8BA help needed

L

lemon

New member
My first post on this forum, so for starters, Hi everyone! My names Drew (from sunny UK!), im 19 and heavily into the nostalgic side of the rodding scene! owned quite a few rods now from when i was 12 (2 x T's, 100e, pop (anglias as you call them ;)), morris minor pickup, 60's slingshot, 34 model y and a few others.

I was hoping you guys could help me with some issues im having with my 8BA cylinder heads, my project for part of my mechanical engineering qualification is to make a jig hold my heads to skim.

Im after:
some drawings and dimensions of the stock 8BA heads if possible,
Info on how much can be skimmed off the stock head before causing problems,
and some ideas of how other people have tackled the problem (or how they were skimmed in production)


And one more question just out of interest, what are the small 'chunks' out of the chambers in the centre? as they are slightly odd sizes?

Thanks in advance guys!
 
Hi Drew. Welcome aboard! There are several experienced engine builders and machinists who post regularly on this site and I'm sure they can help you. With regard to your question about the amount which can be milled off a head, don't forget that part of rebuilding a flathead usually involves "decking" the block - i.e. making the head surfaces of the block flat, parallel to the crankshaft and at the same distance from the crankshaft. The more the block is cut, the less you can cut the heads. Optimally, you are looking for .050" clearance between the head and the piston crown. Slightly less may work. Greater clearance robs performance and economy.
Good luck on your project.
 
Not a complete answer to your questions, but whatever you find, you still need to clay the heads for piston and valve to head clearances. That is the meat of it. Not knowing how many times they have already been cut, forget how much can be cut. Just determine what it takes to get about .050" piston to head clearance, and then hand grind what you need for the valves to clear. If you need help in claying the heads, go here. http://www.flatheadv8.org/clayhead.htm
I did this tutorial a few years ago
 
Cheers for that guys!
Bill thanks I read through that link and the 4 or 6 adjustable jacks set quite high to avoid the table meeting the water spout was what i suggested to my boss, with a few long bolts through the spark plug holes, was thinking of putting the long bolts through to the keyway, but making a nice thick base plate will be a better option i think. so i can mill some shallow pockets for the jacks to sit in, hopefully to ensure they sit square and ensure they are sitting in the right place without moving (?).

Thanks again, cleared that up for me! ill post the process if anyone is interested?

Drew
 
Step one should be to clay the piston top to head clearance before any mods. The clearance there is the likeliest limiter before things hit, and once they hit you will need to make or find a cutting tool that can accurately maintain the dome while deepening it.
The valve area has more clearance to start and requires no apecial tooling to cut deeper.
 
I like the use of aluminum balls for checking clearance. I used clay for years and then Richard from Fla. suggested the aluminum balls I was hooked. Quicker, more accurate and less messy. I've been making combustion chambers for my engines for the past 20 years and find thst on a 276 a 65cc chamber gives aprox 8.5:1 with .050" Clarance. This gives a total chamber volume of 80cc's This is static CR and may cause timing troubles with a stock cam as the dynamic CR will be quite high. That's the main reason for getting the piston to head Clarance as close as you can. We have one engine running with .035", which is about the same as a SBC.
 
For one of the quickest and easiest methods of setting a head up to be surfaced, look up Storm Vulcan model 85 Headmaster.
After you do a few heads with that machine, you can set it up in 5 minutes.
One sweep across the head takes about 1.5 minutes and can take .030 at a time.
 
You mentioned having a 1934 model Y.Approximately how many pounds can one of them be had for in running and driving condition? Thanks
 
You must log in or register to reply here.
Back
Top