 95 and obvioulsy 30 are not good. Fortunately you can get a complete set of pistons with rings and gudgeon pins for £100, so no big expense. What sort of compression test was it, just a dry spin? To determine if it's bores or valves you need to do a wet test as well. Put a small amount of oil in each bore and do the test again. If there's a significant rise in the results, you have worn bores or stuck rings. If the test is much the same then it's down to the valves (of course you could have head gasket problems).

Les.

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I take it you are talking about a 2.25 Petrol? If it was diesel lump - the compression would be seriously pants :lol:.

120 is ok for a fairly worn engine, but 95 and obvioulsy 30 are not good. Fortunately you can get a complete set of pistons with rings and gudgeon pins for £100, so no big expense. What sort of compression test was it, just a dry spin? To determine if it's bores or valves you need to do a wet test as well. Put a small amount of oil in each bore and do the test again. If there's a significant rise in the results, you have worn bores or stuck rings. If the test is much the same then it's down to the valves (of course you could have head gasket problems).

Les.

Les

Its a Petrol

I removed all the plugs, gave each cylinder a couple of shots of oil and then turned the engine over for 5 or 6 revolutions on the starter.

Thanks

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You should have done the test dry and then wet to get a more definite result. It sounds like you will have to whip the head off anyway. If it's a project, then reseating the valves etc is a matter of course.

To measure bores for wear or ovality you need one of these:-

For measuring of bore diameter and groove width. The spring-loaded plunger expands within the hole. Knurled locking screw allows plunger contacts to be held in position, removed and measured with a micrometer.

post-2-1189358359_thumb.jpg

Les.

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You should have done the test dry and then wet to get a more definite result. It sounds like you will have to whip the head off anyway. If it's a project, then reseating the valves etc is a matter of course.

To measure bores for wear or ovality you need one of these:-

For measuring of bore diameter and groove width. The spring-loaded plunger expands within the hole. Knurled locking screw allows plunger contacts to be held in position, removed and measured with a micrometer.

post-2-1189358359_thumb.jpg

Les.

Thanks Les

What improvement will a high compression head give and is it worth the money ?

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To be honest i wouldnt bother spending money rebuilding a 2.25 petrol.

Look out for a 2.5 petrol from a defender instead. Externally they're identical, all the ancilliaries will swap straight accross, and people cant give away 2.5 petrol engines these days. I picked up 2 for free a couple of years back. Its a nuts and bolts job to swap them over - its what i did when I blew up the origional 2.25 that was in my series!

Jon

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Jon

whats the 2.5 performance like in comparison to 2.25

Cheers

OWL

I've just put a 2.5 in my S1 and it goes very well - it certainly feels more powerful than the 2.25 I had in my 86" years ago, but there isn't much difference between a well-sorted 2.25 and a 2.5. Be cheaper to put a 2.5 in and get unleaded 8:1 head as standard than spend the money doing the same to a 2.25.

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So the options seem to be :-

1) Sort out the 2.25 Petrol, but sounds like throwing good money down the drain

2) 2.5 Petrol or 2.5 NA Diesel

4) 200Tdi

As all these will bolt straight on the 2a Chassis or is there any other options ?

So whats the best option and any recomendations where to get a good one ?

Cheers

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Depedns how much work you want. 2.5 petrol is a simple nuts and bolts job with no fabrication required. 200Tdi will fit, and bolting it in is the easy bit, but all the plumbing, mounting of intercoolers etc etc is a load more hassle. I'm just in the process of fitting a Disco 200Tdi into mine having just removed a V8.

A disco 200 will bolt straight onto the series engine mounts, but the exhaust etc is more difficult to make. A defedner 200 will requrie engine mounts fabricating, but the exhaust is alot easier. Disco engines are a lot cheaper than defedner ones are.

Jon

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