400 rebuild plans
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Junior User
Joined: Dec 2003
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400 rebuild plans
It's time to start getting together the parts my rebuild. Anyone see any problems with this set up?
400 with stock heads that I will be porting the exhaust side, cleaning up the intake side, polishing the chambers,
and adding 4v sized ss valves.
Pistions will be KB148 (351c 13cc dish put to the deck or .010 under).
Compcams x262 k-kit and set of roller lifters. Also plan on a set of headers with 2 1/4" or 2 1/2" duel exhaust with x-pipe(mufflers still thinking on those).
Now this is for a 79 Bronco with a 4sp, 33" and 3.50r/p.
Daily driver with some off roading and some light towing.
MUST "run on pump gas" and be a blast to drive.
So how does it look?
Thanks
Jason
400 with stock heads that I will be porting the exhaust side, cleaning up the intake side, polishing the chambers,
and adding 4v sized ss valves.
Pistions will be KB148 (351c 13cc dish put to the deck or .010 under).
Compcams x262 k-kit and set of roller lifters. Also plan on a set of headers with 2 1/4" or 2 1/2" duel exhaust with x-pipe(mufflers still thinking on those).
Now this is for a 79 Bronco with a 4sp, 33" and 3.50r/p.
Daily driver with some off roading and some light towing.
MUST "run on pump gas" and be a blast to drive.
So how does it look?
Thanks
Jason
Last edited by jrongi1; Mar 23, 2004 at 07:19 PM.
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
What seems like a ton of metal comes out with the 4V retrofit. Everything I did prior to having the valves installed was a waste of time. My head guy took a radius cutter to them to blend them in. Talk to whomever is installing your valves. You will need hardened seats on the EX side, at least.
The big valves shine in mid to high end, theory says off idle suffers but I can't feel it. I am in a PU mostly doing 30-90 mph on 275/60/15 with 3.00. It will flat run the 600 cfm out of gas and I couldn't do that with 2V heads using the CompCams "Energizer" RV cam. (212 or so actual).
I have been lazy and not recurved the distributor, but know it needs it.
I am cheap and have stock cast pistons (and stock CR)... all of which is fine on regular gas until I have to tow the boat....then in really demands premium with a loud voice.
Hope this helps. GL and enjoy!
The big valves shine in mid to high end, theory says off idle suffers but I can't feel it. I am in a PU mostly doing 30-90 mph on 275/60/15 with 3.00. It will flat run the 600 cfm out of gas and I couldn't do that with 2V heads using the CompCams "Energizer" RV cam. (212 or so actual).
I have been lazy and not recurved the distributor, but know it needs it.
I am cheap and have stock cast pistons (and stock CR)... all of which is fine on regular gas until I have to tow the boat....then in really demands premium with a loud voice.
Hope this helps. GL and enjoy!
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Jason,
Stainless Steel valves are a good investment, but 4V valves get shrouded by the cylinder wall. I would stick with 2V stainless steel valves.
You should have no problem running on pump gas. The torque curve is almost flat from 445 ft-lbs@2000 RPM to 449 ft-lbs@ 3500 RPM. Peak HP is 351@4500 RPM.
My calculations were with the pistons at 0.010 deck clearance, and a CR of 9.19:1.
Stainless Steel valves are a good investment, but 4V valves get shrouded by the cylinder wall. I would stick with 2V stainless steel valves.
You should have no problem running on pump gas. The torque curve is almost flat from 445 ft-lbs@2000 RPM to 449 ft-lbs@ 3500 RPM. Peak HP is 351@4500 RPM.
My calculations were with the pistons at 0.010 deck clearance, and a CR of 9.19:1.
Thread Starter
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Junior User
Joined: Dec 2003
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Danlee,
The 4v size is easier to find, so is there any real "disatvantage" to them? I have seen many good reports.
And you said "You should have no problem running on pump gas." Is it going to need 93 or will it do fine on 87-89?
The 4v size is easier to find, so is there any real "disatvantage" to them? I have seen many good reports.
And you said "You should have no problem running on pump gas." Is it going to need 93 or will it do fine on 87-89?
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Yes, there is a disadvantage to 4V valves. The shrouding by the cylinder wall reduces head flow, when compared to 2V valves.
It should run on 91/92/93 or whatever is the highest in your area. You might try a couple of gallons of 89 when your tank is low. If it pings top it off with premium, and stick to premium.
It should run on 91/92/93 or whatever is the highest in your area. You might try a couple of gallons of 89 when your tank is low. If it pings top it off with premium, and stick to premium.
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
IMHO,The disadvantage is on paper. The problems people cite with the big valves are loss of low end torque and shrouding. I don't know of any hard data (like dyno runs before and after) showing the actual loss/gains for this mod. It is just not done often enough to generate that kind of interest. There is somewhere out there in cyberspace, I think,some flow numbers and, as you would expect, the 4V valves flow more. What I can tell you is that I have done this and it makes more power, period. Off-idle power is about the same by the seat of the pants... mid range and big end power is noticably improved. It is not cheap but it does work, and well.
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Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
I recently purchased CHI-3V alloy heads to replace my 351C-4V closed chamber heads on my 400. I planned to use the stainless steel 4V valves from the 351c heads in the new CHI heads. I was told by CHI that their dyno tests prove that the best valve size is 2.15" for Intake and 1.65" for Exhaust. The 351C valves at 2.19" and 1.71" are shrouded by the cylinder walls. I took their advice and had my valves cut down to 2.15" and 1.65". I suppose that there may be some improvement over a 2.04" intake valve by going to a 351C intake, but I suggest cutting it down to 2.15".
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Elder User
Joined: Jun 2003
Posts: 886
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From: Houston/Hope BC
Cleveland Flow Data
Thought you would all find this interesting, took me a while to find it again.
http://www.jason.fletcher.net/tech/f.../cleveland.htm
I wish I had mine cut down a little, the numbers sure bear you out. (not that they are bad 4V to 2V), but they could be better as you suggest.
If anyone has any data, It would be great to share it with the above site to establish a more reliable pool. BTW, Danlee, those CHI heads are incredible.
http://www.jason.fletcher.net/tech/f.../cleveland.htm
I wish I had mine cut down a little, the numbers sure bear you out. (not that they are bad 4V to 2V), but they could be better as you suggest.
If anyone has any data, It would be great to share it with the above site to establish a more reliable pool. BTW, Danlee, those CHI heads are incredible.
Last edited by Ecuri; Apr 23, 2004 at 07:30 PM.
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