It took some fabing for studs and spacers off the throttle body to clear the linkage but I was very happy with a 100.00 investment for both motors.


http://aaamarine.com/mpi-arrestor-on...flame-arrestor

They are on ebay also for 40.00.

I couldn't clean and reinstall that 1 inch tall factory arrestor again this year without trying something. Very happy I did!

Good to gain 2 mph that cheap!

Good stuff. You must be psyched you took the initiative to try.
=========================

The popular 3X9 K&N carb'd flame arrestor cost just under 3mph on a sbc single engine boat I tuned.

That's a really good gain. It says it doesn't replace the plastic models. Were your stock ones plastic?

My 2006 6.2's have Mercruiser 863416T flame arrestors which are plastic. I see Mallory makes one that replaced those but have not read any reviews where it made an improvement. Did you try any back-to-back test runs?

http://www.cpperformance.com/p-23225...r-863416t.aspx

Mine where the plastic ones. More humid this time out than last and 150 pounds more fuel. I had to make new longer studs and space the filter up to clear the linkage. No way that stock one inch tall plastic piece of crap can flow enough air to feed any motor spinning over 5000 rpm.

It was rough as hell so I couldn't even ring it out as much as I would normally do. Looking forward to next weekend.

I can't tell you how many times I thought about trying this. Glad to see it worked out. I'm gonna place my order today.

Saw you go by on Saturday. I was the one that yelled "offshore only?" with the 353. Great looking boat

Very interesting...the dyno shows my 383s are choked off for sure. I'd be curious exactly how to do this.

Thanks.... ended up being a great day saturday.

The studs that hold the throttle body down are actally two pieces. The upper cylinder unscrews from the throttle body stud. The throttle body stud is 6m and I just took a 6m union and mig welded it to a 1/4 inch threaded rod. That became the new upper stud for the air cleaners.
The other issue was the throttle linkage. If you simply tighten the air cleaner to the throttle body the linkage will hit the base. I made a one inch thick adaptor out of 4 inch diameter pvc pipe cut on a power miter saw. This spaced it up and out if the way of the linkage. It also gets the air flow straighter into the throttle body instead of that 90 degree turn. I think I will play around with spacer heights to see if I can almost turn into a velocity stack. I have more than enough height under the sunpad.