The 'E' Type Forum

Are e type 4.2 engines interchangeable with 420 engines? Whats the same and whats different

This thread may help:
http://forum.etypeuk.com/viewtopic.php?p=110211#p110211

Thank you so much! that answered all my questions. I have a deal I can't pass up on this 1967 engine, runs with 67,000 original miles. I'm guessing it came out of a 420 but being as my E has pitted cams and probably a pitted crank this will get us flying sooner than later.

Good choice. I have one of those tucked away as a spare. And yours should be a short stud block which is preferable. Check its engine number here http://www.jag-lovers.org/xk-lovers/lib ... umbers.htm

My E has a 1967 420 sourced engine. Originally this was a 8:1, but it now sports 9:1 pistons. The car has had this engine for most of its life, probably since 1978, certainly since 1986.

abowie wrote: ↑

Thu Apr 25, 2019 12:24 am

Good choice. I have one of those tucked away as a spare. And yours should be a short stud block which is preferable. Check its engine number here http://www.jag-lovers.org/xk-lovers/lib ... umbers.htm

Wow, according to that link I may have done better than I thought. This appears to be a Series 1-1.5 E-type engine. Came with an automatic gearbox

Looks like a 7F to me meaning it came from a 420.

Heuer wrote: ↑

Thu Apr 25, 2019 2:20 pm

Looks like a 7F to me meaning it came from a 420.

Thanks for the image enhancement! my eyes must be getting terrible Now we know definitively! I'm always greatful for your help and insight

Mine is 7A, a Daimler badged 420.

So, I have been asking this question for a while now, and simply cannot find a definitive answer, can anyone tell me the actual differences between a 7F (420) block, and a 7E (S1 E Type) block please??

Ive read many different things, but nothing that makes sense??

Thanks all,

Steve.

Hi Steve....you would need to look at the parts catalogues for both as a start to check out the part numbers....are we just talking block or engine, crank, pistons , rods etc...once you know the part number differences you can check how/if they are different.....Steve

Hi Steve, I have done this and the part numbers are different, which means there is clearly A difference, but when I spoke to Robey/SNGB they couldn't tell me what the actual differences are? I have done lots of research on xkedata and even created my own spreadsheet to see how many have used the 420 block as a replacement and there are quite a few. Ive sent a PM to Chrisfell as in this old thread he mentions that his 67 S1 has a Sovereign 420 engine, which is the same as a Jag 420, yet on the engine number data sheet you sent me (Jag-Lovers) the link for the Sovereign engine No starts 7A and the Jag 420 starts 7F, and the engines must be the same as the car is identical barring name and trim??

I did read somewhere that the differences are only some engine ancillary boss holes (alternator/Air Conditioning/PAS) were there but not drilled or tapped but can't recall where...

As I mentioned to you before my car has a 420 block, been in there since the 1970's, and it works!

Best regards,

Steve.

Do you have a correct jaguar 420 service manual it will give the engine specs....you can then compare this to the specs in the E type manual ..Steve

Hi Steve

I have all the Daimler 420 books if you need any help.

Regards