I've recently purchase a mexican marine standard rotation 260 HP, 350 CID used. It's a 1975 model with #882 heads.

I was wondering using a head # 416, or 624, will help me increase the cr? Does 416 fit 350 at all?
Can someone tell me what the CR will be? The original CR of this motor is 9.35:1 and with those 76cc 882's I think that it's only because of the TRW flat top pistons.

the 416's (58cc chamber) will bump up the CR significantly (maybe 10.5-11:1). The 624's have the same chamber size as the 882's.

The beautiful thing of a small block chevy is that most parts are interchangealble. The main difference between the 305 and the 350 is the cylinder bore. the stroke is the same. the heads should boult up. I'm not sure of the size combustion chambers on the heads you mentioned, but if they are smaller than 76cc they will give more compresion. you can tell by looking at the shape of the combustion chamber. The thing to watch out for is the 305 heads, (correct me if i'm wrong anyone) have a 1.84" intake valve and those 882 have a 1.94". unless your going to be doing some cutting you'll be cutting your fuel and air flow. Hope this helps.

Don't use the 305 heads on your boat motor. It will destroy itself with preignition and detonation.

tom

__________________
Ya cain't fix stoopid, but ya kin TAX it!

Can you explain why this preignition will happen?
I'm building up this engine for my 1970 Camaro SS.

because the compression will be so high. You will need to seriously retard the timing, or run like 110 octane.

I ran a set of these heads on a warmed over 350 with flat top pistons. They really do bump up the compression.. I had to run 93 octane or it would knock. I had ported mine and they actually flowed pretty good. Don't look to rev very high with these, but they make a bucket full of torque. Dave

Dave,

Can you give me your motor's spec.? Cam, Intake, Head casting#, carb?

You know since I've posted this subject I've got lots of different answers, I really don't know what to do.
Do you think that this engine would do for a 1970 Camaro SS?
I really need some 300-350 horses + 350-400 of torque.
Does this engine make it?

Please gimme a good advise, I'm really confused.
I need an engine which is reliable, and can be used on the street.
What I'm looking for as and HP engine, is the one which has a good throttle response, and I really need a good 0-60 time.
I need Acceleration.

I wait for your comments.

Tks. Houman

My initial answer was based on the fact that I thought you were running that engine in a boat.

You can run 305 heads on a 350. However, breathing will always be poor compared to using 350 heads due to chamber overhang and valve shrouding.

Federal Mogul and Silvolite both make pistons to work with 305 heads by using a dish to lessen compression.

I built a 350 with 305 heads for a guy. It had 9-1 compression (Federal Mogul pistons), used a torque cam (same grind as the Edelbrock performer). The heads were pocket ported (1.84/1.50 valves) and the rotating assembley was balanced. The engine is a strong runner, but it doesn't see the other side of 5200 rpms.

tom

__________________
Ya cain't fix stoopid, but ya kin TAX it!

Tom,

Thanks for the advise. Actually, everyone is telling me that I will not be reving more that 5000, with such an engine.
But I'm wondering if do I really need a high rpm at all or not?

The engine which you built, did you dyno it? Do you know what the horse power and the torque was?

Do you think that with under 5000 rpm, I'll have problem? Or lets say I will not reach top speed?

With such an engine, at what rpm do you think that I'll get my max performance ( HP & torque)?

I appreciate your assitance.

Take care.
Houman

I think machine shop Tom said it right. This motor isn't going to breath properly with those 305 heads, especially if your keeping the same intake/carb combo. This motor is better of with the stock heads. If you have the cash you can give them a shave to give some more compresion.

I don't think these heads will do what you want them to do on a hot street motor. I had mine in a work truck that I had to pull a trailer. I had a gm aluminum intake 442 lift 272 dur. cam 1.6 rollers, flat tops, 600 edelbrock, HEI ign. headers, flowmasters,2.5 inch duals. 350th with shift kit. It would do 45 in first and spin both tires when it shifted. and sounded real nasty at the stop light. The motor in my S-10 has chevy bowtie heads and I'm very happy with them. I just saw a set of vortek heads on Ebay sell for $340. If I were you I think I would look for something like that. Good Luck Dave