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tips, technology, tools and techniques related to vehicle driveline components

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mgb260
Jim Nichols
Sequim,WA
(2465 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Max valve size for 4.0/4.6 heads?
Posted by: mgb260
Date: March 23, 2023 11:01AM

Dave, Good work. Looks like it moved up a little on the valve too.


turbodave
dave cox

(183 posts)

Registered:
04/30/2018 03:00PM

Main British Car:
SD1

Re: Max valve size for 4.0/4.6 heads?
Posted by: turbodave
Date: March 23, 2023 11:09AM

Yeah, it was always going to, as the original dia at the bottom was fixed, and larger than the dia of the Rover version. Top of the spring is approx .17” below the top of the valve (need to confirm) and was machined reference to this face - they certainly appeared to be very consistent; I checked each one against a valve and retainers as they came off the lathe.
So we will still need to dig-out the spring pockets a little, but less than using any other retainers…



Edited 1 time(s). Last edit at 03/23/2023 11:10AM by turbodave.


MGBV8
Carl Floyd
Kingsport, TN
(4517 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Max valve size for 4.0/4.6 heads?
Posted by: MGBV8
Date: March 23, 2023 12:07PM

Very nice!


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Max valve size for 4.0/4.6 heads?
Posted by: BlownMGB-V8
Date: March 23, 2023 01:23PM

Can't wait to get those, and just in time too. I have an appointment in WV on Monday so a trip to drop those off with Dustin will be in order and I may even be able to put the 340 back together by summertime. Haven't given a lot of thought to how I might rework that engine's blower mount to be a lower height but it raises possibilities.

Jim


turbodave
dave cox

(183 posts)

Registered:
04/30/2018 03:00PM

Main British Car:
SD1

Re: Max valve size for 4.0/4.6 heads?
Posted by: turbodave
Date: April 17, 2023 10:23AM

Well, got the heads built up.
I settled on 1.720" installed height. Got all within a few thou and managed to get one wrong that ended up at 1.725, but that's probably just fine....

head_apr2023_1a.jpg
head_apr2023_2a.jpg

Pretty happy with how this turned out, but wow, I spent a long time in getting there.
This whole exercise in prepping the heads for more lift, including shortening the guides, and then still having to hog out the seat pockets by almost 0.10", then and machining the comp retainers out to 11-deg,, has really made me rethink the best way to go about this exercise for those who may be working on it in the future.

Manley 11502 and 11503 are Buick V6 11/32 stem valves, and 4.725" overall length. The Rover valves are just under 4.60" overall length.
Both the Manley valves would need machining down to reduce the head diameter, but I feel like that is a very easy task, and both have single groove locks, so are pretty easy to make work with catalog retainers, and even allow use of + height locks (such as the TA-Performance TA V1434B+.050); but the extra length of the valve is the real benefit... But the Manley valves do work out at $37 each, so that's $600 at the very least, which is approx double what the DW500 / DW501 valves cost - but then again, you also have the opportunity to put oversize seats in the head, and make the valve whatever size you choose.....

My other realisation is that finding GOOD head folks who still play with 11/32 tooling are becoming fewer. Seems like a 5/16 stem, or even metric, have a lot more reputable folks who would be willing to put nice 5-angle profiles into the heads, so just deciding up-front to go for a different guide ID may be a better option....



Edited 1 time(s). Last edit at 04/17/2023 11:33AM by turbodave.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Max valve size for 4.0/4.6 heads?
Posted by: BlownMGB-V8
Date: April 18, 2023 10:48AM

Might be. My heads are at the shop to be machined for final assembly using the PAC springs. Might be done in a couple weeks.

One of the advantages of staying close to stock height is not having to shim the rocker pedestals to maintain geometry but the longer stems on the valves in my TA heads did not cause much of an issue fitting under the MGB repop valve covers so clearance doesn't seem to be much of a problem. Just had to trim a small notch in the boss for the oil filler plug to clear the chevy stud type adjusters. To go over .550" lift I'm sure a longer valve is needed though. I agree it took a lot of effort to get here but I sure do appreciate your help. I have that bottle sitting on the shelf, the car's back together and all we have to do is figure out the schedule to make that visit happen.

Jim


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Max valve size for 4.0/4.6 heads?
Posted by: BlownMGB-V8
Date: April 29, 2023 03:30PM

IMG_0010.JPG

Still need to do the rocker shafts. These will go on the 340. I still need to order the cam and main bearings but it will go back together this summer. I have the options of using the old intercooled blower intake, (too tall) an iron 4bbl intake, making a new blower intake, or using spacers with a 300 intake. I'm leaning towards making another blower intake. Maybe I'll post the old one in the classifieds or something.

Jim



mgb260
Jim Nichols
Sequim,WA
(2465 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Max valve size for 4.0/4.6 heads?
Posted by: mgb260
Date: April 30, 2023 01:01PM

Jim, what installed height, and pressure closed and open did you end up with?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Max valve size for 4.0/4.6 heads?
Posted by: BlownMGB-V8
Date: May 01, 2023 09:16AM

Dustin did the final assembly so I really don't know. He told me he had to cut the pockets .050" deeper and used a .015" steel shim for a seat. Had .600" range of motion so my .550" lift is OK. Had to cut the guides .150". Installed height should be around 1.7" but I'm not taking it back apart to check. He felt the open and closed pressures were appropriate for a solid lifter cam, and from earlier calculations I think probably around 350 open and 150 seated. I think those were about the numbers he was throwing around. Really my only complaint is that instead of ordering the pocket cutter for the LS springs he used one he had and it cut the pockets bigger than they needed to be but they won't dance around enough to contact the seals so I think it'll be fine.

Jim
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