Jeff Smith's Garage Big Block Chevrolet Engine Combos 

My big block scares the hell out of me THEN puts on the smile 😂

Hey Mike, it's good to hear from you. Thanks for the support!

L

I knew It!! :).. I'm hooked... Great video Jeff!!!

Gotta port those heads and work on the short side radius and a good valve job and proper springs for your cam. Get with Chris Straub for a cam recommendation. Also 10.5:1 compression. That’s all you need to get 550-600 HP. If your heads need much work just buy AFR or Brodix 265 oval port heads, they’re good for 600+ HP out of the box.....

That cam with oval port heads is a torque beast! Just got my 72 C10 454 +0.030” running with that HR cam and when the back barrels open up on the 3310 the truck goes sideways in 1’st or 2’nd gear. Cam is 221/235 @ 0.050” and 0.578”/0.578” lift on 109* LSA

Kenneth - I think that would be a good choice. I don't have any personal dyno experience with that particluar head but Dart knows how to move air so it should work well.

You do know that this is a different engine from the MKIV and Gen V and Gen VI big-blocks. Your engine was a complete redesign. I do know that the heads do not interchange so you will have to work with that casting. As far as compression - I would keep it around 9:1 just so you could use regular pump gas. I'm not sure there are aluminum heads available for this engine. I know Dart used to make iron upgrade heads - you should contact them to see if they are still available - I think they stopped production on them last year. Comp does offer a few camsahfts for this engine. The XR264HR - PN46-413-9 might work well. Hope this helps.

@@jeffsmith2003 Thanks raylar seems to be the go to... if i went alum heads would 9.5 cr be pushing it with a tune? Love your writings and channel!

@@jeffbarnes9331 I think a 9.5:1 compression ratio would be okay. It really matters more how efficient the chamber is rather than aluminum vs iron. I did a test on that many years ago and the aluminum made more power! I don't think the material is a concern. Aluminum is beter because its lighter and easier to repair.

How did your rebuild turn out? I'm building a 408 now. I got a custom roller cam from Cam Motion, Johnson roller lifters, Brodix RR Oval ports with a downsized intake value to add clearance and Icon forged pistons. Should be at about 10.5 compression. The tech at Brodix that helped me choose the heads said it should be good for 600+ hp.

Mike - yes teh lift specs are a bit soft. There are some new lobes that Comp has created that offer more power with similar lifts specs - the key is additional lift is generated on the closing side of the lobe - where you have lots of velocity even with the valve closing. I did an A-B test on an LS engine with similar lobes and picked up 15 hp from peak torque to peak hp rpm point. Otherwise the specs were almost identical! I need to do a video on that.

Pretty weak. I'm using a .748/.748 lift, 288/296@.050, 110 lobe sep stick in my Rat. I'll probably drive it more than he does that mild engine. And I'm using a tunnelram and heads that flow.

The factory aluminum heads on that particular engine were not ported but the combustion chambers were milled before I received the engine so the compression is right at 10.5:1.

Call Chris Straub! Can’t go wrong!

I have kind of a long anxwer for you that may not fit here - send me an email at lanejsmith@yahoo.com and I'll send you my ideas. At least this may start a discussion about what you are looking for.

Jeff will be in touch - CB

Not a expert but I have a rolling thunder in my 555ci. It has 248/256 duration 632/648 lift. 11" of vacuum. I drive the car all the time. Might be a good cam for you. I really like it!!

An answer is it depends upon how you intend to use the Blazer. If it intended to pull torque at low rpm like out in the woods or four-wheeling, something like that then the cam is probably one size too big. but if street performance and more midrange to top end power is your goal then that cam is probably a god choice. Hope this answer helps...

@jeffsmith2003 The K5 is gonna be a weekend toy, mainly street driven with occasional off-road use.

Sure, the big difference with Gen V is the change to the one-piece rear main seal, hydraulic roller cam, and no mechanical fuel pump provision. But the same potential upgrades can be done to that engine. Gen V modified the water jacket outlets on the deck surface slightly, but most aftermarket heads now have been modified to accept those revisions. You will need a camshaft that has a stepped nose that accommodates the limiter plate used on the Gen V which is nice because then you don't need to mess with setting camsahft endplay with a cam button - the factory did that for you! There are stroker cranks available and piston selection is roughly the same as Gen IV stuff. So yes, there's a ton of potential for the Gen V engines.

Generally speaking most aftermarket BBV heads will work on either MKIV or Gen V-VI blocks. Where you run into trouble is with production heads. You cannot run a production MKIV head on a Gen V or Gen VI block as this will cause coolant leaks because the Gen V and VI blocks coolant holes have been modified. This is a much deeper subject but the above statements should keep you out of trouble. I can't answer with more clairty since you didn't offer any specifics as to what you are trying to accomplish. Hope this helps.

@@jeffsmith2003 Thanks for the reply. What you stated is the common wisdom, don't try to put Mark-4- 781 heads on Gen 5 or 6 blocks. The potential coolant leaks aren't worth the risk. Most if not all aftermarket heads with work on either. Don't get too fancy with the mix and match. Thanks again your videos are very helpful.

That is the same camshaft at 0.510 lift.

Appreciate your time Jeff. Thanks!

former editor - but yes!

Yeah, what he said.

If you look at the video at 8:56 - inside the dyno curve is the information on the camshafts - specs and grind numbers. At 9:04 is a list of all the parts we mentioned and the part numbers.

Jeff's partner on this endeavor!

A valid opinion. First of all, there are no sponsors of Jeff Smith's Garage. I did this video to pass along some of the things I've learned from years of dyno testing engines for the major magazines. None of the manufacturers mentioned in this video asked me to do this. I did it as a service to our viewers. The only agneda here was to put out some information that some might feel is helpful. I want to make that very clear. There are perhaps 5,000 different combinations depending upon your specific needs and budget. Sure, there are other less expensive avenues. For a typical street 454, the 049 iron oval port heads can be built into decent street heads especially if you can afford to have the intake valve size increased to 2.190 from 2.06. I would leave the exhaust valve size at 1.7 .2-inches but you could increase the diameter to 1.88-inches. But - by the time you invest that much money into the increased valve size, you have spent about 70 percent of the cost of a set of Edebrock Performer RPM aluminum heads - nobody tells you that until you've already spent the money. I'm telling you this now to save you the grief. Plus, the 049 heads are becoming hard to find. So then you're down to stock heads - sure you can run stock heads. Perhaps I should have made that point in the video but it wasn't really the focus. So the question becomes would you want to spend $900 upgrading a set of iron heads when you could have a set of aluminum heads that would also shave 50-60 pounds off the nose of the car all for less than $1,500? The Edebrock Performer RPM heads are currently selling at $1,500. Frankly, if you can't afford another $600 then we really are not talking about performance anymore. Hot rodding has never been and never will be an inexpensive hobby. In keeping with a budget approach you could certainly go with a flat tappet hydraulic cam. Again to match this package a cam with roughly 225-228 degrees of duration at 0.050 would work well. I would match the iron heads or the Edelbrock heads with a dual plane Edelbrock performer RPM or Holley intake and a 750 cfm carburetor and and HEI and that would be a nice street package that would probably make around 540 lb-ft of torque and 525 hp.

Perfect for street driving

CORRECT@@musclebone7875