performance recipe for 400 small block
Thread Starter
Intermediate
Joined: May 2002
Posts: 41
Likes: 0
From: orlando fl
performance recipe for 400 small block
I have a 72 vette with a TH350 trans (originally a 4 speed car) and I am about to build a 400 small block with 2 bolt main and stock rods. I would like this car to run 13.80's in the quarter on a very tight budget. I plan on using 10.1 "claimer" cast pistons, stock 882 heads (1.94in, 1.50ex), headers and 2.5 inch exhaust. The A/C and powerbrakes must remain operable. What cam will get me to 13.80's while retaining a decent idle. :D
Race Director
Joined: Mar 1999
Posts: 10,258
Likes: 1
From: Calif.
Re: performance recipe for 400 small block (srmcclean)
Big displacement will let you get away with a larger cam before the idle gets noticeable. 13.80s? Wouldn't you rather get into the 12s? Try a cam like Lunati's 07101 That'll have a little hitch to it but it will make pretty good power in a 400.
Instructor
Joined: Jan 2002
Posts: 185
Likes: 0
From: Surrey BC
Re: performance recipe for 400 small block (srmcclean)
You are aiming quite low at 13.80. Last winter I built a 400, although with aluminum 2.02 heads, and ran 12.90 with alot of room for improvement. My brother also built a 400 with stock heads and he tried 4 different cams in two weeks before settling on an Ertle 115871. I used this cam also.
Valve lift :.509 int .533 ex
Sae Dur :313 int .328 ex
Properly tuned it makes enough vacuum for the brakes and headlights, good power range, and a grumpy idle. You may want to go a little smaller if you want a smoother idle, but 400's can take a big cam so don't go too small. It may blow you tight budget, but ARP studs and nuts are good insurance for the bottom end :cheers:
Valve lift :.509 int .533 ex
Sae Dur :313 int .328 ex
Properly tuned it makes enough vacuum for the brakes and headlights, good power range, and a grumpy idle. You may want to go a little smaller if you want a smoother idle, but 400's can take a big cam so don't go too small. It may blow you tight budget, but ARP studs and nuts are good insurance for the bottom end :cheers:
Melting Slicks
Joined: Dec 2000
Posts: 2,198
Likes: 2
From: Eastern Connecticut
Re: performance recipe for 400 small block (lyndave75)
For my street rod I had a 400SB with flat-top cast pistons. I used 882 heads, but with 1.60 exh valves installed, and a GM L82 cam with 1.6 rockers. It pulled awsome from 3000-6000 rpm and idled like a stocker, since it was a GM cam. No times, but it did go over 110 in a 1/4 mile stretch of road. Joe
PS you should get your rotating assembly balanced, too, as that's a lot of stroke for a cast crank.
PS you should get your rotating assembly balanced, too, as that's a lot of stroke for a cast crank.
Melting Slicks
Joined: Jan 2000
Posts: 2,386
Likes: 3
From: far, far away
Re: performance recipe for 400 small block (srmcclean)
Just a small suggestion, based on a lot that I've read, but no personal experience.
Don't use the stock rods. They're too short, causing a lot of side loading on the piston at half-stroke.
Use 5.7" rods (stock 350 rods) instead of the stock 400's 5.565" rods. KB makes a 400 pistion with the pin hole at the correct height for the 5.7" rod. If you can afford it, 6" rods are even better.
Do a little research on this, and I'll bet you find out you want the 5.7" rods.
Good luck with it, however it ends up!! :seeya
Don't use the stock rods. They're too short, causing a lot of side loading on the piston at half-stroke.
Use 5.7" rods (stock 350 rods) instead of the stock 400's 5.565" rods. KB makes a 400 pistion with the pin hole at the correct height for the 5.7" rod. If you can afford it, 6" rods are even better.
Do a little research on this, and I'll bet you find out you want the 5.7" rods.
Good luck with it, however it ends up!! :seeya
Melting Slicks
Joined: Jun 2002
Posts: 2,843
Likes: 99
From: Orrtanna Pa.
Re: performance recipe for 400 small block (srmcclean)
I ran the XE-274 Comp Cam in mine,and thaught the idle was too smooth,so in went the XE-284. Nice rumpity rump now. My combo is pushing 475-500 hp with the AFR heads,but I would expect an easy 400-425 even with the stock heads and 10:1 cr. These motors are huge and don't need too much work at all to pull 13's. Build it for torque. Small tube headers,dual plane intake,and cam it for STREET use. I concider my engine perfect for street use.
