400 small block

scott · August 9, 2002

hey everybody

im currently driving a 79 blazer with the 350/350 combo

anyhow its blowing serious amounts of oil out of the valve cover breathers<esp at hi RPM>plus its making a bottom end noise that sounds an awful lot like a rod knocking

anyways im looking at a rebuilt 400 small block at my local autozone ,price is right at 850! i cant build a motor that cheap and i know it

so to the point of this im going to be running a holley street dominator dual plane intake and 750 vac secondary holley <yeah i know its a little bit too big>

ill probably jet the carb down a bit to make up the difference

anybody have any ideas of <ball park>what kind of numbers this thing will make?

im addition to the aforementioned carb and intake im running dynomax coated headers and glasspacks

also a new accell H.E.I.

anybody have any ideas of where to start with the jetting?

i know smaller lol

anybody have any good ideas as far as a replacment cam for this motor?

im looking for serious low end torque and driveability as the blazer has 35s and <i think >stock gearing

or should i just stick with the stock cam in the 400???

i dont mind giving up a little mileage as long as im making decent torque

anybody know what heads and compression a stock rebuild 400 will have?

thanx in advance for everybodys help

scott

[email protected]

scott · August 14, 2002

me again

i was just wondering if anyone thinks ill need a new torque converter with this new motor

nothing radical just a few hundred higher RPM stall than stock

SoMnDMAX · August 14, 2002

Keep the stock convertor.

Sounds like you should end up with a nice combo. The 750 vac. sec. isn't too big for the 400!! Start with the primary jetting around 72, with a 6.5 power valve, and a brown or silver spring in the vac pod.

Cam selection- Comp Cams # CL12-239-3 (cam and lifter kit) would be a good torquey cam for your Blazer. It's a bit big for a stock type 350, but will work really good in your 400.

Power- hard to say. Depends alot on the cylinder heads and pistons used. The compression ratio could range from 8.5:1 up to 9.5:1+, depending upon the parts used. If you could, post the casting numbers of the 400's cylinder heads. They are located under the valvecovers.

scott · August 14, 2002

thanx for the info

i actually didnt think id need a new converter but i had alot of people tell me i should have one

i had the bowl off the carb the other day to see what size jets were in it and im pretty sure they were already 72s in it <i slammed a set of 68s in it for now as its still on my 350>

ill go back to the 72s tho after the motorswap im not sure about the power valve and the sec spring

whatever comes in holleys from the factory<carb was brand new when i bought it>

belive it or not i was looking at that cam in my jegs catalouge already

i had thought the duration might be a little high but the lift numbers are real nice

i guess however since the motors going to be 400ci instead of 350 the 10-12degrees bigger will be made up by the extra cylnder volume

not sure about the casting numbers on the heads as i dont actually have the motor yet

i dont quite have all the money together for everything i want

1st week of sept i will tho

ill let u guys know whats shakin when i get more info

thanx scott

PineywoodTom · June 2, 2004

My experience with the 400 small block is I dont think you can over cam them.I have ran every combination from stock pistons and a .630 lift roller with a 750 double pumper that ran 12.40s in a 67 Camero.To stroker 411 cubic inch engines with 10.8 to 1 compression with 462 casting heads ported,lunati sloid with 268/278 degres duration @ .050 .580 lift holley strip dominator intake with 850 anular discharge holley in a 70 nova that ran 11.33 @ 119mph on pump gas and thru 3'' flowmasters.The 400 is a good all around engine and the secret keeping them together is the clearance on the bottom end.You need to run a little more tolerance than a 350.A tighter converter works best to utilize the low end torque the 400 put out.I think you will be happy with your choice.

Wingnut · June 2, 2004

Wow....This post is almost 2 years old!

Welcome to the forums PineywoodTom

snoman · June 2, 2004

My experience with the 400 small block is I dont think you can over cam them.I have ran every combination from stock pistons and a .630 lift roller with a 750 double pumper that ran 12.40s in a 67 Camero.To stroker 411 cubic inch engines with 10.8 to 1 compression with 462 casting heads ported,lunati sloid with 268/278 degres duration @ .050 .580 lift holley strip dominator intake with 850 anular discharge holley in a 70 nova that ran 11.33 @ 119mph on pump gas and thru 3'' flowmasters.The 400 is a good all around engine and the secret keeping them together is the clearance on the bottom end.You need to run a little more tolerance than a 350.A tighter converter works best to utilize the low end torque the 400 put out.I think you will be happy with your choice.

Man that is slow. I had a friend that was doing mid to upper 10's with a 72 camaro and alcohol fuel injecting with a 5500rpm stall and 5.38 gears. He got his best times when he started using 350 cranks and rod in 400 blocks and winding it a bit tighter as he had trouble keeping it together with 400 crank at aftermarket parts at 8000rpm and above. He realy blew a few big time and was "lucky" to salvage fuel injection one time as basically every thing else was toast.

Dusterman · June 10, 2004

The 400ci is a lightweight torque montster. I had a virgin 400 (65,000 miles) in a cherry '76 3/4 ton 4x4. I put a two inch lift and 35s on the thing. Added aluminum edelbrock intake, demon carb (750 is fine), "RV" cam, and headers. With my limited slip, it would easily burn halfway through second. It did have 4.10 rearend....

anyway, its a great motor, you'll be happy. its hard to find a 4-bolt main but you wont need one anyway. I beat "hemi" dodges, and late model chevy/fords on the drag strip at the sand dunes pretty easy and didnt take any air outta the tires.

see ya

snoman · June 11, 2004

The 400ci is a lightweight torque montster. I had a virgin 400 (65,000 miles) in a cherry '76 3/4 ton 4x4. I put a two inch lift and 35s on the thing. Added aluminum edelbrock intake, demon carb (750 is fine), "RV" cam, and headers. With my limited slip, it would easily burn halfway through second. It did have 4.10 rearend....

anyway, its a great motor, you'll be happy. its hard to find a 4-bolt main but you wont need one anyway. I beat "hemi" dodges, and late model chevy/fords on the drag strip at the sand dunes pretty easy and didnt take any air outta the tires.

see ya

Slap some 4.56 or 4.88's in that beast and really wake it up! All though it "burns rubber" easily (due to axle torque twist and wrapup unload tire on one side) 4.10 are tall for 35 overall and you would not belive truck with deeper gears. The 400 "mouse" was (and still is) a great motor!