Which Carb spacer 502 carb?
 

Have a new 502 mag carb 415 hp stock, EMI headers, with a gm aluminum intake (brass lined cuz im in salt) and it was a 800 holley DP that hits the intake so i need a spacer. I was going to run one anyways becuse i read u can pick up a little top end on the dual plane intakes......anyways Do i want a open or 4 hole spacer and is 1 inch enough? What brands?

i run a 4hole 2in on mine it made the most hp on the dyno . the other thing is i am runnig a dart single plane intake

I run a Wilson spacer..

http://www.wilsonmanifolds.com/shop/...uct_detail&p=9

You would want to run a 4 hole. Jegs has a large selection of them. I know Teague motors come with 2" spacers on their carbed motors. Those Wilson ones are really nice but quite pricey.
http://www.jegs.com/c/Fuel-Induction...10289/10002/-1

I am running 2" hvh super suckers on my 496's. Every appication is probably going to be different than the other however I don't think you'll be disappointed with either. The 1" would work fine also. These things have always intrigued me as to whether they work or not. I have talked to several pro engine builders as well and always here the same thing. They definately make power. Again every application will vary though. I will be on the dyno in a couple of weeks and will certainly have results with and without. I also have Dart intakes.

I would love to hear your dyno results. I will tell you mine. They are correct....the spacers are worth some power. Everytime I take one off, I gain power.:lolhit: Seriously, I have tried so many different spacers and have always made more power without them. I also have a few other buddies that are engine builders that have said the same thing. I think in the heat on extended runs, they (phenolic, not aluminum) may help with heat isolation. On the dyno in a sweep, the spacers made less power. I have still left some in place for heat isolation anyway (phenolic spacer). Usually only a 1/2" open. We aren't talking about much power. Maybe 10 hp. difference with and without.
Eddie

For a dual plane intake, I would use a 1" open spacer.

We did two 515,s 9.1 comp dart heads merlin 4150 intake and the results with and with out a 1 inch HVH Supersucker was 2 hp at 5600 rpm. We did 4 pulls started without it put it on, took it off put it back on and got the same #'s 2 more hp with it on. That being said the Hp 500 arrester was a loss of 6 Hp to not having one at all. The K&N arester was only a loss of 1 hp.

Just my $0.02

I need one so my carb will clear the intake, not looking for bolt on hp but that would be nice too. the dual plane has a divider in the intake and with a open spacer can the fuel not go to the right side as good as if it doesnt have a spacer. I would think that a 4 hole would be just like the carb being bolted with out the spacer but allow more velocity. Im just tring to see which will work best and not lose hp!!

I asked a similar question a while ago and it led me to similar conclusions. I was told in general terms, the 4 hole works best with single plane manifolds and the open works best with dual plane. It has to do with individual port mixture velocities from the carb to create a semi scavenger effect or something.
Now though, I run a 2" HVH Super Sucker like Getrdunn does. It helps I think, but it also puts the carb up above the risers for ease of tuning! I tried a 4 hole briefly but couldn't seem to get the plugs to run even (so they come out the same colour), that's about as technical as my thought process got!

End result? I'd go a 1" open phenolic for the reasons Eddie said and if you can feel any difference, maybe try a 2" in future?

Good Luck!

Are there any better brands out there than others when it comes to the phenolic ones? I havent looked yet but i'm sure there are a million to chose from.....

The hvh that I used for a shop floor run was ice cold while the engine was running. That's really funny how everyone has so different results on the dyno with those things. I understand your use though.

This is also interesting. I was talking to Brian here on the board the other day. He has a shop over on the east side of the state and also has a dyno. It sounds like he does a lot of extensive testing for his inhouse projects. He did some test with flame arrestors also. I found his recent test extremely interesting. This is a true example of how every application can vary so much. It only makes sense. I hope he doesn't mind me sharing what he kindly educated me over the phone with. I beleive this test was with a modified 572. My numbers may not be exact however I recall as follows.

*741 hp with Gafrig 5x10 flame arrestor.

*746 hp without flame arrestor.

*752 hp with "modified" Gafrig flame arrestor (pulled out 13' of internal mesh).

*30 hp loss with k & N flame arrestor 6x12.

NOTE: Not sure of the spacer HP gain however the 1" was the best.

This makes your brain hurt a little. LOL...

GRD, do you happen to have any knowledge as to why the K&N lost so much Hp?

