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Search: Posts Made By: Tartilla
Showing results 1 to 25 of 500
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Forum: General Q & A
Yesterday, 08:53 PM
Replies: 30
Views: 1,020
Posted By Tartilla

On the looser side of the Merc Spec...a little...

On the looser side of the Merc Spec...a little more than the middle of what they suggest.

The point was to indicate that Merc would pass a 0.001" exh guide clearance if everything else checked...
Forum: General Q & A
Yesterday, 08:47 PM
Replies: 5
Views: 253
Posted By Tartilla

Did you ever check hot lash clearance? Interested...

Did you ever check hot lash clearance? Interested in what it changed to.
Forum: General Q & A
Yesterday, 08:42 PM
Replies: 25
Views: 852
Posted By Tartilla

Yeah the 496 went off the path. GM was...

Yeah the 496 went off the path.

GM was geared up to make a med duty gas engine for their trucks in 2019. Covid ended up killing the plans. Was going to be a true BBC LS style design.

Now that...
Forum: General Q & A
Yesterday, 08:38 PM
Replies: 25
Views: 852
Posted By Tartilla

They need cylinder pressure to seal up correctly.

They need cylinder pressure to seal up correctly.
Forum: General Q & A
Yesterday, 08:27 PM
Replies: 4
Views: 126
Posted By Tartilla

Have you checked for spark? Pull a plug wire and...

Have you checked for spark? Pull a plug wire and see if you're getting any spark. Plenty of methods that won't short out your coil...or light you up!

Unless you get a direction of problem, you're...
Forum: General Q & A
05-24-2026, 04:13 PM
Replies: 5
Views: 253
Posted By Tartilla

Have you got aluminum heads? You have to...

Have you got aluminum heads?

You have to account for the hot engine dimensions. Going solid on a hyd cam can have mixed results depening on hyd roller lobe design.

Lash ramps on solid cams are...
Forum: General Q & A
05-21-2026, 02:13 PM
Replies: 30
Views: 1,020
Posted By Tartilla

22° ign advace is really going to heat up your...

22° ign advace is really going to heat up your exhaust valves.

You don't develop as much total cyl pressure by burning later..less pressure means even slower burn time. Peak pressure is way past...
Forum: Do It Yourself, Boating on a Budget
05-20-2026, 07:53 PM
Replies: 4
Views: 274
Posted By Tartilla

What are your HP goals? WOT rpm goal? 454...

What are your HP goals? WOT rpm goal?

454 rebuild...forged bottom end? What heads?

Very hard to suggest a cam without knowing these details. Exh manifolds will react differently for reversion,...
Forum: General Q & A
05-20-2026, 01:27 AM
Replies: 30
Views: 1,020
Posted By Tartilla

What int/exh seals do you have? What is your all...

What int/exh seals do you have? What is your all in ign timing adv? Late timing really heats up the exh valves.

What is the exh seat contact width? If they're not wide enough..the stem ends up...
Forum: General Q & A
05-18-2026, 09:05 PM
Replies: 9
Views: 458
Posted By Tartilla

You could trim the gaesket in the upper corners,...

You could trim the gaesket in the upper corners, but otherwise you're GTG.

Having the exh port a little smaller helps out with airflow reversion on overlap.
Forum: General Q & A
05-18-2026, 12:25 AM
Replies: 8
Views: 578
Posted By Tartilla

The Gen VI BBC heads (279 casting) are very fast...

The Gen VI BBC heads (279 casting) are very fast burning chambers.

29° max adv is all that is required to put the peak cyl pressure at 15° ATDC.

That being said...the optimal peak timing curve...
Forum: Prop Talk
05-17-2026, 12:22 AM
Replies: 9
Views: 364
Posted By Tartilla

Porpoising is caused from high bow lift, boat...

Porpoising is caused from high bow lift, boat attitude change, then stalling of the lift. Very similar to aircraft.

Hull rocker is going to add to the bow lift.

CG is a dynamic balance that...
Forum: General Q & A
05-15-2026, 10:51 PM
Replies: 11
Views: 544
Posted By Tartilla

Water pressure in salt water at 2ft depth is 0.89...

Water pressure in salt water at 2ft depth is 0.89 psi.

The exhaust system will flow at idle with npt much more than that..or whatever your discharge depth is.

