[253] 253 with VN heads

[DANNY8]

As my 308 is out of action and I'm putting a 253 in me wagz to pass regency. Would VN heads be ok on a 253? Would the valve's hit the block or do they have enough clearance? If no one knows I'll just dummy it up and turn it over by hand and see wat happens, would that be enuf "testing" to make sure it will be ok?

I'd use a stock VN cam, is that much different to a stock 308 cam? I know the lobes are set out differently due to the different ports....but in regards to emissions testing for it to pass.

I've attached a pic showing the Crow Cams specs of stock replacement cams for both carby and EFI....but I don't know wat I'm lookin at so hopefully someone who knows a bit about them can give me a rough indication lol.

Cheers.

 

[soop]

Heads flow way to much for a 253. I don't think it will run very well with EFI let alone a carby.

 

[DANNY8]

If it will physically work I wanna try it. Just to experiment. Been doing a bit of reading and it seems people who have done it have been surprised, and the people who haven't done it expect crap results lol.

Some people have had drama's with the valves hitting, other haven't. I think I'm just gonna have to dummy it up and check. The block is 30thou over which means my chances are probably higher. Will report back tho...

 

[soop]

Where the valves hitting the pistons or the block?
Because 253's had two different types of pistons, flat tops and dome top high compression pistons.

 

[DANNY8]

Actually out of all the feedback I've found, the only person who ran into drama's says the valve hit a piston.

My 253 just has flat tops. If the valve miss the bores, I'll mock it up further so I can turn it over by hand and see if the valves hit the pistons.

How would I go about making sure the lifters don't compress? Maybe I'll just jam 2 old ones open for the test, or just hunt down some real soft springs. I assume if the valves have no trouble in 1 cylinder the rest should be ok (will still turn the finish motor over by hand first tho just incase).

 

[DANNY8]

Mocked up a cylinder 2day and I'm happy to say everything clears! As I mentioned earlier tho my 253 is 30thou over which could be why it clears, and maybe STD bores don't?? Not sure tho coz that would still mean the valves would only be maximum of 30thou away from my bores lol.

Just mocked it up with soft springs. Also fitted the rockers, pushrods, lifters and EFI cam and turned it over by hand. The lifters didn't compress either so should all be fine.

 

[VR38]

I doubt a stock cam would have enough lift to reach the block.
Why don't you drop a piston, throw a head on and look up the bore if it clears the block.

FWIW it will run, if you don't have clearance issues but standard red heads will out power you right up and above 5k, most don't get the full benefit of this cause they are not revving it over 6k

 

[DANNY8]

Nah won't worry bout doing that. There's no drama's how it is so will just assemble it. I might just get the verniers out and do some measuring, but don't wanna pull a piston out.

I've never tried this b4, that's one of the main reasons I'm doing it. This motor in my VB was a slug, nothing special, and that was with stock heads. Also this way I won't need to change the extractors as my 308 already runs VN heads.

 

[VR38]

Ok keep us posted on the progress.

 

[micky69]

yes please keep us updated as i have a lazy couple of 253's laying around and a set of efi heads, keen to junk up a twin turbo setup on them. and blow them to pieces