head question

[accbr]

I'm getting ready to buy an ADA girdled head for a 701 I'm putting together. I'll be running an 83mm bore. Do I need to get the 84mm domes or will the 81mm still work?

 

[Matt_E]

The 81mm domes (701) should be good up to 83 mm - I think.

 

[accbr]

Matt,

I noticed in your MSD-TL thread that you're running 83mm with 35cc domes. What type of head and domes are you running?

 

[Matt_E]

ADA Girdle head, 701 domes, 35 cc

ADA says this about the 701 domes:
Squish relief is .015\" @ 83mm with a 10.5° angle.

I asked Paul about this before, and he stated that they're okay up to 83mm.

 

[ski4]

that is up to and including 83 mm right?

 

[Matt_E]

That's what I read into it. However, I plan on verifying this.
I'll email ADA.

 

[ski4]

ok cool, 83 mm will be my next stop some day and it seems most of the domes are the same in that respect

 

[accbr]

ADA Girdle head, 701 domes, 35 cc

ADA says this about the 701 domes:
Squish relief is .015\" @ 83mm with a 10.5° angle.

I asked Paul about this before, and he stated that they're okay up to 83mm.

Thanks. I could only find a link to the desc. for the 760 domes on the site.... until I just typed 'domes' in the SEARCH field :banghead: on ADA's site.

I noticed you're also using 35cc domes with 190 compression, so that answered my next question. I have one cylinder done with the Race logic templates. Hope to get the other done this weekend.

 

[Matt_E]

Welll....I got 190psi on an 82.5 bore, so it'll be a bit more on 83. The Sport Port should not lower compression.

 

[Matt_E]

Alright, I got my answers from ADA.

Here's my conversation:

Matt_E :Hi there,

I realize that the std domes for the ADA 701 head are spec'd for a certain squish angle at 83mm bore.
Can I -safely- run the 701 domes on an 83mm bore; or do I need to go up to 760 domes?
Thanks


ADA Racing Tech : The 701 domes are for up to an 83.5mm bore size. The compression will be slightly higher than a stock bore and the squish(piston to dome) clearance will be closer as well. The minimum squish clearance you would want would be .040â€.

http://www.adaracing.com/viewitem.php?id=ya21&maincat=watercraft

Thank you


Matt_E:
So I will need to get the domes machined for 0.040" squish relief @83mm, correct?
(Or run 760 domes?)
Thanks,


ADA Racing Tech:
You need to check the squish when you put the head on. The domes should be fine, but you need to make sure. You do not want any less the .040†clearance. On a stock bore the squish clearance is approximately .055â€. That way on the larger bore sizes there is still enough clearance.





ADA gets my thumbs up for their quick & good support.

 

[accbr]

Thanks. Hopefully I can order one this week. Now I just need a good crank. I want to keep the 650 together as a backup or sell it.