Dyno Testing Carb Spacers on the Budget L31 Build (LT4 Hotcam) Open Spacer, 4 hole Spacer and Tapered Combo! Plus a bonus 0w20 Synthetic test! Dont forget to like and subscribe! L31 Dyno video • Cheap Chevy 350 Power!...
I just happen to catch this video. My 70 chevelle LS5 had a 2” open spacer I switched it over to the speedmaster tapered combo installed upside down as you suggested. With out a doubt it improved the throttle response off the line. Thank you for the awesome tip it really worked for me.
Hey was that on a sbc? Cause I didn't know they made a performer RPM Q jet manifold. It's the manifold I would like, without using an adapter for a Q jet
@@alexbrown4820 Yes it was. They make them in both for the pre 86 head bolt pattern and the L31 head bolt pattern. The L31 manifold is only available as a $$$ brass water passageway lined marine manifold though.
By flipping the spacer you introduce a shear edge to the flow path. That will help atomization. You might be able to reduce timing and still light up combustion and gain power.
Yelp ill order on for my 383 I want all the power I can get,just a old motor head love your dyno testing, I wanted more hydraulic roller cam for my 4wd but 7200 lbs I was limited I'm gonna get me w 3000 lbs car to play with 😊😊, keep em coming, build a 383!!!
Pressure being resistance to flow = increased load on cam gear / distibutor gear too. I'd be putting eyeballs on it too, it's nice that it's on a stand, and easy to do. I remember lifting a 302 out of a fox to investigate oiling issues, -good times- !
This really excites me because in one of the engine building FB groups I’m in everyone seems to think that the vortec heads that I picked up are worthless because they’d been upsized to 2.02/1.60s. Most people think that kills the way they flow. Definitely looking forward to seeing your next video on this with more information on the parts you used.
The work with porting. If they aren't ported to the valve they can have a negative affect. The exhauat side really benifits from the larger valve. Check out my latest video 480+ hp from a 355 with ported vortecs 2.02/1.6
I recently built a vortec combo almost similar to yours cutter. It's std bore with stock pistons with the deck milled .020" and 062 heads flat milled .040". I fully ported the heads as well with the stock valves 1.94/1.50 in them. Stock crank and rods with a mellings hv 55 pump. The camshaft is an old hydraulic flat tappet by Crane 286H06 grind. It has a Chinese airgap intake on it along with stock rocker arms and 5/16 chromoly pushrods. We are running a turbo 350 tranny with a 3500 stall and 4.56 rear gears. Car build is steady moving along..
Vizard claimed some good gains from radiusing the notch in the intake. I'm not sure if he added the notch. I noticed the performer rpm on my brothers 350 has no notch. My air gap rpm has it. I've heard great things about those "super sucker" spacers, that upside down trick is very interesting! Really enjoying your channel bud! I've got the hotrod bug again, been over a decade since I've had a project.
Pretty sure the 4 hole tapered spacers are designed for single plane intakes. Very cool that it added power flipped upside down. HVH has a dual plane spacer called the Street Sweeper. It’s basically an open spacer with a radiused bridge to smooth the transition at the plenum divider.
Today, my 359 sbc was on the dyno. Has 9.3 to 1 cr. Using a Perfomer RPM intake and an 850 Proform carb with the flipped 1" HVH four hole tapered spacer. The engine made 470HP and 475 lb ft torque. All in by 6200 rpm. The spacer, upside down, gave me 7hp, and torque down low was good. Your suggestion works! With a 750 Proform carb, lost 5hp and 5 lb ft torque.
While you have the oil pan off, install an inexpensive 5qt Spectre pan for a 1-ton truck or van and a longer milodon windage tray (requires 2 additional studs & nuts). Then run the normal 4 qt oil capacity in the pan. It will pick up power. I run Enos 0w50 and my engines have loved it.
