Hello everyone.
I am in need of some help, please. I am trying to put a 46-54 270cid GMC motor (according to casting numbers) back together in my sprint car. This motor has been heavily hopped up in the past and so is now far from stock.
I have a new gasket set, but the bores are larger than stock (approx 3.15/16"). The head gasket in the kit I have is too small and overhangs the bores. I am worried about hot spots and detonation with the gasket hanging into the top of the bores.
There is a part number on the old gasket (Felpro 7607), but I cannot find any leads on where I can get one from, nor what I can cross reference it with.
Please can any of you experienced guys give me some guidance on this - I am hoping to get to the beach races with the car in May.
I am in the UK, which makes it even more complicated!
Thank you
LT

What size bore is your block currently, that will help giving you the best info we can?

Bore is currently 3.15/16". The gasket I have is right on the edge of the bore and looks like it will protrude once compressed.
Is it possible that I could use a 302cid gasket instead? I don't know if they are the same.
Thanks

The 302 does have a 4" bore, so that can help. The head gasket you have is likely for and intended for the much smaller bore GMC engines like the 228 or 248.

The gasket I have is for a 270 motor.

Unless you are seeing evidence of the fire ring protruding past the bore, the gasket you have will be fine. As you asked originally, if it does go beyond the bore, it can cause problems. But the fire ring area is pretty stable and not easily squished or displaced from torquing the head bolts.

Can you recheck the gasket number. It shoud be stamped somewhere on the gasket.

It is 7607 that's all we can find. oh, and the Felpro logo

I looked in my old CarQuest book today:
270 '39-'62 #1935S
302 "52-'59 # 3013

I dug through my stash & some old gaskets. These numbers are on the gaskets. Measured with a yardstick.

I have a full 270 set Of Best Gasket for the next time. Head gasket # 595 Bore measured 3/7/8"
Victor 270 # 1653K this is from the label of a full set also that the head gasket is missing. Probably on my pickup. But the label says the Victor number replaces GM number 2135866

I also found two 302 gaskets McCord # 6340 & Victor # 3013 both measured 4 1/8"

I would order the Best Gasket because I think they are still in business and it would be fresh.You have to send ua a video of you racing!

Thanks Beater. I have been able to get hold of a 302 gasket from Marx Parts. Hopefully it will get us running again.
I will be sure to post up a video of the racing if any gets taken.

In the meantime, here is a clip from when we got the car running for the first time the other week...

I found that number in a 1991 felpro tractor and truck catalog. The version I found was 7607S under the listing of gmc 302 52-59 as a head gasket. The Head Set was listed as HS 7607S.

Whether that number has since been superseded I don�t know.

Great! I'm sure the 302 gasket is a good choice. It sounds pretty healthy. I like to see it in action!

I think the S after the number means steel and of course HS is Head Set. I've been a way from the counter too long.