370LR dome size

[juan_carlos__007]

Ok I need help from a knowledgeable engine builder. I need dome size for my 370LR and be able to run 91 octane fuel. Here is the list of what it has been done to it:

-Ported to be able to run blaster pistons, also air flow

-Blaster pistons

-Adjustable timing plate advanced +4

-fmf pipes

-K&N pods

-Vforce3 reed valves

-Stock head, seemed milled, but don't remember if dome was machined to change angle for blaster pistons. 

-Stock carbs with proper jetting, don't remember main jet size.

-Elevation is between 2500 and 3500 if it matters 3000

I rebuilt the top end with new rings etc about a year ago, and no the cylinders where not worn out. I did get specs before putting it together, but still have low compression like 90 PSI don't remember exactly how much but somewhere in that ballpark. It turns on and runs very well but figured out it will run way better with proper compression setup. Before I used autozone compression tester. Just ordered an Innova one to get more accurate readings, but it i'll be a week till it gets here. Also did leak down test and fail before rebuild but not after. I've read that 23.3cc is the stock dome size for the stock bore 64mm and stroke 54mm which has a compression ratio of 6.5:1 and static compression of 140PSI. I've been trying to relate this info into my 370LR or more like a 369LR in order to get the right dome size, but I got stuck where I need the blaster piston crown dome volume for the right squish measurement. There's a lot of of geometry involved, and hard to relate since also the blaster pistons have different squish angle than the banshee pistons. I'm looking at the NOSS head domes http://nossmachine.com/795-long-rod-stroker-dome-set/ that are ready for blaster angled pistons, just confused on which ones to choose. It's weird how the smallest dome size is 19cc, maybe this setup does not require that small of dome, but still stroke is 54mm? Also If I decide to bore in future this head wont go larger than 66mm? I though about taking the heads to a machine shop, but for spending some money in a head that will have thinner walls and not last I prefer an aftermarket head, yeah there's the o-ring issue, but I'm willing to take a risk on that. The closest info I've found is on macdizzy website, "I cut the domes so the trapped volume at TDC was 14.2 cc's. That calculates out to a 14:1 compression ratio. The static compression is estimated to be 170 PSI at sea level. The estimated power output is 69 HP at 8500 RPM.". Rudy kurts setup info is nowhere to be found, and to contact him if way probably harder, found several outdated  websites with his phone number, but it does not work and he supposedly has lived in Vegas and later on some CA city. It seems like for now my only way out is to measure static compression with new tester, than take head off, bolt plexy glass with some sort of sealant and obtain cc's from there relate new dome size since I've noticed that for every CC decrease the static compression increases by 10PSI. Another thin is that I don't know if the squish angle matters and if it was changed in the stock head that it has in right now. I don't feel like wasting money and time on trial and error on different size domes. Could be as easy as mickey mouse engineering as 347.26cc to 369.3cc (350 to 370) is equal to 1.063 times larger and multiply that number of stock dome size of 23.3cc equals new dome size of 24.77cc?

 

Sorry about the overwhelming info, just trying to get somewhere here. Thanks in advanced. Help from real engine builder only would be appreciated, and questions from beginners are welcome. 

[registered user]

that link appears to be for +4 domes so they wont work on yours.  im not very familiar with blaster pistons but ill assume they just offset the longer rod but whether its a exact offset i dont know. call noss and say your bore, 54stroke, 115rod, blaster pistons. they shouldnt need anymore info than this, as long as your not using anything funky like thicker than normal base gaskets or something. im sure they made hundreds of these domes

[juan_carlos__007]

that link appears to be for +4 domes so they wont work on yours.  im not very familiar with blaster pistons but ill assume they just offset the longer rod but whether its a exact offset i dont know. call noss and say your bore, 54stroke, 115rod, blaster pistons. they shouldnt need anymore info than this, as long as your not using anything funky like thicker than normal base gaskets or something. im sure they made hundreds of these domes

True thanks for opening my eyes. I thought for some reason +4mil stroker would be the same dome setup as just long rod. Stroker 4mil piston comes out the deck higher.

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