Not at all. I even questioned his comment regarding such. It seems rediculous doesn't it. It has to be the design or the element material used. I take you find this interesting also. To be honest all the years of boating and building boat engines I really never gave the flame arrestors much of a thought and always used a minimum of 8x3 gafrig. Then again most of the engines I have built were all under 675 HP. My dyno session in a couple of weeks I will be doing some various testing myself and will post the numbers.

I am going into this assuming/hoping, I will be close to 600 hp with a nice torque curve on my 496's. Regardless I plan to use three different flame arrestors. The builds consist of 496 CI, 9.8 to 1 comp., Dart Pro 1's, 310cc, 225/188 (very little chamber work), Dart intake, Comp custom grind 244-248 / 647-637 / 111 lobe sep.

VARIOUS TEST:

-gafrig 8x3
-gafrig 10x5
-gafrig 10x5 modified

- 1" hvh super sucker
- 2" hvh super sucker
- without super sucker

- Barry Grant 850 downleg
- Holley hp 950

NOTE: Anyone interest in results and can lend me a 1" hvh super sucker for the test would be appreciated.

John

mine was cold to :drink:its aluminum. i put my hand on it when it was runnig it was like a ice cube .they do give you hp he did it with out and try 5differne ones ! fred told me he try all kinds of spacers till he gets the best hp and a/f . now i have k/n air cleaner . . we didnt use that when we dyno it . i will post who make the best air cleaner ???? thanks for info

That will be a good thread and informative for a bunch of us. Probably will have a lot to do with the amout of HP. What do you have for power?

getrdunn is close with the #'s he posted. I did 5 back to back pulls with Gaffrig 10X5 Dominator flame arrestor. The Gaffrig flame arrestor has 13 feet of fine mesh screen in it, the 1/2 means 6 1/2 feet removed. This test was to see if we were going to lose speed with the flame arrestor and as you can see even if we leave them as sent from Gaffrig on this build we would not lose any, the TQ #'s are to close to make a difference.

1st pull no flame arrestor 746 HP 709 TQ
2nd pull full flame arrestor 743 HP 709 TQ
3rd pull 1/2 flame arrestor 749 HP 711 TQ
4th pull no flame arrestor 746 HP 710 TQ
5th pull 1/2 flame arrestor 751 HP 710 TQ

The K&N test was done on 516 CUI engines we did awhile back but may not of been a real fair test because they were done with a custom lower base that the customer had made but did use K&N 11 X 5 marine filter. The engines made 630 HP and with the K&N filter lost almost 30 HP in 2 consecutive pulls. These engines actually made best power with Barron stock style 6 1/2 X 2 arrestors.

The 572's have custom Wilson single plane intakes and picked up 18 HP and 14 TQ with Wison 4 hole 1 inch spacer.

This is really good info however I know it doesn't come without an expense. I think we owe a big THANKS to Brian for this.

John

Brian,
Great informative post! Let me pick your brain, I am running 502's with approx. 560hp. With Dart single planes and 850 holleys with Gaffrig arrestors. I am going to add a spacer this year was leaning towards the 1" HVH Siuper Sucker. What gains if any can I ballpark and would you suggest another spacer. Thanks I would love to hear your opinion....I love this site it is invaluable.

Brian thanks for info . it makes me wonder about the top lid how high it should be 1in 3in 5in . does that make it flow faster? you would think running no flame arrestor it would make the most hp ? its funny how things work out

i have a 540dart 650hp ijust got it back in the boat cant wait to run her . last summer it was 622hp i put a bigger cam and match the heads and intake . i post the flame arrestor on 4 boating sites so we will see wt they have to say???

From what I get out of this it appears a modified 5x10 gafrig actually makes more power than no flame arrestor at all.

Okay great but how to we actually modify it?

There all pretty simple and straight forward. I would just be sure to get one from a reputable company like Edelbrock, Moroso, Trans Dapt, ect.

ttt

I have two 5x10's and I havn't gotten to it yet or even looked at it closely however it seems as though they are riveted or bolted together in 6 places or so. You may have to disassemble it to do it correctly however I assure you my inners are coming out one way or the other. lol... There should be two different types (coursenss) of screen. The inner most being the finest. That is what you'll want to get rid of. The cleaner the job you do the less conspicuous it will be to the CG. If you wait a day or two I'll be doing mine and will PM you.

Thanks!!