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L20 Block P79 or P90 Head ???


Erick240

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Before someone says use the search buttom I have to say this, I´ve seareched about a sawp like this but no answer, maybe is not possible but I don´t know.

Hi, I´m asking some help wit this swap :

I´m rebuilding a L20 Block Taking from a Old DATSUN truck 1970 model, and came with a E30 Head, at the same time a friend of mine guiveme a P79 Head

The two heads need to be resurfaced, Mi Question is : the P79 is a good combination with the L20 Block ? or is a donwgrade to put the P79 with the L20 block.

pLease I need your opinion , cause I will repair the best head the E30 or the P79 to use with the L20 block

this one question too: Can I use the P79 Cam in the E30 Head ? this cam swap is AN UPGRADE ?

Thanks

Regards

Erick240

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Hi, I´m asking some help wit this swap :

I´m rebuilding a L20 Block Taking from a Old DATSUN truck 1970 model, and came with a E30 Head, at the same time a friend of mine guive me a P79 Head

Hello Erick:

We may not fully understand your situation. You say that the L20 you have was taken from a 1970 Datsun Truck.

I do not know what models of Datsun Trucks were sold in Central America in 1970, so you may have to tell us more about that truck. Here in the USA and Canada the 1970 Datsun Pick-up trucks came with a 4 cylinder, 1600cc engine - L16

The Nissan L20 was an in-line, six cylinder, OHC engine, used in some Nissan vehicles in 1965 to 1968. In 1969 it was replaced with a new design and re-named the L20A. {cylinder heads between the two ie. L20 and L20A - were not interchangeable, nor could you mount a P79 head on an L20 }

The Datsun Pick-up's here used the L16, then later the L18 and finally an L20B. The L20B was a four cylinder OHC engine.

IF you actually have an L20A, in-line six cylinder, OHC engine - with the E30 head, then that would yield a higher compression ratio than using the P79 - - unless you modify the P79 by milling it down to reduce the combustion chamber volume. A second problem may result from using the P79 - - it has larger valves and they may not clear the bore on the L20A - unless you increase the bore on the engine or notch the cylinder walls at the top.

I would use the E30 head to be safe.

If you could send a picture of the engine - it would help identify it.

FWIW,

Carl B.

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The Nissan L20 was an in-line, six cylinder, OHC engine, used in some Nissan vehicles in 1965 to 1968. In 1969 it was replaced with a new design and re-named the L20A. {cylinder heads between the two ie. L20 and L20A - were not interchangeable, nor could you mount a P79 head on an L20 }

There were lots of changes in the 'L20' six engines from 1964 through 1969, and there was no single design change that differentiated an 'L20' six from an 'L20A'.

The reason for adding the 'A' suffix was to differentiate the six cylinder engine from the new four cylinder engine when capacity was two litres - hence 'L20A' and 'L20B'.

Of course, if you prefer to swallow NMC USA corporate and advertising mumbo jumbo whole then you might be happy to believe that the L24 was an "ALL NEW!" design based on the "JUST FOR YOU" L16, but "WITH TWO ADDED CYLINDERS"........... LOL

Erick240: Keep the head and cam that came on the engine originally. If you want more performance, modify the ports slightly for better flow, increase compression slightly and consider changing carbs and exhaust. If you want to change the camshaft, go for an aftermarket item rather than another stock factory piece, as no stock factory camshaft is different enough to justify the swap.

And don't try putting L20A parts onto an L20B. Some of them won't fit!

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There were lots of changes in the 'L20' six engines from 1964 through 1969, and there was no single design change that differentiated an 'L20' six from an 'L20A'.

The reason for adding the 'A' suffix was to differentiate the six cylinder engine from the new four cylinder engine when capacity was two litres - hence 'L20A' and 'L20B'.

Of course, if you prefer to swallow NMC USA corporate and advertising mumbo jumbo whole then you might be happy to believe that the L24 was an "ALL NEW!" design based on the "JUST FOR YOU" L16, but "WITH TWO ADDED CYLINDERS"........... LOL

Erick240: Keep the head and cam that came on the engine originally. If you want more performance, modify the ports slightly for better flow, increase compression slightly and consider changing carbs and exhaust. If you want to change the camshaft, go for an aftermarket item rather than another stock factory piece, as no stock factory camshaft is different enough to justify the swap.

And don't try putting L20A parts onto an L20B. Some of them won't fit!

Wow what a lot of good info, thanks Carl and HS30-H.

I really apreciate the help, Thanks .

The engine is a L20 Six in line, The guy who soldme the engine says the engine came in a, how I explain ? a car - wagon? 1970 model, not in a Truck as I said before.

The block needs a rebuilding, new ringns, the piston seems in good condition, the crankshaft is in good condition too, have to change the metal pieces like half moon how are they called ? where the crankshaft rotate ?, here are called casquetes and need a new gasket kit, etc

But here are dificult to find this parts, The L20 sinx engine is not very common as i thinked, I've found the rings but not the head gasket and the others gaskes. :cry:

can you help me, where I can buy this parts ?

Looked in Rockauto but no luck

I'll keep the E30 Head , and I'll go for a ported intake.

Thanks a lot gain.

Erick

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Wow what a lot of good info, thanks Carl and HS30-H.

I really apreciate the help, Thanks .

Erick,

Sorry that your thread has been somewhat diverted, but you inadvertently brought up a topic that some of us ( or myself at least ) feel quite strongly about. Still, I hope that some of your questions have already been answered.

The engine is a L20 Six in line, The guy who soldme the engine says the engine came in a, how I explain ? a car - wagon? 1970 model, not in a Truck as I said before.

The block needs a rebuilding, new ringns, the piston seems in good condition, the crankshaft is in good condition too, have to change the metal pieces like half moon how are they called ? where the crankshaft rotate ?, here are called casquetes and need a new gasket kit, etc

But here are dificult to find this parts, The L20 sinx engine is not very common as i thinked, I've found the rings but not the head gasket and the others gaskes. :cry:

This sounds like an L20A engine ( L20A was 6 cylinder, and L20B was four cylinder ) and in actual fact the early versions of this with the E30 cylinder head - which you appear to have - are actually very nice engines when they are running to their full potential. If you rebuild it to even stock specifications it is quite powerful for its capacity.

can you help me, where I can buy this parts ?

Looked in Rockauto but no luck

I'll keep the E30 Head , and I'll go for a ported intake.

Luckily for you Erick, all the bearings ( con rod and main bearings ) and most other service parts on the bottom half of the engine are the same as those fitted to Nissan's L24, L26 and L28 engines for Export markets. Therefore Rock Auto should actually stock suitable bearings for the engine, but you will have to ask for L24/L26/L28 parts if they do not recognise the L20 for what it is. If your local suppliers cannot help, then maybe ordering from the nearest alternative ( USA? ) will work?

If you want to send me a PM I will tell you the Nissan part numbers that you need, and can help you with any other data that you might need for your L20 six. It's a good engine, and can be very sweet when it is working right.

Good luck!

Alan T.

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