High CR 347 question
Thread Starter
TECH Senior Member
iTrader: (9)
Joined: Dec 2001
Posts: 5,395
Likes: 1
From: Estero, FL
High CR 347 question I am looking at making a purchase on some lunati parts since one of the sponsors has some good pricing going on. I want to keep the stock displacement so I am looking at the 347 rotating assy. 12.5:1 combo. My questions are:
1) Will this kit drop right into my stock block or will I have to have some work done?
2) With heads milled .030 will piston to valve clearence be an issue with a 230/227 591/571 112lsa cam using a 1:7 rocker arm?
I am seriously looking into this but am worried about the P2V issue the most. Any input would be greatly appreciated.
TIA
1) Will this kit drop right into my stock block or will I have to have some work done?
2) With heads milled .030 will piston to valve clearence be an issue with a 230/227 591/571 112lsa cam using a 1:7 rocker arm?
I am seriously looking into this but am worried about the P2V issue the most. Any input would be greatly appreciated.
TIA
SSU Moderator
Joined: Nov 2001
Posts: 4,857
Likes: 0
From: Austin, TX
Depends on the pistons, but the short answer is that Lunati probably makes them two ways, a stock bore, or a 3.905. Either way you will have to get some machine work since you will have new rings, etc. I would bet the PtoV will be fine since the pistons will have cuts in them.
Thread Starter
TECH Senior Member
iTrader: (9)
Joined: Dec 2001
Posts: 5,395
Likes: 1
From: Estero, FL
I dont think I would want to go any higher than 12.5:1. anything above that and your looking at a straight race gas motor. at 12.5:1 I "should" be able to get away with a 50/50 mix.
what compression are you looking to get?
i know scoobie has the lunati kit and he ran some AS 6.0 heads to get the compression down to 11.5 or something and used the TTP equalizer cam 230+ duration. the pistons in the kit are domed 12cc's and have valve reliefs right? are the 2cc's?
i know scoobie has the lunati kit and he ran some AS 6.0 heads to get the compression down to 11.5 or something and used the TTP equalizer cam 230+ duration. the pistons in the kit are domed 12cc's and have valve reliefs right? are the 2cc's?
Originally Posted by NataSS Inc
I dont think I would want to go any higher than 12.5:1. anything above that and your looking at a straight race gas motor. at 12.5:1 I "should" be able to get away with a 50/50 mix.
Trending Topics
The 12.5:1 compress ratio pistons are dome tops.. They don't fit well on a lot of applications .We went with 6.0l heads unmilled to fit the pistons. AS makes a strong 6.0l head that will make the power. Scoobie worked out to around 11.3:1 compression with these heads. 93 pump gas.
- Matt
- Matt
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
TECH Senior Member
iTrader: (9)
Joined: Dec 2001
Posts: 5,395
Likes: 1
From: Estero, FL
I may be selling the MTI heads that are on the car now with the milled heads and replacing them with the 225 AFR's. Those should give me the clearence that I need.
SSU Moderator
Joined: Nov 2001
Posts: 4,857
Likes: 0
From: Austin, TX
I wouldnt get hung up too much on the static comp ratio (the 12.5:1 you are talking about). your gas will really depend on the cam and the tune. I remember talking to the Colonel a long time ago and on his hyd. 422 he ran like 14:1ish compression, but with the right tune he could drive it on straight 93 and only run like 104 at the track. think dynamic cr.
just remember that if you go with a dome piston they are digitized/designed for a stock Combustion Chamber Design. AFRs have a different CCD... might run into issues with a big dome....
AS has some 6.0L heads being built for me with special valves that make the heads ~61cc without welding or milling. And APE helped me spec out some 6cc dome pistons that make the CR come out to 13.8x
AS has some 6.0L heads being built for me with special valves that make the heads ~61cc without welding or milling. And APE helped me spec out some 6cc dome pistons that make the CR come out to 13.8x
TECH Enthusiast
Joined: Feb 2004
Posts: 743
Likes: 0
From: Foley, Alabama-southern Alabama
Why do you want to keep the stock ci?If you go more stroke say 4.0 with a flat top piston you will have more CR then stock stroke.I'm sure you have a good reason but if you going to buy a new crank seems like extra stroke is free HP!!Just asking???? 
Teching In
Joined: Jul 2004
Posts: 46
Likes: 0
From: Western Suburbs of Chicago
Originally Posted by MUSTANGEATER
You're looking @ the basic hone and deck stuff. Shouldn't be too expensive. Have you thought about welding the chambers to increse compression ratio?
i wouldn't really recommend that....... 
Hey Man, Like Matt and JRP above said i have this set up. Id recommend giving TTP a call. George at TTP built my set up and he used this same kit in his own bottom end build up. For what your looking to do, its a great set up although more costly because of the crank. I would recommend the 6.0 Liter Heads, do the stage 2.5's ! i only did the 2.0's and i put down 437/405 with under 100 miles on the block through the muffler with a **** rear end and clutch. Good luck, and let me know if you have any questions.
-Scoobs
-Scoobs
Originally Posted by buymeavette
i wouldn't really recommend that....... When done properly there are no problems. Should he mill the **** out of the heads and risk P T V problems and possibly ruin valvetrain geometry?
TECH Enthusiast
Joined: Feb 2004
Posts: 743
Likes: 0
From: Foley, Alabama-southern Alabama
Could you use some slightly milled 5.3 heads to raise the CR ? I think with the Lunati parts the piston is like .020 positve deck ht. with reliefs this should be OK for p to v clearance.I would go no closer then .035 quench though, the pistons may have to be machined down some for this.You could use .010 positive with a .045 head gasket or zero deck ht. and .035 head gasket,all this would help raise the CR. Stock bore and stroke with +7 cc piston dome and .035 gasket and 64 cc head is 12.285,62cc is 12.65,60cc is 13.037
this is 0 piston deck ht.
this is 0 piston deck ht.
Teching In
Joined: Jul 2004
Posts: 46
Likes: 0
From: Western Suburbs of Chicago
Originally Posted by MUSTANGEATER
Why is that??????
When done properly there are no problems. Should he mill the **** out of the heads and risk P T V problems and possibly ruin valvetrain geometry?
When done properly there are no problems. Should he mill the **** out of the heads and risk P T V problems and possibly ruin valvetrain geometry?
erik
Originally Posted by buymeavette
i've read that it doesn't make each combustion chamber equal. lots of expenses to go along with this. i read this in ligenfelters book, mainly for race type of deal. just bigger heads, i mean he is buiding the rest up why not dish out the extra cash. i know everyone has there budget but i know not to many people like to burn there cash up.
erik
erik
I'm sure by Bigger Heads Lingenfelter is talking about Runner ports not CC's of the Combustion Chamber.
Teching In
Joined: Jul 2004
Posts: 46
Likes: 0
From: Western Suburbs of Chicago
Originally Posted by MUSTANGEATER
It's a relatively cheap process and if you go with someone who knows what they are doing it will be fine. Smaller Combustion Chambers are a good thing, I'll give a cookie to whoever answers me why....
I'm sure by Bigger Heads Lingenfelter is talking about Runner ports not CC's of the Combustion Chamber.
I'm sure by Bigger Heads Lingenfelter is talking about Runner ports not CC's of the Combustion Chamber.