putting 406 back in need advice..
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 9,622
Likes: 16
From: absecon nj
putting 406 back in need advice..
ok ive run my 350 for 2 weeks now and really miss that awesome torque the 406 put out..question is the 406 has flat top pistons 1 long relief in top piston is .006 in the hole had 41 thousandths gasket and 041 heads 64cc the 233-234 dur.488 lift i took it out cause i couldnt keep it from pinging no matter what i did so i pulled it out.Ok i just got a set of 72cc sportsman2's this week 200cc i really want to put them on the 406 and put it back in but i dont want it to ping.im going with a different cam im putting a smaller cam in it not much but alittle porbably222dur.480 lift with 1.6's.you think this will work ok for compression on pump gas or change the pistons to dished ones...im using performer intake and 750 holley vacuum sec.2200 stall.370 gears hei advanced kit.1 5/8 hooker headers 2 1/4 exuast flowmaster mufflers.it also has 125 horse nitrous on it but not going to use it right now...yeah right!
Pro
Joined: Jun 2001
Posts: 683
Likes: 0
From: Calgary
Re: putting 406 back in need advice.. (pats406nitrovette)
Your compression ratio is about 10.5:1 with the 72cc heads. The more overlap you have with the cam the less chance of detonation, so you may want to stick with your original cam. Keeping the engine cool and the inlet air cool is of utmost importance. Go with a high flow 160 thermostat, high flow waterpump (edelbrock victor is best) and a good rad. Have a cold air inlet system (L-88 hood or ram air box system), no warm underhood air.
Your exhaust is a little small for the size of motor, and the performer intake is a bit of a bottleneck. Consider at least 1.75" headers and min. 2.5" exhaust.
I am building the same size motor with the same compression ratio so I am interested in how your setup will work on the street. Please post and let us know how it works.
Your exhaust is a little small for the size of motor, and the performer intake is a bit of a bottleneck. Consider at least 1.75" headers and min. 2.5" exhaust.
I am building the same size motor with the same compression ratio so I am interested in how your setup will work on the street. Please post and let us know how it works.
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 9,622
Likes: 16
From: absecon nj
Re: putting 406 back in need advice.. (74vetteman)
im using th 160 stat temps never exceed 175 even in hot weather i need to make a cold air box but im looking into a new hood at carlisle first so you rsaying go with the flat top pistons at 10.5 comp.?oh yeah im getting the sportsman intake to match the heads also.and im making anew 2.5 exaust for it since the flowmasters are already 2.5
[Modified by pats406nitrovette, 11:26 PM 8/14/2001]
[Modified by pats406nitrovette, 11:26 PM 8/14/2001]
Pro
Joined: Jun 2001
Posts: 683
Likes: 0
From: Calgary
Re: putting 406 back in need advice.. (pats406nitrovette)
Your original compression with your iron heads was 11.35:1. You are dropping just about a full point of compression. Your still going to be borderline with iron heads vs. aluminum. With your decked motor and lower compression with the 72 cc heads you might get away with it. How bad was the pinging before? You should definately get a cold air inlet.
How hot is the ambient temperature where you live? The hotter it is the greater the chance of detonation.
Maybe someone else with more engine building experience can comment?
How hot is the ambient temperature where you live? The hotter it is the greater the chance of detonation.
Maybe someone else with more engine building experience can comment?
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 9,622
Likes: 16
From: absecon nj
Re: putting 406 back in need advice.. (74vetteman)
pinging was real bad had to put timing at 4degrees or less then it became a dog to drive but temps were around 98 degrees for the week im just outside of atlantic city and its been hot here i think ill go with dished pistons to be safe then decide on gasket size to get the compression i want i want to be around 9.5.thanks again ill check back later going to work now.
Burning Brakes
Joined: Jul 1999
Posts: 1,013
Likes: 0
From: Austin TX
Re: putting 406 back in need advice.. (pats406nitrovette)
Can you return the iron heads and get aluminum ones??? Then you won't need new pistons...probably save a lot of time too.
I'll go take some pics of the cold air box I had made up...it works!!
[Modified by StingrayRacing, 8:56 AM 8/15/2001]
I'll go take some pics of the cold air box I had made up...it works!!
pinging was real bad had to put timing at 4degrees or less then it became a dog to drive but temps were around 98 degrees for the week im just outside of atlantic city and its been hot here i think ill go with dished pistons to be safe then decide on gasket size to get the compression i want i want to be around 9.5.thanks again ill check back later going to work now.
[Modified by StingrayRacing, 8:56 AM 8/15/2001]
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 9,622
Likes: 16
From: absecon nj
Re: putting 406 back in need advice.. (StingrayRacing)
hey stingrayracing that would be great for some pics give me some ideas and yes i can return them havent touched them yet..well see ill decide after carlisle maybe ill see something there like pistons or who knows maybe a crate motor lol...ive really been thinking about ordering a 391 kit from speedomotive ..any pics of the box you can email me or just post them here for all to see.thanks
Race Director
Joined: Mar 1999
Posts: 10,258
Likes: 1
From: Calif.
Re: putting 406 back in need advice.. (pats406nitrovette)
I believe your pinging problem could be solved by nothing more than the addition of .039" head gaskets with a tighter bore. (Try Fel-Pro 1010. They have .039" thickness and a bore size of 4.166". You will have to drill steam holes in them yourself, however.)
Your quench is too big--.041" gasket + .006 "in the hole" = .047" quench.
Lingenfelter says this distance should be between .040" and .045" You're close with what you have now, but what would it hurt to try and fix it by going to a thinner head gasket?
Maybe it'll make a difference, maybe not. Might be worth a try, though. Just a thought...
[Modified by Jack Sweet, 1:50 PM 8/16/2001]
Your quench is too big--.041" gasket + .006 "in the hole" = .047" quench.
Lingenfelter says this distance should be between .040" and .045" You're close with what you have now, but what would it hurt to try and fix it by going to a thinner head gasket?
Maybe it'll make a difference, maybe not. Might be worth a try, though. Just a thought...
[Modified by Jack Sweet, 1:50 PM 8/16/2001]
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Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 9,622
Likes: 16
From: absecon nj
Re: putting 406 back in need advice.. (Jack Sweet)
ok ill try it whats it gone to hurt ..im gone to put it back in till i get the 391 together...i thnk with these heads 72cc compared to what i was running 64cc and that gasket 1010 it should work out...i appreciate all the help you guys are giving me...ive built motors for circle track guys for 8 years asphalt and dirt modifieds but there 9.1 and 10.1 motors and we run them on race gas at 7200 rpm lap after lap..but when it comes to finally doing something for my self it bites me in the ****.lol oh well thats life! :rolleyes: oh one more thing i have a crane cams 110691 238/244at .050 106 lobe separation .502 .516 lift iwith hiintensity lifters i used to run it in my 383 in the 406 it would be a little more streetable and also help out with the compression problem but my converter is 2200 and the power range is 3200-6400 but if i advanced it 4 degrees and also with a 406 it shlould be lower power range right?
[Modified by pats406nitrovette, 7:55 PM 8/16/2001]
[Modified by pats406nitrovette, 7:55 PM 8/16/2001]
