Low comp truck engine performance

[Clynchp]

Hey guys, i have been a follower here for awhile and i have reached a point where i need to consult some FE pros. I will start with the back story....i have an 70 f100 with a 390 (confirmed by measuring stroke) that has been bored 060. I tore down the top end to drill out some broken exhuast manifold bolts and figured while i was doing that i would go ahead and replace the intake with a performer RPM and install the headers that have been sitting in my garage for 6 months. Well after removing the heads it appears i have the low compression 410 pistons that are sunk in the bore approx .1 and i have D2 heads.

Here is my question/concern....will the low compression that is associated with 410 pistons cause detonation issues with the RPM intake or cause a decrease in performance from where i started with a 2v intake? I understand the with low compression ratio i will not be seeing the engines potential but before. I bolt everthing together i am just looking for reassurance that i wont be causing more problems. Also without tearing into the bottom end and replacing pistons are there any feasable options that could bring my compression up to 9:1 or 9.5:1?

[Nitekruizer]

to the site from another FE Bump owner! Having low compression shouldn't cause you any issues with detonation. Usually people will run into problems if they have high compression and run a lower grade of fuel. If you have the engine I think you have, you're probably around 8.5:1 which can run with 87 octane. While the RPM intake is probably overkill for this engine, being a four barrel intake, you'll likely notice a performance increase over the two barrel set up. The main thing is the condition of the engine and the timing, carb size and settings, etc. You picked the right forum to join. There are a lot of very knowledgeable people here who can help you build your truck.

[71PA_Highboy]

I would also suggest you go with a smaller carb. No bigger than 600 CFM.

You will have better off idle performance and it will get slightly better gas mileage.

[Jacksdad]

You could go with a thinner head gasket. It's not going to result in a huge difference, but it'll raise the compression ratio a few points in the right direction. Cometics are MLS construction and kind of spendy, but Mr Gasket does a .020 steel shim head gasket pretty cheap.