Will this combo work on pump gas?

[travis]

5A733143-2BAE-482E-882A-ACA41C11DC1C.jpeg

9.7 compression with these iron heads pictured above, .046” quench, and something around 270@.006” on a 106 lsa, small dual plane, etc. In a 4400 pound truck with 3.55 gears and 2200-2400 rpm converter.

Is the open chamber and lack of much in the way of quench pad area going to be doable on pump gas?

[Walter R. Malik]

5A733143-2BAE-482E-882A-ACA41C11DC1C.jpeg



9.7 compression with these iron heads pictured above, .046” quench, and something around 270@.006” on a 106 lsa, small dual plane, etc. In a 4400 pound truck with 3.55 gears and 2200-2400 rpm converter.

Is the open chamber and lack of much in the way of quench pad area going to be doable on pump gas?

I would make the guess you would need to keep the water temp below 140.

[1980RS]

If it were me I would open that chamber close to the gasket opening and lower it a touch more and make a little bit more power. It should work on pump gas IMO.

[travis]

5A733143-2BAE-482E-882A-ACA41C11DC1C.jpeg



9.7 compression with these iron heads pictured above, .046” quench, and something around 270@.006” on a 106 lsa, small dual plane, etc. In a 4400 pound truck with 3.55 gears and 2200-2400 rpm converter.

Is the open chamber and lack of much in the way of quench pad area going to be doable on pump gas?

I would make the guess you would need to keep the water temp below 140.

Unfortunately 140* isn’t realistic for the application...it’s primary use is towing a 16’ bass boat and the occasional Home Depot run. The owner also wanted a bit of a thump at idle. This combo was from a bunch of leftovers from other projects...we aren’t locked into the pistons we have on hand

[travis]

If it were me I would open that chamber close to the gasket opening and lower it a touch more and make a little bit more power. It should work on pump gas IMO.

Just kind of bevel it in there, or really open it up?

[BOOT]

I'd maybe soften the exh valve side of the deck some. What do the pistons look like, is there enough material to kinda reverse dome D-dish. What do the valves look like, are they dish or flat?

5A733143-2BAE-482E-882A-ACA41C11DC1C.jpeg

[travis]

I'd maybe soften the exh valve side of the deck some. What do the pistons look like, is there enough material to kinda reverse dome D-dish. What do the valves look like, are they dish or flat?

5A733143-2BAE-482E-882A-ACA41C11DC1C.jpeg

Pistons are a 2 VR flat top (KB151), valves are flat as well

[F-BIRD'88]

Buy better gas.. "Thump" costs money.

[F-BIRD'88]

A potential candidate for a DIY windshield washer pump water/methanol injection system. Spray down in the carb.
Throttle position switch trigger. Keep it simple..

[Walter R. Malik]

5A733143-2BAE-482E-882A-ACA41C11DC1C.jpeg



9.7 compression with these iron heads pictured above, .046” quench, and something around 270@.006” on a 106 lsa, small dual plane, etc. In a 4400 pound truck with 3.55 gears and 2200-2400 rpm converter.

Is the open chamber and lack of much in the way of quench pad area going to be doable on pump gas?

I would make the guess you would need to keep the water temp below 140.

Unfortunately 140* isn’t realistic for the application...it’s primary use is towing a 16’ bass boat and the occasional Home Depot run. The owner also wanted a bit of a thump at idle. This combo was from a bunch of leftovers from other projects...we aren’t locked into the pistons we have on hand

For how it is going to be used, NEEDING premium gas is counterproductive.
Get the compression down to about 9/1 for that small of a camshaft.

[n2omike]

You said a 106 LSA for a street truck. The tight LSA will kill fuel mileage and increase its tendency to detonate.
I'd go to a 110 LSA and a dished piston if he doesn't want to live a life of using premium fuel and octane boosters.

[mt-engines]

I would make the guess you would need to keep the water temp below 140.

Unfortunately 140* isn’t realistic for the application...it’s primary use is towing a 16’ bass boat and the occasional Home Depot run. The owner also wanted a bit of a thump at idle. This combo was from a bunch of leftovers from other projects...we aren’t locked into the pistons we have on hand

For how it is going to be used, NEEDING premium gas is counterproductive.
Get the compression down to about 9/1 for that small of a camshaft.

Did he ever mention his elevation?

[BOOT]

Pistons are a 2 VR flat top (KB151), valves are flat as well

Well then you have options. Is it balanced? Look at the back of your pistons to see if they have the material before you cut. Figure out the cc you need to remove and estimate the material from deck & piston or if you'd need valves. Maybe you'd rather save those pistons and just buy some others.

GL let us know what you end up doing.

[travis]

Elevation is around 700’ (NE Oklahoma). He always uses 91 octane pump gas in all his vehicles whether they need it or not (he’s one of those guys).

The engine is balanced. However, off the top of my head I think the FM H336P pistons are very close in weight and they are 12cc which would drop the compression to 9.0.

Would something like a Lunati 262 Voodoo (219/227@.050, 112 lsa) work with the existing pistons? He’d loose most of the idle thump and midrange punch, but maybe it would work better overall?

[n2omike]

Elevation is around 700’ (NE Oklahoma). He always uses 91 octane pump gas in all his vehicles whether they need it or not (he’s one of those guys).

The engine is balanced. However, off the top of my head I think the FM H336P pistons are very close in weight and they are 12cc which would drop the compression to 9.0.

Would something like a Lunati 262 Voodoo (219/227@.050, 112 lsa) work with the existing pistons? He’d loose most of the idle thump and midrange punch, but maybe it would work better overall?

Good moves. 110 LSA is a good compromise with cams in that application. If you custom order it, they could probably grind it on that LSA. Either that, or get hold of Mike Jones and see when he might be able to have you a suitable grind.