@@Thumper68 Why not? Works better than 20w50 and much better than the OE specified 5w30. I ran 0w40 Mobil One in a Goodwrench crate L31 for 10 years, in fact I did the break-in on it and it was near spotless with no real wear on anything. I break engines in on synthetic oil. Why spend time adjusting clearences to be precise then allow added wear to happen on the first startup using conventional oil, makes no sense to me. All Corvettes from the LT1 on were factory filled with synthetic to start.
@@Thumper68 You realize the only difference in 0w50 and 20w50 is when the oil is extremely cold. The 20w50 is like molases and the 0w50 flows much better on initial cold startup.
@@chrisreynolds6520 no it’s not 😂 when they both are full temperature you will have more oil pressure with 20w50 you will also make more power. Look up engine masters episode they test this.
@@chrisreynolds6520 because my father taught me and his experience and knowledge is far beyond 99% of people. He’s a master machinist and mechanic since the early 70s and building 700+hp sbc since 80s
You need to do 1 more test! 2x 1" super suckers at the same time. 1 upside down on the manifold and the other the normal way on the carb. I want you to try that so bad haha
. . This is so awesome. What if you have two tapered 2" spacers on a performer EPS intake. 355 c.i. 10.5:1, XR288HR on 108 LSA and 106* ICL. Promaxx Project X 215 improved heads. 4 and 7 swap. and best size headers to vacuum tube into empty big muffler to pipe then flowmaster 50's . Notched cylinder edge for unshrouding big intake valve. 4.060" gasket and total quench of 0.038". -4cc reverse dome for easy target compression really short O.150" dome with softened edges of dome. This is what i am trying to build, although going to use a VIC JR for real. Although have an EPS laying around right now. And try some spacer stuff on VIC JR with this combo. Also a stroker of this same combo would be cool for comparison, as the compression and cam are the same. PRW 1.65 roller rockers and the stronger version of beehive springs of what is needed.
I know the transdapt 2" Qjet spacer/adapter looks like it flows soooo much better than the almost always used 3/4" & 1" adapters, it has a nice gradual transition looking down it it looks more like just a spacer than an adapter vs the others have a very abrupt transition, maybe there's no difference in flow but it sure looks as if there would be. The shorties look like they would cause a ton of turbulence?
Thanks again as always cool info. I would like to see the gains that can be had on this combo with a decked block and windage/lightening/balancing modifications to the crank. Just the stuff that can be done with effort and a bit of machine work, and not throwing a whole lot of parts at it, and blowing the budget. Break the 450 hp. mark??
Getting electric water pump Run the alternator lower on the motor and just use a belt off the crankshaft to run it and you'll gain 5 to 12 horsepower From the use of electric water
As always good info for the oldschool guys en girls. Love it!! Great knowlidge from top to bottom. I have only one question. Wat is your opinion on the GM 12677151 camshaft? This is hart of the sp350/357 gm crate engine. the “latest” engine from gm with vortec heads.
The oil pressure issue is because you blocked off the filter bypass and probably had a restrictive filter to push through. Ive heard of oil filters bursting due to this. I would try a better filter arrangement or go back to using the OEM filter bypass.
The oil pressure is taken after the filter, so a restricted filter would have caused a low oil pressure. The issue was actually just the pressure regulator in the pump itself
I had a Ole Performer and cut down the pendulum now i seei should have bought the air gap but my cam is 5500 range i guess ill try it before I purchase???
My 68 RS/SS Camaro matching numbers 350 4 speed edlebrock intake holly carb 1 inch open spacer and standard 14” filter is all I can fit if I even get little taller filter it hits hood. My car got quicker with notice gains through entire rpm range. I also refreshed my engine it’s .020 over and has aluminum pistons and I also worked the heads with burr.
What was the jetting combo you used? I have the same setup but with a 218/218 Duration Comp cam? I am sure this would make a difference however. Need to get an A/F gauge on it.
