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1st Engine Build: Modifying heads
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For a 1st Time Engine Build, which size motor should one build?
355 chevy
38%
 38%  [ 5 ]
383 chevy
61%
 61%  [ 8 ]
Total Votes : 13

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SMOKEmUP
PostMaster


Joined: 30 May 2002
Posts: 3169

65097.54 points


1979 Chevrolet Camaro

PostPosted: Mon Dec 16, 2002 11:32 am    Post subject: Reply with quote

You can run that much compression with iron heads? I thought the limit was around 10, 10.25 if your pushing it. What is the quench height?
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heavychevys
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Joined: 18 Nov 2002
Posts: 81
Location: South Carolina
754.46 points


1964 Chevrolet Belair

PostPosted: Mon Dec 16, 2002 6:45 pm    Post subject: Reply with quote

The quench height is .0 deck height and a .037 gasket thickness.The way to run a high compreeion engine on the street is to have a cam with a good overlap.This bleeds off the cylinder pressure.The cam I chosed has a good over lap design and it is a dual pattern.
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1964 Impala 468BBC 6.986 @ 98.69 MPH 1/8 mi

(Bothers) 69 Nova 408 BBC 6.94 @ 96 MPH
96 F250 4X4 PSD 8.24 @ 84 MPH @ 7000 lbs

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osmiumfoot
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Joined: 11 Jun 2002
Posts: 299

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PostPosted: Mon Dec 16, 2002 6:52 pm    Post subject: Reply with quote

HeavyChevy - Am I hearing you right when you say you are running iron heads with a CR between 10.75 and 11, cast pistons and 38 degrees of timing on a locked out distributor? If you're locked out then isn't your 38 degrees the initial timing, which means it is all in all the time? Are you running a vacuum advance? The reason I question this is that I would think you are dancing with disaster if you run pump gas on this setup. That is a huge amount of timing under load off the line. I would think your engine would get rattled pretty hard, and those cast pistons would be clamping down with a vicious bite on that top ring. Once you collapse the land, the game is over. Your combo seems pretty extreme but, hey, if it works for you drive the heck out of it.
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osmiumfoot
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Joined: 11 Jun 2002
Posts: 299

2387.84 points



PostPosted: Mon Dec 16, 2002 7:04 pm    Post subject: Reply with quote

HeavyChevy - While I was writing my last post you replied to Smokemup about your deck height and how your overlap helps you avoid detonation. The cam you list doesn't have a lot of duration at 50 and the bleed down lifters take out some of the low rpm overlap, so I still think your on the edge.
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heavychevys
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Joined: 18 Nov 2002
Posts: 81
Location: South Carolina
754.46 points


1964 Chevrolet Belair

PostPosted: Mon Dec 16, 2002 9:13 pm    Post subject: Reply with quote

osmiumfoot,the distributor still uses it's weights and springs the vacuum advance is all that is not in use.It is a model 8360 MSD.The over lap I am refering to is when the intake valve opens at BTDC.The sooner the more compression it will bleed off.The .050 is 219(int) and 229(exh) with a lift of .497 (int) and .513 (ext).This is with 1.6 rockers.The clearances on the piston rings are by NOS standards and not street.It is a very good combo and has about 60-70,000 miles or so on it.And believe me it is drove hard and put hot alot. Mr. Green
_________________
1964 Impala 468BBC 6.986 @ 98.69 MPH 1/8 mi

(Bothers) 69 Nova 408 BBC 6.94 @ 96 MPH
96 F250 4X4 PSD 8.24 @ 84 MPH @ 7000 lbs

www.musc.us/drag
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87iroczguy
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Joined: 02 Mar 2003
Posts: 1

100.00 points



PostPosted: Sun Mar 02, 2003 12:03 pm    Post subject: l98 heads Reply with quote

GTAracer,
I am in the same situation as you, i am planning on porting polishing..valve job on my iron heads also. Im pretty sure that they will flow plenty, they say go with iron vortech heads, yea but they arent all that cheap if you want them to perform. You will need new springs yada yada yada with machine work also prly another 3-4 hundo addtional to the 450 price. I am not sure what i am gonna do with mine yet, if the stock heads wont work im gonna find others.

iroc enthusiast
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GTAracer
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Joined: 04 Dec 2002
Posts: 36
Location: Southeast, AL
416.22 points



PostPosted: Sat Mar 08, 2003 10:10 am    Post subject: Update Reply with quote

Hey 87IROC,

Have had to put the heads on hold for a little while. Did manage to get som SubFrameConnectors installed, along with a new fuel pump and injectors. Just ordered some 1-58" SLP headers, exhaust cut-out, and new plug wires. WIll see how that helps before jumping on the heads.
Will let everyone know how it goes. Currently car runs 8.9s in the 8th at 77 mph.
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GTAracer
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Joined: 04 Dec 2002
Posts: 36
Location: Southeast, AL
416.22 points



PostPosted: Wed May 28, 2003 4:52 pm    Post subject: Reply with quote

The mods got me 8.76 @ 80.9 mph. Consistent low 8.8s with varying mph b/w 77 and 80. Hadn't figured out why the mph varies so much, yet.

Started on my heads this week. I'll try and get some pictures up for thoughts before its all said and done. I hear where people spend about 10-12 hours on their heads Rolling Eyes ...I think it will take me forever.

This is what I'm going with and the tools I'm using:
2.00 intake and 1.60 exhaust valves (Manley Race Flo w/ undercut stem)
guide plates, non-aligning rockers, screw in studs 7/16
3 angle valve job
I will bowl blend, pocket port, smooth the radius and gasket match the intake and match the exhaust to the headers.
Using Sears electric die grinder 1/4 hp, some carbide cutters from Summitt and swap meet, and using Standard Abrasive Porting Kit. Safety goggles and mask. CHP magazine articles and Car Craft Articles and David Vizard books are guide. Bought the Standard Abrasive Porting video...waste of money.


I'll get it all flow tested when done...

BTW...these heads have the slots for guides, and also use self-aligning rocker arms. Confused
I also stripped the threads on two of the press in studs getting them out. Bought the pro-form tool to align screw in studs for tapping...doesn't work Confused

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69 Camaro X55/4-Speed/3.31

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Paul P
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Joined: 15 Aug 2002
Posts: 2403
Location: Townsend, Mass.
81574.74 points


1971 Chevrolet Chevelle

PostPosted: Thu May 29, 2003 4:33 pm    Post subject: Reply with quote

GTA,
Some advice on porting the heads.
1. Take all the time you need.
2. Do one basic change to all the ports at a time. Don't try to perfect the first port and move to the next you'll hard time duplicating your efforts x8.
3. You might want to wear some ear protection its pretty annoying after a while as well as deafening.
4. If you slip, it will suck so be well rested!
I have ported a few sets of heads and it is for only a selected few people to do as a day to day job. Its definitely not what I expected, the fun wears out pretty quickly.
Good Luck
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