Free 383 for Blaze

[74Blaze]

with this kit installed and it works so good

Yeah, I like that set-up better than what I have now (using the Head bolt holes).

Likely typical 1.94/1.5 valves with 165cc intake runners.

I'll measure the Valves once I take the Heads off the Block.

 

[74Blaze]

ChuckN, you were right about them being 1.94" Heads. Other than that, the engine is checking out to be pretty much what I was told it was. I'm pretty happy with the overall build. Still thinking I'll probably use the Heads off my 290HP 350. That should drop the compression ratio down to about 9.4:1.

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[ChuckN]

ChuckN, you were right about them being 1.94" Heads. Other than that, the engine is checking out to be pretty much what I was told it was. I'm pretty happy with the overall build. Still thinking I'll probably use the Heads off my 290HP 350. That should drop the compression ratio down to about 9.4:1.

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Nice looking build! They put some thought into parts. Speed pro forged pistons, some kind of Eagle or Scat rods with ARP hardware.

 

[ChuckN]

Oh, by the way @74Blaze if you put an “@“ before a username, you will “tag” them and the person will get a notification that you mentioned that person.

Nothing more than a FYI.

Looks like they used head studs too. I think the Summit page listed the valve reliefs as 3.5 cc, but you can look them up by number.

Then if you put a feeler gauge under a straight edge with the piston at TDC it’ll give you an idea how far your slugs are in the hole. Then, take that number and add that to the head gasket thickness you choose, and plug it into a compression ratio calculator and you can zero in on that.

 

[xm20k]

Just off a rough calculation with zero deck 64 cc head .30 over 383 and a rough estimate of gasket thickness and bore comes up 11..2 :1. With a 76cc head will lower it to 9.9 roughly.

 

[74Blaze]

@ChuckN

put a feeler gauge under a straight edge with the piston at TDC

Thanks, I'll do that next.

@xm20k

Thanks for that information.

 

[75gmck25]

I don’t want to sound like a big downer, but the 350/290 hp heads are probably just about one of the worst flowing heads you could find for an SBC build. They are fine for a grocery getter or maybe a plow truck, but you won’t get the power you want when they are used on a 383. However, maybe they will wake up the engine a little once you get compression up from the 8.2 ratio of the GM crate.

I think I would try to find a way to reuse the heads on the track engine, using thicker head gaskets to drop compression a little, and then pick a roller cam that matches the torque range you want. I’m more familiar with cams for the 350, but something in the 225-235@ .050 seems like a reasonable choice for an off-road 383. For a street vehicle you would also want a high stall converter, but I don’t know if it’s the same for off-road.

 

[xm20k]

It is currently 11:1 roughly. He needs to get down around 9.5-10:1 the bigger chamber will work unless he has about 1k in extra cash to get an aftermarket set. Also a cam in the 220-225 duration should not need a converter.

 

[Sad Sack]

@74Blaze

Fun software:

DeskTop Dyno5 Main Page

 

[Craig Nedrow]

I think Dave is right in there, I got 10.98. Any aftermarket head is better then thr 461 heads. They are a good head, most of the specks have already been mentioned. AFR enforcer SBC heads are still 650. ea, and then you will still need things like head bolts, rocker studs, pushrods, etc, so probably not viable, to much$$$. Speed pro/ Sealed power, forged pistons are a plus. The L designates that it is forged. The bottom end looks good if the tolerances are right, as mentioned Arp bolts are 180000 tensel strength, so plenty good. Here is how I see it. I like 11:1 compression, makes the engine thermally much more efficient then 8.5:1. Have to use good gas, 91 or better. You will set up timing by knock progression. IE, starts to knock retard the timing, until it stops. Old school.

 

[Craig Nedrow]

Two of the most important things that must match everything else in the engine, is the heads chamber volumn and runners cc, (160/195,) and the cam. This could be a real long lived engine that makes good HP, and is fun to drive. Don't get in a hurry, (sounds like you have some time,) study, buy some sbc books, make the right choices. 160CC runners have higher velocity then 195's, which translates to better throttle response, better low end torque, less top end. Call half a dozen cam mfg's, tell them what you have, what you think you want, where and how you drive it. The cam you have may work great with the right head. Let them give you some recommendations, see if what you have is in alignment. Were it me, I would leave the engine alone, buy good heads, run a good 650-750 Holly, long tube headers. Put bungs in the headers for a Bosch Wide band, buy a AF gauge, and thank me later. This engine should run like stink, make 450hp, and close to that in torque.

 

[xm20k]

Just an option.

Upgraded version of your current head with a 72cc chamber setup for flat tappet with .490 lift, 2.02 valves, and accessory holes. They are cast iron but unless you want to spend twice as much these would drop you down to a better compression range for pump gas.

Pardon Our Interruption

Running the numbers with these heads would put you right around 10.25:1

 

[74Blaze]

Thanks to everyone for the advice. I am going to keep researching and figuring out what combination that I should go with. The goal is to build a reliable high torque engine on a budget. I'd like to end-up under $2000 invested in this "free" engine, and that includes the $500ish that will be spent on a better set of Headers. Remember to take into consideration that I am not running an automatic transmission. The Blazer has and will continue to have the SM465 Manual Transmission. I intend to order all the parts after my mid-July vacation. And I want to have the Blazer running strong by next Spring at the latest. I don't drive this rig in the Winter, so not in a big rush to complete the engine swap.

 

[Rustisbest]

Sell the camel humps and single plane and put that money towards a new roller cam.
Using your heads its a crate 350 with 33 more cubes, a little more compression and a better cam. I dont see why it wouldn't work for a low RPM trail rig.

 

[xm20k]

Sell the camel humps and single plane and put that money towards a new roller cam.
Using your heads its a crate 350 with 33 more cubes, a little more compression and a better cam. I dont see why it wouldn't work for a low RPM trail rig.

250+ duration is going to run like hell under 3k add 11:1 onto that and you have close to my 388 91-93 octane only and idling/driving part throttle especially off road it's not going to be fun. That cam has such big duration to allow that high of a CR to run on pump gas even if it is premium and it isn't going to clean up until over 3k which isn't conducive to low rpm/small throttle inputs. Hed be better off in the 220-230 range and dropping a point of compression, so it has better manners at low RPM/light throttle input. It also will not have much vacuum for the brakes one pump maybe and bye bye power assist. That's why mine has Hydro boost.

Mine is a modern roller version of his cam 252 .600 110 vs his 250 .500 110 the duration and lobe sep will act just like mine just not as much lift. It hates anything under 3k.

Edit 11.1 and a shorter duration ie. 220-230 will make detonation even more likely even with 93 octane due to the higher cylinder pressure.