307 SBC Small block Chevrolet with COMP XR258HR Roller Cam on the Dyno. Carburetor test
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- Опубликовано: 5 сен 2024
- 307 SBC Dyno testing. Comparing 3 carburetors, a 570 Holley Vacuum Secondary, a 650 Holley Mechanical Secondary and a 750 Holley Mechanical Secondary carburetor with annular boosters.
This engine is going in a 1969 Chevrolet C10. The best carburetor on the dyno is not necessarily the best carburetor in the car.
Built a 350 for a grandma impala 78 model got ready to put together all i had on the shelf was a 252h i went ahead to get it going it had a barrel carb that thing would smoke about 30' of rubber and be gone never had any complaints from grandma!lol😊😊
Great experience Ronald. Thanks for sharing.AG
Great video. I wish you had a video doing the retro roller cam conversion on a SBC.
You are in luck rod. Right now we are working on a budget build 350. As soon as that is done I will be installing a retro roller cam in a 400SBC. I already have the 400 short block complete. I will go through all of the necessary steps in the process. Watch for it. AG
great explanation about carbs-
Welcome back Alex
Thank you, your truly good Gold!
What a nice compliment, thanks John. AG
Nice build, great video.
Thanks Sam. Glad you enjoyed it. AG
Y’all rock 🤙I wish I was y’all s neighbor Lol 😆 I love y’all s videos 👍🏼 1:31
Thanks Jaime!
Ya know all of these small displacement engines are ok to have fun with but there absolutely is no substitute for cubic inch and that’s where the big engines come in don’t have run it to death to create H.P.
Thanks for your comments Mark.AG
I think by law a machinist is obligated to talk someone out of building a 307.
Idk why everybody hates in the 307 and 305
Run it and enjoy it, there will come a day when people wish they had one!
I built one. Doing research on them they got a bad rap because of 2 reasons.
1. they ate cams which at that time gm cut corners and the cams didn't have hardened lobes which is was not just the 307 that did that it was all motors of that same time period of the 307.
2. The heads are junk. Well not junk like prone to crack or warp or anything but junk as in useless boat anchors with large 76cc combustion chambers and small valves like 1.7 intake and 1.5 exhaust. And the compression ratio on them was rated at 7.9:1
My honest opinion change the cam and heads.
Even my 307 I ran for a year before building it up I found the cam lobes were getting wiped out when I opened it up and it ran fine before taking it apart. I went with a dual pattern cam edelbrock 2102 cam kit and I ran 305 heads with 416 casting numbers that were 58cc combustion chambers and 1.85 intake 1.5 exhaust.
But that's what I went with.
But even if you change the heads with 283,305,327 heads its going to be an improvement on compression ranging from 58cc to 64cc but if you want compression with bigger valves I'd look at 305 or 327 heads.
Build a 307 like how you would build a 283 or 327. But change the cam and change the heads.
A 307 is a stroker motor if you really think about it. It's a 283 block with a 327 large journal crank.
Thanks for your comment Wolf. AG
The Chevrolet 307 small truck has some potential all it wants is a forged aluminum 327 crank connecting rods pistons with 305 aluminum cylinder heads even though it’s a fleet engine
Thanks for the input Calvin. AG
I like your cam choice but to bad you didn't use a set of 305 Vortec heads on this build, also a RPM Airgap style intake and a set of 1.55:1 roller rockers or 1.7:1 if converted to screw in studs. IMO this would of got you over the 300 HP mark and the torque would of also been more. The 305 Vortec heads out flow the 416 305 heads by IIRC around 35 intake cfm with the small valves. Upgrade to the larger valves with some bowl blending and you're going to pass up the 350 Vortec head flow.(which is the highest flowing factory production cast iron sbc head produced)
I have never seen a downside when using an RPM Airgap or a genuine imitation RPM Airgap style intake even with a stock cam there is a gain throughout the entire RPM range. In that truck there should be way more than enough hood clearance for the slightly taller intake as well?
If you wanted to do some old school hot rodding with a 307 build you can use a 383 stroker crank, reuse the factory rods or upgrade to aftermarket 5.7" rods and use Jeep 4.0L pistons. With a .040" overbore you can get 361 cid out of the little 307 fairly inexpensively. Top it off with a set of 350 Vortec heads with the same parts as mentioned above and expect at least 1 HP per cube with close to or higher than 400 lb ft of max torque?
Cool little engine build, I really like the underdog sbc 307s. This block out of all the sbc blocks has the thickest cylinder walls out of all of them except 2 casting numbers of the 283 blocks. They are so thick that they can be bored from 3.875" all the way to 4" on the blocks with minimal core shift and as long as the coolant passages don't have a lot of rust damage. A set of custom pistons a stroker crank, install splayed caps and a turbo for tons of boost is what these little 307 blocks was made for even if nobody knew it was. LOL
Thanks for watching and sharing your knowledge of 307's. You have certainly given this a lot of thought.
@@goldsgarage8236
You are welcome. After finding out how thick the cylinder walls are on these underdogs I had to search for a way to take advantage of how heavy duty these blocks are.
