Small block 400

[hirschdalechevy]

Double hump heads were great back in the day , but if you are going the iron head route the vortec's are better , imo.

My girl's truck has a .030 over , 9.8 to 1 , 270 roller cammed 350 , with worked over 202 double hump heads on it and it hauls ass , but it's a little soft out the hole. We had the heads at the time so we used them. It's more of a street car motor , but it's fun to drive. Real coppy idle at the stop light , will still cut the tire's loose , and at 3,000 rpm look out all the way to 6500ish.I would have rather used vortec's but we had the double humps so we went for it.

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[Green79Scottsdale]

Double hump heads were great back in the day , but if you are going the iron head route the vortec's are better , imo.

Thank you for backing me up!

 

[highdesertrange]

no one addressed the over bore of the Siamese sleeves in the 400 having cooling issues. I don't mean like running around town or even doing 1/4 mile runs. I mean like actually working the truck, like pulling an 8,000lb trailer up a 20 mile grade. imo 400ci were never good bored if you ever planned to work it. highdesertranger

 

[Linville33]

Alright that's what I figured. Technology has come a long way since then. I'm debating between the vortec or aluminum route just gotta source the cash right now

 

[Don5]

Back in the day the 202's were the heads to have if you wanted performance. But now, I would go with a set of aluminum heads. You will get better results. You have to love technology.

As far as the overbore question. I would not go over .30 on the 400. I honestly think you might be able to go to .45 but I don't know how long that would hold up. The diameter of the bore would be very high on the list of things to check once you pull that engine out.

BTW-I love your daughter's truck Hirschdale! That is a good looking truck.

 

[morrow07]

.030 is fine for working the truck. My father in law went to 406ci in his 78, and that truck is strictly for work. Dump runs, lumber hauls, towing, etc. Stock cooling system seems to handle it fine.

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[HotRodPC]

Are the double hump heads any good for these 400s? Buddies dad is an old school guy and was telling me how great the 202 double humps are/were. Don't know much about them

Vortecs are still better than double humps. Back in the day double humps were top dog, but not these days.

Yes, years ago double humps, camel humps, fulie and a few other names, WERE the ****. Not so much anymore. Even if you max ported them, you'll never get the flow out of them that you can get out of the Vortecs. Only thing the double humps are really good for these days are for the guys wanting to do # matching OEM restores. Then if you're getting into high lift and very high performance meaning the Vortecs are going to need extensive machine work, then you may as well just go with aftermarket aluminums ready to bolt on right out of the box.

 

[MikeB]

Are the double hump heads any good for these 400s? Buddies dad is an old school guy and was telling me how great the 202 double humps are/were. Don't know much about them

"Were" is right. They were great on 327s and 350s back in the day, but virtually ANY modern heads flow better, and you won't won't have to deal with 45-50-year old castings! Also, the chamber size (around 64 cc) is too small for a 400.

If you find a set of double humps, make them look pretty and hang them on the wall.

 

[firebane]

"Were" is right. They were great on 327s and 350s back in the day, but virtually ANY modern heads flow better, and you won't won't have to deal with 45-50-year old castings! Also, the chamber size (around 64 cc) is too small for a 400.

If you find a set of double humps, make them look pretty and hang them on the wall.

Lets not forget that those older heads also need to be treated properly to be able to use the gas we have today as well as the valve seats can't take it.

 

[Joe383]

If it were me I would get a set of vortec heads and have them modified a little and swap over to new pistons and 5.7" rods. I just got done building a vortec motor a few months back and have a medium sized cam in my Camaro and it has torque like no other. I have not drove the car much sense the build due to the car needing other non motor related stuff but the motor has great bottom end. The vortecs are my favorite stock head. Do be warned though... I had to have mine modified to except new springs and it was not cheep. Every one told me stock size springs would drop in and they did not on mine. Had to have valve guide boss machined. If you went with a set of vortecs and something like the edelbrock performer cam for the 350 not there 400 grind it would have torque for days and drive like a stock motor. I have the 906 castings and the valve guide boss is .9" on these heads. You would have to also have any non 400 head machined with steam holes before using them on your motor. Another great head would be the aluminum L98 TPI heads if you can track down a set.

 

[MadOgre]

Lets not forget that those older heads also need to be treated properly to be able to use the gas we have today as well as the valve seats can't take it.

Valve seats are metal and round and is a metal part of the head valve port. That is what the valve seats on to. Valve Seat. Not to be confused with Valve Seal

 

[MadOgre]

Double hump heads were great back in the day , but if you are going the iron head route the vortec's are better , imo.

My girl's truck has a .030 over , 9.8 to 1 , 270 roller cammed 350 , with worked over 202 double hump heads on it and it hauls ass , but it's a little soft out the hole. We had the heads at the time so we used them. It's more of a street car motor , but it's fun to drive. Real coppy idle at the stop light , will still cut the tire's loose , and at 3,000 rpm look out all the way to 6500ish.I would have rather used vortec's but we had the double humps so we went for it.

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6" lift with 36s ? Nice looking by the way!

 

[MikeB]

Lets not forget that those older heads also need to be treated properly to be able to use the gas we have today as well as the valve seats can't take it.

Yeah, they would need to be changed to induction hardened seats. But, I'm not sure how you could tell if the work had been done to a pair of heads. I mean, it's been a problem since the 70s when unleaded gas went away.

GM did release a "service replacement" double hump head, but I don't recall the casting number, or if it had hardened seats.

 

[MadOgre]

Are we talking about a 1960 something motor ? Early 70s received hardened seats from the factory.

In fact I have a 1976 motor right now that runs just fine with new gasoline and just so happens to have factory hardened seats in it. Which also happens to have the most desirable head casting to be used in truck applications. So why do I have to do something to my heads to run current fuel through it ?

 

[MadOgre]

I also have 2 other mid 80s motors that have no head issues what so ever.