Hi Guys,


My engine is built!!!
Well the bottom end and heads anyway, just have to soak the lifters and install them and the intake, so now it's down to the little bits.


What temperature thermostat should I go for?


Keeping in mind:
* Climate in Queensland Australia would be possibly similar to Chile, drawing a line across the pacific


* Hot days here are around 35-38C in Summer, 17C in winter, no freezing or snow.


* heads are aluminium AFRs, but do not have steam holes drilled. Umm'ed and ahh'ed about it and read all the info and found if its not a delivery truck or idling long, shouldn't be a problem.


*Radiator isn't in great shape but worked fine before. Has twin trans coolers in front of it, and had air-con condenser which may go back on as well.


* Radiator has dual thermo-fans.

 

I would run a 180 degree thermostat with that set up. I'm surprised at your choice of not putting the steam holes in but that's your decision. Factory radiator will handled 450hp without too much of an issue. Just make sure the air dam is in place and functional. Also, since it gets that hot, I'd recommend putting your AC condenser back in to have AC. I couldn't imagine not having it.

What temperatures do your fan switches activate at?

 

Originally i was going to, but the builder working on the block prep forgot to drill them and after 6 months to flex hone and install cam bearings i just wanted the block back.

Fans are currently wired in to both kick on at 160F, but it's via an adjustable dial, so in summer i usually knock it down a bit to help out

 

Drill the steam holes yerself. Quite eeeeezy. SOOOO eeeeeeeeezzzzzzzy in fact, that I can do it.





Use about a 3/16"drill (7.5mm give or take). Drill the ones on the exhaust side straight in, and the ones on the intake side at a 45 degree angle toward the exhaust side.

 

Ok....if you aren't aware of what to expect by NOT drilling the required steam holes on a production SBC400, allow me to share my experience of a motor a friend of mine in a 1970 Camaro which ran mid 7's in the 8th mile.

Previous owner ran some blah blah 882 heads on a 406 and he too elected to NOT have the steam holes drilled. It should be noted the siamese cylinder walls get really hot and thus the need for them. Well, after about 6K miles on this motor and maybe 15 1/8th mile runs, the motor suddenly ran slower.....and slower....and slower.

When the car struggled to make a final run of mid 9 seconds we packed it up and trailered it home. We disconnected the ignition box and with the motor cranking over we kept hearing a weird "woosh-woosh" sound coming from seemingly everywhere. We pulled the top end off and to our surprise, the cylinder wall tops on the block itself were literally melted down between 1-3, 5-7, 2-4 and 6-8!! The head gaskets had broken down from the heat also and it looked like Chernobyl! A local engine builder we spoke with about it said while a 400 will run without drilling for steam holes, its only a matter of time before theres at least a head gasket failure-at worst a ruined block.

GM drilled them for a reason-I wouldnt take the risk if I were you-pull the heads and drill them.

 

I would have probably drilled the holes but don't know it will be a problem for you. I have a Dart SHP "400" block with Siamese bores. It doesn't have steam holes and my heads aren't drilled for them. You may get a little pocket of steam but I doubt it's gonna melt down your engine.

So basically I have the same build, 400 with AFR heads and HSR intake. I'm running a 195*F stat with fans both ecm controlled to come on at 95*C off at 90*C. I run a stock radiator with 4th gen fans. Currently my combo does pretty well running 95*C and creeps up in heavy traffic with AC on to 100*C. I am planning to "improve" the under radiator air dam and put the stock crank pulley back on to see what happens. BTW I idle at 925RPM. My combo doesn't overheat but I'd like to keep it in the 95-98* range at all times. I target 200*F (100*C) oil temp to keep moisture burnt off. I'm running a deep sump 8qt oil pan which takes a while to come to temp so quick coolant temp is important. I plan on trying 5w-30 or maybe 5w-20 oil to improve flow and bottom end cooling.

 

The aftermarket 400's don't have the same cooling issues as production blocks.

 

So 6k miles in total, or 6k miles + 15 1/8th runs + the life of the motor from previous owner?
I'm assuming that motor lead a hard life and probably had a lot of idling between runs?

Well I took the quote from crankshaftcoalition.com that normal duty 400s dont need them:
There are quite a few builders who claim the holes are not needed on an engine that will see "normal" duty, i.e. not idled for extended periods like a delivery truck, for example. Among them is noted engine builder Joe Sherman (of Joe Sherman Racing) who says, "I have built hundreds of 400 engines, WITHOUT the steam holes, and never had a problem. Guys used to send me their heads for me to drill the holes, because I only charged 80 dollars to do the job, but I never did it for my own stuff."

This motor will be a daily driver with an odd 1/4mile run a few times a year, and a little wheel spin for ego.

 

While I understand they most likely aren't needed for a race only application, I would still drill them for a street engine and for any production 400 block-I don't see why one would take the risk-no 400 motor WITH steam holes drilled has ever presented a problem. He car seen approx. 6K street miles with a summer of every other weekend 1/8th mile trips with 8-10 runs per night....and oh yeah there were many street skirmishes....after all, a built 406 isn't any fun to NOT lean on....lol.

 

Street car, under 3k rpm 90% of the time, drill the holes.
I run a 160 T-stat and the fans are programmed for that temp.

 

Yeah, I can understand with steam holes is probably better than without, but the engine is already built, and if I take the heads off and try to drill them, there's a better chance they'll be ruined by me.


I'll see if my mate delivering the motor wants to have a quick go at it.

 

If you have to take the heads to a shop to do the steam holes drilled it will be worth it.If you take your time and drill the holes yourself it's a very easy job to do. call AFR they can talk you through it.You need the steam holes to run the 400 on the street.I know this is a different build ,but I helped a friend fix his Iron headed 400.He didn't have the steam holes drilled.I have never seen so many cracks in a cast Iron head.

 

I may have a go at it myself, but what is the danger of DIY?
I know one set is done at 90degree angle and the other at 30/45(cant remember) but is there a fixed length for drilling, i.e. I can use a drill bit of a specific length to ensure I don't go too far?

 

Just drill until it hits the water jacket (empty space)... then stop.

Not rocket science.

Don't have to. Just read my post above, with the pictures.