So next time you get a customer that wants a sbc 307 rebuild don't be afraid to do the up sell. LOL Or a customer wanting to upgrade to maybe a 350 from a 307 you might want to give them the option to make there 307 run as good as a 350? Or for the guy that wants to run tons of boost!?
Sorry, I should have wrote sbc 350 crank with 5.7" rods in the first comment. With a sbc 383 crank you would need sbc 400 rods but those are to short for a sbc 383 crank it would have to be a 400 crank with the mains ground down to fit a 307 block.(minimum rod length for the sbc 383 crank is 5.7")
Now you have me legitimately looking to build my 307.
@@bpowersman5000
What kind of build, naturally asperated stroker, something with boost or both?
Just looking for some opinions on my plans for a 307 sbc. Stock bottom end 1972 307 73,000 miles, rebuilt 416 heads, 350hp 327 cam, performer intake, 500 edelbrock carb. Going in 1994 s10 with 700r4 transmission with stock converter, with a factory 410 govloc. Just putting together with what parts I have on the shelf.
It all depends on convertor and gear
Thanks Steve.AG
What are you guys running for heads?
I built a 307 for my 1967 gmc pickup using 305 heads with #416 casting as last 3 numbers but i dumped $1000 into heads at a machine shop they shaved them .030 did all new bronze valve guides with positive oil seals and clearanced up to .500 lift stock 305 size swirl polished stainless valves 3 angle valve grind and all the rocker studs were pinned. But my compression ratio should be around 10:1 and i went with a dual pattern cam edelbrock 2102 cam & lifter kit with z28 valve springs.
Also running 1 5/8 headers with x pipe exhaust 2.5 from collectors back dual plane edelbrock performer intake edelbrock carb aftermarket hei distributor.
That little 307 is a beast. So much so it hurt the T5 transmission i put in where it whines and growls now Truck is originally a 3 on the tree i put in a T5 for overdrive first burnout i did after breaking the motor in hurt the transmission lol
Thanks Derek, we did use the 416 heads on this 307. AG
200-230hp at the tire will make a really peppy short wheelbase truck.
Thanks for the comment. AG
I would love to know your opinion of Holley's 'Street Demon' carbs. Do you have any experience with them?
Thanks RANDOMINATION, Sorry I don't have much to offer here. I have used Street Avenger's and have one on my Z28, vacuum secondary carb. It works fine.
@RANDOMINATION
I’m replaced the very capable 600cfm square bore with a 625 Street demon. A little clean up in the venturis from casting flash and I can say in honesty, it is very sharp on the little warm 307. Ye there’s more moving parts but the insulated fuel bowl and overall carburettor design is very refined.
what heads are on it? I did a standard bore 307 for a guy with a set of 081 centerbolt L69 305 HO heads with a hydraulic flat tappet Summit cam #SUM-1202 put out 311 hp @ 5700. This was with an RPM intake, 600 vacuum secondary Holley, Orange Z28 springs, and 1 /5/8 headers into 2.5 inch exhaust with Walker mufflers. This was on a dyno and the timing was @ 38 degrees on 87 octane. If those are 307 heads then it explains the low horsepower numbers youre getting.
Thanks Master, We used the 305 heads mainly to increase compression. I selected a pretty mild cam, considering it went into a full size truck with automatic transmission the priority is nice flat low speed torque curve. AG.
@@goldsgarage8236vice grip garage use 305 heads I think 416 heads they got I think 297 horsepower 300 plus horsepower around there
Wow that sounds good for the 305! I have a 3rd gen F body with the dreaded L03 that I’ll be working on. With only 35K on the clock I’m planning on leaving the short block and working my way up. Already have L69 heads and a ZZ4 intake but was looking at cam choices: the 1202 looks interesting
What do you mean too much carburetor? If the big carburetor is jetted properly the engine can only use as much cfm as it demands.
Thanks for the comment rapidride2 and sorry that I just noticed it now. You are correct, we often see on the dyno, a 750 carb flowing less than 600CFM at full RPM. That said, a smaller carburetor should provide better throttle response at low RPM. Hope this helps to clarify. AG
@@goldsgarage8236 A larger carburetor decreases the intake charge velocity making the fuel puddle and heat up compared to a smaller venturi. I normally keep the carburetor and twice the cubic inches (305 = 600, 350 = 700) on a street application and it works well everywhere. Most people dont realize that slowing down the intake charge velocity actually costs power. The biggest thing that costs power is too much valve overlap. The wrong carb and cam can kill performance.
Does this cam have a nice chop at idle?
Thanks Jose, yes it had a nice rumble, not a radical cam, but a nice powerful sound. AG
@@goldsgarage8236 I got a roller 350 with tbi intake and heads. Do I need a different distributor gear since I plan on using this cam and if so which would you recommend?
307 chevys have weak blocks. Many years ago we stopped playing with them
Thanks for the comment. AG
I love it when guys say this. Keeps em cheap 🤣🤣🤣👍
Shouldve ran the 264hr or 270hr
Thanks for the comment. AG
Whats does this guy charge for dynoing a sbc?
Thanks Ace, usually $400 Canadian. Thanks for the question. Let me know if you want Darrell's contact info. He does a great job. AG
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