As mentioned above...your raw...
Forum: General Q & A
05-14-2026, 05:50 PM
Replies: 2
Views: 297
Posted By Tartilla

A drive that lives in salt water in a marina with...

A drive that lives in salt water in a marina with stray power...vs a trailered machine in the salt and washed/run with fresh water after every exposure.

Sand and feather the chipped areas. Reprime...
Forum: Formula
05-11-2026, 10:00 PM
Replies: 0
Views: 101
Posted By Tartilla

233 Prop Depth?

Just measured my 233 TRS propshaft depth at 9.25".

(Center prop shaft to bottom of keel...single drive)

Essentially a 15.5 X-Dimension with a TRS.

The lower anti-cav plate is in line with...
Forum: General Q & A
05-11-2026, 07:24 PM
Replies: 11
Views: 792
Posted By Tartilla

It's a factor of overlap. Duration and LSA. Also...

It's a factor of overlap. Duration and LSA. Also a factor of exhaust tubing dia...as well as intake port velocity.

Arcticfriends has the answer...mufflers.

Just a factor here, generally, you...
Forum: Prop Talk
05-08-2026, 01:55 PM
Replies: 27
Views: 1,336
Posted By Tartilla

Is the hook the whole width of the transom...or...

Is the hook the whole width of the transom...or just the outer edges?
Forum: General Q & A
05-08-2026, 02:15 AM
Replies: 9
Views: 498
Posted By Tartilla

I ran a 355 with RHS Iron Vortec heads @ 10:1. It...

I ran a 355 with RHS Iron Vortec heads @ 10:1. It had a quench of 0.039". Total timing in was 30°. Ran great, no detonation issues, but I used a small factory marine FT cam. 202° Int..something like...
Forum: Do It Yourself, Boating on a Budget
05-06-2026, 08:56 PM
Replies: 24
Views: 1,273
Posted By Tartilla

Interested in the Eddie Young Timing Chain got...

Interested in the Eddie Young Timing Chain got Gen VI.

Having a hard time sourcing a good balancer for larger Gen VI front seal/hub.
Forum: General Q & A
05-06-2026, 04:57 PM
Replies: 15
Views: 741
Posted By Tartilla

I've seen the 'outlet' side vent system with...

I've seen the 'outlet' side vent system with multiple hose connections. Often 2 of them have dedicated air fans..and one hose was open, so it would flow air unobstructed from the other inlet side.
...
Forum: Do It Yourself, Boating on a Budget
05-06-2026, 04:47 PM
Replies: 18
Views: 861
Posted By Tartilla

Getting a set of old iron heads reworked is...

Getting a set of old iron heads reworked is expensive these days. Guides, seat work, valve job, mild porting etc...adds up.

Bare Alum quality castings can be very economical when viewed from that...
Forum: Do It Yourself, Boating on a Budget
05-06-2026, 04:38 PM
Replies: 18
Views: 861
Posted By Tartilla

Agreed... 0.400 is the best litmus test of overal...

Agreed... 0.400 is the best litmus test of overal port performance. Higher lifts that flow well need a good 0.400 to get it going.

PP heads are the ultimate sleepers. When you thonk about...
Forum: Do It Yourself, Boating on a Budget
05-05-2026, 10:34 AM
Replies: 18
Views: 861
Posted By Tartilla

The 781 and 049 heads are grear performers for...

The 781 and 049 heads are grear performers for sure.

290 alum heads with 2.250" valves are way too big for most marine perf engines...but they flow well to male up for it. Some epoxy on the port...
Forum: General Q & A
05-04-2026, 10:55 PM
Replies: 15
Views: 741
Posted By Tartilla

Generally, the system can be setup so it has an...

Generally, the system can be setup so it has an inlet side and an outlet side. So it flows as you move through the air, purging uoir bilge air.

You want your fan pumped air to be drawn from the...
Forum: Do It Yourself, Boating on a Budget
05-04-2026, 06:29 PM
Replies: 18
Views: 861
Posted By Tartilla

One of the biggest issues with 088 heads is the...

One of the biggest issues with 088 heads is the exhaust port. It doesn't flow very well at all. The L29 1.720" exh port with a little porting help...puts the int/exh flow coeficient at close to 78%....
Showing results 1 to 25 of 500
 
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