The stock holley 750 jetting was just about perfect without any spacers. When using a open spacer or the tapered combo flipped, we had to go up one size on the primary and two sizes up the secondary main jets
So, the added volume of the spacer causes the dual plane to essentially react like a half step below a single plane. A compromise between the two intake types. Interesting.
Thats the interesting parts about the flipped combo spacer compared to the open spacer. The flipped combo doesnt have the drop in low end power compared to an open spacer, so its not just an increase in plenum volume. There's no trade-off, which is good
@@cuttersperformance I'm thinking it's working better than the plain open spacer because of the smooth transition to the split plenum. It would be interesting back to back test flipping the combo spacer on a dual plane with the divider cut down. Another an interesting test try cutting between the primary and secondary on a 4 hole... keeping it dual plane but adding more volume...
I would have to think it is the anti-reversion properties helping the low end torque... the fact it adds plenum volume and some height helps top end. Best of both worlds 😁
Following advise from an erlier video regarding vortec head valve clearance i got the SUM-174002 valve springs and recomended retainers SUM-174003-3 . my question is the cam i am going with SUM-174002 has a .505 lift and i am wondering if i will be ok with factory valve locks? i am using prw rollar tip self aligning 1.6 rockers and putting in the pioneer studs.
My assumption would be something like Hamburger's tapered dual plane spacer (4 hole but keeps true dual plane, divided) and a lot larger carb would be the way to go. I haven't tested it because the only application I run a dual plane on a build is a hobby stock dirt car and you want the engine to see all that carb, it's restricted to a 2bbl so it wouldn't make sense to maintain true dual plane. But I think in a budget BBC towing application with penut port heads, that kinda spacer and a large 4150 would work quite well. Wouldn't show up on the dyno but I'd prefer phenolic over aluminium. Think maintaining the dual plane would give you more meat under the curve and the large carb would feed it at rpm, maintaining the dual plane makes the carb seem smaller to the engine so probably has better throttle response and part throttle manners.
No recent vidoes. Ive neen doing a big shop reno at my home shop. Once im back up and running I will putting out some fresh content. Lots of cool builds coming up
Do you have any experience with AFR 195 Eliminator street heads? On line they say that offset rockers aren't necessary, however the geometry on the intake rockers are horrible.
hey sir i have a question about my set up i want to do i would like to get beehive spring for 96 vortec engine and a zz4 cam will my stock rockers and stock pushrods work with that cam i know my question has nothing to with your video but i have seen alot of your stuff on vortecs builds snd thought you would be a guy to ask great videos by the way thanks
The stock rockers shouldn't be used with that cam, anything over .480 lift is pushing it. The stock push rods are good for about 300lbs of open spring pressure
You can use an old school flat top piston in an L31. The real difference is that vortecs use a smaller metric ring package on the stock pistons. But if you're changing pistons, you can use either
Well after watching this video i just had to experiment. I have a half inch 4 holed tapered cnc spacer. Never once did i think to flip it as even the brand name is engraved so i dont install it "wrong". The difference was very noticeable at mid range and even leaned up my part throttle steady cruise...i was thinking i may have IFRs too large etc. Im really thinking flipping it is vaporized or atomized the fuel much better. SBC sounds more crisp. Flipping the spacer on my RPM Air gap..750DP..cammed 500hp sbc has certainly worked well.
@@cuttersperformance my idle went from high 12s low 13s AFR to 16s AFR...i was 1 1/4 turn from seated now its 1 1/2 turns out and back to high 12s...with a standard air cleaner element... It certainly did something flipping it.
I have a marine vortec engine in my 85 square body. Has the 395 roller cam, aluminum Volvo Penta intake manifoldI, and rated at 325 hp. I have a zz4 cam I have been wanting to use with 1.6/1.5 rockers, a Holley 3310, and try this spacer flipped. I would think the outcome would be similar in results than with no spacer just down a bit from the Hotcam.
