If the bolts are stainless replace them with 8 point header bolts made by arp and see if they break, stainless bolts dont take vibration well Good advice here. We tried SS on our racecars and didn't have much luck. ARP bolts and checking them often fixed all the issues. Drilling them and safety wir...

line boring doesn't change the distance ofk just adds more bearing material sounds l;ike so true does it have any harmonic vibrations Line boring actually does slightly raise the crank in the block. They sell timing chains engineered just for this reason. http://www.summitracing.com/parts/clo-9-310...

http://www.robbmcperformance.com/products/dowels.html

Other people make them also. But you can adjust the height on gearbox. What brand box?

If we could all be so fortunate! That's living.

There is no replacement for displacement! Need some bore and stroke in that girl.

Sounds like a cracked pickup.

Just an FYI. I have a lots of experience with those Eagle rods. They are decent piece for the money. The rod bolt are very durable but need to be stretched multiple times before final assembly torquing and must use the ARP lube. We are mandated by rules to use our Circle track engines and have turne...

Comp cams are on there game.

I have a very similar setup to yours and asked the same questions when I built it. I was referred to Alan @ s&s performance carburater which provided good results. I went from not being able to break free on dry with and eldabrock to running wherever I wanted with a 670 cfm holly. Not sure what...

Is there a ground strap from rigging to engine and one from battery to rigging? Sounds like a lack of grounding to me.

Post a pic or link to part and that will help clarify. But most likely if boat runs cool now and you add a different expansion tank,as long as system can burp air out you will be ok.

Just my opinion but I thought about it during my build and instead of 4 hose clamps you will now have 8 to worry about. It would probably never happen but chances are increased slightly. Food for thought that's all. http://www.summitracing.com/parts/sme-240175 Never worry about a hose clamp again.

Had a 383 making in low 400's for power. 2.68 box and 3 (R) blades set at almost 3 mark turning 5600. Had a really good working 600 cfm holley that was tuned and jetted properly. Installed a 750cfm Holley and picked up 200 RPM's at WOT. Calculator says it only takes like 570cfm but the built in prop...

They are decent boxes. A little loud off idle so don't be scared after you first run it. Guy that builds them is out of Oviedo. He can prob check it out. At 76" long max a 3 blade R would prob be fine if it makes over 300hp. I had one with a 2 blade @ 79" and about 290hp. Worked good.

What prop? How many blades? What length?

What is max diameter prop you can run? I would stay with a narrow blade prop. Less torque roll on that short boat. Depending on length you can run a 5 or 6 blade Saber/Razor would run good.

Calk the guys at Alumitech. Great headers at a fair price.

ptr34 wrote:I have a used 2.5 ballistic box for u. 2900

That's a deal and a good combo for your 400. Lots of torque there most likely.

Looks like a blast to me.

BTW you spelled sense wrong on the opening statement.

Who's gonna weld it? What process will be used? I would recommend DOM tubing as your first choice and conduit as a second. Both are easy to work with (cut/bend) and much easier to weld. Stainless is a great material but is harder to cut,work and drill. Also takes much more skill and more specific we...

Tony and Mark are complete morons. Don't listen to any advise they are offering you. They have years of actual airboating experience and first hand knowledge of boats with and without poly and various different colors and kinds. They are just being jerks and offering you bad advise. Please don't lis...

SWAMPHUNTER45 wrote:Need to name that sled "Insanity"

I was thinking "Delusional"!

Post some close up pics of heads and intake. Someone here will have used them. 32* is a good starting point. It is safe and the engine will run well. All depends on cylinder head design. Older conventional combustion chambers generally like up to 36* of timing to run optimally while newer fast burn ...

K.I.S.S. Have you tried setting the timing to 34* or 36* and doing a SHORT Wot test to see if it gains the lost RPM's?

More ratio and more prop. Slow tip speed and lots of pitch is the key to quieting the that part of the equation. 2.68 and some NGR's set at about 5200 WOT would be quiet. Then some large automotive mufflers, non flowmaster style. You want something that is actually designed to really quiet the engin...